Analysis of change in motional capacitance of quartz-crystal tuning-fork tactile sensor induced by viscoelastic materials in contact with its base

We have derived the analytical formula for motional capacitance of the electrical equivalent circuit of a quartz-crystal tuning-fork tactile sensor at resonance using L-shaped bar´s, viscoelastic foundation models in contact with its base, and conservation low of energy between the electrostatic energy in motional capacitance and the sum of the strain energy of the vibrating quartz arm, the stored and loss energies of the materials in contact with its base. We have found from both the contact experiments and the theoretical considerations on the analytical formula that the change in the reciprocal of motional capacitance, before and after the sensor´s base getting into contact with neoprene rubbers, has been intrinsically induced by both the dynamic Young´s modulus and viscosity of neoprene rubbers at the resonance frequency 32.5 kHz of the quartz tactile sensor.