Advanced Epitaxial Semiconductor Technology, University of Manchester

Advanced Epitaxial Semiconductor Technology, University of Manchester

Nanobioelectronics/Electron Devices/Scanning Hall Probe Microscopy/Medical Diagnostics

Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Electronic devices and equipment

Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Electric/electronic material engineering

Natural sciences, Semiconductors, optical and atomic physics

Life sciences, Medical systems

Oct. 2015
電気通信大学

01 Apr. 2015
University of Electro-Communications (UEC)

01 Apr. 2010 - 31 Mar. 2015
Electronics-Inspired Interdisciplinary Research Institute (EIIRIS)

01 Aug. 2002 - 31 Mar. 2010
Tokyo Institute of Technology

01 Apr. 1995 - 31 Jul. 2002
Tokai University

01 Jul. 1986 - 31 Mar. 1995
Fujitsu Laboratories Ltd, Atsugi, Japan

01 Aug. 1992 - 31 Aug. 1993
Cavendish Laboratory, Cambridge University, Visiting Scholar

30 Jun. 1986
University of Manchester, School of Electrical and Electronic Engineering, United Kingdom

30 Jun. 1982
University of Leeds, Department of Physics

01 Apr. 2021
応用物理学会本部委員会 会員サービス員会, 応用物理学会

03 Jun. 2020
審査委員会 委員, 朝日新聞 高校生科学技術チャレンジ（JSEC）, 継続

01 Apr. 2020
応用物理学会本部委員会 会員サービス員会, 応用物理学会

03 Jun. 2019
審査委員会 委員, 朝日新聞 高校生科学技術チャレンジ（JSEC）, 継続

01 Apr. 2015 - 31 Mar. 2016
会員サービス委員会, 応用物理学会

01 Apr. 2015 - 31 Mar. 2016
総務（全般）会議, 応用物理学会

01 Apr. 2014 - 31 Mar. 2016
理事, 応用物理学会

01 Apr. 2015
代議員推薦委員会, 応用物理学会

01 Apr. 2014
JSAP International Member’s Chapter(JIMeC)

May 2013
一般社団法人 粉体粉末冶金協会
JAPAN
ICF 11 New Product & Novel Technology Award, 高村司;Adarsh Sandhu
Japan

Mar. 2013
公益社団法人応用物理学会 有機分子 バイオエレクトロニクス分科会
JAPAN
M&BE7 Outstanding Student Poster Awards, 岡本吉晃;サンドゥー アダルシュ;手老 龍吾;岩佐精二
Japan

Sep. 2012
日本微生物生態学会
JAPAN
外国人審査員ポスター賞, 後藤裕子;長尾祐二;平石明;サンドゥー アダルシュ;吉田奈央子
Japan

Apr. 2001
学校法人東海大学
巽良知研究奨励賞
学校法人東海大学松前重義記念基金, 巽良知研究奨励賞（２００１年度）

Smartphone-based On-chip Homogenous Sensing by Analysis of Dynamics of Oscillating Polystyrene Particles under Dielectrophoretic Forces
Jaiyam Sharma; Taisuke Ono; Naohito Satake; Adarsh Sandhu
Sensors and Materials, MYU, SCIENTIFIC PUBLISHING DIVISION, 34, 6, 2104-2104, 04 Jun. 2022, Peer-reviwed, Invited
Scientific journal, English

Solvatochromic peptidic binder obtained via extended phage display acts as a fuororeporter for fragment‑based drug discovery (FBDD)
Riku Katsuki; Tsubasa Numayama; Yudai Tabuchi; Jaiyam Sharma; Naohito Satake; Adarsh Sandhu; Masumi Taki
Analytical and Bioanalytical Chemistry, COMMUNICATION, Springer-Verlag GmbH Germany, part of Springer Nature 2022, 414, 17, 4803-4807, 04 Jun. 2022, Peer-reviwed, Invited
Scientific journal, English

Global snapshot of the effects of the COVID-19 pandemic on the research activities of materials scientists between Spring and Autumn 2020
Adarsh Sandhu,Roland Hany; Atsufumi Hirohata; Shunichi Hishita; Ken Kimlicka; Masanobu Naito; Chikashi Nishimura
Science and Technology of Advanced Materials, Taylor and Francis, 25 Feb. 2021, Peer-reviwed, Invited
Scientific journal, English

Smartphone enabled medical diagnostics by optically tracking electromagnetically induced harmonic oscillations of magnetic particles suspended in analytes
Jaiyam Sharma; Taisuke Ono; Adarsh Sandhu
Sensing and Bio-Sensing Research, Elsevier B.V., 24 Apr. 2020, Peer-reviwed, Invited
Scientific journal, English

Micro-Hall Sensors Based on Two-Dimensional Molybdenum Diselenide
A Abderrahmane; JM Oh; NH Kim; PJ Ko; A Sandhu
Journal of nanoscience and nanotechnology, 19, 7, 4330-4332, 01 Jul. 2019, Peer-reviwed
Scientific journal, English

Smartphone based platform for real-time sharing of medical diagnostics information by optical detection of functionalized fluorescent magnetic nanoparticles
J Sharma; T Ono; R Yukino; H Miyashita; N Hanyu; H Handa; A Sandhu
Biomedical Physics & Engineering Express, IOP, 5, 3, 035014-035014, 28 Mar. 2019, Peer-reviwed
Scientific journal, English

The Irago Conference 2018: A 360-degree Outlook on Critical Scientific and Technological Challenges for a Sustainable Society
Adarsh Sandhu; Jaiyam Sharma
2067, 1, 010001, 24 Jan. 2019, Peer-reviwed
International conference proceedings, English

Optoelectronic Characterizations of Two-Dimensional h-BN/MoSe2 Heterostructures Based Photodetector
Abdelkader Abderrahmane; Pil Ju Ko; Pan-Gum Jung, Kim; Nam-Hoon Kim; Adarsh Sandhu
SCIENCE OF ADVANCED MATERIALS, AMER SCIENTIFIC PUBLISHERS, 26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA, 10, 5, 627-631, 01 May 2018, Peer-reviwed, In this paper, we studied metal-oxide-semiconductor field-effect transistors (MOSFETs) based on two-dimensional materials.
Scientific journal, English

Magnetic Nanoparticle-Based Nano-Grating Guided-Mode Resonance Biosensors
Ryoji Yukino; Jaiyam Sharma; Tsukasa Takamura; Joby Joseph; Adarsh Sandhu
IEEE Transactions on Magnetics, Institute of Electrical and Electronics Engineers Inc., 54, 2, 01 Feb. 2018, Peer-reviwed, Biomolecular detection systems based on monitoring changes in the refractive indices of functionalized surfaces are promising for applications as chemical and biological sensors. Here, we describe the design and figures of merit of our refractive index-based guided-mode resonance (GR) biosensor consisting of thin film silicon nitride sub-wavelength nano-gratings. The sensitivity of our nano-grating GR sensor was experimentally determined to be 59.3 nm per refractive index unit. We describe how the wavelength for maximum intensity of diffraction (peak wavelength) of nano-gratings was affected when functionalized magnetic nanoparticles (MNPs) were attached onto GR sensor surfaces. Moreover, we demonstrate with avidin-biotin model experiments that attaching MNPs to sensor surfaces enhances the dynamic range of detection of the GR system detection. The peak wavelength value (PWV) shifted by 0.35 nm in the case of avidin with a concentration of avidin 400 nmol/L immobilized on the sensor surface. In contrast, we achieved a 1.41 nm PWV shift after adding 5% MNPs to the solution of avidin. Not only did the MNPs enhance the dynamic range of detection, but also magnetically induced interaction of avidin-biotin significantly reduced the detection time.
Scientific journal, English

Hyperthermia at the single-cell level for disseminated cancer disease with immuno-magnetic nanoparticles
Tetsuya Kagawa; Hiroyuki Kishimoto; Toshiaki Ohara; Hiroshi Tazawa; Shunsuke Kagawa; Takeshi Nagasaka; Satoshi Nohara; Ichiro Kato; Adarsh Sandhu; Hiromichi Aono; Toshiyoshi Fujiwara
American Association for Cancer Research, 77, 13, 02 Jul. 2017, Peer-reviwed
International conference proceedings, English

High-performance near-infrared photodetector based on nano-layered MoSe2
Pil Ju Ko; Abdelkader Abderrahmane; Nam–Hoon Kim; Adarsh Sandhu
Semiconductor Science and Technology, 32, 6, 1-8, 22 May 2017, Peer-reviwed
Scientific journal, English

Gate-tunable optoelectronic properties of a nano-layered GaSe photodetector
Abdelkader Abderrahmane; Pan-Gum Jung; Nam-Hoon Kim; Pil Ju Ko; Adarsh Sandhu
OPTICAL MATERIALS EXPRESS, OPTICAL SOC AMER, 7, 2, 587-592, Feb. 2017, Peer-reviwed, Recently, two-dimensional materials were widely studied as candidates for a new generation of photodetectors. In this paper, we reported on the fabrication and the optoelectronic characterizations of a p-type gallium selenide (GaSe) back-gated field effect transistor based photodetector. The phototransistor showed excellent gate control capability with an ION/IOFF value exceeding 10(3). The photoresponsivity can be easily tunable to maximum value of 1.4 AW(-1) by changing the gate voltage; however, the photodetector showed the best performance at a gate voltage of - 18V, with photoresponsivity, external quantum efficiency, and detectivity of 0.9 AW(-1), 210% and 8.08 x 1011 cmHz(0.5)W-(1), respectively. (C) 2017 Optical Society of America
Scientific journal, English

Wide wavelength range tunable one-dimensional silicon nitride nano-grating guided mode resonance filter based on azimuthal rotation
Ryoji Yukino; Pankaj K. Sahoo; Jaiyam Sharma; Tsukasa Takamura; Joby Joseph; Adarsh Sandhu
AIP ADVANCES, AMER INST PHYSICS, 7, 1, 015313-1-015313-6, Jan. 2017, Peer-reviwed, We describe wavelength tuning in a one dimensional (1D) silicon nitride nano-grating guided mode resonance (GMR) structure under conical mounting configuration of the device. When the GMR structure is rotated about the axis perpendicular to the surface of the device (azimuthal rotation) for light incident at oblique angles, the conditions for resonance are different than for conventional GMR structures under classical mounting. These resonance conditions enable tuning of the GMR peak position over a wide range of wavelengths. We experimental demonstrate tuning over a range of 375 nm between 500 nm similar to 875 nm. We present a theoretical model to explain the resonance conditions observed in our experiments and predict the peak positions with show excellent agreement with experiments. Our method for tuning wavelengths is simpler and more efficient than conventional procedures that employ variations in the design parameters of structures or conical mounting of two-dimensional (2D) GMR structures and enables a single 1D GMR device to function as a high efficiency wavelength filter over a wide range of wavelengths. We expect tunable filters based on this technique to be applicable in a wide range of fields including astronomy and biomedical imaging. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license
Scientific journal, English

Thickness dependence on the optoelectronic properties of multilayered GaSe based photodetector
Pil Ju Ko; Abdelkader Abderrahmane; Tsukasa Takamura; Nam-Hoon Kim; Adarsh Sandhu
NANOTECHNOLOGY, IOP PUBLISHING LTD, 27, 32, 325202-1-325202-6, Aug. 2016, Peer-reviwed, Two-dimensional (2D) layered materials exhibit unique optoelectronic properties at atomic thicknesses. In this paper, we fabricated metal-semiconductor-metal based photodetectors using layered gallium selenide (GaSe) with different thicknesses. The electrical and optoelectronic properties of the photodetectors were studied, and these devices showed good electrical characteristics down to GaSe flake thicknesses of 30 nm. A photograting effect was observed in the absence of a gate voltage, thereby implying a relatively high photoresponsivity. Higher values of the photoresponsivity occurred for thicker layers of GaSe with a maximum value 0.57AW(-1) and external quantum efficiency of of 132.8%, and decreased with decreasing GaSe flake thickness. The detectivity was 4.05 x 10(10) cm Hz(1/2)W(-1) at 532 nm laser wavelength, underscoring that GaSe is a promising p-type 2D material for photodetection applications in the visible spectrum.
Scientific journal, English

Fast and sensitive medical diagnostic protocol based on integrating circular current lines for magnetic washing and optical detection of fluorescent magnetic nanobeads
Jaiyam Sharma; Shunji Ishizawa; Ryoji Yukino; Tsukasa Takamura; Naohiro Hanyu; Hiroshi Yasuno; Hiroshi Handa; Adarsh Sandhu
Sensing and Bio-Sensing Research, Elsevier B.V., 9, 7-12, 01 Jul. 2016, Peer-reviwed, Magnetic nanoparticles (MNPs) are increasingly being used as 'magnetic labels' in medical diagnostics. Practical applications of MNPs necessitate reducing their non-specific interactions with sensor surfaces that result in noise in measurements. Here we describe the design and implementation of a sensing platform that incorporates circular shaped current lines that reduce non-specific binding by enabling the "magnetic washing" of loosely attached MNPs attached to the senor surface. Generating magnetic fields by passing electrical currents through the circular shaped current lines enabled the capture and collection of fluorescent MNPs that was more efficient and effective than straight current lines reported to-date. The use of fluorescent MNPs allows their optical detection rather than with widely used magnetoresistive sensors. As a result our approach is not affected by magnetic noise due to the flow of currents. Our design is expected to improve the speed, accuracy, and sensitivity of MNPs based medical diagnostics.
Scientific journal, English

High sensitivity refractive index sensor based on simple diffraction from phase grating
Pankaj K. Sahoo; Joby Joseph; Ryoji Yukino; Adarsh Sandhu
OPTICS LETTERS, OPTICAL SOC AMER, 41, 9, 2101-2104, May 2016, Peer-reviwed, We present a technique for refractive index sensing using a phase grating structure. A grating under normal incidence can be designed such that the first-order diffracted light travels at a diffraction angle of 90 degrees with respect to the zeroth order. The diffracted light, which is along the direction of periodicity, can further be diffracted from the grating and interfere with the zeroth-order light. Under this condition, the pi phase difference that arises between the two interfering beams results in a transmission dip. We can tune this dip wavelength for senor applications, based on the grating equation. This Letter presents both simulation and experimental data that show good agreement with each other. (C) 2016 Optical Society of America
Scientific journal, English

Magnetic-Particle-Sensing Based Diagnostic Protocols and Applications
Tsukasa Takamura; Pil Ju Ko; Jaiyam Sharma; Ryoji Yukino; Shunji Ishizawa; Adarsh Sandhu
SENSORS, MDPI AG, 15, 6, 12983-12998, Jun. 2015, Peer-reviwed, Magnetic particle-labeled biomaterial detection has attracted much attention in recent years for a number of reasons; easy manipulation by external magnetic fields, easy functionalization of the surface, and large surface-to-volume ratio, to name but a few. In this review, we report on our recent investigations into the detection of nano-sized magnetic particles. First, the detection by Hall magnetic sensor with lock-in amplifier and alternative magnetic field is summarized. Then, our approach to detect sub-200 nm diameter target magnetic particles via relatively large micoro-sized "columnar particles" by optical microscopy is described. Subsequently, we summarize magnetic particle detection based on optical techniques; one method is based on the scattering of the magnetically-assembled nano-sized magnetic bead chain in rotating magnetic fields and the other one is based on the reflection of magnetic target particles and porous silicon. Finally, we report recent works with reference to more familiar industrial products (such as smartphone-based medical diagnosis systems and magnetic removal of unspecific-binded nano-sized particles, or "magnetic washing").
Scientific journal, English

Laser Power Dependent Optical Properties of Mono-and Few-Layer MoS2
Pil Ju Ko; Abdelkader Abderrahmane; Tran Viet Thu; Daniel Ortega; Tsukasa Takamura; Adarsh Sandhu
Nanoscience and Nanotechnology, 15, 9, 6843-6846, Jun. 2015, Peer-reviwed
Scientific journal, English

Fluidity evaluation of cell membrane model formed on graphene oxide with single particle tracking using quantum dot
Y. Okamoto; T. Motegi; S. Iwasa; A. Sandhu; R. Tero
Jpn. J. Appl. Phys, 54, 4s, 04DL09-(6pp), Mar. 2015, Peer-reviwed
Scientific journal, English

Origin of 1/f noise in graphene produced for large-scale applications in electronics
V. Kochat; R. Tero; S. Eashwer; G. Ramalingam; A. Ghosh; A. Sandhu; S. Raghavan; A. N. Pal; A. Sahoo; H. Okada; T. Viet Thu; S. Kaushal; A. Sampathkumar
IET Circuits, Devices Syst., 9, 1, 52-58, Feb. 2015, Peer-reviwed
Scientific journal, English

On-chip magnetometer for characterization of superparamagnetic nanoparticles
Kun Woo Kim; Venu Reddy; Sri Ramulu Torati; Xing Hao Hu; Adarsh Sandhu; Cheol Gi Kim
LAB ON A CHIP, ROYAL SOC CHEMISTRY, 15, 3, 696-703, 2015, Peer-reviwed, An on-chip magnetometer was fabricated by integrating a planar Hall magnetoresistive (PHR) sensor with microfluidic channels. The measured in-plane field sensitivities of an integrated PHR sensor with NiFe/Cu/IrMn trilayer structure were extremely high at 8.5 mu V Oe(-1). The PHR signals were monitored during the oscillation of 35 pL droplets of magnetic nanoparticles, and reversed profiles for the positive and negative z-fields were measured, where magnitudes increased with the applied z-field strength. The measured PHR signals for 35 pL droplets of magnetic nanoparticles versus applied z-fields showed excellent agreement with magnetization curves measured by a vibrating sample magnetometer (VSM) of 3 mu L volume, where a PHR voltage of 1 mu V change is equivalent to 0.309 emu cc(-1) of the volume magnetization with a magnetic moment resolution of similar to 10(-10) emu.
Scientific journal, English

High Proton Radiation Tolerance of InAsSb Quantum-Well-Based micro-Hall Sensors
Abdelkader Abderrahmane; Pil Ju Ko; Hiroshi Okada; Shin-Ichiro Sato; Takeshi Ohshima; Ichiro Shibasaki; Adarsh Sandhu
IEEE ELECTRON DEVICE LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 35, 12, 1305-1307, Dec. 2014, Peer-reviwed, Tolerance of AlInSb/InAsSb/AlInSb heterostructures quantum-well-based micro-Hall sensors against proton irradiation of 380 keV and proton fluence in the range 10(11) and 10(16) (proton/cm(2)) is reported. Defects and deep levels induced by proton irradiation into the heterostructures caused decreases in the mobility of the micro-Hall sensors. Degradation of the magnetic sensitivity started at a proton fluence of 10(13) (proton/cm(2)) and continued with increasing proton fluence. The variation of the micro-Hall sensors sensitivity was minimal in low-doped AlInSb/InAsSb/AlInSb heterostructure quantum wells. These micro-Hall sensors were operable even at proton fluence of 10(16) (proton/cm(2)), which makes these devices suitable for space applications with lifetime of thousands of years in the outer space.
Scientific journal, English

Functionalization of magnetotactic bacteria for microrobotic applications
T Takamura; T Tashiro; A Arakaki; A Sandhu
EEE Transactions on Magnetics, 50, 11, 4700202-(2pp), Nov. 2014, Peer-reviwed
Scientific journal, English

