Adarsh Sandhu

Thickness dependence on the optoelectronic properties of multilayered GaSe based photodetector

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 0.57 AW(-1) and external quantum efficiency of of 132.8%, and decreased with decreasing GaSe flake thickness. The detectivity was 4.05 × 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.

Gate-tunable optoelectronic properties of a nano-layered GaSe photodetector

Recently, two-dimensional materials were widely studied as candidates for new generation of photodetectors. In this paper, we reported on the fabrication and the optoelectronic characterizations of 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 103. 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 gate voltage of −18V, with photoresponsivity, external quantum efficiency and detectivity of 0.9 AW–1, 210% and 8.08 × 1011 cmHz0.5W–1, respectively.

High sensitivity refractive index sensor based on simple diffraction from phase grating.

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° 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 π 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.

Magnetic Nanoparticles for Medical Diagnostics

Magnetic Nanoparticles for Medical Diagnosticsxa0aims to encourage members of the medical profession to join experts from other fields of research in exploring the unique physical properties of magnetic nanoparticles for medical applications.

Abstract 3101: Hyperthermia at the single-cell level for disseminated cancer disease with immuno-magnetic nanoparticles

Hyperthermia using magnetic nanoparticles and alternating magnetic field is promising for cancer therapy. In most cases, the usefulness of this magnetic nanoparticle-based hyperthermia has been shown by applying magnetic nanoparticles to tumor tissue such as a subcutaneous tumor with direct injection technique; however, if the magnetic nanoparticles can be cancer cell-specifically delivered at the cellular level, the magnetic field hyperthermia would have the potential to treat various sorts of disseminated cancer diseases. The aim of this study is to prove this concept. Maghemite nanoparticles (MNPs) were conjugated with the anti-HER2 antibody (Tmab) for cancer targeting, and the Tmab-MNPs were applied to the co-culture flask containing both HER2-expressing breast cancer AU565 cells and normal fibroblast FEF3 cells. Thirty minutes later from the Tmab-MNPs administration, the medium was removed and the cells were washed to remove excess Tmab-MNPs. Prussian blue iron staining and immunostaining for Tmab showed co-localization of the maghemite nanoparticles and Tmab only on the cancer cells, which suggested that MNPs conjugation with Tmab was successful and that cancer specific delivery of MNPs at the cellular level was achieved in vitro. Moreover, application of alternating current magnetic field at 280 kHz for 1 hour caused apoptotic-like cell death only to cancer cells without any cell damage to normal fibroblast FEF3 cells. Intracellular hyperthermia using cancer-specific antibody-modified magnetic nanoparticles have the potential to be applied to the treatment of disseminated cancer diseases. Citation Format: Tetsuya Kagawa, Hiroyuki Kishimoto, Toshiaki Ohara, Hiroshi Tazawa, Shunsuke Kagawa, Takeshi Nagasaka, Satoshi Nohara, Ichiro Kato, Adarsh Sandhu, Hiromichi Aono, Toshiyoshi Fujiwara. Hyperthermia at the single-cell level for disseminated cancer disease with immuno-magnetic nanoparticles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3101. doi:10.1158/1538-7445.AM2017-3101

GMR-based PhC biosensor: FOM analysis and experimental studies

Guided Mode Resonance based Photonic crystal biosensor has a lot of potential applications. In our work, we are trying to improve their figure of merit values in order to achieve an optimum level through design and fabrication techniques. A robust and low-cost alternative for current biosensors is also explored through this research.