Highly\nSensitive Flexible Piezoresistive Sensor with\n3D Conductive Network

Abstract

The flexible piezoresistive\nsensor has attracted more and more\nattention in health monitoring as a man–machine interface due\nto its simple structure and convenient signal reading. Herein, a highly\nsensitive flexible piezoresistive sensor with a 3D conductive sensing\nunit is presented. The 3D conductive sensing unit consists of a 3D\nnetwork thermoplastic elastomer (TPE) substrate fabricated by fused\ndeposition molding (FDM) 3D printing and carbon nanotubes (CNTs) conductive\nlayer embedded into the surface of the TPE substrate. The finite element\nanalysis (FEA) shows that the 3D network structure has excellent mechanical\nproperties, which is basically consistent with the experimental results.\nExperimentally, based on the novel 3D conductive network, the flexible\npiezoresistive sensor exhibits superior comprehensive properties in\nthe compressed or stretched state. The sensitivity of the sensor is\nas high as 136.8 kPa^–1 at an applied pressure <200\nPa while compressing, and its gauge factor (GF) can reach 6.85 while\nstretching. Meanwhile, the sensor shows excellent stability and durability\nperformance because CNTs embedded into the surface of the TPE substrate\nhave little effect on the flexibility of the elastomeric composite\nof the sensor. Finally, the piezoresistive sensor is used for detecting\nsubtle muscular movements (facial expressing and throat swallowing)\nand body movement like arm bending. These results indicate that the\nnovel 3D conductive structure provides an alternative way to improve\nthe performance of piezoresistive sensors and extend their potential\napplications in health monitoring.