Research On Preparation Method Of Pdms Flexible Capacitive Sensor

With the development of modern sensor technology,flexible sensors have been widely used because of their advantages of light,small and intelligent.The research on flexible sensors has gradually become a hot spot.Flexible capacitive sensors have become one of the most common types of flexible sensors because of their simple principle,fast response speed and high precision.However,it is still a difficult problem to prepare flexible capacitive sensors with excellent sensing characteristics on a large scale and high efficiency in the field of scientific research at home and abroad.On the basis of this problem,this paper aimed at finding a method of using polydimethylsiloxane(PDMS)as matrix,filled in short carbon fiber(SCF)and carbon nanotube(CNT),assembling it into capacitive sensor,and improving the structure and technology of the sensor to improve the sensitivity of the sensor.The main contents of this paper are as follows:(1)PDMS/SCF/CNT conductive composites were prepared by spacial confining forced network assembly(SCFNA)and differential temperature hot pressing,Assembles it into a "sandwich" structure sensing element clamp the upper and lower electrodes,And self-designed water bath heating package silicone device,Packed into capacitive flexible sensors,And explore the 2%?4%?6%SCF,effect of different packing concentration on sensor performance at 1%CNT.It turns out,Sensor sensitivity increases with SCF concentration,The sensitivity is 0.036 PF/N,when the SCF concentration is 6%,97.4%linearity,7.4%repeatability error and 14.1%hysteresis error in range of 0-500N.(2)Aimed at the improvement of the tensile rate of the sensing element,the SCFNA-Scraping dielectric layer method and the scraping conductive silica gel and dielectric layer method are designed,The results show that the tensile rate of the sensor is increased from 110%to 140%,And the adhesive effect of electrode and dielectric layer prepared by scraping conductive silica gel and dielectric layer is the best,By using the SCFNA-Scraping dielectric layer method,The maximum sensitivity of the sensor is 0.036PF/N,prepared by PDMS/4%SCF/1%CNT electrode material.The hysteresis error is 12.3%.When the thickness of dielectric layer is 0.2 mm,the maximum sensitivity of the sensor is 0.141 PF/N,prepared by scraping conductive silica gel and dielectric layer,The hysteresis error is 7.8%,The repeatability error is 2.5%,The working performance is improved.(3)The flexible capacitive sensor is applied to the dynamic load experiment of high-speed railway damping spring.The stress state of high-speed railway spring is simulated by ANSYS software,and the dynamic load experiment platform and signal acquisition system are designed independently.The system can record the real-time load and monitor the force curve of the high-speed rail spring.Experiments show that the sensor works well under the dynamic load of 10-60kn,and the maximum lag is only 0.4%.The deformation of the high-speed rail spring under normal state is 14%,and the elastic limit is 20%.