Self-Healing, Degradable, and Biobased Polyurethane Elastomer for High-Performance Piezoresistive Pressure Sensors with a Hump-like Microstructure

Abstract

Flexible sensors are widely applied in the fields of electronic skins and wearable devices, yet it is still a big challenge to effectively prolong the lifespan of the damaged sensors and reduce environmental pollution caused by discarded sensors after updating and upgrading. Herein, we proposed a self-healing, degradable, and biobased polyurethane elastomer for high-performance flexible pressure sensors. The elastomer synthesized using fatty diamine as a chain extender possessed a high tensile strength of 13.25 MPa and an elongation at break of 830%, and the self-healing efficiency reached up to 109.2%. Additionally, the elastomer could be fully degraded within 7 days in a 1 mol L^–1 NaOH solution with the assistance of ethanol. The elastomer-based pressure sensor with a hump-like microstructure was fabricated with reduced graphene oxide as the conductive material via a simple template method. The sensor showed a high sensitivity of 9.448 kPa^–1, a large sensing range of 0–300 kPa, a short response/recovery time of 40/80 ms, and a good sensing stability of 14,000 cycles. Moreover, the sensor was utilized to monitor different human motions, including muscle contraction, joint bending, swallowing, voice recognition, and pulse beat. Importantly, even after being severely damaged, the sensor was able to recover its function in detecting human motions. The findings of this research provide a strategy for the sustainable development of environmentally friendly and functional elastomers and flexible sensors.