Design and analysis of a PCF SPR biosensor for glucose concentration in urine employing external sensing

This research introduces a surface plasmon sensor utilizing photonic crystal fiber (PCF) for measuring glucose concentrations in urine. The sensor employs a configuration with TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and gold as plasmonic materials, layered strategically to improve its performance. Simulation of the proposed sensor, using a finite element approach, focuses on detecting urine glucose levels. The setup involves applying a thin analyte layer onto the TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> layer of the PCF to enable external sensing capabilities. Testing is conducted across four distinct glucose concentration levels: 0 gm / dL, 2.5 gm / dL, 5 gm / dL, 10 gm / dL, and 20 gm / dL, corresponding to refractive indices (RI) of $1.335,1.338,1.341,1.346$, and 1.358, respectively. A perfectly matched layer (PML) acts as the boundary condition for the topmost PCF layer. By adjusting geometrical parameters, an optimized structural design is achieved, resulting in a wavelength sensitivity of 3945.12 ~nm / RIU and an amplitude sensitivity of 438 RIU⁻¹ for 2.5 gm / dL. Experimental validation using various urine samples demonstrates superior accuracy and sensitivity compared to existing methods.