Bilayer piezoionic sensors for enhanced detection of dynamic, static, and directional forces with self-healing capabilities

Abstract

Electronic skin (e-skin) aims to replicate the tactile feedback mechanism of natural skin, offering great potential across robotics, healthcare monitoring, and human-machine interfaces. Traditional e-skin systems utilize electron-based sensing through capacitance and piezoresistivity for static forces, and piezoelectricity and triboelectricity for dynamic forces. However, the former group struggles with dynamic stimuli and external power dependencies, while the latter excels in self-powering but fails in static detection. Addressing these gaps, iontronics emerges as a versatile solution, providing innovative avenues for energy harvesting, sensing, and actuation through ion redistribution in response to varied stimuli, but shows limitations in output signals and response times. We report herein the development of bilayerstructured piezoionic materials with significantly enhanced output signal and response time. The piezoionic bilayer structure not only harnesses an ion accumulation interface, leading to amplified output signals and fast response times, but also exhibits an ion-dipole interactive self-healing property. Our sensor generates a signal output of 95 mV and features a quick response time of 30 ms, with an impressive self-healing capability of similar to 100%. It demonstrates the ability to accurately detect both static and dynamic forces, including specific movements like bending and vibrations, maintaining its robustness through 8000 cycles of repetitive deformation. Its utility is further proven in a practical setting with a braille reader device, highlighting its potential for incorporation into a wide array of soft, autonomous iontronic systems that require enhanced sensitivity, rapid detection capabilities, and self-sustainability.