Research On Impedance Characteristics Of Pressure And Displacement Sensitive Component Based On Eddy Current Effect

The existing eddy current sensor can only measure displacement. However, it can not measure pressure. The carbon nanotube/silicone rubber composites can be used to measure pressure based on its piezoresistive effect. However, it can not measure displacement. To solve the problem, two sensitive components are prepared which combine metal coils and carbon nanotube/silicone rubber composites to realize displacement and pressure measure. These two sensitive components are called compounded element and integrated element. The new components have good mechanical and electrical characteristics. It not only replaces two traditional probes by a single probe, but also can measure displacement and pressure by impedance characteristic. Simplify the signal processing method.The major completed works include:(1) The integrated element which composite materials and metal coil was contacted completely and compounded element in which composite and coil are insulated were designed. The mass ratio of conductive phase and matrix phase ranges from 0.001 to 0.20, and the number of the metal coil is 60.(2) The effects of mass ratio and driving frequency on the impedance characteristic of compounded element were analyzed. The rules show that:mass ratio has little effect on monotonicity. The higher driving frequency is, the more big impedance value will be.(3) The effects of mass ratio and driving frequency on the impedance characteristic of integrated element were analyzed. The rules show that:impedance value constant first and then decreased as mass ratio increasing. The higher driving frequency is, the more big impedance value will be.(4) The effect of pressure to sensitive components’impendance characteristics are analyzed. The rules show that:when the driving frequency is low, the sensitivity will increase after suffering pressure and when the driving is high, the sensitivity is constant.(5) The noise, sensitivity and resolution of sensitive complements were analyzed in quantitatively. When the displacement be measured, the resolution can reach 0.1mm; minimum noise can reach 0.024% and the highest sensitivity can reach 12.35Ω/mm. When the pressure be measured, minimum noise can reach 1.32%.All indicators of compounded-sensitive complements in which mass ratio is 0.02 and integrate-sensitive components whose mass ratio is 0.01 are good within 1MHz. It is verified the feasibility of using carbon nanotube/silicone rubber and metal coil to measure geodesic and pressure.