A smart contact lens with plasmonic nano-confinement nanowire array for non-invasive ocular blood oxygen saturation monitoring

Ocular blood oxygen saturation is critical for detecting vision-threatening and systemic diseases. Existing wearable oxygen sensors are unsuitable for ocular use, and current ocular SpO₂ measurements rely on bulky equipment. This work introduces a flexible plasmonic nano-confinement (PNC) nanowire photodetector, based on a PNC nanowire array consisting of highly aligned and ordered PEDOT:PSS nanowires with embedded gold nanoparticles, for high-sensitivity oxygen saturation sensing. The PNC nanowire array acts as an anode interfacial modification layer, where nanowire-geometry-induced confinement and localized surface plasmon resonance synergistically lower the hole-extraction barrier, suppress interfacial recombination, and enhance photoconversion efficiency. Its flexible and transparent design, combined with a compact backend circuit using wavelet-threshold denoising, enables integration into a smart contact lens for accurate and stable non-invasive ocular oxygen monitoring. In vivo experiments demonstrate that this smart contact lens could provide a simple, non-invasive platform for continuous ocular SpO₂ monitoring, with potential relevance to systemic oxygen-status assessment.