Design and Fabrication of Plasmonic Nano-Array Patterns for Near-Infrared Fluorescent Biosensors

Detecting biological samples in blood plasma poses challenges due to interference from the blood plasma matrix. Enhancing sensitivity through near-infrared (NIR) detection is imperative to mitigate this interference. In this work, we have designed plasmonic nano-array patterns to enhance near-infrared fluorescence. A cylinder nano-array pattern has been studied systematically to tune electromagnetic field and quality factor. In addition, a metal-insulator-metal configuration has been designed and fabricated to achieve a plasmonic gap mode, which is coupled to the NIR fluorophore. Next, fluorescence enhancement by this plasmon gap mode has been measured. Finite-difference time-domain simulation has been performed to understand the fluorescence enhance mechanism. The results provide guidelines to design plasmonic nanostructures for enhancing near-infrared fluorescence, improve sensitivity of biosensors.