A dielectiric liquid-based capcitive tactile sensor for normal and shear force sensing

In this paper, we propose a novel dielectric liquid-based tactile sensor with three axial sensing ability and high sensitivity. The sensor which consists of 3 capacitors uses Polydimethylsiloxane (PDMS) structure to encapsulate two liquids, i.e. a polyalcohol droplet (with higher dielectric constant) and oil (with lower dielectric constant, surrounding). The three axial force signals are detected by the capacitance change due to the mechanical deformations of the capacitors and the position change of the droplet. The proposed sensor´s sensitivities in z-, x-and y-axes are 2.02 pF/N, 0.472 pF/N and 0.496 pF/N, respectively. The high sensitivity with promising spatial resolution would satisfy requirements of humanoid robotic applications.