# Practical and Compact Guided Mode Resonance Sensing System for Highly Sensitive Real-Time Detection

## TL;DR

This paper introduces an improved guided mode resonance sensor system that enables highly sensitive and real-time detection with enhanced usability and performance.

## Contribution

The study introduces an optimized GMR detection system using the Jones matrix method and optimized sensor structure parameters for improved practicality and sensitivity.

## Key findings

- The GMR sensor achieved a normalized sensitivity of 0.4 RIU−1 and an RI resolution of 8.15 × 10−5 RIU.
- The system demonstrates exceptional performance in detecting refractive index changes using sucrose concentration variations.
- The optimized design improves user-friendliness, cost efficiency, and performance for biosensing and optical metrology applications.

## Abstract

Guided mode resonance (GMR) sensors are known for their ultrasensitive and label-free detection, achieved by assessing refractive index (RI) variations on grating surfaces. However, conventional systems often require manual adjustments, which limits their practical applicability. Therefore, this study enhances the practicality of GMR sensors by introducing an optimized detection system based on the Jones matrix method. In addition, finite element method simulations were performed to optimize the GMR sensor structure parameter. The GMR sensor chip consists of three main components: a cyclic olefin copolymer (COC) substrate with a one-dimensional grating structure of a period of ~295 nm, a height of ~100 nm, and a ~130 nm thick TiO2 waveguide layer that enhances the light confinement; an integrated COC microfluidic module featuring a microchannel; and flexible tubes for efficient sample handling. A GMR sensor in conjunction with a specially designed system was used to perform RI measurements across varying concentrations of sucrose. The results demonstrate its exceptional performance, with a normalized sensitivity (Sn) and RI resolution (Rs) of 0.4 RIU−1 and 8.15 × 10−5 RIU, respectively. The proposed detection system not only offers improved user-friendliness and cost efficiency but also delivers an enhanced performance, making it ideal for scientific and industrial applications, including biosensing and optical metrology, where precise polarization control is crucial.