Superhydrophobic MXene@carboxylated carbon nanotubes/carboxymethyl chitosan aerogel for piezoresistive pressure sensor

Flexible and wearable pressure sensors have attracted considerable attention for the wide application prospect in robot sensing, intelligent electronic skin and healthcare monitoring. Herein, a superhydrophobic MXene-coated carboxylated carbon nanotubes (C-CNTs)/carboxymethyl chitosan (CCS) aerogel with honeycomb-like porous microstructure was proposed for piezoresistive pressure sensor. Firstly, a C-CNTs/CCS aerogel with superior robustness, resilience and durability was fabricated via directional freeze-drying method. Secondly, the C-CNTs/CCS aerogel was dip-coated with a layer of MXene nanosheets and then chemically modified with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS). The obtained [email protected]/CCS aerogel demonstrated superhydrophobicity and the water contact angle and artificial sweat contact angle reached 157° and 154°, respectively. Thanks to the synergism of the dual-conductive MXene-CNTs network, the aerogel-based pressure sensor realized fast response time (62 ms), wide detection range (up to 80 kPa) as well as excellent electrical stability and repeatability even under humid and sweaty environments. Additionally, the sensor was successfully applied for monitoring human motions including not only large-scale actions (joint movements, walking and running) but also small-scale muscle movements (pronunciation recognition and finger tapping). Interestingly, the sensor connected to an Arduino microcontroller circuit with Bluetooth module was able to wirelessly detect real-time movements of finger joints. Our findings conceivably stand out as a new strategy to fabricate high-performance piezoresistive pressure sensors for wide applications even at special working conditions.