Proton Irradiation Enhancement of Low-Field Negative Magnetoresistance Sensitivity of AlGaN/GaN-Based Magnetic Sensor at Cryogenic Temperature
Abdelkader Abderrahmane; Pil Ju Ko; Hiroshi Okada; Shin-Ichiro Sato; Takeshi Ohshima; Adarsh Sandhu
IEEE ELECTRON DEVICE LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 35, 11, 1130-1132, Nov. 2014, Peer-reviwed, The longitudinal and transverse magnetoresistances of AlGaN/GaN heterostructure-based micro-Hall sensors were compared with samples irradiated with protons with an energy of 380 keV and fluence of 10(14) (protons/cm(2)). Increases in the elastic and inelastic scattering were deduced from weak localization behavior in both samples. The AlGaN/GaN micro-Hall sensors showed stable magnetic sensitivity in non and irradiated samples and increased resistivity after proton irradiation yielded an enhanced magnetoresistance sensitivity in nonirradiated sensors from 160 to 417 VA(-1)T(-1). The minimum detectable magnetic field of irradiated micro-Hall sensors determined from magneto-voltage measurements at similar to 4 K was similar to the minimum detectable magnetic field in the nonirradiated sensors.
Scientific journal, English

High photosensitivity few-layered MoSe2 back-gated field-effect phototransistors
A Abderrahmane; P J Ko; T V Thu; S Ishizawa; T Takamura; A Sandhu
Nanotechnology, 25, 36, 4700202-(5pp), Sep. 2014, Peer-reviwed
Scientific journal, English

Partial recovery of the magnetoelectrical properties of AlGaN/GaN-based micro-Hall sensors irradiated with protons
A. Abderrahmane; T. Tashiro; H. Takahashi; P. J. Ko; H. Okada; S. Sato; T. Ohshima; A. Sandhu
Applied Physics Letters, 104, 1, 203508-(4pp), Jan. 2014, Peer-reviwed
Scientific journal, English

Magnetically Induced Self-Assembly of Superparamagnetic Particles for Medical Diagnostics
P. J. Ko; T. Takamura; A. Sandhu
Journal of the Japan Society of Powder and Powder Metallurgy, 61, s1, s111-s116, Jan. 2014, Peer-reviwed
Scientific journal, English

Chemical synthesis of Fe3O4-graphene oxide nanohybrids as building blocks for magnetic and conductive membranes
Tran Viet Thu; Adarsh Sandhu
Materials Science and Engineering B: Solid-State Materials for Advanced Technology, Elsevier Ltd, 189, 1, 13-20, 2014, Peer-reviwed, We have developed a facile and scalable method for synthesising superparamagnetic Fe3O4 nanocrystals (NCs) anchored on graphene oxide (GO) sheets by a co-precipitation reaction. As-synthesized Fe3O4-GO nanohybrids (NHs) were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, field-emission scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer. Fe3O4 NCs with a narrow size distribution (4.5 ± 0.6 nm) were uniformly decorated over GO surface at high density. The GO sheets act as two-dimensional substrates and surfactants for the growth and adhesion of Fe3O4 NCs. Structural changes induced in the GO due to Fe3O4 decoration were clearly observed using Raman spectroscopy. The magnetic properties of Fe3O4-GO NHs could be tuned by varying Fe3O4 content and a saturation magnetization as high as 39.2 emu g-1 was achieved. Fe3O4-GO NHs in their colloidal suspension were used as building blocks to fabricate magnetic and electrically conductive membranes by a vacuum-assisted assembly process. © 2014 Elsevier B.V. All rights reserved.
Scientific journal, English

Viral protein-coating of magnetic nanoparticles using simian virus 40 VP1
Teruya Enomoto; Masaaki Kawano; Hajime Fukuda; Wataru Sawada; Takamasa Inoue; Kok Chee Haw; Yoshinori Kita; Satoshi Sakamoto; Yuki Yamaguchi; Takeshi Imai; Mamoru Hatakeyama; Shigeyoshi Saito; Adarsh Sandhu; Masanori Matsui; Ichio Aoki; Hiroshi Handa
JOURNAL OF BIOTECHNOLOGY, ELSEVIER SCIENCE BV, 167, 1, 8-15, Aug. 2013, Peer-reviwed, Artificial beads including magnetite and fluorescence particles are useful to visualize pathologic tissue, such as cancers, from harmless types by magnetic resonance imaging (MRI) or fluorescence imaging. Desirable properties of diagnostic materials include high dispersion in body fluids, and the ability to target specific tissues. Here we report on the development of novel magnetic nanoparticles (MNPs) intended for use as diagnosis and therapy that are coated with viral capsid protein VP1-pentamers of simian virus 40, which are monodispersive in body fluid by conjugating epidermal growth factor (EGF) to VP1. Critically, the coating of MNPs with VP1 facilitated stable dispersion of the MNPs in body fluids. In addition, EGF was conjugated to VP1 coating on MNPs (VP1-MNPs). EGF-conjugated VP1-MNPs were successfully used to target EGF receptor-expressing tumor cells in vitro. Thus, using viral Capsid protein VP1 as a coating material would be useful for medical diagnosis and therapy. (C) 2013 Elsevier B.V. All rights reserved.
Scientific journal, English

Ecofriendly route for the synthesis of highly conductive graphene using extremophiles for green electronics and bioscience
Sreejith Raveendran; Neha Chauhan; Yoshikata Nakajima; Higashi Toshiaki; Shunji Kurosu; Yuji Tanizawa; Ryugo Tero; Yasuhiko Yoshida; Tatsuro Hanajiri; Toru Maekawa; Pulickel. M. Ajayan; Adarsh Sandhu; D. Sakthi Kumar
Particle and Particle Systems Characterization, 30, 7, 573-578, Jul. 2013, Peer-reviwed, Highly conductive biocompatible graphene is synthesized using ecofriendly reduction of graphene oxide (GO). Two strains of non-pathogenic extremophilic bacteria are used for reducing GO under both aerobic and anaerobic conditions. Degree of reduction and quality of bacterially reduced graphene oxide (BRGO) are monitored using UV-vis spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Structural morphology and variation in thickness are characterized using electron microscopy and atomic force microscopy, respectively. Electrical measurements by three-probe method reveal that the conductivity has increased by 104-105 fold from GO to BRGO. Biocompatibility assay using mouse fibroblast cell line shows that BRGO is non-cytotoxic and has a tendency to support as well as enhance the cell growth under laboratory conditions. Hereby, a cost effective, non-toxic bulk reduction of GO to biocompatible graphene for green electronics and bioscience application is achieved using halophilic extremophiles for the first time. Ecofriendly reduction of graphene oxide (GO) using extremophilic bacterial species yields highly conductive large-area graphene with excellent biocompatibility. The process involves two halophilic bacterial strains that reduce GO under both anaerobic and aerobic conditions. A one-step cost effective, non-toxic bulk reduction of GO for green electronics and bioscience applications is reported. © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Scientific journal, English

Effect of proton irradiation on AlGaN/GaN micro-Hall sensors
A. Abderrahmane; S. Koide; H. Okada; H. Takahashi; S. Sato; T. Ohshima; A. Sandhu
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 102, 19, May 2013, Peer-reviwed, The magnetoelectric properties of AlGaN/GaN micro-Hall effect sensors were studied after 380 keV proton irradiation. After irradiation the current-voltage measurements, stability of the magnetic sensitivity of the sensors, and the sheet electron density were degraded with a dramatic decrease of the electron mobility at high temperatures. Raman spectroscopy showed a degradation in the crystalline quality of GaN crystal, but there was no change in the strain. (C) 2013 AIP Publishing LLC.
Scientific journal, English

Supported lipid membranes on graphene oxide and reduced graphene oxide: Effect of the degree of reduction
Tero, Ryugo; Muazam-Shah; Mat-Nor B; Okamoto, Yoshiaki; Iwasa, Seiji; Sandhu, Adarsh
ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 245, 142-142, Apr. 2013, Peer-reviwed
Scientific journal, English

Optimization of Pathway Pattern Size for Programmable Biomolecule Actuation
XingHao Hu; ByungHwa Lim; IlGyo Jeong; Adarsh Sandhu; CheolGi Kim
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 49, 1, 408-413, Jan. 2013, Peer-reviwed, We generalize a method for optimization of pattern size for an programmable actuation of magnetic beads, as biomolecule carriers, by analytically formulating the governing forces in terms of bead and pattern sizes. There is a good agreement between analytically calculated and numerically obtained forces, giving a validity of the analytical actuation force for the optimization of pattern size. The maximum actuation force is given at the phase angle of pi/4 between the direction of magnetic field and the bead position, and the optimum radius of disk pattern is in the range of 2-5 times of bead radius, depending on the magnetization of the disk pattern under an external magnetic field.
Scientific journal, English

Room-temperature synthesis and enhanced catalytic performance of silver-reduced graphene oxide nanohybrids
Tran Viet Thu; Pil Ju Ko; Nguyen Huu Huy Phuc; Adarsh Sandhu
Journal of Nanoparticle Research, 15, 10, 450-451, 2013, Peer-reviwed, The synthesis of supported, ultrasmall metallic nanoparticles (NPs) is of great importance for catalytic applications. In this study, silver-reduced graphene oxide nanohybrids (Ag-rGO NHs) were prepared by reducing Ag ions and graphene oxide (GO) at room temperature using sodium borohydride (NaBH 4) and trisodium citrate. The resulting products were characterized using UV-Vis spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy. The rich chemistry of GO surface provided many sites for the nucleation of Ag ions and efficiently limited their growth. Ag NPs were uniformly grown on basal planes of rGO with a high density (~1,700 NPs μm-2) and well-defined size (3.6 ± 0.6 nm) as evidenced in SEM and HRTEM studies. The resulting Ag-rGO NHs were readily dispersed in water and exhibited enhanced catalytic activity toward the reduction of 4-nitrophenol by NaBH4 in comparison to unsupported Ag NPs. The role of rGO as an excellent support for Ag catalyst is discussed. © 2013 Springer Science+Business Media Dordrecht.
Scientific journal, English

Radical-assisted chemical doping for chemically derived graphene
Ryousuke Ishikawa; Pil Ju Ko; Masashi Bando; Yasuyoshi Kurokawa; Adarsh Sandhu; Makoto Konagai
Nanoscale Research Letters, 8, 1, 1-7, 2013, Peer-reviwed, Carrier doping of graphene is one of the most challenging issues that needs to be solved to enable its use in various applications. We developed a carrier doping method using radical-assisted conjugated organic molecules in the liquid phase and demonstrated all-wet fabrication process of doped graphene films without any vacuum process. Charge transfer interaction between graphene and dopant molecules was directly investigated by spectroscopic studies. The resistivity of the doped graphene films was drastically decreased by two orders of magnitude. The resistivity was improved by not only carrier doping but the improvement in adhesion of doped graphene flakes. First-principles calculation supported the model of our doping mechanism. © 2013 Ishikawa et al.
licensee Springer.
Scientific journal, English

Detection of Nanometer Magnetic Labels' Concentration Via the Movement of Micrometer Superparamagnetic in Application of Magnetic Field
T. Takamura; P. J. Ko; R. Ishikawa; A. Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 48, 11, 2835-2837, Nov. 2012, Peer-reviwed, Research on medical diagnostics for point of care treatment (POCT) is driven by demand for rapid, high sensitivity, and inexpensive point of care diagnosis of heart disease, infection, allergies and cancer. Demands to improve quantification and affinity necessitate magnetic labels with sizes comparable to target molecules. However, it is extremely challenging to detect small concentrations of sub-200 nm functionalized magnetic labels using magnetoresistive-based sensors. In order to overcome these limitations we have developed a simple procedure for detecting similar to 130 nm sized magnetic labels via magnetically induced capture of micrometer sized superparamagnetic beads by several 130 nm-diameter target beads immobilized on substrates. Here we demonstrate a new method to improve the quantification of our protocol that exploits magnetically induced frictional forces between micro-sized beads and target magnetic labels. By reducing the external magnetic field, the magnetically captured micro-sized beads restart to flow due to electrostatic forces and the strength of the critical external magnetic field for release depends on the number of nano-sized beads immobilized on substrate. Our protocol has the possibility for quantitative biomaterial detection.
Scientific journal, English

Robust Hall Effect Magnetic Field Sensors for Operation at High Temperatures and in Harsh Radiation Environments
Abdelkader Abderrahmane; Shota Koide; Shin-Ichiro Sato; Takeshi Ohshima; Adarsh Sandhu; Hiroshi Okada
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 48, 11, 4421-4423, Nov. 2012, Peer-reviwed, We describe the fabrication and magnetoelectric properties of robust, high sensitivity Hall effect sensors fabricated using AlGaN/GaN and AlInSb/InAsSb/AlInSb heterostructures with a two-dimensional electron gas at the heterointerface. The sensitivity of AlInSb/InAsSb/AlInSb heterostructure clearly degrades above similar to 150 degrees C. The AlGaN/GaN 2DEG Hall sensors were stable up to at least 400 degrees C and even after irradiation of 380 keV protons with a fluence of 1 x 10(14) cm(-2), where AlInSb/InAsSb/AlInSb heterostructure showed an increase in the sheet carrier density. The feasibility of applications of the AlGaN/GaN and AlInSb/InAsSb/AlInSb Hall sensor for harsh radiation environment is discussed.
Scientific journal, English

Porous Silicon Based Protocol for the Rapid and Real-Time Monitoring of Biorecognition Between Human IgG and Protein A Using Functionalized Superparamagnetic Beads
Pil Ju Ko; Ryousuke Ishikawa; Tsukasa Takamura; Honglae Sohn; Adarsh Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 48, 11, 2846-2849, Nov. 2012, Peer-reviwed, Optical interferometer biosensors based on porous silicon (PSi) are being studied for chemical and biological sensor applications. In particular, single PSi is a promising sensing platform for biomolecules and based on monitoring changes in the optical thickness (2nL) from Fabry-Perot fringes due to magnetic particle-labels covering PSi surfaces. These methods offer a fast, and one-step method for immunoassaying by combining nano-sized superparamagnetic beads (SPBs) with interferometer PSi platforms. Furthermore, SPBs covered with biomolecules have a higher reflective index than the biomolecules alone, which results in larger shifts of the optical thickness (2nL) by the penetration of SPBs inside pore walls of PSi. In this work, we immobilized protein A onto macropore PSi and used optical reflection to detect human IgG immobilized onto nano-sized SPBs by measuring changes of optical thickness (2nL). Furthermore, the optical thickness (2nL) was proportional to mass of the biomolecules, thus the Delta 2nL corresponded to the mass fraction of active IgG with SPBs inside PSi pores. Therefore, we quantified the changes of optical thickness (2nL) to enable the detection of SPBs functionalized human IgG based on protein-A modified macropore sized PSi platform.
Scientific journal, English

Biosensing Based on Magnetically Induced Self-Assembly of Particles in Magnetic Colloids
Ye Yang; Yoshitaka Morimoto; Tsukasa Takamura; Adarsh Sandhu
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, AMER SCIENTIFIC PUBLISHERS, 12, 3, 2081-2088, Mar. 2012, Peer-reviwed, Superparamagnetic beads and nonmagnetic beads of different sizes were assembled to form a "ring-structure" in a magnetorheological (MR) fluid solution by the application of external magnetic fields. For superparamagnetic beads and non-magnetic beads functionalized with probe and target molecules, respectively, the ring-structure was maintained even after removing the external magnetic field due to biomolecular bonding. Several experiments are described, including the formation process of ring-structures with and without molecular interactions, the accelerating effect of external magnetic fields, and the effect of biotin concentration on the structures of the rings. We define the small nonmagnetic particles as "petals" because the whole structure looks like a flower. The number of remnant ring petals was a function of the concentration of target molecules in the concentration range of 0.0768 ng/ml similar to 3.8419 ng/ml which makes this protocol a promising method for biosensing. Not only was the formation process rapid, but the resulting two-dimensional colloidal system also offers a simple method for reducing reagent consumption and waste generation.
Scientific journal, English

Modification and observation of quantum dots on lipid bilayers supported on graphene oxide
Okamoto Yoshiaki; Iwasa Seiji; Sandhu Adarsh; Tero Ryugo
Abstract of annual meeting of the Surface Science of Japan, The Surface Science Society of Japan, 32, 56-56, 2012, グラフェン酸化物はバイオセンシングへの応用が期待されている材料である。我々は脂質二重膜中の分子挙動を調べるためグラフェン酸化物上への脂質膜形成を行ってきた。現在は蛍光プローブとして量子ドットを用いて、グラフェン酸化物上に形成した脂質膜の性質と蛍光クエンチ機能の距離依存性を評価することを目指している。本講演ではグラフェン酸化物上に形成した脂質膜への量子ドットの修飾、および観察結果について報告する。

Porous-Silicon Photonic-Crystal Platform for the Rapid Detection of Nano-Sized Superparamagnetic Beads for Biosensing Applications
Pil Ju Ko; Ryousuke Ishikawa; Tsukasa Takamura; Yoshitaka Morimoto; Bomin Cho; Honglae Sohn; Adarsh Sandhu
NANOSCIENCE AND NANOTECHNOLOGY LETTERS, AMER SCIENTIFIC PUBLISHERS, 3, 5, 612-616, Oct. 2011, Peer-reviwed, Biosensing platforms based on functionalized submicron-sized superparamagnetic beads (SPBs) that act as magnetic labels are being extensively researched for applications involving portable, rapid, easy-to-use and highly sensitive point-of-care medical testing (POCT) equipment. Recently, in order to achieve greater sensitivity and improved quantification, there have been increasing demands for the use of SPBs with diameters of less than 300 nm. However, the detection of low densities of sub-250 nm diameter SPBs using typical magnetoresistive-based biosensors is extremely challenging due to the intrinsic noise that affects these devices, as well as the weak magnetic signals that are derived from nano-sized SPBs. Here, we demonstrate an easy, quick, and economical method for the detection of small numbers of SPBs by optically monitoring the intensity of light that is reflected back from porous silicon photonic crystals (multi-layer-PSi) in less than 60 seconds.
Scientific journal, English

Hybrid AlGaN/GaN-ZnO-Nanowire Gas Sensors
Abdeldjelil Habib Zahmani; Adarsh Sandhu
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, AMER SCIENTIFIC PUBLISHERS, 11, 5, 3938-3942, May 2011, Peer-reviwed, The potential of AlGaN/GaN heterostructures integrated with zinc oxide (ZnO) nanowires for gas sensing applications is demonstrated. Single crystal ZnO nanowires, serving as sensing probes, were selectively grown between two ohmic electrodes of AlGaN/GaN two dimensional electron gas heterostructures by thermal oxidation of sputtered zinc films in air. Electron diffraction and transmission electron microscopy showed the ZnO-nanowires to be crystalline structures oriented in the [001] direction. The fabricated structures were used to detect ethanol, acetone and methanol in a nitrogen background. The results indicate that the hybrid AlGaN/GaN-ZnO nanowires gas sensors are operable over a broad range of temperatures and could potentially be integrated with devices for wireless environmental monitoring.
Scientific journal, English

Planar Microfluidic System Based on Electrophoresis for Detection of 130-nm Magnetic Labels for Biosensing
Tsukasa Takamura; Yoshitaka Morimoto; Adarsh Sandhu
JAPANESE JOURNAL OF APPLIED PHYSICS, JAPAN SOC APPLIED PHYSICS, 50, 4, 228-233, Apr. 2011, Peer-reviwed, Superparamagnetic beads (SPBs) used as magnetic labels offer potential for the realization of high sensitivity and low cost biosensors for point of care treatment (POCT). For better biomolecular affinity and higher sensitivity, it is desirable to use sub-200-nm-diameter SPBs comparable in size to actual biomolecules. However, the detection of small concentrations of such SPBs by magnetoresistive devices is extremely challenging due to small magnetic response of SPBs. As a solution to these limitations, we describe a simple detecting procedure where the capture of micro-SPBs by immobilized nano-target SPBs due to self-assembly induced by an external magnetic field, which was monitored under an optical microscope. Here we describe biosensing system based on self-assembly of micro-SPBs by nanoSPBs targets using a system without external pumps, thereby enabling greater miniaturization and portability. (C) 2011 The Japan Society of Applied Physics
Scientific journal, English

