Ultrasensitive and Highly Compressive Piezoresistive Sensor Based on Biopolyol-Reinforced Polyurethane Sponge Coated with Silver Nanoparticles and Carbon Nanotubes/Cellulose Nanocrystals
Wearable, lightweight and wide-range detecting piezoresistive sensor is highly desired for the development of flexible electronic industry. However, it is still a great challenge to fabricate piezoresistive sensor with both wide sensing range and high sensitivity. In this study, we prepared a biopolyol-reinforced self-healing polyurethane sponge containing reversible oxime-carbamate bonds for the first time. Based on this sponge, a lightweight piezoresistive sensor based on silver nanoparticles/carbon nanotubes-cellulose nanocrystals and tannic acid decorated polyurethane (AgNPs/CNTs-CNCs@TA-PU) sponge was obtained through simple repeated dipping-drying procedures. The resultant conductive AgNPs/CNTs-CNCs@TA-PU sponge exhibits wide compressive stress range (0~788.3 kPa), superior sensitivity and exceptional durability. Owing to the presence of dynamic oxime-carbamate bonds in sponge matrix, the conductive sponge can be self-healed by heating at 110 ℃ for 1 h and shows a self-healing efficiency of 80.3%. More importantly, this conductive sponge is sensitive enough, and its gauge factor is as high as 17.1 in the compressive strain range of 0~1% due to the microcrack structure and fractured skeletons. Finally, we demonstrated the applications of the as-prepared AgNPs/CNTs-CNCs@TA-PU sponge-based piezoresistive sensor in human motion monitoring and detecting water droplets, indicating its potential for wearable electronics and artificial intelligence.