Tracheid-inspired nanoarchitectured carbon-based aerogels with ultra-compressibility for wearable piezoresistive sensors

Carbon-based aerogels are difficult to accomplish satisfactory mechanical strength and fatigue resistance due to the brittleness of framework, limiting their application in piezoresistive sensors. In this work, inspired by tracheid structure in plants, flexible piezoresistive sensors were prepared based on stable and elastic carbon-based aerogels with a long-range oriented multiscale matrix structure. The carbon-based aerogel was generated by bidirectional freezing and further assembled to i) 2D morphology Ti3C2Tx MXene as conductive framework and ii) cellulose nanofibers (CNF) offering abundant hydroxyl groups as flexible substrate. Besides, positively charged chitosan was introduced to serve as “bridging junction reinforcement element”, which tightly connects CNF and Ti3C2Tx, contributing to improved strength and stability of the carbon-based aerogel. According to finite element simulation, the bonding and supporting effect of chitosan is confirmed, and the aligned carbon layer and elastic supporting microstructure can be directly modulated. Interestingly, the piezoresistive sensor exhibits super-compressibility which can withstand 10,000 cycles under 50% strain, showing a fast response time (6.3 ms) and high sensitivity (177.08 kPa−1). Briefly, this work provides an innovative strategy to obtain nanoarchitecture functional materials integrating multiscale microstructures into carbon-based aerogels, demonstrating their potential to improve the sensing characteristics and functionality of wearable piezoresistive sensors.