Amplification of direct current magnetic responses of magnetic nanobeads due to induced self-assembly of magnetic microbeads
Y. Morimoto; T. Takamura; R. Ishikawa; P. J. Ko; A. Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 109, 7, 11-12, Apr. 2011, Peer-reviwed, Detection of small concentrations of sub-200-nm-sized SPBs (superparamagnetic beads with sizes similar to target molecules) used as 'magnetic labels' is critical for the development of rapid, highly sensitive, and portable point of care treatment (POCT) systems. Currently, magnetoresistive (MR) biosensors are used for the detection of large concentrations of SPBs but such an approach is not suitable for monitoring small numbers of sub-200-nm SPBs due to the intrinsic noise of these electronic devices. In order to overcome this limitation of conventional MR sensors, we have developed a simple procedure for detecting small concentrations of sub-200-nm-diameter SPBs for biosensing by exploiting magnetically induced self-assembly of micrometer-sized SPBs onto nanometer targets. Here, our approach enables the physical amplification of the signal from otherwise undetectable nano-SPB targets using Hall biosensors without using the application of ac, magnetic fields or lock-in detection, thereby enabling the production of a simple POCT protocol for a wide range of applications. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556957]
Scientific journal, English

Microstructure and optical properties of Ag-doped ZnO nanostructures prepared by a wet oxidation doping process
Ruiqun Chen; Chongwen Zou; Jiming Bian; Adarsh Sandhu; Wei Gao
NANOTECHNOLOGY, IOP PUBLISHING LTD, 22, 10, 276-280, Mar. 2011, Peer-reviwed, Silver-doped zinc oxide (Ag:ZnO) nanostructures were prepared by a facile and efficient wet oxidation method. This method included two steps: metallic Zn thin films mixed with Ag atoms were prepared by magnetron sputtering as the precursors, and then the precursors were oxidized in an O-2 atmosphere with water vapour present to form Ag:ZnO nanostructures. By controlling the oxidation conditions, pure ZnO and Ag:ZnO nanobelts/nanowires with a thickness of similar to 20 nm and length of up to several tens of microns were synthesized. Scanning electron microscopy, transmission electron microscopy, cathodoluminescence and low temperature photoluminescence (PL) measurements were adopted to characterize the microstructure and optical properties of the prepared samples. The results indicated that Ag doping during magnetron sputtering was a feasible method to tune the optical properties of ZnO nanostructures. For the Ag:ZnO nanostructures, the intensity of ultraviolet emission was increased up to three times compared with the pure ones. The detailed PL intensity variation with the increasing temperature is also discussed based on the ionization energy of acceptor in ZnO induced by Ag dopants.
Scientific journal, English

Doping graphene films via chemically mediated charge transfer
Ryousuke Ishikawa; Masashi Bando; Yoshitaka Morimoto; Adarsh Sandhu
Nanoscale Research Letters, 6, 1, X1-5, Jan. 2011, Peer-reviwed, Transparent conductive films (TCFs) are critical components of a myriad of technologies including flat panel displays, light-emitting diodes, and solar cells. Graphene-based TCFs have attracted a lot of attention because of their high electrical conductivity, transparency, and low cost. Carrier doping of graphene would potentially improve the properties of graphene-based TCFs for practical industrial applications. However, controlling the carrier type and concentration of dopants in graphene films is challenging, especially for the synthesis of p-type films. In this article, a new method for doping graphene using the conjugated organic molecule, tetracyanoquinodimethane (TCNQ), is described. Notably, TCNQ is well known as a powerful electron accepter and is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films. Small amounts of TCNQ drastically improved the resistivity without degradation of optical transparency. Our carrier doping method based on charge transfer has a huge potential for graphene-based TCFs. © 2011 Ishikawa et al.
Scientific journal, English

A two-step ligand exchange reaction generates highly water-dispersed magnetic nanoparticles for biomedical applications
Mamoru Hatakeyama; Hiroshi Kishi; Yoshinori Kita; Kensuke Imai; Kosuke Nishio; Satoki Karasawa; Yuka Masaike; Satoshi Sakamoto; Adarsh Sandhu; Akihiro Tanimoto; Tatsuya Gomi; Eiichi Kohda; Masanori Abe; Hiroshi Handa
JOURNAL OF MATERIALS CHEMISTRY, ROYAL SOC CHEMISTRY, 21, 16, 5959-5966, 2011, Peer-reviwed, The high-temperature thermolysis of fatty acid-iron complexes generates magnetic nanoparticles (MNPs) of a precisely controlled size coated with fatty acids and dispersed in oil. Because they are water-immiscible, MNPs are unsuitable for water-based biomedical applications. Ligand exchange reactions that transform oil-into water-dispersed MNPs have attracted considerable attention, but are difficult to perform. In this paper, we report the successful preparation of size-controlled and highly water-dispersed MNPs, which have 4, 8 and 20 nm diameter by a unique two-step ligand exchange reaction. As temporary ligands, we selected thiomalic acid (TMA), which possesses moderate affinity toward MNPs and is soluble in both oil and water to remove fatty acids by XANES analyses. Next we selected the citric acids as secondary ligands for TMA-exchanged MNPs to be highly dispersed in water to remove TMA from the surface of MNPs. And the resulting highly water-dispersed MNPs are expected to be available as MRI contrast agents and hyperthermia carriers.
Scientific journal, English

Synthesis and applications of magnetic nanoparticles for biorecognition and point of care medical diagnostics
Adarsh Sandhu; Hiroshi Handa; Masanori Abe
NANOTECHNOLOGY, IOP PUBLISHING LTD, 21, 44, 464-465, Nov. 2010, Peer-reviwed, Functionalized magnetic nanoparticles are important components in biorecognition and medical diagnostics. Here, we present a review of our contribution to this interdisciplinary research field. We start by describing a simple one-step process for the synthesis of highly uniform ferrite nanoparticles (d = 20-200 nm) and their functionalization with amino acids via carboxyl groups.
For real-world applications, we used admicellar polymerization to produce 200 nm diameter 'FG beads', consisting of several 40 nm diameter ferrite nanoparticles encapsulated in a co-polymer of styrene and glycidyl methacrylate for high throughput molecular screening. The highly dispersive FG beads were functionalized with an ethylene glycol diglycidyl ether spacer and used for affinity purification of methotrexate-an anti-cancer agent. We synthesized sub-100 nm diameter magnetic nanocapsules by exploiting the self-assembly of viral capsid protein pentamers, where single 8, 20, and 27 nm nanoparticles were encapsulated with VP1 pentamers for applications including MRI contrast agents. The FG beads are now commercially available for use in fully automated bio-screening systems.
We also incorporated europium complexes inside a polymer matrix to produce 140 nm diameter fluorescent-ferrite beads (FF beads), which emit at 618 nm. These FF beads were used for immunofluorescent staining for diagnosis of cancer metastases to lymph nodes during cancer resection surgery by labeling tumor cell epidermal growth factor receptor (EGFRs), and for the detection of brain natriuretic peptide (BNP)-a hormone secreted in excess amounts by the heart when stressed-to a level of 2.0 pg ml(-1).
We also describe our work on Hall biosensors made using InSb and GaAs/InGaAs/AlGaAs 2DEG heterostructures integrated with gold current strips to reduce measurement times.
Our approach for the detection of sub-200 nm magnetic bead is also described: we exploit the magnetically induced capture of micrometer sized 'probe beads' by nanometer sized 'target beads', enabling the detection of small concentrations of beads as small as 8 nm in 'pumpless' microcapillary systems.
Finally, we describe a 'label-less homogeneous' procedure referred to as 'magneto-optical transmission (MT) sensing', where the optical transmission of a solution containing rotating linear chains of magnetic nanobeads was used to detect biomolecules with pM-level sensitivity with a dynamic range of more than four orders of magnitude. Our research on the synthesis and applications of nanoparticles is particularly suitable for point of care diagnostics.
Scientific journal, English

Determination of Inter-Molecular Forces by Magneto-Optical Transmittance of Molecule-Covered Superparamagnetic Particles in Solution
Sang Yoon Park; Hiroshi Handa; Adarsh Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 46, 6, 1409-1411, Jun. 2010, Peer-reviwed, We describe a simple magneto-optical transmittance technique for determining molecular forces between avidin-biotin molecules. The effective length of rotating superparamagnetic chains (SPCs) in a solution determines the amplitude of oscillating transmittance corresponding to the formation of SPCs as described by the Mason number. We propose that the Mason number of SPCs formed via inter-molecular interaction between superparamagnetic beads covered with molecules is modified due to the action of molecular forces. The change in modified Mason number was quickly detected by the change in the amplitude of oscillating transmittance of rotating SPCs in a solution.
Scientific journal, English

Compact electromagnetically operated microfluidic system for detection of sub-200-nm magnetic labels for biosensing without external pumps
Y. Morimoto; T. Takamura; A. Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 107, 9, 169-179, May 2010, Peer-reviwed, The combination of small sample analyte volumes, high sensitivity, ease of use, high speed, and portability is an important factor for the development of protocols for point of care biodiagnosis. Currently, handling small amounts of liquids is achieved using microfluidic systems but it is challenging to satisfy the remaining factors using conventional approaches based on biosensors employing detection of fluorescent labels. Thus to resolve the other requirements, biosensing systems based on the detection of functionalized superparamagnetic beads acting as "magnetic labels" are being studied as an alternative approach. Notably, for greater quantification, there are increasing demands for the use of sub-200-nm magnetic labels, which are comparable in size to actual biomolecules. However, detection of small numbers of sub-200-nm diameter magnetic beads by magnetoresistive device-based platforms is extremely challenging due to the intrinsic noise of the electronic devices. In order to overcome the limitation, we have developed a simple procedure for detecting sub-200-nm diameter magnetic labels for biosensing via magnetically induced self-assembly of superparamagnetic beads. Applying our approach to conventional microfluidic systems satisfies the most of prerequisites; however conventional microfluidic systems attached to the external pumps are yet suitable for point of care biodiagnosis. Here we propose the development of an alternative biosensing system based on our previous work that does not require external pumps to achieve miniaturization. (c) 2010 American Institute of Physics. [doi:10.1063/1.3352584]
Scientific journal, English

Magneto-Optical Biosensing Platform Based on Light Scattering from Self-Assembled Chains of Functionalized Rotating Magnetic Beads
Sang Yoon Park; Hiroshi Handa; Adarsh Sandhu
NANO LETTERS, AMER CHEMICAL SOC, 10, 2, 446-451, Feb. 2010, Peer-reviwed, We describe a simple protocol for the rapid, highly sensitive, and quantitative measurement of the concentration of biomolecules in a solution by monitoring light scattered by self-assembled chains of functionalized superparamagnetic beads (SBs) rotating in the solution. A rotating external field (H-ex) applied to an aqueous solution containing 250 nm diameter biotinylated SBs produced linear chains of SBs rotating in phase with Hex due to magnetically induced self-assembly. At constant Hex, the addition of avidin to the solution led to the formation of longer SB-chains than without the presence of avidin. The generation of longer SB-chains was revealed by increases in the amplitude of the oscillating optical transmittance signal of the magnetic colloid solution. Monitoring changes in the amplitude of the optical transmittance of the solution enabled quantitative determination of the concentration of avidin added to the solution with a sensitivity of 100 pM (6.7 ng/mL) and a dynamic range of at least 3 orders of magnitude. The rotating chains acted as biomolecule probes and micromagnetic mixers, enabling detection of biomolecular recognition in less than 30 s. This approach offers a rapid, highly sensitive, inexpensive, and homogeneous means for detecting biorecognition processes.
Scientific journal, English

Detection of 8 nm Diameter Superparamagnetic Beads by Magnetically-Induced Manipulation of Micrometer-Sized Magnetic Beads: A Novel Protocol for Magnetically-Labeled Biosensing
Yoshitaka Morimoto; Tsukasa Takamura; Sang Yoon Park; Satoshi Sakamoto; Shintaro Kawata; Hiroshi Handa; Adarsh Sandhu
JAPANESE JOURNAL OF APPLIED PHYSICS, JAPAN SOC APPLIED PHYSICS, 49, 4, 195-195, 2010, Peer-reviwed, Biosensing platforms based on functionalized superparamagnetic beads acting as "magnetic-labels" show tremendous potential for rapid and highly-sensitive point of care medical diagnosis. Recently, for greater quantification, there are increasing demands for the use of magnetic labels with diameters of 8-150 nm, which are comparable in size to actual biomolecules. However, detection of small numbers of sub-150 nm sized magnetic beads by magnetoresistive device-based platforms is extremely challenging due to the intrinsic noise of these electronic devices. Here, we describe an easy and economical detection method of low areal densities of 8-nm-diameter superparamagnetic "target beads" immobilized over millimeter-sized substrates by optically monitoring the magnetically induced "capture" of easily visible, micrometer sized superparamagnetic "columnar beads" by the targets in less than a few tens of seconds. (C) 2010 The Japan Society of Applied Physics
Scientific journal, English

Strictly nanotubes in Beijing
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 4, 7, 396-397, Jul. 2009, Peer-reviwed
Scientific journal, English

Detection of Magnetic Nanobeads by Self-Assembly of Superparamagnetic Microbeads for Biosensing
Y. Morimoto; M. Abe; M. Hatakayama; H. Handa; A. Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 45, 6, 2871-2874, Jun. 2009, Peer-reviwed, Detection of magnetically labeled biomolecules is a promising method for fast and inexpensive medical diagnosis. Recently, there has been an increasing interest in using magnetic labels with diameters of 20-150 nm-dimensions that are similar to actual biomolecules. However, detection of small numbers of nanometer-scale magnetic beads (labels) distributed over large surface areas by magnetoresistive devices is extremely challenging due to the intrinsic noise and design limitations of giant magnetoresistance (GMR) and Hall-type of biosensors. Here, we describe proof of principle experiments on exploiting magnetically induced self-assembly of superparamagnetic beads for detecting superparamagnetic nanobeads with diameters of less than 150 nm. We successfully detected low areal densities of similar to 130 nm diameter superparamagnetic "target beads" immobilized over millimeter-sized substrates, by optically monitoring the "capture" of easily visible, micrometer-sized superparamagnetic beads by the targets. Our procedure could readily be extended for the defection of magnetically labeled biomolecules.
Scientific journal, English

High-throughput bioscreening system utilizing high-performance affinity magnetic carriers exhibiting minimal non-specific protein binding
Naohiro Hanyu; Kosuke Nishio; Mamoru Hatakeyama; Hiroshi Yasuno; Toshiyuki Tanaka; Masaru Tada; Takashi Nakagawa; Adarsh Sandhu; Masanori Abe; Hiroshi Handa
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 321, 10, 1625-1627, May 2009, Peer-reviwed, For affinity purification of drug target protein we have developed magnetic carriers, narrow in size distribution (184 +/- 79 nm), which exhibit minimal non-specific binding of unwanted proteins. The carriers were highly dispersed in aqueous solutions and highly resistant to organic solvents, which enabled immobilization of various hydrophobic chemicals as probes on the carrier surfaces. Utilizing the carriers we have automated the process of separation and purification of the target proteins that had been done by manual operation previously. (C) 2009 Elsevier B.V. All rights reserved.
Scientific journal, English

Preparation of spherical and uniform-sized ferrite nanoparticles with diameters between 50 and 150 nm for biomedical applications
Toshiyuki Tanaka; Ryuichi Shimazu; Hironori Nagai; Masaru Tada; Takashi Nakagawa; Adarsh Sandhu; Hiroshi Handa; Masanori Abe
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 321, 10, 1417-1420, May 2009, Peer-reviwed, Spherical uniform-sized iron ferrite nanoparticles were synthesized by adding a disaccharide and seed ferrite crystals into an aqueous reaction solution. The average size range 50-150nm was controlled by choosing one out of five disaccharides and by changing the amount of the seed crystals. The particles had a saturation magnetization and a crystalline structure which are similar to those of intermediate Fe(3)O(4)-gamma-Fe(2)O(3). When coated with citrate, the particles with nearly 100nm diameter were stably suspended in water for 2 days. These novel particles will be utilized as magnetic carriers in biomedical applications. (C) 2009 Elsevier B.V. All rights reserved.
Scientific journal, English

High-throughput bioscreening system utilizing high-performance affinity magnetic carriers exhibiting minimal non-specific protein binding
Naohiro Hanyu; Kosuke Nishio; Mamoru Hatakeyama; Hiroshi Yasuno; Toshiyuki Tanaka; Masaru Tada; Takashi Nakagawa; Adarsh Sandhu; Masanori Abe; Hiroshi Handa
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 321, 10, 1625-1627, May 2009, Peer-reviwed, For affinity purification of drug target protein we have developed magnetic carriers, narrow in size distribution (184 +/- 79 nm), which exhibit minimal non-specific binding of unwanted proteins. The carriers were highly dispersed in aqueous solutions and highly resistant to organic solvents, which enabled immobilization of various hydrophobic chemicals as probes on the carrier surfaces. Utilizing the carriers we have automated the process of separation and purification of the target proteins that had been done by manual operation previously. (C) 2009 Elsevier B.V. All rights reserved.
Scientific journal, English

High speed magneto-optical valve: Rapid control of the optical transmittance of aqueous solutions by magnetically induced self-assembly of superparamagnetic particle chains
S. Y. Park; H. Handa; A. Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 105, 7, 38-38, Apr. 2009, Peer-reviwed, Magneto-optical effects of magnetorheological fluids are of interest for applications including magnetic field sensors and optical modulators. Here, we describe the rapid control of the optical transmittance of a magnetorheological fluids by rotating columnar arrays of self-assembled superparamagnetic bead (SPB) chains by applying an external field using a permanent magnet. The columnar arrays of chains of magnetic beads acted as optical valves exhibiting distinct "on" and "off" states. For a given magnetic field, the maxima/minima of transmittance occurred when the applied field was parallel/perpendicular to light path and the intensity of light at the maxima varied with the strength of the applied field. Importantly, the response time for rotating the columnar arrays of magnetic chains was very rapid, and in the millisecond range. Our procedure provides a simple means for producing fast, magneto-optical switches that does not require cumbersome and power consuming electromagnetic coils and related peripheral equipment. (c) 2009 American Institute of Physics. [DOI: 10.1063/1.3072762]
Scientific journal, English

Preparation and medical application of magnetic beads conjugated with bioactive molecules
M. Abe; N. Nishio; M. Hatakeyama; N. Hanyu; T. Tanaka; M. Tada; T. Nakagawa; A. Sandhu; H. Handa
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 321, 7, 645-649, Apr. 2009, Peer-reviwed, Ferrite nanobeads were synthesized from an aqueous solution utilizing Fe(2+) to Fe(3+) oxidation for use as magnetic carriers in bioscreening, bio-molecular recognition and anti-cancer diagnosis and therapy. The beads had a crystal structure that was intermediate between Fe(3)O(4) and gamma-Fe(2)O(3). Functional biomolecules were strongly conjugated onto the surfaces of the ferrite beads via COOH and SH groups. The addition of ferrite seed crystals (3-8 nm in size) together with a disaccharide enabled the synthesis of monodisperse, spherical ferrite beads with average diameters ((d) over bar) between 50 and 150 nm and relative deviation Delta d/(d) over bar = 9-16%. Hollow ferrite nano-spheres ((d) over bar 150-450 nm, Delta d/(d) over bar approximate to 10%) were prepared using silica spheres as templates, which were dissolved in NaOH solution. Ferrite beads 40 nm in size were encapsulated in polymer spheres of styrene and polymerized glycidyl methacrylate (poly-GMA), 18479 nm in diameter. They were used for high throughput bioscreening system for affinity purification of target proteins which make specific bindings to anti-cancer drugs, porphyrins, environment hormones, etc. (C) 2008 Elsevier B. V. All rights reserved.
Scientific journal, English

