Research On The Force-Electricity Response Of Flexible Strain Sensors With Carbon Nanoparticle-Filled Polymer

With the development of smart manufacturing technology,flexible sensors have received significant attention.Compared to traditional metal or semiconductor strain sensors,flexible sensors have the characteristics of lightweight,large deformation,and adaptability to irregular surfaces,demonstrating tremendous potential in fields such as flexible robotics,intelligent health monitoring,and wearable devices.Carbon-based filled polymer composites,as typical materials for flexible strain sensors,have been widely used in areas such as damage detection,liquid sensing,mass sensing,motion detection,and flexible skins due to their excellent electromechanical performance.Currently,research on conductive polymers mainly focuses on material preparation processes and electromechanical properties,while studies on their strain sensing mechanisms,particularly the influence of microstructural changes on strain sensing behavior,are relatively limited.Therefore,this paper takes carbon nanoparticle-filled silicone rubber as an example and proposes a multiscale analysis method for the electromechanical performance of carbon-filled polymers,employing a combination of theory,simulation,and experimentation.Based on this method,the electromechanical performance of conductive polymers with different structural parameters,such as filling ratio and filler type,is simulated and compared with experimental results to verify the effectiveness of the multiscale analysis method.The main research content of this paper is as follows:(1)Mechanistic study of conductive polymer composites.Carbon nanoparticle-filled polymers belong to composite conductive polymer materials.This paper discusses several commonly used conductivity mechanisms,such as percolation theory and effective medium theory.Taking carbon nanoparticle-filled polymers as an example,the fillers are usually present in the polymer substrate in the form of aggregates,and the impedance of the composite material depends on the conductive path formed between the aggregates.Therefore,the calculation of the impedance of this conductive polymer can be converted into the calculation of the tunneling resistance between the aggregates in the conductive path.The paper summarizes and analyzes the description of the micro-circuit model of conductive polymers in the literature,and establishes a micro-equivalent circuit model based on the combined effects of the conductive path theory and the tunneling effect theory.(2)Development of a multi-scale analytical method for describing the forceelectrical response of carbon-filled polymers.Taking carbon nanoparticle-filled polymer composites as an example,the three-dimensional coordinate information of the random distribution of the aggregates is first generated according to a modified nearest distance algorithm,a representative volume cell model of the conducting polymer is established with the help of the secondary development function of ABAQUS software,and the periodic boundary conditions imposed by the model and the characteristic dimensions σ of the model are discussed in detail.The Yeoh hyperelastic model was selected as the constitutive model for the matrix material.The finite element analysis of carbon nanoparticle-filled silicone rubber under uniaxial compression was performed,and the change in distance between adjacent conductive aggregates in the model was extracted from the results.Secondly,using the distance between adjacent conductive aggregates as a link,the equivalent resistance of the random resistor network was calculated using the established microscale equivalent circuit model,the transformation matrix method,and the tunneling resistance formula.Finally,the obtained force-electricity response curve was compared with the data in the literature to verify the validity of the model.(3)Prediction of the force-electric response of carbon nanoparticle-filled silicone rubber for different material parameters under uniaxial tensile conditions.In the experimental aspect,test specimens were prepared using a solution blending method,and the internal microstructure of the composite material was observed using scanning electron microscopy.To capture and record real-time resistance changes of the carbon nanoparticle-filled polymer,a corresponding data acquisition system was designed,including hardware circuitry and software design.Finally,through quasi-static uniaxial tensile tests,the predicted electromechanical response of the conductive polymer under different material parameters was validated.The predicted response curves showed good agreement and correlation with the experimental data within a significant range.Taking carbon nanoparticle-filled polymer as an example,this article studies the flexible strain sensor of carbon-based filled polymer and proposes a multiscale analysis method that can simulate the force-electric response of carbon nanoparticle-filled polymer.By comparing with experimental results,it is proved that this method can effectively simulate the force-electric response behavior of carbon nanoparticle-filled polymer under different parameters,and reveal the strain sensing mechanism from the microscopic scale,providing a theoretical basis for the design and improvement of this type of strain sensor.