Impedance Change of Non-Contact Gap Sensor Coil Made of Conductive Polymer Composite Under Compression and Decompression
Luheng Wang, Zhen Gui · IEEE/ASME Transactions on Mechatronics · 2025
Flexible sensor coil, made of carbon nanotubes and silicone rubber, can measure gaps and stress. During the noncontact process, the impedance amplitude/angle increases as the gap decreases, reaching a critical value at the zero-gap point, differentiating it from the compression/decompression process. During loading, the impedance increases with stress buildup. During unloading, the impedance angle drops; while the impedance amplitude increases sharply when unloading to the target stress of 0.3, 0.2, and 0.1 MPa, and decreases sharply when unloading to 0 MPa with a change rate of less than -0.002 s−1. In the relaxation stage, the impedance amplitude/angle shows an exponential decay trend, and the impedance amplitude change rate ranges from 0 to -0.002 s−1. Therefore, a method to measure gaps and stress has been developed by utilizing the critical value and the change rate, laying a preliminary foundation for monitoring gaps and stress with the sensor coil.