To develop a smart contact lens for non-invasive ocular blood oxygen saturation monitoring.
Approach:
Device Design: A flexible plasmonic nano-confinement nanowire photodetector integrated into a soft contact lens, adapting pulse oximetry principles for ocular use.
Measurement Technique: Utilizes red and near-infrared LEDs to illuminate the eyelid and captures photoplethysmography signals from eyelid capillaries.
Nanowire Architecture: Employs a PEDOT:PSS nanowire array embedded with gold nanoparticles to enhance organic photodetector performance.
Testing and Validation: Initial testing showed high agreement with commercial oximeters, and evaluations in anesthetized rabbits demonstrated parallel SpO₂ readings.
Key Findings:
The smart lens achieved approximately 99 percent average agreement with a commercial finger-clip oximeter.
The PNC nanowire architecture improved test accuracy by 35 percent compared to sensors without it.
Eyelid SpO₂ readings changed in parallel with peripheral SpO₂ under varying oxygen conditions.
Interpretation:
The device maintained high transmittance and mechanical stability, showing promise for continuous monitoring of ocular oxygen saturation.
Limitations:
Validation covered an SpO₂ range of roughly 84–100 percent, excluding severe hypoxaemia.
Testing was conducted in anesthetized animals, minimizing blinking and eye-motion artefacts.
Conclusion:
Future work will focus on improving lens stability, long-term exposure to tear fluid, and integrating wireless operation.
