MXene/rGO piezoresistive sensor based on Longan leaves’ hierarchical microstructure for human-motion detection

Abstract

Flexible pressure sensors exhibit great application potential in wearable devices, human-computer interaction, medical monitoring and other fields and thereby have attracted much attention. However, a common challenge in piezoresistive sensors is the trade-off between sensing range and sensitivity, which limits their versatility across various applications. By employing Longan leaf as a hierarchical microstructure template, the sensing range and sensitivity can be significantly improved at low cost, based on fractal theory. MXene was used as the sensing material, and a systematic study was conducted concerning the effect of MXene concentration on the sensor's sensitivity and detection range, which revealed that the sensitivity firstly increased and then decreased with MXene concentration ranging from 5 mg/mL to 30 mg/mL. Furthermore, based on the solution method to prepare composite sensing layer, MXene and rGO were mixed in proportion to obtain a sensing network that can coordinate with each other. When the volume ratio was 1:1, and the concentration of MXene was up to 15 mg/mL, the fabricated sensor demonstrated high sensitivity (47.36 kPa−1) and wide detection range (>100 kPa) at the same time. In addition, the sensor was successfully used to monitor various human joint activities and physiological signals, which was also expected to provide a competitive scheme for wearable flexible electronic devices in human-motion detection.