Executive Summary : | The COVID-19 pandemic has highlighted the need for reliable rapid diagnostic tests, such as point-of-care biosensors, which have made medical care accessible to individuals at home. These biosensors are often expensive and fabricated with Au, making them difficult to use. This project aims to create a cost-effective point-of-care sensor using AuAg alloyed metasurfaces to detect chiral molecules like glucose and α-synuclein responsible for diabetes and Parkinson's disease. The metasurface will be designed based on spin-orbit-interaction (SOI) principles, with multiple unit cells varying in geometry. Prof. Ghosh's expertise and artificial intelligence model will help design the optimum geometry for the sensing application. The metasurface will be plasmonic, capable of high sensitivity, and will benefit from low loss of Ag and high stability of Au, reducing costs. The metasurface will be fabricated in the nanofabrication facility at IISER using a novel fabrication technique developed during the PhD. The nanostructures, defined by e-beam lithography and made of a bilayer of Au and Ag, will be annealed at low temperature to form AuAg alloy. The low-temperature annealing helps retain the shape of the nanostructure and optical responses. The metasurface will be measured using the plasmon polarimetry setup available in Prof. Ghosh's laboratory. The metasurfaces made of two different alloys, resonant at different wavelengths, will be multiplexed using a microfluidic chip, resulting in a lab-on-chip biosensor. Measurements will be carried out with collaborators in the material science department at IISER Kolkata. |