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

Abstract

We investigated experimentally and theoretically the change in the reciprocal of the motional capacitance Δ(1/Ca) of a quartz-crystal tuning-fork tactile sensor before and after its base comes into contact with neoprene rubbers. We derived the analytical formula for the motional capacitance of the electrical equivalent circuit of the sensor at resonance based on the combination of the L-shaped bar model and viscoelastic foundation model, and the law energy of conservation. We found from both contact experiments and theoretical considerations on the analytical formula that Δ(1/Ca) is intrinsically induced by both the dynamic Young’s modulus and viscosity of neoprene rubbers at 32.5 kHz, which is the actual resonant frequency of the quartz tactile sensor. In this paper, we showed experimentally and theoretically for the first time that the motional capacitance of the tuning fork tactile sensor is affected by the dynamic viscosity of materials in contact with the sensor’s base, except their dynamic Young’s modulus.

Introduction of measurement techniques in ultrasonic electronics: Basic principles and recent trends

“…Force sensors [279][280][281][282][283][284][285] Object detection [286][287][288] Acceleration [289][290][291][292][293] Gyro sensors [294][295][296][297][298][299] Bio sensors 234,256,257,[300][301][302] Gas=chemical sensors 186,233,240,243,[246][247][248]250,251,253,254,261,303,304) Application of piezoelectric thin films 214,215,218,305) Microfluidic control 306) Continued on next page:…”

“…260,277,278) As described in the previous section, piezoelectric devices can be modulator-type sensors, in which the target phenomena affect the signals from the devices. In this way, piezoelectric devices can be used as mechanical sensors such as force sensors, [279][280][281][282][283][284][285] object detection sensors, [286][287][288] acceleration sensors, [289][290][291][292][293] and gyro sensors. [294][295][296][297][298][299] In these sensors, direct forces or inertial forces are applied to a vibrating resonator, so that the output signal is modulated such as its resonance frequency.…”