Preliminary Study On Soft Pressure Sensitive Coil

It is very critical to monitor the displacement and pressure between small curved surfaces to ensure the safety of the large defense and industrial equipment.But the traditional sensor probes can't satisfy the actual requirement when the curved surface gaps are measured.The existing eddy current sensor can only measure displacement and it cannot measure pressure.Meanwhile,the carbon nanotubes/silicone rubber composites can be used to measure pressure based on its piezoresistive effect and it can't measure displacement.To solve this problem,a kind of soft pressure-sensitive coil based on carbon nanotubes/silicone rubber conductive polymer composites was prepared.This kind of coils has good mechanical and electrical properties,which is made of silicone rubber filled with carbon nanotubes and contains no metal.Non-contact displacement measurement probe based on eddy current effect and pressure measurement probe based on conductive polymer composites' piezoresistive effect were combined into a new pressure-sensitive coil.The major works are summarized as follows:(1)The soft pressure-sensitive coils and composite films were designed by using silicone rubber filled with carbon nanotubes.(2)The impedance-displacement characteristics of the soft pressure-sensitive coils were researched.In addition,the effect of the mass ratios,the frequencies and the objects on the soft pressure-sensitive coils' eddy current characteristics was mainly studied.When the displacement was measured,the sensitivity was higher when the mass ratio of the coil was 0.12:land the excitation frequency ranged from 500kHz to 2MHz;the sensitivity was higher when the object was the composite films with the mass ratio ranges from 0.12:1 to 0.20:1.The study found that the impedance-displacement relation followd a polynomial relationship.(3)The impedance-pressure characteristics of the soft pressure-sensitive coils were researched.When the displacement was measured,the greater the pressure changed,the greater the change in impedance,furthermore,the change in impedance had a good linear relation to the change in pressure.(4)The noise,sensitivity and resolution of the soft pressure-sensitive coils were analyzed in quantitatively.When the displacement was measured,the noise of the studied coils wass lower than 10%,the resolution of the studied coils reached 0.30mm,and the sensitivity reached 0.5k?/mm.When the pressure was measured,the resolution of the studied coils reached 0.25mm,and the sensitivity reached 1.8k?/mm.Based on the aforementioned results,the feasibility of using this kind of soft pressure sensitive coil to measure the double parameters(non-contact displacement and pressure)is preliminarily verified.