TPU/MOFs Electrospun Composite Film for Underwater Tactile Sensing and Finger Joint Bending Monitoring

Most flexible tactile pressure sensors can hardly be used in deep sea due to the strict water sealing requirement on the soft material and the hardening effect due to high hydroSstatic pressure. To address these issues, a self-powered and hydrostatic pressure-balanced underwater flexible tactile sensor based on an electrospun nanofiber film composed of a thermoplastic polyurethane elastomer (TPU) and Metal Organic Frameworks (MOFs-801) is presentedr. The sensor generates ionic current via different ion movement speeds under pressure, and can simultaneously achieve pressure and position sensing. Experimental results show the signal magnitude increases with the increase in the applied pressure, carboxyl group concentration, and stretching length. The direction and magnitude of the signal depend on the pressing or stretching position of the film, with bigger current magnitude closer to the film ends. The maximum sensitivity is 1.31 kPa^-1, with the response and recovery times of 0.16 and 0.51 s, respectively. The sensor remains operational after over 1400 cycles under 600 kPa external load. Furthermore, the signal magnitude decreased only by 10.38% under 100 m water depth. Proof of concept demonstration of object shape differentiation by monitoring the bending of finger joints is successfully achieved.