Zhu Ziying, Cao Yunqi, Chi Haozhen, Wang Xiaowei, Hou Dibo
State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University.
State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University;
J Vis Exp. 2023 Mar 24(193). doi: 10.3791/65143.
Soft pressure sensors play a significant role in developing "man-machine" tactile sensation in soft robotics and haptic interfaces. Specifically, capacitive sensors with micro-structured polymer matrices have been explored with considerable effort because of their high sensitivity, wide linearity range, and fast response time. However, the improvement of the sensing performance often relies on the structural design of the dielectric layer, which requires sophisticated microfabrication facilities. This article reports a simple and low-cost method to fabricate porous capacitive pressure sensors with improved sensitivity using the solvent evaporation-based method to tune the porosity. The sensor consists of a porous polydimethylsiloxane (PDMS) dielectric layer bonded with top and bottom electrodes made of elastic conductive polymer composites (ECPCs). The electrodes were prepared by scrape-coating carbon nanotubes (CNTs)-doped PDMS conductive slurry into mold-patterned PDMS films. To optimize the porosity of the dielectric layer for enhanced sensing performance, the PDMS solution was diluted with toluene of different mass fractions instead of filtering or grinding the sugar pore-forming agent (PFA) into different sizes. The evaporation of the toluene solvent allowed the fast fabrication of a porous dielectric layer with controllable porosities. It was confirmed that the sensitivity could be enhanced more two-fold when the toluene to PDMS ratio was increased from 1:8 to 1:1. The research proposed in this work enables a low-cost method of fabricating fully integrated bionic soft robotic grippers with soft sensory mechanoreceptors of tunable sensor parameters.
软压力传感器在软机器人技术和触觉接口中“人机”触感的发展中发挥着重要作用。具体而言，具有微结构聚合物基体的电容式传感器因其高灵敏度、宽线性范围和快速响应时间而受到了大量研究。然而，传感性能的提升往往依赖于介电层的结构设计，这需要复杂的微加工设备。本文报道了一种简单且低成本的方法，通过基于溶剂蒸发的方法来调节孔隙率，从而制造出具有更高灵敏度的多孔电容式压力传感器。该传感器由一个多孔聚二甲基硅氧烷（PDMS）介电层和由弹性导电聚合物复合材料（ECPC）制成的顶部和底部电极组成。电极是通过将碳纳米管（CNTs）掺杂的PDMS导电浆料刮涂到模具图案化的PDMS薄膜中制备的。为了优化介电层的孔隙率以提高传感性能，PDMS溶液用不同质量分数的甲苯稀释，而不是将糖造孔剂（PFA）过滤或研磨成不同尺寸。甲苯溶剂的蒸发使得能够快速制造出具有可控孔隙率的多孔介电层。证实了当甲苯与PDMS的比例从1:8增加到1:1时，灵敏度可提高两倍以上。这项工作中提出的研究实现了一种低成本的方法，用于制造具有可调传感器参数的软感觉机械感受器的完全集成仿生软机器人抓手。