High sensitivity and multifunctional micro-Hall sensors fabricated using InAlSb/InAsSb/InAlSb heterostructures
M. Bando; T. Ohashi; M. Dede; R. Akram; A. Oral; S. Y. Park; I. Shibasaki; H. Handa; A. Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 105, 7, 3569-3571, Apr. 2009, Peer-reviwed, Further diversification of Hall sensor technology requires development of materials with high electron mobility and an ultrathin conducting layer very close to the material's surface. Here, we describe the magnetoresistive properties of micro-Hall devices fabricated using InAlSb/InAsSb/InAlSb heterostructures where electrical conduction was confined to a 30 nm-InAsSb two-dimensional electron gas layer. The 300 K electron mobility and sheet carrier concentration were 36 500 cm(2) V(-1) s(-1) and 2.5 x 10(11) cm(-2), respectively. The maximum current-related sensitivity was 2 750 V A(-1) T(-1), which was about an order of magnitude greater than AlGaAs/InGaAs pseudomorphic heterostructures devices. Photolithography was used to fabricate 1 mu m x 1 mu m Hall probes, which were installed into a scanning Hall probe microscope and used to image the surface of a hard disk. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3074513]
Scientific journal, English

SCANNING TUNNELLING MICROSCOPY Probing superconductivity at the nanoscale
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 4, 3, 142-142, Mar. 2009, Peer-reviwed
Scientific journal, English

A new approach to intellectual property
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 4, 1, 7-8, Jan. 2009, Peer-reviwed
Scientific journal, English

Contact Mode Scanning Hall Probe Microscopy
Toru Ohashi; Hirotaka Osawa; Adarsh Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 44, 11, 3252-3254, Nov. 2008, Peer-reviwed, Scanning Hall probe microscopy (SHPM) is an established method for monitoring localized magnetic fields at the surfaces of ferromagnetic materials and magnetic media, as well as vortices in superconductors. Magnetic imaging measurements are usually made using Hall sensors with integrated scanning tunneling microscope tips (STM-tips). Hall probes are fixed to piezoelectric tubes and lowered to the sample surface until a tunneling current is detected, when feedback circuitry takes over to maintain the probe-sample separation and prevent damage to the device. However, Hall probes with STM-tips have limitations that include measurements requiring conducting sample surfaces and complicated electronics to monitor the tunneling current. Hall probe microscopy could be made more robust and offer improved magnetic sensitivity and spatial resolution by making measurements with the Hall probe in actual contact with sample surfaces without the use of STM tips and piezoelectric actuators. Here, we describe the development of a contact mode SRPM system (CM-SHPM), where the Hall probe was attached to a flexible cantilever and the probe-sample separation monitored using a simple strain gauge integrated onto the cantilever. The CM-SHPM offers a simple and highly reliable means of magnetic imaging of nonconducting samples over large areas and wide temperature ranges.
Scientific journal, English

Thailand resorts to nanotech
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 3, 8, 450-451, Aug. 2008, Peer-reviwed, Its economy might be dominated by agriculture and tourism, but Thailand is investing heavily in nanotechnology, although a shortage of scientists and engineers remains a problem, as Adarsh Sandhu reports.
Scientific journal, English

Sensitivity dependence of Hall biosensor arrays with the position of superparamagnetic beads on their active regions
Yoshimichi Kumagai; Yasuharu Imai; Masanori Abe; Satoshi Sakamoto; Hiroshi Handa; Adarsh Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 103, 7, Apr. 2008, Peer-reviwed, This paper describes a numerical and experimental analysis on the variation of the magnetic sensitivity of the active surface region of AlGaAs/InGaAs two dimensional electron gas Hall effect biosensors with location and number of superparamagnetic beads. Experiments were conducted using linear arrays of devices consisting of ten sensors each with an area of 5 x 5 mu m(2). The edges and corners of the Hall sensors were most sensitive and exhibited a linear response. These results are important for commercialization of high sensitivity Hall effect biosensors with a wide dynamic range. (c) 2008 American Institute of Physics.
Scientific journal, English

Sensitivity dependence of Hall biosensor arrays with the position of superparamagnetic beads on their active regions
Yoshimichi Kumagai; Yasuharu Imai; Masanori Abe; Satoshi Sakamoto; Hiroshi Handa; Adarsh Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 103, 7, 2675-2677, Apr. 2008, Peer-reviwed, This paper describes a numerical and experimental analysis on the variation of the magnetic sensitivity of the active surface region of AlGaAs/InGaAs two dimensional electron gas Hall effect biosensors with location and number of superparamagnetic beads. Experiments were conducted using linear arrays of devices consisting of ten sensors each with an area of 5 x 5 mu m(2). The edges and corners of the Hall sensors were most sensitive and exhibited a linear response. These results are important for commercialization of high sensitivity Hall effect biosensors with a wide dynamic range. (c) 2008 American Institute of Physics.
Scientific journal, English

Biosensing - New probes offer much faster results
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 2, 12, 746-748, Dec. 2007, Peer-reviwed
Scientific journal, English

Ultrafast imagination
Adarsh Sandhu
NATURE PHOTONICS, NATURE PUBLISHING GROUP, 1, 11, 638-638, Nov. 2007, Peer-reviwed
Scientific journal, English

The endoscope of the future
Adarsh Sandhu
NATURE PHOTONICS, NATURE PUBLISHING GROUP, 1, 9, 514-514, Sep. 2007, Peer-reviwed
Scientific journal, English

South Korea plays to its strengths
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 2, 8, 455-456, Aug. 2007, Peer-reviwed, Focusing on the commercialization of research results and avoiding unnecessary duplication of effort are central to South Korea's approach to nanotechnology, as Adarsh Sandhu reports.
Scientific journal, English

Quantum-dot venture unveiled
Adarsh Sandhu; Mitsuru Sugawara
NATURE PHOTONICS, NATURE PUBLISHING GROUP, 1, 7, 392-392, Jul. 2007, Peer-reviwed, Fujitsu of Japan has created a new venture company called QD Laser to bring commercial quantum-dot lasers and amplifiers to the market as rapidly as possible. Adarsh Sandhu spoke to its chief executive officer about the firm's plans.
Scientific journal, English

High temperature scanning Hall probe microscopy using AlGaN/GaN two dimensional electron gas micro-Hall probes
Zaki Primadani; Hirotaka Osawa; Adarsh Sandhu
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 101, 9, S410-S413, May 2007, Peer-reviwed, Hall sensors fabricated using conventional narrow band gap semiconductors such as InSb and GaAs are unstable above room temperature due to the onset of intrinsic conduction and physical degradation of the semiconductor materials. Gallium nitride (GaN) based wide band gap semiconductors are stable at elevated temperatures and show potential for fabrication of high temperature electronic devices. Here, we incorporated high sensitivity AlGaN/GaN two dimensional electron gas heterostructure micro-Hall probes (HPs) into a high temperature scanning Hall probe microscope and for magnetic imaging of domains in crystalline iron garnet thin films from room temperature to 100 degrees C. The active area and Hall coefficient the HPs were 2x2 mu m(2) and 0.01 Omega/G at 100 degrees C, respectively. The evolution of the size of magnetic domains with increasing temperature under external magnetic fields is described. (c) 2007 American Institute of Physics.
Scientific journal, English

High efficiency Hall effect micro-biosensor platform for detection of magnetically labeled biomolecules
Adarsh Sandhu; Yoshimichi Kumagai; Adam Lapicki; Satoshi Sakamoto; Masanori Abe; Hiroshi Handa
BIOSENSORS & BIOELECTRONICS, ELSEVIER ADVANCED TECHNOLOGY, 22, 9-10, 2115-2120, Apr. 2007, Peer-reviwed, Detection of magnetically labeled biomolecules using micro-Hall biosensors is a promising method for monitoring biomolecular recognition processes. The measurement efficiency of standard systems is limited by the time taken for magnetic beads to reach the sensing area of the Hall devices. Here, micro-current lines were integrated with Hall effect structures to manipulate the position of magnetic beads via field gradients generated by localized currents flowing in the current lines. Beads were accumulated onto the sensor surface within seconds of passing currents through the current lines. Real-time detection of magnetic beads using current lines integrated with Hall biosensors was achieved. These results are promising in establishing Hall biosensor platforms as efficient and inexpensive means of monitoring biomolecular reactions for medical applications. (c) 2006 Elsevier B.V. All rights
Scientific journal, English

Thousands gather in Japan for massive nanotechnology event
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 2, 4, 195-195, Apr. 2007, Peer-reviwed
Scientific journal, English

Variable temperature scanning Hall probe microscopy of ferromagnetic garnet thin films
Zaki Primadani; Adarsh Sandhu
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 310, 2, 2693-2695, Mar. 2007, Peer-reviwed, Variable temperature scanning Hall probe microscope system (VT-SHPM) was constructed for magnetic imaging of domains over large areas at cryogenic temperatures using InGaAs/AlGaAs heterostructure micro-Hall probes. The VT-SHPM system was used to measure the temperature dependence of magnetic domains in 50 mu m thick (BiTbHo)(3)Fe5O12 epitaxially grown garnets. The domain width increased with decreasing temperature with a rapid increase occurring at the compensation point of the garnets. Correlation of the stray magnetic field measured by the VT-SHPM and conventional magnetization measured is discussed. (c) 2006 Elsevier B.V. All rights reserved.
Scientific journal, English

Preparation of size-controlled (30-100 nm) magnetite nanoparticles for biomedical applications
K. Nishio; M. Ikeda; N. Gokon; S. Tsubouchi; H. Narimatsu; Y. Mochizuki; S. Sakamoto; A. Sandhu; M. Abe; H. Handa
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 310, 2, 2408-2410, Mar. 2007, Peer-reviwed, Size-controlled magnetite nanoparticles (MNPs) with several dozen nanometers ( nm) were synthesized for biomedical applications. Nanoparticles of single-phase magnetite, as revealed by X-ray analyses and magnetic measurements, were prepared by oxidizing ferrous hydroxide (Fe(OH)(2)) with a weak oxidant NaNO3 in an N-2-deaerated aqueous NaOH solution ( pH = 12-13) at various temperatures below 37 degrees C. As the synthesis temperature increases from 4 to 37 degrees C, the MNPs are decreased in size (d) from 102 +/- 5.6 to 31.7 +/- 4.9 nm and widened in size distribution, Delta d/d increases from 5.5% to 15%. Prepared without using any surfactant, the MNPs are advantageous for immobilizing functional molecules stably on the surfaces for biomedical applications. (c) 2006 Elsevier B.V. All rights reserved.
Scientific journal, English

Light pipe to the home
Adarsh Sandhu
NATURE PHOTONICS, NATURE PUBLISHING GROUP, 1, 3, 162-162, Mar. 2007, Peer-reviwed
Scientific journal, English

Monitoring DNA hybridization by quantification of nitrogen content using X-ray photoelectron spectroscopy
Adam Lapicki; Fumitaka Sakamoto; Adarsh Sandhu
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, INST PURE APPLIED PHYSICS, 46, 1-3, L49-L52, Jan. 2007, Peer-reviwed, X-ray photoelectron spectroscopy (XPS) was used to detect hybridization of surface-immobilized oligonucleotides for potential quantification of surface coverage and hybridization efficiency. XPS offers an alternative to DNA analysis with fluorescence radioisotope detection. The nitrogen content and the ratio of nitrogen from DNA to sulfur from alkanethiols introduced in surface immobilization was used as a proof of hybridization with statistical errors of less than 20%.
Scientific journal, English

The future of ultraviolet LEDs
Adarsh Sandhu
NATURE PHOTONICS, NATURE PUBLISHING GROUP, 1, 1, 38-38, Jan. 2007, Peer-reviwed
Scientific journal, English

The birth of nanoChina
Adarsh Sandhu
NATURE NANOTECHNOLOGY, NATURE PUBLISHING GROUP, 2, 1, 11-12, Jan. 2007, Peer-reviwed, With new research centres opening in Beijing, Shanghai and Tianjin, close links between government-funded laboratories and industry, and a plentiful supply of researchers, China is set to become a major player in nanotechnology.
Scientific journal, English

Hall biosensor with integrated current microstrips for control of magnetic beads
Yoshimichi Kumagai; Kiyoshi Togawa; Satoshi Sakamoto; Masanori Abe; Hiroshi Handa; Adarsh Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 42, 12, 3893-3895, Dec. 2006, Peer-reviwed, Magnetic labeling of biomolecules shows potential as an alternative to fluorescence for monitoring molecular interactions associated with DNA hybridization and antibody-antigen analysis. Current carrying microstrips were integrated with micro-Hall biosensors to manipulate and collect superparamagnetic beads by field gradients generated due to direct currents passed through the strips. Magnetic beads with 2.8-mu m diameters were collected over the active regions of AlGaAs/InGaAs heterostructure micro-Hall biosensors and detected in real time. The integration of current-carrying microstrips with Hall biosensors will decrease the time required for detecting biomolecular recognition processes in Hall sensor-based bioscreening platforms.
Scientific journal, English

"Ferrite route" preparation of iron nanoparticles and their encapsulation in styrene-GMA co-polymer for biomedical applications
Carlos S. Kuroda; Takuma Shimura; Masahito Maeda; Masaru Tada; Hiroshi Handa; Adarsh Sandhu; Masanori Abe
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 42, 10, 3569-3571, Oct. 2006, Peer-reviwed, The novel "ferritie route" was developed for synthesis of iron nanoparticles. Precursor Fe3O4+delta nanoparticles were synthesized by coprecipitation oxidation from aqueous solutions of xFeCl(2) +(1 - x)/FeCl3 (0 <= x <= 1), which were reduced by hydrazine at 90 degrees C. Under optimum conditions of x = 0.66, the iron nanoparticles were 15 +/- 3.7 nm in diameter and had a saturation magnetization of 110 emu/g. The nanoparticle yield was ca. 5 g/experiment, which is about ten times better than the ca. 0.4 g/experiment produced by the polyol-reduction method. Mini-emulsion copolymerization was used to encapsulate the iron nanoparticles in a copolymer of polystyrene and poly-glycidyl methacrylate that exhibits minimal nonspecific protein adsorption, thus suppressing biomolecular contamination. The polymer-coated iron, beads were 80-120 nm in diameter and had a saturation magnetization of 51 emu/g, which is a value close to the 60 emu/g obtained when the core iron nanoparticles were synthesized by our previous polyol-reduction method.
Scientific journal, English

Detection of magnetically labeled DNA using pseudomorphic AlGaAs/InGaAs/GaAs heterostructure micro-Hall biosensors
K Togawa; H Sanbonsugi; A Sandhu; M Abe; H Narimatsu; K Nishio; H Handa
JOURNAL OF APPLIED PHYSICS, AMER INST PHYSICS, 99, 8, 2386-2387, Apr. 2006, Peer-reviwed, Hall-effect biosensors with a magnetic-field sensitivity of 23 nT/(Hz)(1/2) (30x30 mu m(2), at a drive current of 400 mu A) were fabricated using pseudomorphic AlGaAs/InGaAs/GaAs heterostructures for detection of DNA labeled with magnetic beads. Magnetic beads with diameters of 120 nm were selectively immobilized onto the surfaces of the Hall biosensors using highly specific hybridization of complementary oligonucleotides and were subsequently detected by measurement of the ac magnetic susceptibility of the beads. (C) 2006 American Institute of Physics.
Scientific journal, English

High-sensitivity InSb thin-film micro-Hall sensor arrays for simultaneous multiple detection of magnetic beads for biomedical applications
K Togawa; H Sanbonsugi; A Lapicki; M Abe; H Handa; A Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 41, 10, 3661-3663, Oct. 2005, Peer-reviwed, An InSb thin-film linear micro-Hall sensor array of eight sensors, each with a sensitivity of 10 nT/Hz(1/2) was developed for biomedical applications. The individual Hall sensors had an active area of 5 mu m x 5 mu m and were separated by a distance of 5 mu m. A combination of these Hall devices and a magnetization system incorporating both dc and ac bias magnetic fields, enabled the simultaneous detection of multiple 2.8 mu m diameter superparamagnetic beads.
Scientific journal, English

Functionalization of micro-Hall effect sensors for biomedical applications utilizing superparamagnetic beads
A Lapicki; H Sanbonsugi; T Yamamura; N Matsushita; M Abe; H Narimatsu; H Handa; A Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 41, 10, 4134-4136, Oct. 2005, Peer-reviwed, Fabrication of Hall sensors that are compatible with biological environments has been accomplished in an effort to provide an analytical tool for the detection, identification and quantification of deoxyribonuclaeic acid. Sensors are formed by InSb thin films grown on (100) GaAs wafers. Amorphous silicon nitride was deposited as waterproof sensor insulation, and topped by a gold overlayer serving as an interface for the immobilization of biomolecules. The key analytical processes utilize hybridization of complementary strands of oligonucleotides as a biorecognition mechanism, closing a chain sequence leading to attachment of magnetic beads, where the thiol-gold chemical reactivity produces bonding to the sensor surface.
Scientific journal, English

Electrical and magnetic properties of La1-xBixMnO3
T Ogawa; A Sandhu; M Chiba; H Takeuchi; Y Koizumi
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 290, 933-936, Apr. 2005, Peer-reviwed, The perovskite-type crystals La1-xBixMnO3 (LBMO), which are prepared by substituting Bi atoms for some of the La atoms in the crystal LaMnO3, exhibit colossal magnetoresistance (CMR). From X-ray diffraction measurements, we found that Jahn-Teller distortion existed in the LBMO crystal structure, which formed of orthorhombic (or rhombohedral)-type structures with lattice parameter γ (= c/a) = 1.02 in the range 0< x< 0.3, pseudo-cubic ones with γ = 1.005 for 0.3 < x < 0.5, and tetragonal ones with γ = 1.014 for 0.5 < x. The CMR effect for LBMO with x = 0.2 was about 400% at 88 K. © 2004 Elsevier B.V. All rights reserved.
Scientific journal, English

High sensitivity InSb Hall effect biosensor platform for DNA detection and biomolecular recognition using functionalized magnetic nanobeads
K Togawa; H Sanbonsugi; A Sandhu; M Abe; H Narimatsu; K Nishio; H Handa
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, JAPAN SOC APPLIED PHYSICS, 44, 46-49, L1494-L1497, 2005, Peer-reviwed, A compact, high sensitivity and low cost biosensing platform based on InSb thin film micro-Hall effect biosensors [30 x 30 mu m(2); magnetic field sensitivity of 1.8 nT/(Hz)(1/2)] was developed and used for the detection of DNA molecules labeled with magnetic beads. Magnetic beads (similar to 200nm diameter) were functionalized and selectively immobilized onto Hall biosensor surfaces via highly specific hybridization of complementary oligonucleotides and subsequently detected by magnetic susceptibility measurements. The potential for parallel biomolecular analysis with 5 x 5 mu m(2) linear sensor arrays was demonstrated.
Scientific journal, English

High sensitivity InSb ultra-thin film micro-hall sensors for bioscreening applications
A Sandhu; H Sanbonsugi; Shibasaki, I; M Abe; H Handa
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, INST PURE APPLIED PHYSICS, 43, 7A, L868-L870, Jul. 2004, Peer-reviwed, A high sensitivity, 4.5 mum x 4.5 mum InSb thin film micro-Hall sensor (micro-HS) with a minimum field detection (B-min) of 77 nT/(Hz)(1/2) was developed for bioscreening applications and used for the detection of a single 2.8 mum diameter superparamagnetic microbead by monitoring its ac magnetic susceptibility. The scalability of the InSb micro-HS was demonstrated by fabricating 500 nm x 500 nm InSb nano-Hall sensors with B-min of 0.72 muT/(Hz)(1/2) that could potentially be used to detect 100 nm sized superparamagnetic particles.
Scientific journal, English

