Study On The Sensing Properties Of Flexible Polymer Coupled With Liquid

With the development of the internet of things and information technology,various fields require a large number of sensors to realize the signal perception,and the demand for sensors is large.Traditional sensor manufacturing process is complex and costly,while flexible polymer is low cost,easy to process and industrially produced.Based on the principle of triboelectric charging and the principle of contact electrification,the development of sensor with coupled sensing characteristics using flexible polymer can be used in human health monitoring,building state assessment,object motion state monitoring,which has important scientific significance and application value.Compared with the two solid materials,the flexible polymer has a larger contact area with the liquid and a smaller friction coefficient,which is more favorable for charge migration.Therefore,firstly this paper analyzes the coupled sensing technology of flexible polymer and liquid,analyzes four sensor models and use the fluid-solid coupling method in the finite element method for simulation calculation.Based on this,a flat curved tubular flexible polymer sensor structure is proposed.Secondly,by analyzing the advantages and disadvantages of water and liquid metal,it is proposed to use nano metal suspension as the liquid in the cavity to make the sensor,and use nano iron powder and copper oxide powder to make the suspension.Explaining the processing technology and production process and studying the effects of liquid concentration on the sensing properties.A sensor prototype with coupled sensing function is fabricated using PTFE,and an experimental platform is built for testing and analysis.Since the electrical signal of the sensor is relatively small,and the sensor has a high impedance,it is easily interfered by the external electromagnetic environment such as the power frequency.Therefore,the signal acquisition circuit is designed specifically,and the circuit board is used for the sensor signal sampling.Firstly,the charge transfer characteristics between different liquids and PTFE are tested and analyzed.The experimental results show that nano metal suspension is better than deionized water in terms of output voltage signal.Saturated nano iron powder suspension is superior to unsaturated nano iron powder suspension and nano copper oxide suspension.Secondly,by analyzing the output signal of the sensor,it is shown that it can measure the equilibrium state of the object,reflect the inclination of the object,and the output voltage has a linear relationship with the tilt angle.It is also possible to identify the motion state of the object by analyzing the parameters of the output signal voltage amplitude,frequency characteristics,and variance.Compared with the commercial piezoelectric accelerometer,the frequency characteristics of the human body walking and running are basically the same,which proves that it is feasible to make the coupled sensor based on the polymer and nano metal suspension.In summary,based on flexible polymers and liquids,sensors with coupled sensing properties can be fabricated,and the test results are consistent with theoretical analysis.