The Research On Capacitive Flexible Pressure Sensor Based On PDMS Thin Film Dielectric Layer

With the rapid development of modern internet of things and artificial intelligence industry,capacitive flexible pressure sensors are not only widely used in wearable interactive electronic devices,but also have a broad prospect in electronic skin,flexible screen,medical detection,intelligent textile,aerospace and many other applications.As the most important performance index of sensors,sensitivity has always been the focus of research at home and abroad.In the work of this paper,selection of PDMS as the basis of composite dielectric layer material,the sensitivity of the sensor is improved by dielectric layer doping and hole making,finally achieved a high sensitivity,wide linear response range,small hysteresis error,high cycle stability,wide working temperature range,fast response and excellent integrated sensing properties.1?The pressure sensor can be divided into capacitive type,piezoelectric type and piezoresistive type according to its working characteristics.According to the detection range can be divided into ultra-low pressure,small low force,medium pressure and high pressure sensors;According to the touch mode,it can be divided into ordinary,touch and multi-touch pressure sensors.The research status of capacitive flexible pressure sensors mainly focuses on the improvement of sensitivity.Common methods include the doping of dielectric layer to improve the dielectric constant,the introduction of pore structure in dielectric layer,and the fabrication of surface microstructure.In addition,this chapter also gives a detailed introduction to the engineering electroactive dielectric PDMS with excellent performance and the theory of sensitivity enhancement of capacitive flexible pressure sensor.2?Through comprehensive comparison,ITO-PET was selected as the electrode,and multi-walled nanotubes(MWCNTs)were selected to doping PDMS based on the percolation theory to improve the sensitivity.By optimizing the doping concentration,the optimal sensitivity of the MWCNTs-PDMS capacitive flexible pressure sensor reached 1.512 k Pa^-1 in the low voltage range,which was about 3 times of the sensitivity of the PDMS pressure sensor.At the same time,the sensor has a wide operating temperature range(-18?to 100?),fast response time(65 ms),high cycle stability and small hysteresis error and other excellent sensing characteristics.In addition,the manufacture process and testing method of the sensor are described in detail in this chapter,and the leakage situation of the sensor under higher pressure is discussed.3?Sensitivity can be improved by making holes in the dielectric layer to make the sensor easier to compress under pressure.In this chapter,dinitropentamethylenetetramine(DPT)was used as the pore-forming reagent.After repeated experimental exploration,a mature and stable PDMS new pore-forming scheme was determined,and the number and diameter of pores were studied.DPT perforated PDMS significantly improved the sensor's sensitivity,reaching 1.06k Pa^-1 in the low voltage range,nearly doubling that of the PDMS sensor without perforated,and the linear response range was up to 60 k Pa or more,at the same time also increased 500g,100g,20g weight sensing application test.In addition,CH₃CH₂O₂ pore-forming PDMS was tried in this chapter,which provides some reference value for CH₃CH₂OH acting on PDMS.4?Although a wide linear response range was obtained by perforating the intermediate dielectric layer of the DPT-PDMS for capacitive flexible pressure sensor,the sensitivity improvement was limited.In this chapter,the improvement of sensor sensitivity and other sensing characteristics are studied by combining DPT pore-forming with MWCNTs doping.The test results show that:The sensitivity is 2.8 times higher than that of the MWCNTs-PDMS pressure sensor in the pressure range of 0.16-8 k Pa,and approximately 2 times higher than that of the DPT-PDMS pressure sensor in the pressure range of 8-60 k Pa.In addition,the comprehensive sensing characteristics,such as wide linear response range(0-80 k Pa),fast response speed(65 ms),excellent cycle stability,wide operating temperature range and small hysteresis error,have been obtained.In addition,this chapter also adds the actual application scenario test of the sensor holding the beaker.5?The research results of this paper are summarized,and the shortcomings and prospects of the research work are discussed.