Compressive Pressure and Noncontact Gap Measurements Based on 2-D Coil Covered by Polydimethylsiloxane Film

To realize the compressive pressure measurement and the noncontact gap measurement in the small interlayer structure of industrial equipment, a compressive pressure and noncontact gap sensing element based on eddy-current effect is designed and fabricated by covering a polydimethylsiloxane film on the 2-D coil. The impedance of the 2-D coil in the sensing element is used to reflect the compressive pressure and the noncontact gap. There exists a critical impedance, which can be used to judge whether the sensing element contacts the metal object or not. At the noncontact stage, the impedance amplitude and the impedance angle of the 2-D coil increase with the increase of the gap between the sensing element and the object made of aluminum. At the contact stage, the impedance amplitude and impedance angle decrease with the increase of the compressive pressure. The experimental results verify the feasibility of using the 2-D coil covered with polydimethylsiloxane film to measure the compressive pressure and the noncontact gap.