Preparation and electromechanical performance of CS-MXene-NH₂-CNTs/PU composite sponge pressure sensor based on 1D/2D hierarchical hybrid networks

To address the shortcoming that current flexible pressure sensor struggle to balance sensitivity and detection range, a chitosan-MXene-amino-functionalized carbon nanotubes/polyurethane (CS-MXene-NH₂-CNTs/PU, denoted as CMNP) composite sponge flexible pressure sensor with a hierarchical conductive network was constructed using polyurethane (PU) sponge as the substrate through an electrostatic layer-by-layer self-assembly technique. The electrostatic interaction between the positively charged chitosan (CS), amino-functionalized carbon nanotubes (NH₂-CNTs), and negatively charged MXene was utilized. The surface morphology of the CMNP sponge was characterized, and the sensing mechanism, mechanical properties, and electromechanical response characteristics of the sensor were investigated.The results show that, benefiting from the hybrid conductive network formed by one-dimensional (1D) NH₂-CNTs and two-dimensional (2D) MXene as well as the synergistic mechanism of micro-crack effect and contact conductance, the sensor possesses a high sensitivity of 34.93 kPa⁻¹ (1.83~4.98 kPa), a very low detection limit (100 Pa), a wide detection range (1000 kPa), fast response/recovery times 40 ms/46 ms), and excellent cyclic stability (> 12000 cycles). The developed sensor holds great promise for human health monitoring and motion recognition applications. Furthermore, by integrating this sensor with a one-dimensional convolutional neural network (1D-CNN), an intelligent tactile interactive keyboard system was constructed, achieving a 100% overall accuracy in identifying five typical dynamic tactile actions. This work highlights the broad application prospects of the sensor in wearable electronics and human-machine interaction.