Development of a stretchable skin-like tactile sensor based on polymeric composites

This paper presents the design, fabrication and characterization of a novel tactile skin-like sensor with the capability of detecting at the same time external mechanical stimuli like pressure and shear strain and that possesses some of the intrinsic properties of human skin, like extensibility, flexibility and compliance. The proposed sensor is resistive based and integrates two sensing parts built by means of electrically conductive polymer composites and elastic metallic thin films. The final prototype consists of a 1.5 mm silicone-Carbon Black (at 23.6%) layer on which a stretchable 90 nm Au thin film is deposited by providing a 20% bidirectional substrate stretching before Au deposition. Compression tests showed high values (70 k¿-80 k£2) of the electrical resistance, that decreases quite regularly with the pressure (in the range of 0 N/mm²-0.16 N/mm²). In parallel, from shear strain testing, a low range of electrical resistance (20 ¿-70 ¿) from the extension and release phase was measured having a quite regular trend, increasing with the applied strain which reached 14%. The preliminary experimental analysis indicates that the new tactile skin-sensor can detect mechanical stimuli (e.g. pressure and shear strain) in a decoupled way through cross measurement of electrical resistance and it can be used for skin-like tactile arrays.