MEMS-Based Biosensor Design and Microfabrication for Tear Glucose Sensing

Continuous glucose monitoring using smart contact lenses offers a promising non-invasive alternative for diabetes management; however, reliable wireless power delivery and integration of rigid microelectronic components into soft contact lens substrates remain significant engineering challenges. This study presents a battery-free smart contact lens platform integrating MEMS biosensors with a wireless power transfer (WPT) system for real-time tear glucose monitoring. The system employs a near-field communication (NFC) inductive coupling architecture operating at 13.56 MHz, incorporating a miniaturized microcoil embedded within a transparent SU-8/PDMS composite to maintain optical clarity and biocompatibility. A peripheral active-zone integration strategy places electronic components outside the optical region, ensuring unobstructed vision while maximizing power transfer efficiency. The power management module integrates a multi-stage rectifier and a high-efficiency buck–boost converter fabricated on a flexible polyimide substrate, achieving conversion efficiencies exceeding 95%. Experimental evaluation demonstrates a wireless power transfer efficiency of 31.4%, delivering a stable continuous power supply of 30–35 mW suitable for sustained biosensor operation and wireless telemetry. A supercapacitor-based energy buffering system further stabilizes transient load variations during data transmission. To enable reliable integration on curved substrates, a sacrificial-layer flattening technique and compliance-based stress mitigation framework were developed, ensuring mechanical reliability and long-term lens comfort. The proposed architecture establishes a scalable wireless power and integration framework for next-generation wearable biosensing platforms, enabling clinically deployable smart contact lenses for continuous, non-invasive glucose monitoring in diabetic patients.