Freezing-induced interfacial growth of polypyrrole layers on hierarchical carbon aerogels for robust ultrasensitive pressure sensors

Abstract

Constructing carbon-based aerogels with mechanical flexibility and good conductivity remains a challenge. Herein, cellulose nanofibers (CNF) as the building block to prepare CNF-based carbon aerogels (CCAs) by the “Bottom to up” strategy, while the polypyrrole (PPy) was interfacially grown on the CCAs to obtain PPy-carbon aerogels composites (CCAs-P). The PPy was uniformly and firmly loaded onto the CCAs framework, leading to the CCAs-P with excellent mechanical properties. The compressive stress of CCAs-P was over 20 times higher than that of CCAs under 80% strain, and its compressive stress was up to 800 kPa. Meanwhile, the CCAs-P had a great sensitivity to weak signals (~ 69 ms) which was capable of accurately monitoring and recording the signals of varied human motions. This is because the interfacial growth process of PPy produces more conducting channels. This study may help to advance the use of carbon-based aerogels in flexible wearable sensing systems.