Characterization of improved tactile sensors using piezoelectric resonator

An improved tactile sensor probe which detects the viscoelastic property of media has been developed. This sensor probe consists of a 1.5 mm×1.5 mm thickness mode piezoelectric resonator on a mounter sized 2.4 mm in diameter with energy trapped electrodes and two wires connected to the electrodes at the backside of the resonator. This size is small enough to be inserted into the human body for diagnostics. In addition the output signal of the sensor is stable even if the contact force or contact angle between the sensor and a medium changes because of its simple structure. The authors also experimentally confirmed the relationship between the sensor output and viscoelastic property expressed as a complex modulus (E*=E\´+_JE"). The frequency shift of the sensor is closely related with the real part (E\´), and the amplitude change of the sensor mainly corresponds to the imaginary part (E"). It is possible to estimate the viscoelastic property of media with the frequency and the amplitude of the output signal of the new tactile sensor