Soft dielectrics for capacitive sensing in robot skins: Performance of different elastomer types

In a capacitive tactile sensor the dielectric layer plays an important role: both its electrical and mechanical properties affect the capacitance variation and the sensor response in terms of sensitivity, since the deformation ability of the dielectric layer allows for the detection of small pressures, and spatial resolution, since the dielectric layer acts as a low-pass spatial filter decreasing the spatial resolution. In this work we comparatively evaluate the effect of different elastomers on the performance of a capacitive sensor designed to cover large areas of a robot body. In particular, we compare the sensitivity, the spatial resolution and the durability of the sensor using foams, bulk elastomers and high permittivity composites.