# Design and Optimization of SiON Ring Resonator-Based Biosensors for Aflatoxin M1 Detection

## TL;DR

This paper presents a biosensor using SiON ring resonators to detect aflatoxin M1 in milk with high sensitivity and low cost.

## Contribution

The study introduces a novel SiON-based biosensor optimized for detecting aflatoxin M1 at low concentrations.

## Key findings

- The biosensor achieved a detection limit of 12.5 nm for aflatoxin M1.
- SiON resonators demonstrated high sensitivity to refractive index changes below 10−6 RIU.
- Functionalized sensors showed reliable performance in real-world milk samples.

## Abstract

In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10−6 refractive index units (RIU). We tested various samples with different SiON refractive indexes as well as the waveguide dimensions for selecting the sensor with the best performance. Propagation losses and bending losses have been measured on test structures, along with a complete characterization of the resonator’s performances. Sensitivities and limit of detection (LOD) were also measured using glucose-water solutions and compared with expected results from simulations. Finally, we functionalized the resonator and performed sensing experiments with Aflatoxin M1 (AFM1). We were able to detect the binding of aflatoxin for concentrations as low as 12.5 nm. The results open up the path for designing cost-effective biosensors for a fast and reliable sensitive analysis of AFM1 in milk.