Fabrication And Properties Of Flexible Strain Sensor Based On Novel Conductive Layer Structure

With the development of society and the advancement of science and technology,human beings are eager for electronic equipment to closely fit the human body to achieve the purpose of convenient signal exchange.Therefore,as the most important component of flexible electronic devices,flexible strain sensors have been rapidly developed.The research on flexible strain sensors has evolved from the simple physical mixing of conductive particles and flexible substrates to the design of their structures.Flexible substrate-conductive layer-flexible substrate,a typical sandwich structure,has attracted wide attention from researchers due to its good protective effect on the conductive layer.However,the agglomeration of conductive particles and the conductive network in the sandwich structure are vulnerable to damage and cannot be repaired,and the poor compatibility of the conductive layer and the coating layer severely affects the performance improvement of the sensor.Therefore,this subject solves the above problems by introducing an electrostatic spinning film into a conventional conductive layer.In this experiment,silver nanowires(AgNWs)with a certain aspect ratio were prepared as conductive particles by a polyol reduction method.Polydimethylsiloxane/polyvinylidene fluoride(PDMS/PVDF)was selected as the experimental raw material to prepare the electrospun membrane.AgNWs were evenly distributed on the surface of the electrospun membrane through a suction filtration process,and a new-type conductive layer was obtained.The prepared conductive layer was covered with PDMS on both sides and then coated with PDMS to prepare a flexible strain sensor based on a novel conductive layer structure.In addition,a series of new-structure conductive layers were prepared by filtering the AgNWs with different masses on the surface of the electrospun membrane to investigate the effect of the content of conductive particles on the performance of the flexible strain sensor.Characterization of AgNWs,PDMS/PVDF electrospun membrane,new conductive layer structure,and cross section of self-made flexible strain sensor by X-ray diffraction(XRD)and scanning electron microscope(SEM).The self-made device was used to test and analyze the related performance of the flexible strain sensor.The results show that AgNWs with a length of about 25-30 ?m,a diameter of about 80 nm,an aspect ratio of more than 300,and a high purity are successfully prepared in this experiment.The fiber diameter of PDMS/PVDF electrostatic spinning membrane is about 1 ?m,and it has certain elasticity.AgNWs are evenly distributed on the surface of the electrospinning membrane and are closely adhered to each other to form a conductive network.The performance of the flexible strain sensor based on the new conductive layer structure has been greatly improved,while reducing the hysteresis while increasing the sensitivity and repeatability of the sen sor.The quality of AgNWs in the conductive layer of the new structure has a great influence on the sensitivity of the self-made flexible strain sensor.As the mass of conductive particles in the conductive layer increases,the sensitivity of the flexible strain sensor increases first and then decreases.When the strain ?=10%and the AgNWs mass is 0.020g,the sensitivity of the self-made flexible strain sensor reaches the maximum value GF=654.01.After a month-long test of 5 times of daily stretch-recovery cycles,the resistance value of the flexible strain sensor increased by only about 0.71%compared to the initial resistance value.The flexible strain sensor based on the novel conductive layer structure prepared in this subject has good comprehensive practicability.