Development of tactile sensor using thin film made of poly-urethane and its characterization

A novel capacitive tactile sensor using a gelled poly-urethane thin film is proposed in this paper. In previous studies, capacitive tactile sensors have an air gap between two electrodes in order to enhance sensitivity of the sensors. On the other hand, there is only poly-urethane thin film between the electrodes in this study. However, sensitivity of this sensor is higher than the established capacitive tactile sensors because the poly-urethane is vey flexible elastomer and the poly-urethane film is very thin (about 1 μm). The poly-urethane film is formed by spin-coating and etched back from 6 μm to 1 μm by using 48% sulfuric acid. As a result of evaluation of the tactile sensor, it is found that its sensitivity to the applied compressive pressure is about 0.8 nF/N and Young´s modulus of the poly-urethane is about 20 kPa.