A skin-beyond tactile sensor as interfaces between the prosthetics and biological systems

Abstract

Tactile electronic skin that could interface with biological nerve systems is essential for intelligent robotic prosthetics, human augmentation, novel human-machine interfaces. Although the use of soft elastomers with large compressibility and creating microstructures improved sensitivity and pressure sensing range, the intrinsic viscoelasticity of soft elastomers still results in slow response and cyclic hysteresis. Furtherly, due to the contradiction between compressibility and viscoelasticity of soft elastomers, elastomer-based tactile sensors with an optimal trade-off among sensitivity, sensing range, response speed, and low hysteresis remain a long-standing challenge. Here, we introduce the composite film through doping expandable microspheres into soft elastomers to achieve the optimal trade-off between compressibility and viscoelastic. We then report a tactile sensor based on the composite film with an enhanced irregular structure, which features high sensitivities (2093 kPa-1), low limit of detection (< 0.43 mN), fast response (< 4 ms), and low hysteresis (3.26%), exhibiting SA-I beyond and comparable low-frequency FA-I sensing capabilities. We demonstrate that the tactile sensor can simultaneously and independently encode the dynamic and static components of the pressure signals into frequency-modulated signals, respectively, closely mimicking SA-I receptors and FA-I receptors through computational approaches. This work provides a possible routine for advanced tactile sensors and minimalist artificial skin interfacing with biological nerve systems.