A novel variable temperature scanning nano-Hall probe microscope system for large area magnetic imaging incorporating piezoelectric actuators maintained at room temperature
A Sandhu; H Masuda; H Senoguchi; K Togawa
NANOTECHNOLOGY, IOP PUBLISHING LTD, 15, 6, S410-S413, Jun. 2004, Peer-reviwed, A unique variable temperature scanning Hall probe system (VT-SHPM) has been developed for large area, nanometre scale lateral resolution imaging of ferromagnetic domains, in which piezoelectric actuators are maintained at ambient temperature and only the semiconducting micro-Hall probe and sample are cooled. Its design overcomes the limitations of conventional cryogenic SHPM systems, where the piezoelectric actuators are cooled thus reducing the maximum scan area to about 10 mum x 10 mum due to a reduction of the piezoelectric constant at cryogenic temperatures. The VT-SHPM operates between 300 and 77 K and consists of a liquid nitrogen glass Dewar housing the sample and the semiconducting micro-Hall probe (active area = 900 nm x 900 nm; magnetic sensitivity at 300 K 6 mG Hz(-1/2)) Used to detect surface magnetic fields. The VT-SHPM was used to image perpendicularly magnetized domains at the surfaces of 5.5 mum thick single crystal bismuth substituted garnet thin films between 300 and 77 K. Areas of about 120 mum x 130 mum were readily imaged by synchronizing the action of x-y piezoelectric actuators and corresponding stepper motors to move and scan the sample at a constant height of 0.25 mum over the surface of the micro-Hall probe. The average width of magnetic domains in the garnet thin films was found to increase as the measurement temperature decreased.
(Some figures in this article are in colour only in the electronic version).
Scientific journal, English

Nano and micro Hall-effect sensors for room-temperature scanning hall probe microscopy
A Sandhu; A Okamoto; Shibasaki, I; A Oral
MICROELECTRONIC ENGINEERING, ELSEVIER SCIENCE BV, 73-4, 524-528, Jun. 2004, Peer-reviwed, GaAs/AlGaAs two-dimensional electron gas (GaAs-2DEG) Hall probes are impractical for sub-micron room-temperature scanning Hall microscopy (RT-SHPM), due to surface depletion effects that limit the Hall driving current and magnetic sensitivity (B in). Nano and micro Hall-effect sensors were fabricated using Bi and InSb thin films and shown to be practical alternatives to GaAs-2DEG probes for high resolution RT-SHPM. The GaAs-2DEG and InSb probes were fabricated using photolithography and the Bi probes by optical and focused ion beam lithography. Surface depletion effects limited the minimum feature size of GaAs-2DEG probes to similar to1.5 mum(2) with a maximum drive current I-max of similar to3 muA and B-min similar to 0.2 G/rootHz. The B-min of 1.5 mum(2) InSb Hall probes was 6 x 10(-1) G/rootHz at I-max of 100 muA. Further, 200 nm x 200 nm Bi probes yielded good RT-SHPM images of garnet films, with I-max and sensitivity of 40 muA and similar to0.80 G/rootHz, respectively. (C) 2004 Elsevier B.V. All rights reserved.
Scientific journal, English

Nano and micro Hall-effect sensors for room-temperature scanning hall probe microscopy
A Sandhu; A Okamoto; Shibasaki, I; A Oral
MICROELECTRONIC ENGINEERING, ELSEVIER SCIENCE BV, 73-4, 524-528, Jun. 2004, Peer-reviwed, GaAs/AlGaAs two-dimensional electron gas (GaAs-2DEG) Hall probes are impractical for sub-micron room-temperature scanning Hall microscopy (RT-SHPM), due to surface depletion effects that limit the Hall driving current and magnetic sensitivity (B in). Nano and micro Hall-effect sensors were fabricated using Bi and InSb thin films and shown to be practical alternatives to GaAs-2DEG probes for high resolution RT-SHPM. The GaAs-2DEG and InSb probes were fabricated using photolithography and the Bi probes by optical and focused ion beam lithography. Surface depletion effects limited the minimum feature size of GaAs-2DEG probes to similar to1.5 mum(2) with a maximum drive current I-max of similar to3 muA and B-min similar to 0.2 G/rootHz. The B-min of 1.5 mum(2) InSb Hall probes was 6 x 10(-1) G/rootHz at I-max of 100 muA. Further, 200 nm x 200 nm Bi probes yielded good RT-SHPM images of garnet films, with I-max and sensitivity of 40 muA and similar to0.80 G/rootHz, respectively. (C) 2004 Elsevier B.V. All rights reserved.
Scientific journal, English

50 nm Hall sensors for room temperature scanning Hall probe microscopy
A Sandhu; K Kurosawa; M Dede; A Oral
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, JAPAN SOC APPLIED PHYSICS, 43, 2, 777-778, Feb. 2004, Peer-reviwed, Bismuth nano-Hall sensors with dimensions similar to50 nm x 50 nm were fabricated using a combination of optical lithography and focused ion beam milling. The Hall coefficient, series resistance and optimum magnetic field sensitivity of the sensors were 4 x 10(-4) Omega/G 9.1 kOmega and 0.8 G/ rootHz, respectively. A 50 nm nano-Bi Hall sensor was installed into a room temperature scanning Hall probe microscope and successfully used for directly imaging ferromagnetic domains of low coercivity garnet thin films.
Scientific journal, English

Room temperature scanning micro-Hall probe microscopy under extremely large pulsed magnetic fields
A Sandhu; H Masuda; A Oral
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 39, 5, 3462-3464, Sep. 2003, Peer-reviwed, The versatility of a room-temperature scanning Hall probe microscope system with an integrated minicoil capable of generating pulsed magnetic fields up to 2.9 T was demonstrated by imaging magnetic structures on the surface of 1.4-MB floppy disks and demagnetized strontium ferrite permanent magnets. Vibration isolation between the sample and minicoil was achieved by using a combination of quartz glass plates and silicone gel layers and enabled extremely fast measurements under fields as high as 2.9 T, without detrimental effects on a GaAs-AlGaAs micro-Hall probe sensor located at a height of 0.5 mum above-the sample surface.
Scientific journal, English

Formation of nano-oxide regions in p(2+)-GaAs epilayers by localized atomic force microscope probe oxidation for fabrication of nano-structure devices
Y Matsuzaki; N Ota; A Yamada; A Sandhu; M Konagai
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 251, 1-4, 276-280, Apr. 2003, Peer-reviwed, An AFM probe was used to locally oxide the surfaces of very smooth, 10 nm thick, epitaxial p(2+)-GaAs films grown by metalorganic molecular beam epitaxy to fabricate test structures for nanometer scale devices. Nano-oxide regions formed by AFM probe oxidation using a combination of DC and pulsed voltages were found to be extremely good insulators even under external electric fields as large as 3 MV/m. (C) 2002 Elsevier Science B.V. All rights reserved.
Scientific journal, English

Room temperature scanning micro-Hall probe microscope imaging of ferromagnetic microstructures in the presence of 2.5 Tesla pulsed magnetic fields generated by an integrated mini coil
A Sandhu; H Masuda; A Oral
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, INST PURE APPLIED PHYSICS, 41, 12A, L1402-L1405, Dec. 2002, Peer-reviwed, A unique magnetic imaging system comprising of a room temperature scanning Hall probe microscope with an integrated mini-coil capable of generating pulsed magnetic fields up to 2.5 Tesla (width of 3 ms) was developed for the direct and non-invasive magnetic imaging of ferromagnetic micro-domains in the presence of extremely large external pulsed magnetic fields without adverse vibrational disturbance of the sample during measurements. The system was successfully used for magnetic imaging of the erasure process of bit patterns on the surface of IAMB written floppy disks and the dynamics of micro-domain structures of demagnetized strontium ferrite permanent magnets under large external pulsed magnetic fields.
Scientific journal, English

A scanning Hall probe microscope for large area magnetic imaging down to cryogenic temperatures
JK Gregory; SJ Bending; A Sandhu
REVIEW OF SCIENTIFIC INSTRUMENTS, AMER INST PHYSICS, 73, 10, 3515-3519, Oct. 2002, Peer-reviwed, We describe the design, construction, and operation of a large area scanning Hall probe microscope that is built around a closed-cycle refrigerator capable of cooling samples down to 35 K. The system operates in a custom vacuum housing that utilizes a flexible vacuum bellows to link to external stepping motor positioning stages allowing x-y scans of 5 mmx5 mm under vacuum at 35 K, increasing to 25 mmx25 mm in atmospheric pressure at 300 K and in magnetic fields up to 0.06 T. The Hall probe can be viewed with a microscope through a window and lowered to the desired scanning height and tilted with micrometer screws. The system has an effective lateral spatial resolution of 1.25 mum and a minimum detectable field of similar to0.08 muT/rootHz. We describe the performance of the system and illustrate its potential with images of the local magnetic induction at the surface of various magnetic recording media at room temperature as well as an array of superconducting YBa2Cu3O7-delta squares at 40 K. (C) 2002 American Institute of Physics.
Scientific journal, English

Room-temperature scanning Hall probe microscope (RT-SHPM) imaging of garnet films using new high-performance InSb sensors
A Oral; M Kaval; M Dede; H Masuda; A Okamoto; Shibasaki, I; A Sandhu
IEEE TRANSACTIONS ON MAGNETICS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 38, 5, 2438-2440, Sep. 2002, Peer-reviwed, High-performance InSb micro-HaIl sensors were fabricated by optical lithography and incorporated in a room-temperature scanning Hall probe microscope for imaging of localized magnetic fluctuations in close proximity to the surfaces of crystalline uniaxial garnet films. The room-temperature noise figure of the InSb sensors was 6-10 mG/v/Hz, which is an order of magnitude better than GaAs-AlGaAs two-dimensional electron gas sensors used to date.
Scientific journal, English

Room temperature scanning Hall probe microscopy of localized magnetic field fluctuations on the surfaces of magnetic recording media, permanent magnets and crystalline garnet films in external bias fields
A Sandhu; N Iida; H Masuda; A Oral; SJ Bending
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, 242, 1249-1252, Apr. 2002, Peer-reviwed, A sub-micron room temperature scanning Hall probe microscope (RT-SHPM) was used for real-time imaging of surface magnetic domains of floppy disks, Sr ferrite magnets and Bi-substituted iron garnets placed in large external bias fields. Domain wall nucleation was observed in the garnets where bubble lattices expanded, collapsed and transformed into stripe domains in cyclic bias fields. Evolution of RT-SHPM images was compared with conventional vibrating sample magnetometer measurements. (C) 2002 Elsevier Science B.V. All rights reserved.
Scientific journal, English

Bismuth nano-Hall probes fabricated by focused ion beam milling for direct magnetic imaging by room temperature scanning Hall probe microscopy
A Sandhu; H Masuda; K Kurosawa; A Oral; SJ Bending
ELECTRONICS LETTERS, INST ENGINEERING TECHNOLOGY-IET, 37, 22, 1335-1336, Oct. 2001, Peer-reviwed, Bismuth nano-Hall probes with dimensions similar to 120 x 120 nm were fabricated by focused ion beam milling and used for the direct room temperature magnetic imaging of crystalline garnet thin films and strontium ferrite permanent magnets by scanning Hall probe microscopy. At driving currents of 40 muA, the Hall coefficient and magnetic field sensitivity of the Bi nano-Hall probes were 3.3 x 10(-4) CYG and 7.2 G/root Hz, respectively.
Scientific journal, English

Room temperature magnetic imaging of magnetic storage media and garnet epilayers in the presence of external magnetic fields using a sub-micron GaAs SHPM
A Sandhu; H Masuda; A Oral; SJ Bending
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 227, 899-905, Jul. 2001, Peer-reviwed, A multipurpose room temperature scanning Hall probe microscope (RT-SHPM) system incorporating an ultra-high sensitive sub-micron GaAs Hall probe (active area of similar to0.8 x 0.8 mum(2) room temperature Hall coefficient of 0.3 Ohm /G) exhibiting extremely high magnetic field sensitivity (0.04G/root Hz) was used for the direct, non-invasive and quantitative imaging of magnetic field fluctuations in very close proximity to the surfaces of thin film magnetic storage media, Bi substituted iron garnet epilayers and demagnetized Sr-ferrite permanent magnets placed in external magnetic fields. A scanning tunnelling microscope tip integrated adjacent to the Hall probe was used for precise vertical positioning of the probe. RT-SHPM images of 1.4 MB written floppy disks clearly showed well-defined magnetic transitions to coalesce into small island-like structures under external perpendicular fields greater than 1300 Oe. The RT-SHPM is demonstrated to be a versatile means of quantitatively monitoring micron-sized magnetic domain structures in the presence of external magnetic fields at: room temperature. (C) 2001 Elsevier Science B.V. All rights reserved.
Scientific journal, English

Room temperature sub-micron magnetic imaging by scanning Hall probe microscopy
A Sandhu; H Masuda; A Oral; SJ Bending
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, INST PURE APPLIED PHYSICS, 40, 6B, 4321-4324, Jun. 2001, Peer-reviwed, An ultra-high sensitive room temperature scanning Hall probe microscope (RT-SHPM) system incorporating a GaAs/AlGaAs micro-Hall probe was used for the direct magnetic imaging of localized magnetic field fluctuations in very close proximity to the surface of ferromagnetic materials. The active area, Hall coefficient and field sensitivity of the Hall probe were 0.8 mum x 0.8 mum, 0.3 Omega /G and 0.04G/root Hz, respectively. The use of a semiconducting Hall probe sensor enabled measurements in the presence of externally applied magnetic fields. Samples studied included magnetic recording media. demagnetized strontium ferrite permanent magnets, and low coercivity perpendicular garnet thin films. The RT-SHPM offers a simple means for quantitatively monitoring sub-micron magnetic domain structures at room temperature.
Scientific journal, English

Direct magnetic imaging of ferromagnetic domain structures by room temperature scanning hall probe microscopy using a bismuth micro-hall probe
Sandhu, A; Masuda, H; Oral, A; Bending, SJ
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 40, 5B, L524-L527, May 2001, Peer-reviwed
Scientific journal, English

Investigation of deep levels and precipitates related to molybdenum in silicon by DLTS and scanning infrared microscopy
A Sandhu; T Ogikubo; H Goto; Csapo, V; T Pavelka
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 210, 1-3, 116-121, Mar. 2000, Peer-reviwed, We report on the properties of Si diffused with molybdenum (Mo) investigated using experimental techniques that included Fourier transform deep-level transient spectroscopy (FT-DLTS) and scanning infrared microscopy (SIRM). Samples were prepared using boron-doped float zone (100)Si wafers (100-400 Omega cm) and Mo was diffused into them by placing Mo powder onto the Si surface and annealing in a vacuum (8 x 10(-6) Torr) at temperatures between 400 and 800 degrees C for 1-10 h. FT-DLTS measurements revealed that deep levels due to Mo (E-v + 0.29 eV) were only formed in samples when Mo was diffused above a threshold temperature of 650 degrees C. SIRM imaging showed the presence of Mo-related precipitates having a density of 2.3 x 10(7)-5.8 x 10(9) cm(-3) near the surface region and iron-related precipitates having a density of 1.2 x 10(7)-1.1 x 10(8) at a depth of 30 mu m. The precipitate size was found to be strongly dependent on diffusion temperature and ranged between 50 and 100 nm as calculated from the scattered light intensity. The minority carrier lifetime was found to decrease with increasing density of iron traps that were unintentionally incorporated during the diffusion process. (C) 2000 Elsevier Science B.V. All rights reserved.
Scientific journal, English

Piezoresistive properties of 3C-SiC films anodically bonded to aluminosilicate glass substrates
A Sandhu; S Jinno
ELECTRONICS LETTERS, IEE-INST ELEC ENG, 36, 6, 497-498, Mar. 2000, Peer-reviwed, Current leakage problems observed in conventional 3C-SiC/Si heterojunction piezoresistive structures at high temperatures have been resolved through the anodic bonding of the 3C-SiC thin films onto insulating aluminosilicate glass substrates having a thermal expansion coefficient close to that of Si. The gauge factor of such 3C-SiC/SiO2/glass structures was extremely stable up to temperatures as high as 600K with a fluctuation of < 5%.
Scientific journal, English

Thermal behavior of residual strain in silicon-on-insulator bonded wafer and effects on electron mobility
T Iida; T Itoh; Y Takano; A Sandhu; K Shikama
SOLID-STATE ELECTRONICS, PERGAMON-ELSEVIER SCIENCE LTD, 43, 6, 1117-1120, Jun. 1999, Peer-reviwed, Residual lattice strain in a bonded SOI wafer and its influence on the electron mobility were investigated as a function of heat-treatment temperature ranging from 900 to 1050 degrees C and duration from 6 to 30 h, The change in residual strain was measured by using the X-ray diffraction method. In as-received SOI wafers, tensile strain (tensile stress along the direction parallel to the surface) of the order of 10(-5)-10(-4) was observed. For the specimens annealed at above 950 degrees C, the strain varied abruptly from a tensile to a compressive one at an annealing time of 12-15 hi then approached a certain value with increasing annealing time. On the other hand, the remaining strain of the specimen annealed at 900 degrees C exhibited the tensile region only, and did not achieve to the compressive one, even for long treatment. Significant variation in the electron Hall mobility was observed for both 1.5 and 5 mu m thick SOI layers as the residual strain changes, Although samples with no strain showed identical mobility to the value in a bulk Si, the presence of the strain may anomalously affect the electron transportation. (C) 1999 Elsevier Science Ltd. All rights reserved.
Scientific journal, English

Effect of low-energy nitrogen molecular-ion impingement during the epitaxial growth of GaAs on the photoluminescence spectra
T Shima; Y Makita; S Kimura; H Sanpei; Y Fukuzawa; A Sandhu; Y Nakamura
APPLIED PHYSICS LETTERS, AMER INST PHYSICS, 74, 18, 2675-2677, May 1999, Peer-reviwed, Low-energy (similar to 100 eV) nitrogen molecular ions (N-2(+)) were impinged during molecular beam epitaxial growth of GaAs at the substrate temperature of 550 degrees C. In the low-temperature (2 K) photoluminescence (PL) spectra, extremely sharp N-related emissions (X-i, i = 1, 2, and 5) were observed in as-grown condition. These emissions were roughly two orders of magnitude stronger than those formed by the impingement of nitrogen atomic ions (N+). The results indicate that nitrogen (N) atoms are in situ substituted at As sites without inducing large structural damages and become quite efficient radiative recombination centers as isoelectronic impurities in GaAs. Further, to study the substitutional condition of N isoelectronic impurity, N isotope (N-15) doped GaAs was grown by N-15(2)+ ion impingement. When N-15 is doped, PL peak energy of X-5 shifted towards higher energy side by 1.8 meV. The value is fairly close to the expected one of 1.9 meV when N-15 replaces N-14. Together from energy separation between X-2 emission (similar to 60 meV), origin of X-5 was ascribed to the local vibrational mode of X-2 emission. (C) 1999 American Institute of Physics. [S0003-6951(99)01518-1].
Scientific journal, English

Optical and electrical characterizations of Mn doped p-type beta-FeSi2
T Takada; Y Makita; T Shima; T Banba; K Shikama; H Sanpei; M Hasegawa; A Sandhu; Y Hoshino; H Katsumata; S Uekusa
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, ELSEVIER SCIENCE BV, 147, 1-4, 337-342, Jan. 1999, Peer-reviwed, beta-FeSi2 has attracted increasing attention as a promising material for optoelectronic and thermoelectronic devices due to a high optical absorption coefficient (alpha) of about 10(5) cm(-1) near 1.0 eV and its chemical stability at higher temperatures. For the future practical use of this material in devices, the control of each electrical conductivity type and the improvement of the material quality are highly required. Although unintentionally doped beta-FeSi2 layers formed on n-type Si(1 0 0) by the conventional electron-beam deposition (EBD) have typically shown n-type conductivity, the p-type beta-FeSi2 layers were formed by the introduction of Mn impurity using ion-implantation at room temperature (RT) and subsequent annealing procedures. In this study, we aimed to make p-type beta-FeSi2 by implantation of Mn-55(+) ions into EBD-grown n-type beta-FeSi2 layers/n-Si, where Mn-55(+) ions were implanted at two different temperatures (T-sub) of RT and 250 degrees C using an energy and a dose of 300 keV and 2.68 x 10(15) cm(-2), respectively. Their optical and electrical properties, which ought to be affected by implantation and annealing temperatures (T-a2), were investigated by Raman scattering, optical transmittance, reflectance and van der Pauw measurements. The results showed that the Mn-55(+) doping with T-sub = RT and higher thermal annealing at T-a2 = 900 degrees C produced p-type layers of good quality with maximum hole mobility of 454.5 cm(2)/Vs at about 65 K. (C) 1999 Elsevier Science B.V. All rights reserved.
Scientific journal, English

