Intrinsically Flexible Non contact Gap and Pressure Transducer System Made of Coil shaped Conductive Polymer Composite

High-precision real-time monitoring of gaps and pressure is essential in precision manufacturing and robotic manipulation. This study develops a transducer system based on a coil-shaped sensor made of carbon nanotube-filled silicone rubber composite material, capable of dual-mode detection of both gap and pressure. The system is supported by custom-developed hardware circuitry and host computer software. A critical impedance threshold is employed to distinguish between non-contact and contact processes, while the impedance change rate is used to differentiate loading and relaxation stages. The non-contact gap is determined using the impedance angle–gap relationship due to its higher sensitivity. The loading pressure is estimated through impedance magnitude–pressure calibration; during relaxation, the pressure is inversely interpolated using the magnitude–pressure relationships of adjacent calibration points (0.1/0.2/0.3/0.4 MPa). Experimental results indicate maximum errors of 3.0 % F.S. for gap measurement and 8.0 % F.S. for pressure measurement. This study lays a preliminary foundation for industrial applications in long-term gap/pressure monitoring.