Highly Accurate Wearable Piezoresistive Sensors without Tension Disturbance Based on Weaved Conductive Yarn

Abstract

Wearable piezoresistive sensors have attracted wide attention for application in human activities monitoring, smart robots, medical detection, etc. However, most of the sensing signals collected from the piezoresistive sensor are triggered by coupling forces, such as the combination of tension and pressure. Thus, the piezoresistive sensor would be incapable of accurately monitoring and evaluating specific human motion due to the mutual interference from tension and pressure, as the tension is difficult to be decoupled or eliminated from the coupling forces. Herein a prestretchable conductive yarn (PCY) sensor with pressure sensitivity but tension insensitivity was introduced to remove the disturbance from tension. The PCY-based piezoresistive sensor is tension insensitive (gauge factor of 0.11) but pressure sensitive (sensitivity of 187.33 MPa-1). The fabric-based pressure sensor assembled with cross-arranged PCY weft and warp revealed magnified pressure sensitivity compared with the single PCY yarn sensor, as well as tension insensitivity to strain and tensile angle. Moreover, it possessed benign cyclicity during 5000 cycles of pressing/releasing. Therefore, the fabric piezoresistive sensor based on weaved conductive yarns is suitable for highly accurate and large area pressure detection, such as monitoring massage intensity of acupuncture points.