Low-energy nitrogen-ion doping into GaAs and its optical properties
T Shima; Y Makita; S Kimura; H Sanpei; A Sandhu
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ELSEVIER SCIENCE SA, 253, 1-2, 301-305, Sep. 1998, Peer-reviwed, Nitrogen (N) ions were impinged during the epitaxial growth of GaAs using combined ion beam and molecular beam epitaxy (CIBMBE) method. Low-temperature photoluminescence measurements showed that incorporated nitrogen ([N] < similar to 1 x 10(18) cm(-3)) is optically active with a substrate temperature of 550 degrees C and a N+ ion acceleration energy of 100 eV. For higher [N] of similar to 2 x 10(18) cm(-3), N-related emissions can be found after high temperature (650-850 degrees C) annealing. We discuss the annealing effects and also the novel emissions found after annealing at high temperature (750 degrees C) with a [N] of similar to 1 x 10(19) cm(-3). (C) 1998 Elsevier Science S.A. All rights reserved.
Scientific journal, English

InGaP/InGaAs/GaAs high electron mobility transistor structure grown by solid source molecular beam epitaxy using GaP as phosphorous source
Missous, M; Aziz, AA; Sandhu, A
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 36, 6A, L647-L649, Jun. 1997, Peer-reviwed
Scientific journal, English

Properties of silicon doped silicon dioxide thin films deposited by Co-sputtering of silicon and silicon dioxide
A Sandhu; Y Show; T Katano; M Iwase; T Izumi; T Yabe; S Nozaki; H Morisaki
APPLIED SURFACE SCIENCE, ELSEVIER SCIENCE BV, 117, 634-637, Jun. 1997, Peer-reviwed, The effect of annealing on silicon doped SiO2 films was studied by X-ray diffraction, electron spin resonance (ESR) and Fourier transform photoluminescence (FTPL, 30 to 300 K). FTPL was not observed from as-deposited samples bur annealed samples showed FTPL at room temperature centred at about 900 nm and also an anomalous variation of thr FTPL intensity with temperature. ESR measurements showed the presence of g = 2.003 and g = 2.006 centres. implications of the results will be discussed in thr context that silicon crystallites were formed due to the annealing.
Scientific journal, English

Residual ion damage in GaAs:C prepared by combined ion beam and molecular beam epitaxy
T Iida; Y Makita; J Horn; HL Hartnagel; T Shima; S Kimura; K Shikama; H Sanpei; A Sandhu; N Kobayashi; S Uekusa
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, ELSEVIER SCIENCE BV, 127, 884-887, May 1997, Peer-reviwed, Ion-induced damage in the films grown by low-energy (30-30 000 eV) ion-beam doping method was investigated using the minority-carrier lifetime and temperature-dependent Hall-effect measurements, Minority-carrier lifetime measurement using scanning tunneling microscope stimulated time-resolved luminescence (STM-L) demonstrated the presence of residual ion damage in as-grown samples at C+-ion acceleration energy EC+ = 240 and 350 eV, and annealed ones at EC+ = 5, 10 and 30 keV, For EC+ = 30 eV, no ion damage was observed in as-grown condition, For EC+ greater than or equal to 5 keV, ion damage remains even after high-temperature annealing and degrades the activation of C atoms. In the temperature-dependent Hall-effect measurements, samples with Ec = 240 and 350 eV showed unusual characteristics in net hole carrier concentration (\N-A - N-D\) with decreasing temperature. For EC+ = 10 and 30 keV, \N-A - N-D\ in lower temperature regions indicates higher values than that obtained at room temperature, It was suggested that the conduction mechanisms of these two specimens are significantly affected by impurity conduction mainly due to ion damage.
Scientific journal, English

Properties of high quality InP epilayers grown by solid source molecular beam epitaxy using polycrystalline GaP as a phosphorous source
A Sandhu; M Missous
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, JAPAN J APPLIED PHYSICS, 35, 4A, 2108-2109, Apr. 1996, Peer-reviwed, We report on the properties of high quality epitaxial InP grown by solid source molecular beam epitaxy (MBE) using polycrystalline GaP as a phosphorous source. The as-grown InP was n-type with a background impurity concentration of 1.2 x 10(15) cm(-3) and mobility of 4500 cm(2)/Vs at room temperature. Low temperature photoluminescence at 5 K showed free exciton together with donor and acceptor related band-edge emission. These results show that high quality InP can be grown by solid source MBE without the need for high temperature crackers or toxic hydride phosphorous sources.
Scientific journal, English

GAS-SOURCE MBE GROWTH OF ALGAAS AND GAAS FOR HBT APPLICATIONS
FUJII, T; ANDO, H; SANDHU, A; OKAMOTO, N
FUJITSU SCIENTIFIC & TECHNICAL JOURNAL, 29, 2, 169-179, Jan. 1993, Peer-reviwed
Scientific journal, English

GROWTH OF CARBON-DOPED BASE GAAS/ALGAAS HBT BY GAS-SOURCE MBE USING TEG, TEA, TMG, ASH3, AND SI2H6
H ANDO; T FUJII; A SANDHU; T TAKAHASHI; H ISHIKAWA; N OKAMOTO; N YOKOYAMA
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 120, 1-4, 228-233, May 1992, Peer-reviwed, High-performance carbon-doped-base GaAs/AlGaAs heterobipolar transistors (HBTs) were grown by gas-source MBE using only gaseous sources including dopant sources. The AlGaAs emitter layer was doped with Si from uncracked SI2H6 (n = 9 x 10(17) cm-3), and the base layer (92.5 nm) was doped with carbon from TMG (p = 4 x 10(19) cm-3). From SIMS analysis it was confirmed that a well-defined emitter-base junction with sharp carbon profile was obtained. The base-current ideality factor from the Gummel plot was 1.47, and the emitter-base junction ideality factor was 1.12. A high DC current gain of 53 was obtained at a current density of 4 x 10(4) A/CM2. The device characteristics of our carbon-doped HBTs were found to be stable under current stress.
Scientific journal, English

THE ELECTRICAL, OPTICAL AND CRYSTALLINE PROPERTIES OF GAASC GROWN BY GSMBE USING TMG AND ASH3 FOR APPLICATION TO HBTS
A SANDHU; T NAKAMURA; H ANDO; K DOMEN; N OKAMOTO; T FUJII
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 120, 1-4, 296-300, May 1992, Peer-reviwed, We report the results of a comprehensive study on the electrical, optical and crystalline properties of heavily carbon doped p-type (100) GaAs epilayers (p = 6.3 x 10(18) -1.3 x 10(20) cm-3; thickness = 250-420 nm) grown by gas source molecular beam epitaxy using trimethylgallium and arsine. X-ray analysis showed epilayer lattice contraction with a mismatch of DELTA-a/a = -1.8 x 10(-3) at p = 1.3 x 10(20) cm-3. Room temperature photoluminescence peak energy shifted from 1.40 eV (p = 6.3 x 10(18) cm-3) to 1.37 eV (p = 1.3 x 10(20) cm-3). Stokes Raman spectra showed two modes assigned as the unscreened LO phonon (292 cm-1) and the low frequency branch of the coupled hole-plasmon-LO-phonon (266 cm-1). Conservation of Raman scattering rules under all incident light configurations showed that the (100) GaAs:C epilayers were of high crystalline quality without the presence of faceting or other such crystalline defects. Annealing at 900-degrees-C for between 30 s to 45 min, resulted in a significant reduction in the hole concentration, lattice contraction and photoluminescence intensity for all epilayers. The implications of these results for the development of GaAs/AlGaAs HBTs are discussed.
Scientific journal, English

GAS SOURCE MOLECULAR-BEAM EPITAXY GROWTH OF HIGH-QUALITY ALGAAS USING TRIMETHYLAMINE ALANE AS THE ALUMINUM SOURCE
N OKAMOTO; H ANDO; A SANDHU; T FUJII
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, JAPAN J APPLIED PHYSICS, 30, 12B, 3792-3795, Dec. 1991, Peer-reviwed, We investigated the dependence of the background impurity incorporation on growth conditions and optical properties of undoped AlGaAs grown by gas source molecular beam epitaxy using trimethylamine alane (TMAAl), triethylgallium, and arsine. The use of TMAAl enabled us to reduce the carbon concentration (7 x 10(16) cm-3) to over one order of magnitude less than that using triethylaluminum (TEAl). The 77 K photoluminescence spectrum of undoped AlGaAs grown using TMAAl was dominated by excitonic band-edge emission not observable in AlGaAs grown using TEAl. Furthermore, we report for the first time the doping characteristics of n-type AlGaAs grown using disilane (Si2H6) as an n-type gaseous dopant source together with TMAAl. The carrier concentration (5 x 10(17)-3 x 10(18) cm-3) in n-AlxGa1-xAs (x = 0.09-0.27) was reliably controlled and showed the same Si2H6 flow rate dependence as that of GaAs. The activation efficiency of silicon was more than 60%. We demonstrated the excellent n-type doping characteristics by using TMAAl.
Scientific journal, English

CARBON-DOPED-BASE ALGAAS GAAS HBTS GROWN BY GAS-SOURCE MOLECULAR-BEAM EPITAXY USING ONLY GASEOUS SOURCES
T TAKAHASHI; Y YAMAGUCHI; A SANDHU; H ANDO; T FUJII; N YOKOYAMA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, JAPAN J APPLIED PHYSICS, 30, 12B, 3843-3845, Dec. 1991, Peer-reviwed, We report the fabrication and electrical characteristics of carbon-doped-base AlGaAs/GaAs heterojunction bipolar transistors (HBTs) grown by gas-source molecular beam epitaxy (GSMBE) using only gaseous sources. The base of HBTs is compositionally uniform and doped with carbon to a carrier concentration of 4 x 10(19 cm-3. A current gain of 45 was obtained at a collector current density of 4 x 10(4) A/cm2. These HBTs were electrically stable under current stress, as confirmed by current gain and Gummel plots.
Scientific journal, English

P+/N GAAS-ALGAAS HETEROSTRUCTURES GROWN BY GAS SOURCE MBE USING GASEOUS P-TYPE AND N-TYPE DOPANT SOURCES
A SANDHU; T FUJII; H ANDO; T TAKAHASHI; H ISHIKAWA; N YOKOYAMA
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 111, 1-4, 559-563, May 1991, Peer-reviwed, We report on the first growth of p+/N GaAs-Al(x)Ga1-xAs heterostructures using all gaseous sources by gas source MBE (GSMBE). GaAs was doped p-type (1.3 x 10(20) cm-3) using trimethylgallium as both a dopant and group III source and Al(x)Ga1-xAs (x = 0-0.28) was doped n-type (5 x 10(17) cm-3) using uncracked disilane as an n-type dopant and triethylgallium and triethylaluminium as group III sources. In both cases 100% arsine was used as the group V source. The current-voltage ideality factor of the heterojunctions was found to depend on the aluminium mole fraction of Al(x)Ga1-xAs (x = 0.12, 0.23, 0.28) and the width (DELTA-s = 5, 10, 20 nm) of an undoped GaAs spacer layer at the heterojunction. A value of 1.17 was obtained for a heterostructure with x = 0.23 and DELTA-s = 20 nm.
Scientific journal, English

GAS SOURCE MBE GROWTH OF GAAS/ALGAAS HETEROJUNCTION BIPOLAR-TRANSISTOR WITH A CARBON DOPED BASE USING ONLY GASEOUS SOURCES
A SANDHU; T FUJII; H ANDO; T TAKAHASHI; H ISHIKAWA; N OKAMOTO; N YOKOYAMA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, JAPAN J APPLIED PHYSICS, 30, 3, 464-465, Mar. 1991, Peer-reviwed, We report on the first growth of a GaAs/Al0.2Ga0.8As heterojunction bipolar transistor by gas source MBE using only gaseous sources. The p-type GaAs base layer was carbon doped using trimethylgallium (p = 4 x 10(19) cm-3) and the n-type Al0.2Ga0.8As emitter layer was silicon doped (n = 9 x 10(17) cm-3) using uncracked disilane. A dc current gain of 40 was obtained at a current density of 50 A/cm2.
Scientific journal, English

DOPING CHARACTERISTICS OF GAS-SOURCE MBE-GROWN NORMAL-ALXGA1-XAS (X=0-0.28) DOPED USING DISILANE
T FUJII; A SANDHU; H ANDO; Y KATAOKA; H ISHIKAWA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, JAPAN J APPLIED PHYSICS, 29, 11, 2386-2387, Nov. 1990, Peer-reviwed, Si doping using uncracked disilane (Si2H6) in gas-source molecular beam epitaxy of n-Al(x)Ga(1-x)As (x = 0-0.28) using triethyl gallium, triethyl aluminum, and arsine was studied in a carrier concentration from 5 x 10(17) to 2 x 10(18) cm-3. We found that (1) the Si atomic concentration of AlGaAs is proportional to the Si2H6 flow rate, and decreases with increasing Al content at a constant Si2H6 flow rate, and (2) the carrier concentration of AlGaAs shows a square-root dependence on the Si atomic concentration incorporated.
Scientific journal, English

GAAS/ALGAAS QUANTUM-WELL STRUCTURES GROWN BY GAS-SOURCE MBE USING TEG, TEA, AND ASH3
H ANDO; A SANDHU; H ISHIKAWA; T FUJII
JOURNAL OF CRYSTAL GROWTH, ELSEVIER SCIENCE BV, 105, 1-4, 149-154, Oct. 1990, Peer-reviwed
Scientific journal, English

A STUDY OF COLD DOPANT SOURCES FOR GAS SOURCE MBE - THE USE OF DISILANE AS AN N-TYPE DOPANT OF ALXGA1-XAS (X=0-0.28) AND TRIMETHYLGALLIUM AS A P-TYPE DOPANT OF GAAS
SANDHU, A; FUJII, T; ANDO, H; ISHIKAWA, H
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 29, 7, L1033-L1035, Jul. 1990, Peer-reviwed
Scientific journal, English

GAS-SOURCE MBE GROWTH OF AL0.3GA0.7AS USING TEG, TEA AND ASH3
ANDO, H; SANDHU, A; ISHIKAWA, H; SUGIYAMA, Y; FUJII, T
INSTITUTE OF PHYSICS CONFERENCE SERIES, 106, 217-222, 1990, Peer-reviwed
Scientific journal, English

White Paper on Quantum Computing
Adarsh Sandhu
Springer Nature, May 2019, Springer Nature, English, Invited, Introduction other

Bandgap Semiconductors : Fundamental Properties and Modern Photonic and Electronic Devices 2007
Kiyoshi Takahashi; Akihiko Yoshikawa; Adarsh Sandhu
Scholarly book, English, Joint editor, Springer, Apr. 2007

Fabrication of Liquid Flow Nanocapsules for Transmission Electron Microscopy and In-Situ Observation of Water Freezing Process in Real Time
Naohito Satake; Tomoki Murakami; Hiroto Takahashi; Mitsuki Fujimoto; Li Xiaoguang; Masaki Takeguchi; Adarsh Sandhu
Oral presentation, Japanese, JSAP Spring Meeting 2022, Domestic conference
26 Mar. 2022

Smartphone based medical diagnosis protocol enabled by dynamic tracking of electromagnetically induced harmonic oscillation in magnetic particles
N. Satake; J. Sharma; A. Sandhu
Poster presentation, English, Virtual Irago Conference 2020, International conference
11 Oct. 2020

VI0013 Electrical properties of tin-doped β-Ga2O3 under high-pressure
M. Kato; H. Arima; A. Sandhu
Poster presentation, English, Virtual Irago Conference 2020, International conference
11 Oct. 2020

VI 0014 Liquid transmission electron microscopy of gold and polymer nanoparticles in liquid solution with a fluidic capsule
S. Ly; T. Onodera; N. Satake; T. Murakami; A. Sandhu
Poster presentation, English, Virtual Irago Conference 2020, International conference
11 Oct. 2020

VI 0015 AlGaN/GaN heterostructure based Hall sensors for high temperature operation
F. Nakamura; M. Katoh; S. Yamada; A. Sandhu
Poster presentation, English, Virtual Irago Conference 2020, International conference
11 Oct. 2020

スマートフォン型医療診断センシングシステム及び顕微鏡観察セル
Adarsh Sandhu
Nominated symposium, Japanese, 新技術説明会 主催 科学技術振興機構、電気通信大学, Domestic conference
12 May 2020

Fabrication of Liquid Flow Capsule for In Situ Transmission Electron Microscopy
S. Ly; T. Onodera; N. Satake; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

Smartphone based medical diagnosis protocol enabled by dynamic tracking of electromagnetically induced harmonic oscillation in magnetic particles
T. Ono; J. Sharma; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

Potential of gallium oxide for power devices
M. Kato; F. Nakamura; Akito Kuramata; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

In situ chemical reaction observation using multi-function capsule
N. Satake; T.Onodera; Ly Seam; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

Detection of Biotin by Tracking Movements of Functionalized Magnetic Particles in Solution
J. Sharma; T. Ono; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

Rapid biosensing protocol based on self-assembly of monolayers and magnetic particles
J. Sharma; T. Ono; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

AlGaN/GaN hetero-structure based Hall sensors for high temperature operation
F. Nakamura; M. Katoh; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

In situ transmission electron microscopy of gold and polymer nanoparticles in liquid solution with a using vacuum proof liquid flow cell
Takanori Onodera; Ly Seam; A. Sandhu
Poster presentation, English, Irago Conference 2019, International conference
24 Oct. 2019

セレンディピティを促進する！
A. SANDHU
Public discourse, Japanese, RA協議会第3回年次大会 企業セッション 世界に発信する大学 ～未来を創るブランド向上戦略～, Invited, International conference
30 Aug. 2017

Magnetic nanoparticle-based nano-grating guided-mode resonance biosensors
Ryoji YUKINO; Sharma JAIYAM; Tsukasa TAKAMURA; Joby JOSEPH; Adarsh SANDHU
Poster presentation, English, MNTC International Symposium 2017, International conference
27 Aug. 2017

Magnetically Induced Manipulation of Functionalized Magnetic Nanoparticles for Point of Treatment Medical Diagnostics
A. SANDHU
Invited oral presentation, English, MNTC International Symposium 2017, Invited, International conference
26 Aug. 2017

Medical Diagnostics with Functionalized Fluorescent Magnetic Nanobeads and Planar Micro-coils
Jaiyam SHARMA; Ryoji YUKINO; Tsukasa TAKAMURA; Adarsh SANDHU
Oral presentation, English, ICMAT 2017, International conference
19 Jun. 2017

Magnetic nanoparticle-based nano-grating guided-mode resonance biosensors
R. Yukino; J. Sharma; T. Takamura; J. Joseph; A. Sandhu
Oral presentation, English, INTERMAG Europe 2017, International conference
25 Apr. 2017

Smartphone-based Platform for Medical Diagnostics
R. Yukino; J. Sharma; T. Takamura; J. Joseph; A. Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Tunable color filter using guided mode resonance structures
R. Yukino; P. K Sahoo; J. Sharma; T. Takamura; J. Joseph; A. Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Gate-Tunable Optoelectronic Properties of Nano-layered GaSe Based Photodetector
Abdelkader Abderrahmane; Pil Ju Ko; Adarsh Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Magnetic control of self-assembled superparamagnetic micro-particles for microrobotic applications
Abdelkader Abderrahmane; Hideki Miyashita; Ryoji Yukino; Tsukasa Takamura; Adarsh Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

