The Potential of Refractive Index Nanobiosensing Using a Multi-Band Optically Tuned Perfect Light Metamaterial Absorber

Abstract

An optically tunable perfect light absorber as a refractive index (RI) metamaterial (MM) nanobiosensor (NBS) is designed for sensing chemicals, monitoring the concentration of water-soluble glucose, and detecting viruses. This plasmon induced tunable metasurface works based on multiband super-absorption in the infrared frequency regime. It consists of a metal mirror that facilitates the MM to work as an absorber where the metal pattern at the top layer creates an enhanced evanescent wave that facilitates the metasurface to work as a RI optical sensor. The modelling and numerical analysis are carried out using Finite Difference Time Domain (FDTD) method-based software, CST microwave studio where a genetic algorithm (GA) is used to optimize the geometric parameters. We demonstrate multiband super-absorption spectra having maximum absorption of more than 99%. Furthermore, we show how the multiband super-absorber nanostructure can be used as a RI NBS, where the resonance frequency shifts with the RI of the surrounding medium. The achieved opto-chemical sensitivity is approximately 65 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nm</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RIU</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RIU</i> , the bio-optical sensitivity to detect viruses is approximately 76 nm / RIU; and the optical sensitivity of the water-soluble glucose concentration is about 300 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nm</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RIU</i> ; all sensitivities are comparable in comparison with the reported values in the literature.