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Racetrack ring resonator-assisted MZI-based integrated optical biosensor with buffer layers for measuring blood
Kamakshi Manchikalapati1, Gopalkrishna Hegde2, Srinivas Talabattula1
1Dept of ECE, Indian Institute of Science, Bengaluru, 560012, India.
Biomedical Optics Express
|May 11, 2026
Summary
This study introduces a novel biosensor for glucose detection, combining racetrack ring resonators and Mach-Zehnder interferometers. It enhances accuracy and sensitivity using silicon nitride or fluorinated silicon dioxide buffer layers.
Area of Science:
- Photonics and Biosensing
- Optical Interferometry
- Nanomaterials
Background:
- Accurate glucose detection is crucial for diabetes management.
- Existing biosensors face challenges in achieving both high sensitivity and accuracy.
- Mach-Zehnder interferometers (MZI) offer accuracy, while racetrack ring resonators (RRR) provide sensitivity.
Purpose of the Study:
- To develop a highly sensitive and accurate glucose biosensor.
- To investigate the impact of buffer layers on biosensor performance.
- To present a novel two-racetrack ring assisted Mach-Zehnder interferometer (RRAMZI) configuration.
Main Methods:
- Fabrication of RRAMZI biosensor with silicon nitride (Si3N4) and fluorinated silicon dioxide (FSiO2) buffer layers.
- Integration of RRR for enhanced sensitivity and MZI for accuracy.
- Analytical modeling using the signal-flow graph (SFG) method.
Main Results:
- The Si3N4 buffer layer increased the quality factor to 1.435×10^3 by enhancing resonant depth.
- The FSiO2 buffer layer improved sensitivity to 400 nm/RIU by enhancing penetration depth.
- The RRAMZI configuration successfully combined high sensitivity and accuracy for glucose detection.
Conclusions:
- The RRAMZI configuration with optimized buffer layers offers a promising approach for advanced glucose biosensing.
- Buffer layer material selection significantly impacts biosensor performance metrics like resonant depth and penetration depth.
- The developed biosensor demonstrates potential for improved diagnostic tools in healthcare.