γ-Irradiation Effect on AlGaN/GaN Heterostructures
Abdelkader Abderrahmane; Tsukasa Takamura; Hiroshi Okada; Adarsh Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Biosensing by digital image processing based detection of fluorescent magnetic nanolabels and micro-current coils for reduction of non-specific interactions
J. Sharma; R. Yukino; T. Takamura; A. Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Surface functionalization of magnetotactic bacteria for precise transportation of tiny loadings
T. Takamura; A. Arakaki; A. Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Novel capsule for nanoscale observation of materials in liquid by transmission electron microscopy
T. Takamura; R. Yukino; H. Tahara; A. Abderrahmane; A. Sandhu
Poster presentation, English, The Irago Conference 2016, International conference
01 Nov. 2016

Review of recent developments in ‘wet’ high resolution electron microscopy
Adarsh Sandhu; T. Takamura; C. Blanco-Andujar; J. Llandro; D. Ortega; Q. Pankhurst; P. Southern; M. Boutchich; K. Kobayashi; E. Nakamura
Invited oral presentation, English, The Irago conference 2015, International conference
22 Oct. 2015

High-performance near-infrared phototransistors based on MoSe2 nanosheets
Pil Ju Ko; Tsukasa Takamura; Abdelkader Abderrahmane; Adarsh Sandhu
Poster presentation, English, The Irago Conference 2015, International conference
22 Oct. 2015

Smartphone-based Platform for Medical Diagnostics
Ryoji Yukino; Jaiyam Sharma; Tsukasa Takamura; Joby Joseph; Sandhu Adarsh
Poster presentation, English, The Irago conference 2015, International conference
22 Oct. 2015

Design of an innovative smartphone based spectrometer for medical diagnostics
Jaiyam Sharma; Ryoji Yukino; Tsukasa Takamura; Adarsh Sandhu
Poster presentation, English, The Irago conference 2015, International conference
22 Oct. 2015

Photosensitivity of multi-layered two dimensional GaSe nanosheets
Shunji Ishizawa; Pil Ju Ko; Tsukasa Takamura; Adarsh Sandhu
Poster presentation, English, The Irago conference 2015, International conference
22 Oct. 2015

スマートフォン系医療診断用分光分析プラットホーム
雪野 瞭治; シャルマ ジャイヤム; 高村 司; ジョセフ ジョビー; サンドゥー アダルシュ
Oral presentation, Japanese, 2015年 第76回応用物理学会秋季学術講演会, Domestic conference
16 Sep. 2015

Design and operation of innovative smartphone based spectrometer for medical diagnostics
Jaiyam Sharma; Ryoji Yukino; Tsukasa Takamura; Adarsh Sandhu
Oral presentation, English, 2015年 第76回応用物理学会秋季学術講演会, Domestic conference
14 Sep. 2015

グラフェン酸化物上に形成した人工脂質二重膜の構造・物性評価
岡本吉晃; 茂木俊憲; 岩佐精二; サンドゥー アダルシュ; 手老龍吾
Oral presentation, Japanese, 電子情報通信学会 電子デバイス研究会, Domestic conference
16 Apr. 2015

Graphene Oxide-Based Nanohybrids for Multifunctional Applications
T. V. Thu; A. Sandhu
Oral presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

High proton irradiation tolerance of InAsSb quantum well based micro-Hall sensors
A. Abderrahmane; P. J. Ko; H. Okada; S. Sato; T. Ohshima; I. Shibasaki; A. Sandhu
Poster presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

High photosensitivity few-layered MoSe2 back gated eld-e ect phototransistors
A. Abderrahmane; P. J. Ko; S. Ishizawa; T. Takamura; A. Sandhu
Poster presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

Reducing few-layered MoSe2 lm to single-layer by laser etching
P. J. Ko; A. Abderrahmane; T. Takamura; A. Sandhu
Poster presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

Observation of electrical evolution of graphene under electron beam irradiation
A. Nagahara; H. Okada; H. Takahashi; A. Sandhu
Poster presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

Microcapillary capsule for nanoscale and real time observation of materials in liquid TEM environment
T. Takamura; S. Koide; P. J. Ko; T. Tahara; S. Ishizawa; M. Ishida; P. Southern; D. Ortega; Q. Pankhurst; A. Sandhu
Poster presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

Nano-thermocouple AFM for monitoring heating of magnetic nanoparticles
C. Blanco-Andujar; P. Southern; T. Takamura; A. Sandhu
Poster presentation, English, The Irago Conference 2014, International conference
06 Nov. 2014

Single particle tracking of Qdot-conjugated lipid bilayer on graphene oxide for evaluation of membrane fluidity
Y. Okamoto; T. Motegi; S. Iwasa; A. Sandhu; R. Tero
Oral presentation, English, The 7th International Symposium on Surface Science, International conference
Oct. 2014

マイクロロボット応用へ向けた磁性細菌表面の機能化
高村司; 田代起也; 新垣篤史; アダルシュ サンドゥー
Oral presentation, Japanese, 第75回応用物理学会秋季学術講演会, Domestic conference
17 Sep. 2014

MoSe2 semiconductor indirect-to-direct transition by laser induced etching
高必周; Tran Viet Thu; 高村司; Abdelkader Abderrahmane,アダルシュ サンドゥー
Oral presentation, English, 第75回応用物理学会秋季学術講演会, Domestic conference
17 Sep. 2014

Radiation Hard AlGaN/GaN Heterostructure- Micro-Hall Sensors
Abdelkader Abderrahmane,高村司; 佐藤真一郎; 大島; 岡田浩; アダルシュ サンドゥー
Oral presentation, English, 第75回応用物理学会秋季学術講演会, Domestic conference
17 Sep. 2014

Importance of networking for science and engineering based students: The perils of ‘tunnel vision’
A. SANDHU
Oral presentation, English, IONS-Asia 5 Hokkaido, 北海道大学, International conference
Sep. 2014

Strategies for writing papers and giving oral presentations for science and engineering
A. SANDHU
Oral presentation, English, 応用物理 学会学生会員スチューデントチャプター主催会議, 北海道大学, International conference
Sep. 2014

研究戦略としての国際情報発信～効果的な国際情報発信戦術のあり方を共に考える
A. SANDHU
Oral presentation, English, 第４回URAシンポジウム／第６回RA研 究会合同大会シン ポジウムのプログラム, 北海道大学, International conference
Sep. 2014

透過型電子顕微鏡による液中試料観察用カプセルに関する研究
田原知行; 高村 司; 雪野瞭治; 石澤峻路; サンドゥ アダルシュ
Oral presentation, Japanese, 電子情報通信学会 電子デバイス研究会
11 Jul. 2014

iPhoneを用いた分光測定システムの開発
雪野瞭治; 高村 司; 高 必周; アダルシュ サンドゥー
Oral presentation, Japanese, 電子情報通信学会 電子デバイス研究会, Domestic conference
10 Jul. 2014

“How my scientific career was shaped through writing articles
A. SANDHU
Nominated symposium, English, 15th Anniversary Symposium of Journal Science and Technology of Advanced Materials Conference, 東京大学, International conference
Jul. 2014

Nanotechnology Discussions podcasts: Electromagnetism at the nanoscale
A. SANDHU
Oral presentation, English, Nanotechnology Discussions podcasts celebrating 150 years of Maxwell equations, International conference
Jun. 2014

Functionalization of magnetotactic bacteria for microrobotic applications
T. Takamura; T. Tashiro; A. Arakaki; A. Sandhu
Oral presentation, English, IEEE International Magnetics Conference, INTERMAG Europe 2014., International conference
May 2014

Porous silicon based protocol for the rapid and real-time monitoring of biorecognition between human IgG and protein A using functionalized superparamagnetic beads
P.J. Ko; R. Ishikawa; T. Takamura; H. Sohn; A. Sandhu
Oral presentation, English, International Magnetics Conference, INTERMAG 2012, International conference
May 2014

Detection of nanometer magnetic labels by magnetically induced frictional forces with micrometer superparamagnetic beads.
T. Takamura; P.J. Ko; I. Ishikawa; A. Sandhu
Oral presentation, English, International Magnetics Conference, INTERMAG 201, International conference
May 2014

Fabrication of micro-coils for generating localized magnetic fields
S. Ishizawa; T. Takamura; T. Tahara; A.Sandhu
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Artificial Cell Membrane Systems at Solid-Liquid Interfaces
R. Tero; T. Motegi; Y. Okamoto; T. Kobayashi; M.N.B; Muazam Shah; S. Iwasa; A. Sandhu; M. Futagawa; K. Sawada
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Synthesis of Magnetic Thermoplastic-based nanocomposites
T. V. Thu; T. Takamura; D. Tsetserukou; A. Sandhu
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Graphene Oxide as an Excellent Two-Dimensional Support for Functional Nanostructures
T. V. Thu; A. Sandhu
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Quantum Dot Conjugation to Model Cell Membranes on Graphene Oxide for the Evaluation of Membrane Fluidity
Y. Okamoto; T. Motegi; S. Iwasa; A. Sandhu; R. Tero
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Laser thinning of MoS2 for producing single layered MoS2
P.J.Ko; T.V.Thu; H.Takahashi; A.Abderrahmane; A.Sandhu
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

GMR based PhC biosensor: FOM analysis and experimental studies
J. Syamprasad; H. Takahashi; R. Jindal; A. Sandhu; J. Joseph
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Dynamics of Magnetotactic Bacteria Under Rotating Magnetic Fields
T. Tashiro; P.J. Ko; R. Yukino; A. Arakaki; A. Sandhu
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Detection of Nano-sized Magnetic Beads' Concentration via Micro-sized Magnetically Assembled Beads' Movement
T. Takamura; A. Sandhu
Poster presentation, English, The Irago Conference 2013, International conference
Oct. 2013

Ecofriendly Reduction of Graphene Oxide Using Extremophile Bacteria
Y. Tanizawa; Sreejith Raveendran; Neha Chauhan; R. Tero; Y. Yoshida; T. Maekawa; D. Sakthi Kumar; A. Sandhu
Poster presentation, English, Graphene 2012, International conference
Nov. 2012

Innovative capsule for measuring aqueous samples by transmission electron microscopy
T. Takamura; S. Koide; P. J. Ko; T. Tahara; S. Ishizawa; M. Ishida; P. Southern; D. Ortega; Q. Pankhurst; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Hall sensors driven by alternating currents
T.Tahara; S.Koide; P.J.Ko; S.Paul; Q. Pankhurst; A.Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Effect of Proton Irradiation on 2DEG in AlGaN/GaN heterostructures
A. Abderrahmane; S. Koide; T. Tahara; H.Okada; H. Takahashi; S. Sato; T. Ohshima; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Graphene based 2D photonic crystal micro-cavity for Terahertz Frequency
M. Kumar; J. Joseph; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Observation of the dynamics of superparamagnetic beads under magnetic fields by laser light scattering
Yuji. Tanizawa; Tatsuya. Tashiro; Pil Ju. Ko; Adarsh. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Monitoring the behavior of magnetic colloids using dynamic light scattering and acoustic wave spectroscopy
R. Basak; R. Bandyopadhyay; T.Tashiro; Y. Tanizawa; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Dynamics of chemically mediated interaction between magnetic nanoparticles monitored by laser scattering
T. Tashiro; Y.Tanizawa; P. J. Ko; Adarsh Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Physical characterization of graphene oxide reduced through chemical and biological processes
M. Boutchich; D.Almarguy; A.Barras; A.Jaffr; J.Alvarez; J.P Kleider; A.Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Study of Transfer Method of Graphene Formed by Chemical Vapor Deposition Using Dicing Tape
Y.Kumazawa; H.Takahashi; H.Okada; A. Sandhu; A.Wakahara; H.Sekiguchi
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Raman studies of graphene grown by chemical vapor deposition
H. Takahashi; P.J. Ko; H. Okada; C. Prakash; J. Joseph; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Synthesis and Characterization of Graphene Nanoparticles
T.V. Thu; Y. Tanizawa; N.H.H. Phuc; P.J. Ko; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Transfer of graphene from metallic catalytic substrates to flexible surfaces
P. J. Ko; H. Takahashi; H. Sakai; T. V. Thu; H. Okada; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Microfluidic lab-on-a-chip for liquid transmission electron microscopy
P. J. Ko; S. Koide; P. Southern; Daniel Ortega; Q. Pankhurst; A. Sandhu
Poster presentation, English, The Irago Conference 2012, International conference
Oct. 2012

Artificial lipid bilayer platform on graphene and graphene oxide
Ryugo Tero; Yoshiaki Okamoto; Kazuyuki Tsuzuki; Seiji Iwasa; Ryousuke Ishikawa; Adarsh Sandhu
Oral presentation, English, Materials Research Society Conference, International conference
Apr. 2012

Extremophiles for Biologically-based Reduction of Graphene Oxide into Graphene
Y. Tanizawa; S. Raveendran; Y. Yoshida; T. Maekawa; D.S. Kumar; R. Tero; H. Okada; A. Sandhu
Oral presentation, English, Materials Research Society Conference, International conference
Apr. 2012

Magnetoelectronic devices for point of care medical diagnostics using functionalized superparamagnetic particles
A. SANDHU
Oral presentation, English, Department of materials science, 中国 清華大学, International conference
Mar. 2012

Point of care medical diagnostics using functionalized superparamagnetic particles
A. SANDHU
Oral presentation, English, Nanoscience & Quantum Information Centre, University of Bristol, Tyndall Ave, Bristol, UK, International conference
Mar. 2012

Bio Hall sensors for point of care medical diagnostics
A. SANDHU
Oral presentation, English, CAVENDISH LABORATORY, CAMBRIDGE, 英国CAMBRIDGE 大学, International conference
Mar. 2012

Optically based biosensing for point of care medical diagnostics
A. SANDHU
Oral presentation, English, INSTITUTE for PHOTONICS, MANCHESTER, 英国 MANCHESTER 大学, International conference
Mar. 2012

Point of care medical diagnostic protocols based on self‐assembly  of functionalized superparamagnetic particles
A. SANDHU
Oral presentation, English, 2012 International LifeChips Symposium,, University of California, Irvine, USA, International conference
Feb. 2012

Point of care medical diagnosis based on manipulation and detection of functionalized SPBs
A. SANDHU
Oral presentation, English, The 9th International Symposium on Bioscience and Nanotechnology, Toyo University, Kawagoe Campus, International conference
Dec. 2011

Potential of nanotechnology for the diagnosis of head and neck cancer: Challenges facing maxillofacial surgeons and pathologists
A. Jones; A. Sandhu; S. Sandhu; S. Kumar; T. Maekawa; B. Sivakumar; A. Sandhu
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Proton Irradiation of 2-DEG AlGaN/GaN Micro-Hall Sensors
A. Abderrahmane; S. Koide; H. Takahashi; H. Okada; S. Sato; T. Ohshima; A. Sandhu
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

The enrichment and characterization of microbial communities that reduce graphene oxide
Y. Nagao; Y. Okamoto; K. Tsuzuki; R. Tero; S. Iwasa; A. Sandhu; A. Hiraishi; N. Yoshida
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Detection of Nanometer Magnetic Labels Frictional Forces with Self-assembled Magnetic Microbeads
T. Takamura; P.J. Ko; A. Sandhu
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Fabrication of Supported Lipid Bilayer on Graphene Oxide
Y. Okamoto; K.Tsuzuki; S. Iwasa; R. Ishikawa; A. Sandhu; R. Tero
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Effect of Reducing Graphene Oxide as Support for Lipid Bilayer Membrane
K. Tsuzuki; Y. Okamoto; S. Iwasa; R. Ishikawa; A. Sandhu; R. Tero
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Electrophoretic deposition of high quality transparent conductive graphene films on insulting glass substrates
R. Ishikawa; P. J. Ko; M. Bando; M. Konagai; A. Sandhu
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Optical Transmittance for Analysis of the Dynamics of Self-Assembled Rotating Chains of Superparamagnetic Micro- and Nano beads in Solution
Pil Ju Ko; Tsukasa Takamura; Adarsh Sandhu
Oral presentation, English, AP-IRC 2011, International conference
Nov. 2011

Fabrication of Single-Layered Porous Silicon for Rapid Biosensing with Functionalized Superparamagnetic Nanobeads
P. J. Ko; R. Ishikawa; Y. Morimoto; T. Takamura; A. Sandhu
Oral presentation, English, ICANS24, International conference
Aug. 2011

Multilayered Porous Silicon Platform for Rapid Detection of Functionalized Nanometer Sized Superparamargnetic Beads via Magnetic Manipulation
P. Ko; Y. Morimoto; R. Ishikawa; B. Cho; H. Sohn; A. Sandhu
Poster presentation, English, INTERMAG 2011 Conference,, International conference
Apr. 2011

Rapid Biosensing Platform based on Monitoring Changes in the Optical Reflectance of Porous Silicon due to Penetration by Functionalized Superparamagnetic Beads
P. J. Ko; Y. Morimoto; R. Ishikawa; B. Cho; H. Sohn; A. Sandhu
Oral presentation, English, SSDM 2010,, International conference
Sep. 2010

Magneto-optical biosensing based on self-assembly of magnetic particles.
A. SANDHU
Oral presentation, English, NanoTR- 6th Nanoscience and Nanotechnology Conference, Izumir Institute of Technology, Izmir, Turkey., International conference
Jun. 2010

determination of forces between biomolecules in solution by magneto-optical transmittance of biofunctionalized supermagnetic particles.
S.Y. Park; P. Ko; A. Sandhu
Oral presentation, English, 11th Joint MMM-Intermag Conference,, International conference
Jan. 2010

Dynamics of rotating chains of magnetic nanoparticles by optical transmittance.
P. Ko; S.Y. park; y. morimoto; a.sandhu
Oral presentation, English, 11th Joint MMM-Intermag Conference,, International conference
Jan. 2010

magneto-optical properties of bio-functionalized magnetic chains for developing label-free immunoassays.
S.Y. Park; P. Ko; H. handa; A. sandhu
Oral presentation, English, 11th Joint MMM-Intermag Conference,, International conference
Jan. 2010

Detection of 28nm Diameter Superparamagnetic Beads by Magnetically- Induced Self-assembly with Micrometersized Magnetic Beads: A New Protocol for Magneticallylabeled Biosensing
Y. Morimoto; S. Sakamoto; H. Handa; A. Sandhu
Oral presentation, English, 2009 International Conference on Solid State Devices and Materials (SSDM 2009), International conference
Oct. 2009

Temperature Dependence of the Resistance of AlGaN/GaN Heterostructures and their Applications as Temperature Sensors
A. H. Zahmani; A. Nishijima; Y. Morimoto; H. Wang; J. F. Li; A. Sandhu
Oral presentation, English, 2009 International Conference on Solid State Devices and Materials (SSDM 2009), International conference
Oct. 2009

Detection of Magnetic Nanoparticles by Magnetically Mediated Self-Assembly of Superparamagnetic Microbeads for Biosensing
Yoshitaka Morimoto; Sang Yoong Park; Hiroshi Handa; Adarsh Sandhu
Oral presentation, English, 4th Asian and Pacific Rim Symposium on Biophotonics (APBP),, International conference
May 2009

Magnetically labelled immunoassay based on magneto-optical transmittance of solutions containing self-assembled chains of functionalized magnetic nanoparticles
Sang Yoon Park; Y. Morimoto; H. Handa; A. Sandhu
Oral presentation, English, 4th Asian and Pacific Rim Symposium on Biophotonics (APBP),, International conference
May 2009

