Skin-Inspired Modulus Gradient Porous Conductive Elastomers for High-Performance Tactile Sensors

We report a simple, low-cost approach to fabricate porous conductive elastomers for high-performance flexible tactile sensors. Sodium chloride (NaCl) microparticles was used as the template sacrifice reagent and elastic modulus tuner to tune the as-prepared elastomers from “hard” to “soft”. Inspired by the gradient modulus structure, the flexible tactile sensors with modulus from “hard to soft” and “soft to hard” were successfully fabricated via three layers of thermoplastic and a demolding process. The skin-inspired “soft to hard” flexible tactile sensors exhibited a high sensitivity of 12.9 MPa$^{-1}$ (0-50 kPa) with a wide operating range of 0-277.5 kPa than that of the individual layers. The mechanism working principles were discussed. The as-prepared “soft to hard” flexible tactile sensor showed an ultrafast response (14.2 ms) and recovery time (57.1 ms), vibration perception ability (0.1 Hz to 1.0 Hz), and over 10,000 excellent durability and stability without noticeable creeping. This work provides a new perspective and strategy to fabricate sensitive, wide-range, low-cost tactile electronics for soft robots, wearable electronics, and human-machine intelligence.