Tunable thermal-response shape memory bio-polymer hydrogelsas body motion sensors

Wearable health monitoring smart systems are considered to be the next generation artificial intelligence devices for real-time tracking down human body motion. However, due to the stress relaxation and viscosity, the existed stretching sensor, especially most ultra-stretching ones, are hard to recover to their original shape after cycles repeatedly stretching, leading to inspection hysteresis and shorter service life. Herein, we reported an intelligent ionic conductive hydrogel (SAMA) as stretching sensor with good mechanical property and controllable thermal-response shape memory property. The obtained hydrogel sensor exhibited outstanding sensitivity to human body motion. Besides, it had a controllable upper critical solution temperature (UCST) from 15 ^oC to 58 ^oC through adjusting the concentration of Li⁺ in the hydrogel. When temperature above UCST, the deformed hydrogel could quickly recover to original shape within 30 seconds and regain sensitive inspection ability. Moreover, the shape memory ability of SAMA hydrogel exhibited a good reuseability at least 50 cycles. The unique stretching hydrogel sensor with controllable thermal-response shape memory could effectively solve the deformation problem of stretching sensor and prolong the service life, demonstrating great potential in the flexible wearable electronics and biologic devices.