Wide-Range and Sensitive Piezoresistive Sensor Based on Chitosan-Modified Polyurethane Foam-Coated MXene Nanosheets

Current flexible piezoresistive sensors face the common problem that there is always a mutual limitation between high sensitivity and a wide measuring range, causing the current highly sensitive sensors to concentrate only on a narrow range. In this work, inspired by biological architecture, we design a needle-shaped column array decompression structure, combined with chitosan-modified polyurethane foam-coated MXene nanosheets as the sensor active layer. By leveraging the decompression of the needle column structure and the high elasticity properties of the porous structure, the piezoresistive sensor demonstrates a broad testing range of 550 kPa and a maximum sensitivity of 428.94 kPa–1 in the measurable range, which are 10 and 2 times higher than those of existing studies. Combined with medical devices, the designed devices can meet the testing requirements of different scenarios to accurately capture all kinds of training and human movement behavior recognition in the rehabilitation medical process. We provide a strategy in which introducing a voltage divider structure in the active layer enables flexible piezoresistive sensors to combine high sensitivity with a several-fold increase in range.