Evaluation of foil transducers and their use in tactile sensors

•Evaluating of conductive rubber and conductive ink as a foil pressure-resistance transducer.•Direct comparison of both materials on a robotized measuring workplace.•Both materials proved their ability to act as a transducer within a limited range of applied pressure.•Best results were obtained for the thinnest layer of conductive ink. The article presents end evaluates foil transducers, namely conductive rubber and conductive ink, and their use in the pressure distribution measurement system Plantograf. The ability of both materials to act as transducer between pressure and electrical quantities is assessed by means of measurement on a robotized workspace; two electrode types and various ink layer thicknesses are studied. Basing on the measurements, we present graphically the dependency of the electrical resistance of the materials on the applied pressure. Although both materials proved their ability to act as a transducer in a planar sensor, they both exhibit some limitations. In case of rubber it is limited pressure range up to ca. 1 400 kPa and significant hysteresis of the material. The main limiting factor with conductive ink is its poor adherence to the electrodes, which poses important problem for its practical use, although this material evinces better transfer characteristics, particularly in the configuration with 7 μm ink layer and LD type electrode.