Wearable eye health monitoring sensors based on peacock tail-inspired inverse opal carbon

Multifunctional, comprehensive sensing and wear ability are desirable features for next-generation wearable sensors. Wearable sensors that simultaneously monitor human motion and biochemical indexes are increasingly exploited and are a rapidly evolving topic in point-of-care testing, personalized medicine and even artificial intelligence. However, fabricating highly integrated sensors with multiple functions remains challenging. Here, inspired by colorful peacock tail feathers, we designed and fabricated inverse opal carbon (IOC) rod electrodes by scarifying SiO₂ colloidal crystal templates and polymerizing a resorcinol-formaldehyde resin. Two parallel pillar electrodes were combined to mimic the barbs of bird feathers. The capillary forces between the pillars caused liquid to flow along the electrode. The unique optical properties of photonic crystals were utilized for fluorescence enhancement sensing of lactoferrin (LF) in tears. The IOC fibers’ high porosity enable highly sensitive electrochemical detection and high energy storage capacity. As a proof of concept, the IOC rod-based sensors were attached to eyelids to sense tear LF, glucose content and eye-movement frequency for the purpose of diagnosing diabetes-associated eye diseases. In addition to applications in eye healthcare, our concept offers a solution for hybrid physiological and biochemical monitoring of diseases, such as Huntington's and Parkinson's, that call for full-range diagnosis.