Research On 3D Force Flexible Sensor And Sensitive Materials

The flexible three-dimensional force sensor is a tactile sensor that has good flexibility and can cover multi-dimensional force information on the surface of the irregular carrier,which can help the intelligent robot to perceive and acquire external environmental information,thereby realizing the interaction between the intelligent robot and the external environment.Therefore,the study of flexible three-dimensional force sensors is a vital part of the development of robots.In addition,flexible three-dimensional force sensors have broad application prospects in the fields of smart wearable devices,medical detection and rehabilitation,industrial manufacturing and biomechanics.At the same time,research on sensitive materials is also crucial to the development of tactile sensors.Carbon black has good electrical conductivity,while polyimide?PI?has good mechanical properties.The composite of carbon black and polyimide?PI?is expected to obtain sensitive materials with good sensitivity and flexibility,which lays a good foundation for the research of flexible three-dimensional force sensor.In this paper,based on the search for suitable sensitive materials,the research on the conductivity and force-sensitive effect of carbon black polymer materials was carried out.The carbon black/PI polymer materials were proposed,and the force-sensitive properties were verified and optimized through experiments.Thus,a flexible three-dimensional force sensor based on carbon black/PI flexible force sensitive film was designed.Firstly,the basic theoretical research on carbon black polymer materials was carried out,and the theory of seepage model was studied.The conductive mechanism of carbon black polymer materials was studied and proposed the commonly used conductive path theory and tunneling theory.At the same time,the pressure-sensitive properties of carbon black polymer materials were also explored,and a pressure-sensitive property model of carbon black/PI flexible force sensitive film was proposed.The performance characterization method of the flexible force sensitive film is then described in detail in this paper.Secondly,the material system of carbon black polymer materials was studied,and the material system of polymer sensitive materials was systematically studied.Polyimide?PI?was selected as the matrix material,carbon black was used as the conductive filler,N-N dimethylacetamide?DMAC?was used as solvent and nano-silica?SiO₂?as a modified material.In using of cast coating method,carbon black/PI flexible force sensitive film was made.After testing the prepared carbon black/PI flexible pressure sensitive film with different carbon black concentration,the results showed that the carbon black/PI flexible film prepared by doping carbon black with a mass concentration of 4 wt.%has the best force sensitivity and is suitable as a sensitive material for flexible three-dimensional force sensors.By carrying out the hysteresis test on carbon black/PI flexible force sensitive film with carbon black mass concentration of4 wt.%,the results showed that the sensitivity coefficient was 1.51 k?/N and the hysteresis was 1.58%.By observing the electron scanning microscopy image?SEM?of carbon black/PI flexible force sensitive film,the addition of proper amount of SiO₂ has increased the dispersion effect of conductive filler in PI matrix material,reduced the agglomeration effect between conductive fillers,and thus formed stable conduction.It has also improved the mechanical properties of the film and increased flexibility.Finally,we designed a“sandwich”type integrated layered sensor,which was mainly composed of PDMS stress loading layer,upper electrode layer,carbon black/PI flexible force sensitive film layer and lower electrode layer.Based on the design of the flexible three-dimensional force sensor,the mechanical model of the flexible three-dimensional force sensor was established and the simulation experiment was designed to verify its feasibility.In this paper,the preparation process of the sensor is also introduced in detail,and the preparation process and preparation parameters of each layer are studied.The self-designed and built calibration platform was used to test the x,y and z directions of the flexible three-dimensional force sensor.The average percentage errors of the sensor in the x,y and z directions were 4.9%,4.2%,3.8%,and the sensitivity in the three directions of x,y,z were 0.414 k?/N,0.626 k?/N and 1.739k?/N,respectively.The experimental performance of the sensor was redesigned in order to verify the overall performance of the flexible three-dimensional force sensor.This experiment mainly tests the detection performance of the sensor on the shear forces.The results showed that the average relative errors of the total amplitude of the shear forces and shear directions detected by the sensor were 3.2%and 0.7%,respectively.