Preparation And Properties Of A Strain Sensor Based On AgNW Decorated Electrospun Fiber Mat And PDMS Flexible Self-laying Sandwich Structure

The main function of flexible sensors is to convert external sound,light,force,and heat signals into visible electrical signals.Upgrades all play a vital role.Piezoresistive sensors are mainly composed of three types of structure:induction material,flexible substrate and conductive electrode.Flexible sensor materials mainly include metal materials,carbon materials and conductive polymers.Among them,silver nanowires?AgNWs?is a sensing material with high electrical conductivity and has been widely used in the research of flexible strain sensors.The morphology uniformity and dispersion of AgNWs in the flexible matrix are the main factors affecting the performance of the sensor.In this project,PVDF/PANI composite glue solution and PVA/PANI composite glue solution were prepared by in-situ polymerization method and solution blending method,respectively.PVDF/PANI composite fiber membranes and PVA/PANI composite fiber membranes were prepared by electrospinning the four types of composite glue solution.AgNWs prepared by the ethylene glycol reduction method were uniformly attached to the surface of the PVDF/PANI fiber membrane by suction filtration.A mold forming method was used to fix the PVDF/PANI composite fiber membrane with AgNWs attached in the middle of PDMS,and two wires were led out at both ends to form a sandwich-type flexible strain sensor.The morphology of AgNWs,PVA/PANI composite fiber membrane,PVDF/PANI composite fiber membrane,and PVDF/PANI fiber membrane with AgNWs were characterized by x-ray diffraction?XRD?and scanning electron microscope?SEM?.The functional group structures of PVA/PANI composite fiber membrane and PVDF/PANI composite fiber membrane were characterized by Fourier Infrared Spectrometer?FI-IR?.The electrical conductivity of the PVDF/PANI composite fiber membrane was characterized by a wideband dielectric impedance spectroscopy.The differential scanning calorimeter?DSC?was used to test and characterize the curing temperature of PDMS.The combined use of a multimeter and a universal stretcher is used to test the tensile-recovery performance,hysteresis effect,and practical application of a flexible strain sensor.The results show that AgNWs is a face-centered cubic structure with an aspect ratio of about 120.The PVDF/PANI composite fiber membrane with a PANI mass fraction of 5wt%has a conductivity of 1.3501×10^-5S/cm at 107 Hz.When the mass fraction of PANI is 8wt%,the electrical conductivity of PVDF/PANI composite fiber membrane is abruptly changed.AgNWs was successfully adhered to the surface of the PVDF/PANI composite fiber membrane by suction filtration.The thickness of the AgNWs layer was about 20?m,and the thickness of the PVDF/PANI composite fiber film was about 100?m.The optimal experimental curing temperature range of PDMS's mold forming method is between 75°C and 135°C.The sheet-shaped flexible strain sensor has a GF coefficient of up to 50 and remains stable.Regardless of multiple stretching and recovery under the same strain or stretching and recovery under different strains,the changes of?R/R₀and?L/L₀of the flexible strain sensors have a good positive correlation,and the hysteresis effect obvious.The hollow cylindrical flexible strain sensor successfully realizes the multi-joint sensing function of fingers,which has certain practical application value.