Fabrication of flexible tactile force sensor using conductive ink and silicon elastomer

A novel design for a flexible tactile force sensor, which is called conductive elastic silicon tactile (CEST) sensor, is proposed in this paper. The flexible tactile force sensor is fabricated using a molding process of a composite material, which is a mixture of two components: conductive ink and silicon elastomer. The composite material is poured into a mold, which contains an array of cavities with desired shapes. After curing at room temperature, the solidified part is ejected out of the mold and attached to a designed flexible printed circuit board film. Five tactile sensing elements in the fabricated CEST sensor layer enable independent detection of the external normal force. The efficacy of this sensor is tested when a 0-5 N normal force is applied. Good linearity of 0.93, high selectivity in real-time measurement, and good repeatability of 98.67% are observed. By comparing the characteristics of CEST with those of one of the most used force-sensitive resistor sensor, the CEST sensor achieved competitive sensitivity with better repeatability, high selectivity, and extremely low cost.