基于双向拉伸制备还原氧化石墨烯-碳纳米管复合薄膜的高性能柔性压阻传感器

High-performance flexible piezoresistive strain sensor based on biaxially stretched conductive polymer composite films with reduced graphene oxide-carbon nanotubes

随着现代科技的快速发展及人们生活水平的提高,柔性压阻传感器在人体健康监测、智能机器人、可穿戴电子设备和人机交互等方面展现了巨大应用潜力。本文采用Hummer’s法制备了还原氧化石墨烯(rGO),其后通过静电组装将碳纳米管(CNT)负载在rGO的表面上,并将其引入热塑性聚氨酯(TPU)基体中制备成导电纳米复合材料。此外,采用逐次双向拉伸技术实现了基体中纳米填料的进一步分散和平行取向,并基于所获得的复合薄膜研制出了一种可监测微小应变的高性能柔性压阻传感器。研究发现,rGO-CNT/TPU_(4×4)传感器(拉伸比为4×4)在保持高灵敏度(1.5%应变的情况下灵敏度(G_(F))=46.7)和高线性度(R^(2)=0.98)的同时,能够适用于不同应变和频率变化,并且在循环加载测试中展出优异的稳定性和可重复性。该柔性压阻传感器可以用于识别细微的人体生理活动,包括脉搏和呼气等。此外,还设计制备了一个可压缩的传感器阵列来监测在不同压力下的信号变化情况。本研究对于高性能柔性压阻应变传感器的快速宏量制备及结构与性能调控具有重要的科学指导意义。

In recent years,flexible piezoresistive sensors have shown great application potential in human health monitoring,smart robots,wearable electronic devices,and human-computer interaction,while it is challenging to efficiently fabricate highly sensitive and low-cost flexible piezoresistive sensor for detecting micro strains.In this work,reduced graphene oxide(rGO)was prepared by Hummer's method,then carbon nanotubes(CNTs)were immobilized on the surface of rGO by electrostatic assembly.Subsequently,the hybrid nanofillers were introduced into thermoplastic polyurethane(TPU)matrix to prepare conductive polymer composite.The further dispersion and parallel orientation of nanofillers in the matrix were achieved by the sequential biaxial stretching process.It is shown that the sensor prepared by biaxially stretched conductive polymer composite exhibits higher sensing per-formance compared to the sensor without experiencing biaxial stretching.The rGO-CNT/TPU_(4×4) sensor(with a stretching ratio of 4×4)shows high sensitivity(G_(F)=46.7 at 1.5%strain),high linearity(R^(2)=0.98),responsive capability to different strains and frequencies,excellent stability and repeatability in cyclic loading tests.The flexible piezoresistive sensor can be used to identify subtle human physiological activities,including pulse and exhalation.In addition,a compressible sensor array was fabricated to achieve accurate identification of weight distribution.This study provides an important scientific guidance for the rapid large-scale fabrication and structure and property tuning of high-performance flexible piezoresistive strain sensors.