Research

The goal of this work is to develop a rotationally symmetric nanowire array based WGM resonator for label-free detection of virus-like particles (VLPs). For investigation and analysis finite difference time domain (FDTD) based numerical analysis has been performed to correlate resonant wavelengths of the structure with spatial location of a single virus onto the sillicon NW array. As no fluorescent, colorimetric or enzymatic tag is needed in the proposed scheme, it should be applicable for rapid diagnosis of VLPs with a high degree of accuracy at low-cost. In fact the proposed technique offers an ingenious means of label-free detection of not only viruses, but also numerous other pathogens, biomolecules and extraneous particles relevant to biosensing, clinical diagnostics and environmental monitoring.

InAs nanowire (NW) based structure is investigated in this work for achieving ultra broadband perfect absorber unlike previous works that were based on Si or III-V materials like GaAs. Finite difference time domain (FDTD) based numerical analysis has been performed to optimize the InAs nanowire based structure for achieving efficient solar absorber by varying different dimensional parameters and guided mode resonance based theoretical analysis is developed to support the results and to get an intuition of the tunability of the nanowire based structure. The absorption spectra for these structures are polarization independent and exhibit robust performance for varying angle of incidence. In addition, arrangement of the NW array (hexagonal or square) has negligible effect on the absorption spectra. Such ultra-broadband absorption capability of the proposed structure compared to existing works suggests that InAs nanowire based structure is very promising as the absorber layer of photovoltaic solar cells.

Engineering the thermal and optical properties of windows is a key to reducing building energy demand, which constitutes a major portion of world-wide electricity consumption. Depositing thin film photovoltaic coating that will simultaneously generate power and allow visible light is a viable route towards nearly net-zero energy building. Such windows with Semi-Transparent Photovoltaics (STPV) have unique physical properties that requires comprehensive modeling to properly estimate the performance. In this paper, we adopt an integrated approach to unify device level simulation - which provides the electrical, optical and thermal parameters - with building energy simulation using EnergyPlus and a Matlab based power generation platform. The power generation code contains a model for shadow from nearby buildings, geography and climate dependent solar insolation model and ambient temperature variation to predict efficiency accurately. We also develop a thermal model to find the U-value of a glass that is coated with STPV. We find that such coating dramatically improves insulation by reflecting infra-red radiation. Our results show that - contrary to roof-top solar panels - STPV modules, when put on all four vertical surfaces, provide robust performance in the presence of both shadow and cloud.