Dual-mode strain sensor with visible spectrum color switching and resistive responses for complex deformation monitoring

The rapid development of flexible electronics has driven an urgent demand for advanced sensors in fields such as health monitoring. However, most of the existing flexible strain sensors still rely solely on electrical signal output and cannot provide intuitive and real-time visual feedback. Inspired by the rapid color changing ability of natural organisms, a stretchable and visualized optical-electrical cooperative response sensor was proposed. The sensor integrates a dynamic structural color hydrogel with patterned liquid metal electrodes, enabling simultaneous deformation sensing and visualization by adjusting periodic structural spacing and reconstructing conductive paths. Specifically, the sensor exhibits a stable, vivid, and continuously adjustable structural color response, achieving a strain detection sensitivity of 1.66 nm/% with a measurement range covering 0 %–100 %, and features good cycling stability and mechanical durability (>1000 cycles). It presents a unique optical-electrical cooperative response, enabling real-time visualization and precise electrical signal monitoring of human joint motions and complex tactile forces. This research provides an effective strategy for strain visualization sensing and is expected to be applied in fields such as wearable devices and human-computer interaction.