This paper describes the development of a new type of tactile sensor which is designed to operate with a piezoelectric element employed as the sensor. Conventional tactile sensors, which consist of a strain gauge, conductive elastomer and piezoelectric polymer film, are confined solely to data acquisition relating to pressure or force, However, the new sensor proposed here is able to detect, very much like the human hand, the hardness and/or softness of an object. Several experiments have been carried out to investigate its possible applications in robotics and medicine. It is demonstrated that the visualization of tactile sensory performance using the new sensor is most useful in a robotics application; the sensor is also able to detect the hardness of an extraneous substance and that of skin.
