Finite element analysis of tactile sensors made with screen printing technology.

Abstract

Tactile sensors have increasing presence in different applications, especially in assistive robotics or medicine and rehabilitation. They are basically an array of force sensors (tactels) and they are intended to emulate the human skin. Large sensors must be implemented with large area oriented technologies like screen printing. The authors have proposed and made some piezoresistive sensors with this technology. They consist of a few layers of conductive tracks to implement the electrodes and elastomers to insulate them, on a polymer substrate. Another conductive sheet is placed atop the obtained structure. Pressure distribution in the interface between this conductive sheet and the electrodes has a direct impact on the sensor performance. The mechanical behavior of the layered topology with conductive tracks, elastomers and polymers must be studied. For instance, the authors have observed experimentally the existence of pressure thresholds in the response of their sensors. Finite element simulations with COMSOL explain the reason for such thresholds as well as the dependence of the pressure distribution profile on the properties of the materials and the geometry of the tactel. This paper presents results from these simulations and the main conclusions that can be obtained from them related to the design of the sensor.