Tactile sensor based on piezoelectric resonance

We discuss here the realization of tactile sensors based on the principle of change in piezoelectric resonance frequency with the applied pressure. An array of electrodes has been adopted on either side of the PZT material to have independent resonators. The common areas sandwiched between the electrodes and excitable at resonance frequency of the PZT material are used to form the sensitive area of the tactile sensor. The electrodes were deposited using sputtering technique. Tactile sensors with 3 x 3, 7 x 7, and 15 x 15 array of electrodes are developed with different electrode dimensions and separation between the electrodes. The tactile sensor has been interfaced to computer for the convenience of automatic scanning and making it more user interactive. The tactile sensors developed with different spatial resolution were tested for different shaped objects placed in contact with the sensor. The 3 x 3 matrix tactile sensor showed relatively poor spatial resolution, whereas the 15 x 15- matrix tactile sensor showed improved spatial resolution. The sensor with 7 x 7 matrix elements was tested for its sensitivity to different extents of applied force/pressure. The output response study carried out on the sensors indicated that these sensors can provide information not only about the extent of force/pressure applied on the object, but also the contour of the object which is in contact with the sensor.