A dielectric liquid based capacitive tactile sensor for humanoid robots

Abstract

This paper presents a novel capacitive tactile sensor with high sensitivity for humanoid robots. The main structure of the sensor is a cubic `box' (3 × 3 × 2.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) made of Polydimethylsiloxane (PDMS). Two dielectric liquids, i.e. a polyalcohol droplet (with a higher dielectric constant) surrounded by oil (with a lower dielectric constant), were sealed in the box under iso-density condition. Electrodes were fabricated on the upper and lower inner surfaces of the box to form a capacitor. The two liquids, sandwiched by the electrodes, increased the capacitance of the capacitor. The sensitivity of the sensor increased due to the novel configuration. The proposed sensor was fabricated by microfabrication technology. This sensor's sensitivity is 61.77%/N, which is 3.3 times greater than that of typical sensors containing no liquid.