Using a flexible substrate to enhance the sensitivity of dielectric elastomer force sensors

Abstract

The application of a force sensor in a robotic gripper is essential as it can provide feedback in the control of the grasping force. This paper examined a way to increase the sensitivity of dielectric elastomer force sensors by adding a flexible substrate and demonstrated how the finite element method (FEM) could be used for identifying the optimum substrate thickness. A capacitive force sensor with a substrate made from liquid silicone rubber (LSR) is studied here. The influence of the contact mechanics and the effect of substrate thickness on the sensitivity of these capacitive sensors were studied. Substrates of different thicknesses were also investigated with a compressive force up to 10 N. Different indenters in spherical shapes made from metal and fruits to mimic the objects being grasped by the gripper were used in this study. This study shows that for forces up to 10 N, a substrate thickness of 5 mm led to an optimum sensitivity, irrespective of the indenter type.