银纳米线电极微结构对柔性压力传感器灵敏度的影响

The Effect of Electrode Micro-structure Based on Ag Nanowires on Sensitivity of Flexible Pressure Sensor

新型柔性压力传感器具有类似人体皮肤的可拉伸性以及对外力的感知特性,可被用于仿生电子皮肤及各种可穿戴电子设备,近年来引起了学术界和产业界的广泛关注。开发具有优异的传感灵敏度且制作工艺简单、节能、成本低廉的柔性压力传感器具有重要的科学与实际意义。本文以银纳米线(AgNWs)为电极材料,聚二甲基硅氧烷(PDMS)为柔性基底,分别采用PDMS相纸原位固化和抽滤转移固化2种方式制备银纳米线/PDMS复合电极,以聚酰亚胺薄膜(PI)为介电层,将两电极面对面层压封装,得到电容式柔性压力传感器。利用激光共聚焦显微镜和扫描电镜比较了2种制作工艺得到的电极微结构,并研究了上述电极微结构结构对传感器灵敏度的影响。研究结果表明,电极表面银纳米线的蓬松程度及粗糙度能显著影响器件灵敏度。电极表面银纳米线处于较密实状态、粗糙度为0.4μm的传感器灵敏度约为0.43kPa-1;当电极表面银纳米线较为蓬松且粗糙度增大为0.7μm时,传感器灵敏度增大到0.65kPa-1。本文制作的柔性压力传感器具有高灵敏度、低成本的特点,可用于诸如脉搏、心率,发声震动,细微压力变化监控等方面。

The novel flexible pressure sensor with skin-like stretchability and sensibility has attracted tremendous attention in academic and industrial fields in recent years. And it also has demonstrated great potential in the applications of electronic skin and wearable devices. It is significant and challenging to develop a highly sensitive flexible pressure sensor with a simple, low energy consuming and low cost method. The silver nanowires （AgNWs） as electrode material were synthesized by polyol process. The polydimethylsiloxane（PDMS ） was chosen as a flexible substrate and polyimide （PI）film as dielectric layer. The AgNWs based electrode wasprepared in two methods. One is coating the AgNWs on photographic paper followed by in situ PDMS curing. Another one is suction filtration of the AgNWs suspension followed by glass slide transfer and PDMS curing Then the capacitive pressure sensor was packaged by two electrodes face to face and a sandwiched PI film. The micro-structure.of the electrodes based AgNWs was observed by laser scanning confocal microscope and scan- ning electron microscope. And the effect of electrode micro-structure on the sensitivity of sensor was studied The results indicate that the tightness of AgNWs coating on electrode surface plays an important role in the sen-sitivity of sensor. When the AgNWs is well-knit and the surface roughness of electrode is about 0.4 μ m, the sensitivity is about 0.43kPa-1. Meanwhile when the AgNWs is loosened and the surface roughness is about 0.7 μ m, the sensitivity increase to 0.65kPa-L The flexible pressure sensor was prepared with low cost, low energy consuming and high sensitivity, which has great potential in the detection of pulse, heart rate, sound vibra-tion and tiny pressure.