Modelling of a Highly Sensitive Polymer Composite Tactile Pressure Sensor

High sensitivity is one of the desirable characteristics for a tactile pressure sensor, especially in soft robotics and biomedical applications, e.g., prothesis and smart orthosis. We perform a detailed Finite Element Method analysis of a novel tactile sensor. It is comprised of interdigitated electrodes coated with a composite made of Polydimethylsiloxane (PDMS) and nanoparticles. The developed model allows studying the dependence of the sensitivity on the nanoparticle material properties, content, and distribution. The results show that a homogenous distribution of the nanoparticles offers a high sensitivity. However, a methodical placement of the nanoparticles in a certain region of the PDMS results in a further enhancement of the sensitivity. Using COMSOL Multiphysics, expressions for the Limit of Higher Influence (LHI) and Limit of Similar Influence (LSI) for the placement of the nanoparticles are calculated. Placing the nanoparticles within the region from the top of the PDMS layer to the LHI or LSI leads to the highest enhancement of the sensitivity of the tactile sensor.