Self-Powered Integrated Tactile Sensing System Based on Ultrastretchable, Self-Healing and 3D Printable Ionic Conductive Hydrogel

Abstract

Self-healing ionic conductive hydrogels have shown significant potential in applications like wearable electronics, soft robotics, and prosthetics because of their high strain sensitivity and mechanical and electrical recovery after damage. Despite the enormous interest in these materials, conventional fabrication techniques hamper their use in advanced devices since only limited geometries can be obtained, preventing proper conformability to the complexity of human or robotic bodies. Here, a photocurable hydrogel with excellent sensitivity to mechanical deformations based on a semi-interpenetrating polymeric network is reported, which holds remarkable mechanical properties (ultimate tensile strain of 550%) and spontaneous self-healing capabilities, with complete recovery of its strain sensitivity after damages. Furthermore, the developed material can be processed by digital light processing 3D printing technology to fabricate complex-shaped strain sensors, increasing mechanical stress sensitivity with respect to simple sensor geometries, reaching an exceptional pressure detection limit below 1 Pa. Additionally, the hydrogel is used as an electrolyte in the fabrication of a laser-induced graphene-based supercapacitor, then incorporated into a 3D-printed sensor to create a self-powered, fully integrated device. These findings demonstrate that by using 3D printing, it is possible to produce multifunctional, self-powered sensors, appropriately shaped depending on the various applications, without the use of bulky batteries.