Biomimetic Photonic Crystal Double Network Hydrogel for a Wearable Strain Sensor with Photoelectric Synergy

Wearable electronic devices mainly respond to a single electrical signal and lack direct visual feedback, which limits their diversified applications in human-computer interfaces. Furthermore, traditional wearable strain sensors necessitate additional devices for wearing. Addressing the limitations of conventional sensors that rely solely on a single electrical signal and are cumbersome to wear, a novel dual-signal wearable sensor with a composite structure has been designed and fabricated. This device comprises a photonic crystal film (embedded with PS@SiO 2 core–shell nanosphere arrays) and a double-network conductive hydrogel (AA-NVP/CMC/Zn 2+ ), enabling the synchronous output of electrical and optical signals. Additionally, the hydrogel layer provides robust skin adhesion, allowing for direct wearing. Within the effective tensile range of 0% to 58%, the sensor exhibited favorable cooperative response characteristics with an optical sensitivity of 1.43 nm% –1 and an electrical strain coefficient of 2.8; furthermore, its performance remained stable after 100 cycles. In practical applications, the sensor successfully achieves real-time monitoring of finger, wrist, and knee movements. Structural color changes offer intuitive visual feedback without the need for electronic devices. The dual-signal mechanism effectively mitigates environmental interferences such as temperature and humidity. The stable dual-signal response output provides a universal platform for visual interaction with electronic devices.