Preparation And Performance Of Flexible Strain Sensor Based On Ionic Liquid Conductive Layer Structure

With the increasing need of artificial intelligence,human movement and health detection,people pay more attention to flexible electronic devices.Therefore,as an important part of flexible electronic devices,flexible strain sensors have been developed rapidly.Piezoresistive strain sensor is one of the most widely studied sensors at present because of its easy structure design and convenient data integration and output.Piezoresistive flexible strain sensors have developed from the initial preparation of conductive filler and flexible matrix to a variety of new conductive structures.Flexible substrate-conductive layer-flexible substrate is a typical sandwich structure,which is widely concerned by researchers because of its good protective effect on conductive layer.However,the agglomeration and conductive network of conductive particles in sandwich structure are easily damaged and cannot be repaired,and the poor compatibility between conductive layer and cladding layer seriously affects the improvement of sensor performance.Therefore,this topic through to the traditional conductive layer in the electrostatic spinning membrane and ionic liquid are introduced to solve the above problems,the ionic liquids can solve the problems of the traditional conductive particles together,electrostatic spinning film for ionic liquid storage platform and have ability to deformation,will help the ionic liquid in the process of the sensor to do regular exercise.In this experiment,PVDF and PVDF-HFP were used as materials to prepare electrospinning films.At the same time,PVDF/PDMS and PVDF-HFP/PDMS electrospinning films were prepared using PDMS as fillers.In this way,the compatibility and large deformation capacity of the flexible strain sensor are enhanced.The ionic liquid 1-ethyl 3-methylimidazole tetrafluoroborate(EMIBF4)was selected as the conductive filler of the flexible strain sensor.The ionic liquid was impregnated into the electrospinning film,and the remaining ionic liquid was removed by the extraction process to obtain a new conductive layer structure.A new type of flexible strain sensor based on conductive layer structure was prepared by double coated PDMS with wires attached to the prepared conductive layer.In addition,the performance of the two conductive layers of the flexible strain sensor was tested by scanning electron microscope(SEM),liquid absorption and ionic conductivity.At the same time,the related performance of the flexible strain sensor is tested and analyzed by using universal stretcher and multimeter.The results show that: In this experiment,PVDF and PVDF-HFP electrospun films were successfully prepared.Electrostatic spinning film fiber diameter 1-2 m,with good porosity.The fiber diameter of the PDMS blended film is obviously coarser than that of the pure electrostatic spinning film,and the fiber has certain elasticity when bending,but the liquid absorption rate of the blended film is lower than that of the pure electrostatic spinning film.As a result,PDMS blend films cannot impregnate ionic liquids well.Therefore,PVDF-HFP electrostatic spinning film is used as the conductive layer carrier film of the flexible strain sensor.Ionic liquid can be evenly dispersed in the inside of the electrospinning film,forming a conductive network.The performance of the flexible strain sensor based on the new conductive layer structure has been greatly improved,reducing the hysteresis while increasing the sensitivity and repeatability of the sensor.The linearity of the new flexible strain sensor is obvious.In 0-10% deformation,Guage Factor can be maintained around 2.4.After one-month stretch-recovery cycle test,the resistance of the flexible strain sensor is not obvious compared with the initial resistance value.The flexible strain sensor based on the new conductive layer structure prepared in this project has good comprehensive practicability.