Flexible Capacitive Tactile Sensors Based on Carbon Nanotube Thin Films

Carbon nanotubes (CNTs) are an interesting material for mechanically flexible electronic devices. The possibility to fabricate CNT thin films from solution by scalable coating and printing techniques has paved the way for large-area and low-cost sensor applications. In this paper, we demonstrate mechanically flexible capacitive tactile sensors utilizing spray deposited CNT thin-films and microstructured PDMS spacers. The capacitance is monitored during sensor operation and forces smaller than 10 mN could be detected and changes of up to 20% are achieved for 1 N of applied force. Sensor response can be tailored through an appropriate design of the dielectric spacer. The long-term operational stability of the proposed sensors is demonstrated. Further, a theoretical model is proposed and fitted to experimental data, providing a powerful tool to facilitate the design process.