Yu Rui, Xia Tiancheng, Wu Bang, Yuan Jun, Ma Lijun, Cheng Gary J, Liu Feng
School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China.
Institute of Technological Sciences, Wuhan University, Wuhan, Hubei 430072, China.
ACS Appl Mater Interfaces. 2020 Aug 5;12(31):35291-35299. doi: 10.1021/acsami.0c09552. Epub 2020 Jul 23.
The flexible piezoresistive sensor has attracted more and more attention in health monitoring as a man-machine interface due to its simple structure and convenient signal reading. Herein, a highly sensitive flexible piezoresistive sensor with a 3D conductive sensing unit is presented. The 3D conductive sensing unit consists of a 3D network thermoplastic elastomer (TPE) substrate fabricated by fused deposition molding (FDM) 3D printing and carbon nanotubes (CNTs) conductive layer embedded into the surface of the TPE substrate. The finite element analysis (FEA) shows that the 3D network structure has excellent mechanical properties, which is basically consistent with the experimental results. Experimentally, based on the novel 3D conductive network, the flexible piezoresistive sensor exhibits superior comprehensive properties in the compressed or stretched state. The sensitivity of the sensor is as high as 136.8 kPa at an applied pressure <200 Pa while compressing, and its gauge factor (GF) can reach 6.85 while stretching. Meanwhile, the sensor shows excellent stability and durability performance because CNTs embedded into the surface of the TPE substrate have little effect on the flexibility of the elastomeric composite of the sensor. Finally, the piezoresistive sensor is used for detecting subtle muscular movements (facial expressing and throat swallowing) and body movement like arm bending. These results indicate that the novel 3D conductive structure provides an alternative way to improve the performance of piezoresistive sensors and extend their potential applications in health monitoring.
柔性压阻式传感器因其结构简单且信号读取方便，作为人机接口在健康监测领域越来越受到关注。在此，我们展示了一种具有三维导电传感单元的高灵敏度柔性压阻式传感器。该三维导电传感单元由通过熔融沉积成型（FDM）3D打印制造的三维网络热塑性弹性体（TPE）基板和嵌入TPE基板表面的碳纳米管（CNT）导电层组成。有限元分析（FEA）表明，三维网络结构具有优异的力学性能，这与实验结果基本一致。实验上，基于这种新型三维导电网络，柔性压阻式传感器在压缩或拉伸状态下均表现出优异的综合性能。在压缩时，当施加压力<200 Pa时，传感器的灵敏度高达136.8 kPa，而在拉伸时其应变片系数（GF）可达6.85。同时，该传感器表现出优异的稳定性和耐久性，因为嵌入TPE基板表面的碳纳米管对传感器弹性体复合材料的柔韧性影响很小。最后，该压阻式传感器用于检测细微的肌肉运动（面部表情和吞咽）以及诸如手臂弯曲等身体运动。这些结果表明，这种新型三维导电结构为提高压阻式传感器的性能并扩展其在健康监测中的潜在应用提供了一种替代方法。
