Design And Study On The Properties Of Capacitance Pressure Sensor Based On Spacer Fabric

With the advancement of textile technology and the integration of textile technology with materials,communications,electronics,computers and other technologies,more and more scholars are studying sensors based on textile structures.The flexible pressure-capacitance sensor is a principle that changes the capacitance value caused by the change of the plate spacing,the plate area or the intermediate medium when the capacitor is stressed,and converts the measured pressure into a type of sensor that can output an electrical signal with a certain relationship.The flexible pressure-capacitance sensors are used in a wide range of applications,including tactile sensing,attitude monitoring,and security.This subject has carried out a series of studies based on the purpose of monitoring the pressure distribution of the cushion.It is hoped that can lay a foundation for the flexible pressure-capacitance sensor with superior design and preparation performance for the following researches.First,the dielectric layer,electrode and adhesive of the pressure-capacitance sensor are designed and prepared.Eight warp-knitted spacer fabrics were woven on the double needle bed warp knitting machine as the dielectric layer of the capacitive sensor.A high-density conductive woven fabric,a weft-knit conductive fabric,and warp-knitted conductive fabrics are designed and woven as electrode plates of the capacitive sensor.In order to fix the electrode plate and the dielectric layer together,the electrode and the medium cannot be hardened,and the coating curing is simple and convenient,three kinds of glues are selected as the bonding agent.And the experimental scheme was designed,using the compression instrument and the capacitance instrument to measure the electrical performance of the spacer fabric pressure-capacitance sensor.Secondly,the principle of spacer fabric pressure-capacitance sensor is introduced,and then the electrical performance test is carried out.The mechanical properties and electrical properties of the spacer fabric pressure-capacitance sensor are studied.The stress-strain curve,capacitance-strain curve and capacitance-stress curve are drawn.The linear regression analysis of the stress and initial relative dielectric constant of the spacer fabric pressure-capacitance sensor was carried out by SPSS software.The influence of the spacer fabric parameters on its mechanical properties and electrical properties was studied.Then,the capacitance-stress curve and the capacitance change rate-stress curve are segmented to determine the linearity,sensitivity,repeatability error and hysteresis of the spacer fabric pressure-capacitance sensor with different dielectric layers,different bonding adhesives and different electrode forms.Conduct research and analysis to explore the effects of dielectric layers,adhesives and electrodes on the static performance of the sensor,and to lay the foundation for designing pressure-capacitance sensors with superior performance.Finally,based on the performance research of a single pressure-capacitance sensor,the pressure sensor array is designed and prepared,the pressure monitoring system is built,the intelligent seat cushion is prepared,the hardware debugging and optimization are carried out,and finally the sitting pressure monitoring test is carried out,and the pressure distribution map under different sitting postures is obtained.Therefore,it is verified that the intelligent cushion designed by this subject realizes the function of monitoring the pressure distribution.Through the above research,it is found that the specifications of the spacer fabric,the type of adhesive,the coating method,the performance of the electrode fabric,and the range of strain all have an influence on the sensing characteristics of the pressure-capacitance sensor.The spacer fabric with smaller spacer filament density,smaller spacer filament diameter and larger spacer length is used as the dielectric layer,and the sensitivity and repeatability of the sensor are better.The double-sided adhesive and partially coated adhesive spacer spacer pressurecapacitance sensor are used.The linearity and sensitivity are better;the spacer fabric pressurecapacitance sensor with the weft-knitted fabric as the electrode has the highest sensitivity;the compression error and the hysteresis rate of the sensor can be greatly reduced under the compression of a small deformation range.