Detection of magnetically labled biomolecules by self-assembly of superparamagnetic microbeads.
A. SANDHU
Oral presentation, English, 第30回ナノバイオ磁気工学専門研究会 （ＩＥＥE Magnetics Society of Japan）, 東工大キャンパス イノベーショイン センター 田町, International conference
Apr. 2009

Self-assembly of superparamagnetic particles for high-speed magneto-optical modulators and biosensors.
S.Y. Park; A. Sandhu
Oral presentation, English, AMC 2008. Asian Magnetics Conference 2008, International conference
Dec. 2008

Electrical Characteristics of Hall and Magnetoresistive Effect Magnetic Field Sensors Fabricated using Ultra-High Mobility 2DEG-InAsSb/InAlSb Heterostructures.
M. Bando; S. Y. Park; I. Shibasaki; A. Sandhu
Oral presentation, English, AMC 2008. Asian Magnetics Conference 2008, International conference
Dec. 2008

Detection of Magnetic Nanoparticles by Magnetic Self-Assembly of Superparamagnetic Microbeads for Biosensing.
Y. Morimoto; S.Y Park; A. Sandhu
Oral presentation, English, AMC 2008. Asian Magnetics Conference 2008, International conference
Dec. 2008

High Sensitivity and Multi-Functional Micro-Hall Sensors Fabricated using InAlSb/InAsSb/InAlSb Heterostructures
M. Bando; T. Ohashi; M. Dede; R. Akram; A. Oral; S. Y. Park; I. Shibasaki; H. Handa; A. Sandhu
Oral presentation, English, 53rd Conference on Magnetism and Magnetic Materials, International conference
Nov. 2008

Biomolecular recognition protocol based on optical transmittance of solutions containing self-assembled chains of functionalized magnetic nanoparticles.
S.Y Park; A. Sandhu
Oral presentation, English, 53rd Conference on Magnetism and Magnetic Materials, International conference
Nov. 2008

Multifunctional Hall Sensors for Scanning Hall Probe Microscopy and Biomedical Applications
A. SANDHU
Oral presentation, English, Nature Nanotechnology Seminar, Nagano, JAPAN, International conference
Jun. 2007

Nanotechnlogy in asia-pacific.
A. SANDHU
Oral presentation, English, Nature Nanotechnology Seminar, Tokyo Bigh Sight, International conference
Feb. 2007

Manipulation of magnetic beads on Hall biosensors by integrated current lines,
A. SANDHU; Y. Kumagai; M. Abe; H. Handa
Oral presentation, English, Magnetics Society of Japan,, Shimane, International conference
Sep. 2006

Nano-Hall Effect Sensors for Imaging Magnetic Domains and Biomedical applications
A. Sandhu; M. Abe; H. Handa
Oral presentation, English, International Symposium on Bio- and Nano-Electronics,, International conference
Sep. 2006

Robust Hall effect magnetic field sensors for operation at high temperatures and in harsh radiation environments
A. Abderrahmane; H. Okada; S. Koide; S. Sato; T. Ohshima; A. Sandhu
Oral presentation, English, International Symposium on Bio- and Nano-Electronics,, International conference
Sep. 2006

HALL BIO-SENSOR MICROFLUIDIC PLATFORM FOR DETECTION OF SUPERPARAMAGNETIC BEADS
M. Iino; Y. Kumagai; A. Abe; S. Sakamoto; H. Handa; A. Sandhu
Oral presentation, English, International Conference on Magnetism (ICM2006), International conference
Aug. 2006

LEXIBLE MICRO-HALL EFFECT SENSORS FOR CONTACT-MODE SCANNING HALL PROBE MICROSCOPY AND ‘WET’–BIOMEDICAL APPLICATIONS
M. Tamura; Z. Primadani; A. Sandhu
Oral presentation, English, International Conference on Magnetism (ICM2006), International conference
Aug. 2006

Nano-Hall Effect Sensors for Imaging Magnetic Domains and Biomedical Applications,
A. SANDHU; M.Abe
Oral presentation, English, Tohoku University, International Symposium on Bio- and Nano-Electronics,, Sendai, International conference
Mar. 2006

GaN/AlGaN for High Sensitivity and Quantitative Magnetic Field Measurements
T. Yamamura; A. SANDHU
Oral presentation, English, 50th Mangetism and Magnetic Materials Conference, (MMM 2005), International conference
Oct. 2005

Practical Hall Effect Sensors for Biomedical Instrumentation
A. SANDHU; H. Handa
Oral presentation, English, Intermag 2005, Nagoya, International conference
Apr. 2005

Functionalization of micro-Hall effect sensors for biomedical applications utilizing superparamagnetic beads
A. Lapicki; H. Sanbonsugi; N. Matsushita; M. Abe; H. Narimatsu; H. Handa; A. SANDHU
Oral presentation, English, Intermag 2005, International conference
Apr. 2005

High sensitivity indium antimonide thin film micro-hall sensor arrays for biomedical detection of magnetic beads for biomedical applications
K. Togawa; H. Sanbonsugi; A. Lapicki; M. Abe; A. SANDHU
Oral presentation, English, Intermag 2005, International conference
Apr. 2005

Magnetic collection and washing of superparamagnetic beads onto micro-hall biosensors bu integrated field gradient line paths for biomedical applications
Y. Kumagai; K. Togawa; M. Abe; H. Handa; A. SANDHU
Oral presentation, English, Intermag 2005, International conference
Apr. 2005

High Sensitivity InSb Thin Film Nano-Hall Sensors for Medical Applications,
A.SANDHU
Oral presentation, English, Advanced Heterostructure Workshop,, Hawaii,, International conference
Dec. 2004

Nano and micro Hall-effect sensors for room-temperature scanning hall probe microscopy
A. SANDHU; A. Okamoto b; I. Shibasaki b; A. Oral
Oral presentation, English, Micro and Nano-Engineering Conference, International conference
Sep. 2004

Ultra high sensitivity inSb micro-Hall biosensor system for high speed bioscreening applications
H. Sanbonsugi; M. Abe; A. SANDHU
Oral presentation, English, 9th International Conference on Ferrites, International conference
Aug. 2004

Room Temperature Scannning Hall Probe Microscopy of Ferromagnetic Microstructures under 2.5 Tesla Pulsed Bias Fields,
A .SANDHU; H .Masuda; A. Oral
Oral presentation, English, The 10th International Colloquium on Scanning Probe Microscopy, International conference
Oct. 2002

Room Temperature Scanning Hall Probe Microscopy using GaAs/AlGaAs and Bi Micro-Hall Probes,
A. SANDHU; H. Masuda; A. Oral; S.J.Bending
Oral presentation, English, Scanning Probe and Microscopy Sensors and Nanostructures Conference, International conference
May 2002

Magnetic Imaging of Ferromagnetic domains by room temperature scanning Hall probe microscopy using GaAs/AlGaAs and bismuth micro-Hall probes.
A.SANDHU; H. Masuda; A. Oral; S.J. Bending
Oral presentation, English, 11th International Workshop on the Physics of Semiconductor Devices,, International conference
Dec. 2001

Magnetic Imaging by room temperature scanning Hall probe microscopy
A. SANDHU; A. Oral; H. Masuda; S.J. Bending
Oral presentation, English, Joint European Magnetic Symposia (JEMS’01), International conference
Aug. 2001

The Effect of CdCl2 Treatment Conditions and Stoichiometry on The Deep Level Density, Carrier Lifetime and Conversion Efficiency of CdTe Thin Film Solar Cells.
A. SANDHU; K. Kobayashi; T. Okamoto; A. Yamada; M. Konagai
Oral presentation, English, Proceedings 12th International Photovoltaic Science and Engineering Conference, International conference
Jun. 2001

Study on the use of a bismuth micro-Hall probe for magnetic imaging of ferromagnetic domain structures by room temperature scanning Hall
A. SANDHU; A. Oral; H. Masuda; S.J. Bending; A. Yamada; M. Konagai
Oral presentation, English, Tokyo-2001: Scanning Probe Microscopy, Sensors and Nanostructures, International conference
May 2001

Effect of Treatment Conditions on the Deep Level Density, and Conversion Efficiency of CdTe Thin Film Solar Cells.
A. SANDHU; K. Kobayashi; T. Okamoto; A. Yamada; M. Konagai
Oral presentation, English, Materials Research Society Spring Meeting, International conference
Apr. 2001

Direct and Real-Time Observation of Sub-Micron Domain Dynamics in Magnetically Biased Strontium Ferrite Permanent Magnets by RT-SHPM
A. SANDHU; H. Masuda; Oral; S.J. Bending
Oral presentation, English, Materials Research Society Spring Meeting, International conference
Apr. 2001

Magnetic Imaging at Room Temperature by Scanning Micro-Hall Probe Microscopy
A.SANDHU; H. Masuda; A. Oral; S.J. Bending
Oral presentation, English, The Magnetics Society of Japan, ‘Applied Magnetics Seminar, International conference
Dec. 2000

Room Temperature Scanning Hall Microscopy
A.SANDHU; H. Masuda; A. Oral; S.J. Bending
Oral presentation, English, The Magnetics Research Group meeting of The Institute of Electrical Engineers of Japan,, International conference
Dec. 2000

Room Temperature Sub-Micron Magnetic Imaging by SHPM
A. SANDHU; H. Masuda; Oral; S.J. Bending
Oral presentation, English, The 8th International Colloquium on Scanning Probe Microscopy and Asian SPM (3)., International conference
Dec. 2000

RT Magnetic Imaging of micrometer-sized Ferromagnetic Domains in the presence of External Magnetic Fields by Scanning hall probe microscopy
A. SANDHU; H. Masuda; Oral; S.J. Bending
Oral presentation, English, Materials Research Society Fall Meeting, International conference
Nov. 2000

Room Temperature Magnetic Imaging of Magnetic Storage Media and Garnet Epilayers in the Presence of External Magnetic Fields using a Sub-Micron GaAs SHPM
A. SANDHU; H. Masuda; Oral; S.J. Bending
Oral presentation, English, Molecular Beam Epitaxy XI, International conference
Sep. 2000

Room Temperature Magnetic Imaging of Micron Sized Ferromagnetic Domains using SHPM
A. SANDHU; H. Masuda; Oral; S.J. Bending
Oral presentation, English, The 8th Asia-Pacific Physics Conference, International conference
Aug. 2000

Scanning Probe Microscopy of Magnetic Imaging: Current Status and Future
A. Oral; H. Masuda; D.D. Howells; A. SANDHU
Oral presentation, English, Proceedings of NATO ASI, International conference
Jun. 2000

Carbon Doping into GaAs using low-energy hydrocarbon ions.
H. Sanpei; T. Shima; Y. Makita; S. Kimura; Y. Fukuzawa; Y. Nakamura; A. SANDHU
Oral presentation, English, MRS Spring Meeting, International conference
Mar. 1998

Highly Efficient Nitrogen Doping using Low Energy Molecular Nitrogen Ions into GaAs.
T. Shima; Y. Makita; H. Sanpei; S. Kimura; A. SANDHU; Y. Fukuzawa
Oral presentation, English, MRS Spring Meeting, International conference
Mar. 1998

3C-SiC Material Growth and Device Potential
Adarash Sandhu
Oral presentation, English, Advanced Heterostructure Workshop, International conference
Dec. 1996

Growth of Ultra-High Speed Opto-Electronic Devices by GSMBE
Adarash Sandhu
Oral presentation, English, Semiconducting Quantum Optics and Electronics Conference (SQUOPE), International conference
Jan. 1995

Properties and Future Applications of III-V Compound Semiconductors by GSMBE
Adarash Sandhu
Oral presentation, English, Superlattice Structures and Related Devices Workshop, University of Manchester, UK, International conference
Oct. 1989

Interdisciplinary Research Fundamentals II
Tokyo Institute of Technology

Interdisciplinary Research Fundamentals II
Tokyo Institute of Technology

Interdisciplinary Research Fundamentals II
Tokyo Institute of Technology

電子工学実験第二
The University of Electro-Communications

Technical English for graduate students
The University of Electro-Communications

大学院技術英語
The University of Electro-Communications

電子工学実験第二
The University of Electro-Communications

電子工学実験第二
電気通信大学

Modern Engineering and Science
電気通信大学

Graduate Technical English
The University of Electro-Communications

大学院技術英語
電気通信大学

Modern Engineering and Science
The University of Electro-Communications

Modern Engineering and Science
The University of Electro-Communications

総合コミュニケーション科学
The University of Electro-Communications

総合コミュニケーション科学
電気通信大学

応用物理学会

日本磁気学会

IEEE Magnetics Society

日本外国特派員協会

極高温用GaN/AlGaNヘテロ構造ホール素子の作製と応用
SANDHU ADARSH; 東脇 正高
日本学術振興会, 科学研究費助成事業, 東京工業大学, 萌芽研究, 次世代の高保磁力永久磁石、超高密度磁気記録技術及び「スピンエレクトロニクス」等の新分野の研究には、磁性体特有のキュリー温度(Tc)の測定が非常に重要である。現在、磁性体のTcの測定は通常、振動試料型磁力計(VSM)装置を使って行われている。しかし、VSMによるTcの測定の難点として、(1)試料全体の平均的な値しか得られない;(2)熱電対と試料が離れているため、試料の正確な温度測定ができずTcの値に誤差(±20%)が生じる;(3)VSM装置は複雑な仕組みで操作が困難である;(4)VSM装置は高価(〜2000万円)である、等が挙げられる。そこで、申請者はVSM装置ではなく、Tcをホール素子により測定する方法を提案した。しかし従来のホール素子の材料であるGaAs、 InSb等の半導体は、温度変化により、磁界に対する出力であるホール電圧が変化するという問題がある。そこで、本研究ではホール素子に用いる半導体材料として二次元電子ガスを有するGaN/AlGaNヘテロ構造に着目し、ホール電圧の温度変化が極めて小さいホール素子の作製を目的とする。 平成18年度の研究予定は実際に極高温で安定な動作する50〜100μm角のGaN/AlGaNホール素子の応用として、高温におけるBaフェライトの磁化曲線(キュリー温度)の測定を行った。通常のVSM測定はマクロ的であり、GaN/AlGaNホール素子を用いた測定は局所的な情報を得ることができ、測定した円形の等方性Baフェライトのキュリー温度はVSM測定と若干異なり、460℃であることは分かった。さらに、センサ部分は2μm×2μmのSHPM用ホール素子を作製し、50μm厚のガーネットサンプルを測定し、磁区幅約10μmを有する磁区構造の観察に成功した。 以上の高温におけるBaフェライトの磁化曲線の測定に成功したこと、ガーネットの磁区観察に成功したことで高温で局所的な磁界測定が可能であるを証明した。さらに約数μm角のGaN/AlGaNホール素子をSHPMに搭載し、高温で磁性体表面の熱による磁区反転・磁壁移動の観察への応用を検討した。, 17656107
2005 - 2006

Fabrication of Bismuth Thin Films Nano-Hall Sensors for Room Temperature Scanning Micro-Hall Probe Microscope Imaging of Ferromagnetic Microstructures
SANDHU Adarsh
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, TOKYO INSTITUTE OF TECHNOLOGY, Grant-in-Aid for Scientific Research (C), A fundamental understanding of the behavior of magnetic domains in external magnetic fields is important for the development of information technology such as ultra-high density magnetic recording media, high coercivity permanent magnets and multilayered ferromagnetic structures used for fabricating novel ‘spintronic'' devices. We have developed a room temperature scanning Hall probe microscopy (RT-SHPM) for the non-invasive and quantitative imaging of localized stray fields at the surfaces of ferromagnetic magnetic microstructures in the presence of pulsed external magnetic fields of 3 T Oe. However, advances in magnetic recording media have led to increasing demands for improvements in the spatial resolution of SHPM which using semiconducting GaAs/AlGaAs micro-Hall sensors is limited to 1.0 x 1.0μm due to surface depletion effects. The use of bismuth (Bi)(a semimetal, which exhibits a large Hall coefficient and negligible surface depletion) for fabrication of submicron Hall sensors shows promise as a means of improving the spatial resolution of RT-SHPM technology. Conventional MFM systems have a spatial resolution of 〜100nm, a figure which serves as a benchmark and target for studies on spatial resolution. In this research we succeeded in fabricating 50nm x 50nm Hall sensors using Bi thin films deposited by thermal evaporation. The electrical properties of the films were improved by post-deposition annealing in vacuum. The nano-Hall sensors were successfully used for magnetic imaging the surface of crystalline garnet thin films. This report describes the research carried out on "Fabrication of Bismuth Thin Films Nano-Hall Sensors for Room Temperature Scanning Micro-Hall Probe Microscope Imaging of Ferromagnetic Microstructures" as part of the Grant-in-Aid for Scientific Research (c)(2)for two years between 2003 and 2004. The fabrication and electrical characteristics of the Bi nano-Hall sensors are described. Also, the use of the Bi-nanosensors for imaging garnet thin films is demonstrated., 15560271
2003 - 2004

Room Temperature Scanning Micro-Hall Probe Microscope Imaging of Ferromagnetic Microstructures Under Large Pulsed Magnetic Fields Generated by an Integrated Mini-Coil
SANDHU Adarsh; INUSHIMA Takashi
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), A fundamental understanding of the behavior of magnetic domains in external magnetic fields is important for the development of information technology such as ultra-high density magnetic recording media, high coercivity permanent magnets and multilayered ferromagnetic structures used for fabricating novel 'spintronic' devices. In this research, a unique magnetic imaging system comprising of a room temperature scanning Hall probe microscope with an integrated mini-coil capable of generating pulsed magnetic fields up to 3 Tesla (width of 3.5ms) was developed for the direct and non-invasive magnetic imaging of ferromagnetic micro-domains in the presence of extremely large external pulsed magnetic fields without adverse vibrational disturbance of the sample during measurements. The system was successfully used for magnetic imaging of the erasure process of bit patterns on the surface of 1.4MB written floppy disks and the dynamics of micro-domain structures of demagnetized strontium ferrite permanent magnets under large external pulsed magnetic fields. The combined mini-coil/RT-SHPM system was demonstrated to be a valuable instrument for the direct, quantitative and non-invasive observation of localized stray magnetic fields at the surfaces of magnetic recording media and ferromagnetic materials in the presence large external bias fields., 13650354
2001 - 2002

携帯型フィルタレス顕微鏡、及びこれを用いた蛍光観察方法
Patent right, サンドゥー アダルシュ, 雪野 瞭治, 高村 司, 宮下 英樹, シャルマ ジャイヤム, 特願2017-154097, Date applied: 09 Aug. 2017

波長選択フィルタ装置、波長選択フィルタリング方法、及びフィルタ素子のキャリブレーション方法
Patent right, サンドゥ-アダルシュ, 雪野瞭治, 高村司, 特願2016-010981, Date applied: 22 Jan. 2016, サンドゥー アダルシュ , 雪野 瞭治 , 高村 司, 特開2017-129821, Date announced: 27 Jul. 2017

基板上の粒子の検出装置
Patent right, サンドゥーアダルシュ, 安野寛, シャルマジャイヤム, 浜信治, 高村司, 田中俊行, 雪野瞭治, 羽生尚広, 特願2016-026818, Date applied: 16 Feb. 2016, サンドゥー アダルシュ , シャルマ ジャイヤム , 高村 司 , 雪野 瞭治 , 羽生 尚広 , 安野 寛 , 浜 信治, 特許第6155452号, Date issued: 16 Jun. 2017

磁性粒子を用いたバイオセンシング方法及び装置
Patent right, サンドゥーアダルシュ, 安野寛, シャルマジャイヤム, 浜信治, 高村司, 田中俊行, 雪野瞭治, 羽生尚広, 特願2016-026823, Date applied: 16 Feb. 2016

ウェット試料の封入用カプセルならびに構成部材およびその製造方法
Patent right, 特願2013-106479, Date applied: 20 May 2013, 特開2014-229401, Date announced: 08 Dec. 2014