A Low Normal Force Interference Piezoelectric Friction Force Sensor Based on Spatial Polarization Field Design

In this article, a novel and practical double-sided comb-liked misaligned electrode structure based on spatial polarization field design was proposed. Simulation results indicated that a voltage of 7.66 mV was produced under the friction force of 100 Pa, whereas output voltage closed to zero at normal force up to 1000 Pa when the polarization electric field is set at 60°. Additionally, tests at different polarization electric field angles showed the sensor to maintain minimal response to normal force and to have a maximum response to friction force when polarization electric field was 60°, which proved good agreement with the simulations. When the polarization electric field is 60°, the sensor exhibited a large friction force perception range of 1–16 N and a sensitivity of 2.95 mV/N, and at normal force up to 80 N, the sensor output voltage was close to zero. It indicated that the polyvinylidene fluoride (PVDF) film sensor based on double-sided comb-liked misaligned electrode structure with ability to generate output voltage under friction force and low interference by normal force. Additionally, the friction force sensor exhibited good stability at low temperatures. Furthermore, under 2000 cycle tests, the sensor still maintained a stable output voltage under friction force and the underwater characterization of the sensor was also investigated. Thus, the sensor prepared with potential applications value for precise ship-ice friction force measurements and reduced the crosstalk of normal force.