Research On Flexible Piezoelectric Sensor Based On P (VDF-TrFE) Film

Organic piezoelectric materials(polyvinylidene fluoride)PVDF and(polyvinylidene fluoride trifluoroethylene)P(VDF-TrFE)have good piezoelectricity and flexibility,and can be used to make flexible piezoelectric sensors.In this paper,a flexible piezoelectric sensor is designed based on P(VDF-TrFE)piezoelectric film.It has a five-layer structure,from bottom to top: substrate PET,bottom electrode Al,piezoelectric film P(VDF-TrFE),top electrode Al and protective layer PDMS.First,the piezoelectric film of the sensor is manufactured.Prepare 5 kinds of PVDF solutions with different concentrations to prepare films under different conditions such as spin coating speed and annealing temperature,and observe the film-forming effect.From these,select appropriate test conditions to prepare P(VDF-TrFE)films.Analyze the difference between P(VDF-TrFE)and PVDF in melting temperature,element content,chemical bond and grain shape using DSC,XPS,FTIR,SEM,and analyze annealing temperature using SEM,XRD,AFM,ATR,etc.And the effect of spin coating times on P(VDF-TrFE)film.The results show that the P(VDF-TrFE)solution with a mass fraction of 10% has uniform thickness,complete surface and good flexibility when the spin coating speed is low speed(20s)800r/min and high speed(40s)1500r/min.The baking temperature is 70?,the annealing temperature is 130?,and the ?-phase content in the P(VDF-TrFE)film with one spin coating is large.Finally,the process conditions were selected to prepare the piezoelectric layer of the sensor.Two sizes of P(VDF-TrFE)piezoelectric sensors were designed and produced.At the same time,the Workbench tool in the finite element simulation software Ansys15.0 was used to build a simulation model of the P(VDF-TrFE)piezoelectric sensors and carried out Static mechanical simulation analysis.The relationship between the output voltage of the sensor and the frequency and the relationship between the output voltage and the driving voltage of the vibrating table were tested using the built piezoelectric sensor test system.Among them,the maximum sensitivity of the sensor frequency with a length of 50 mm is 0.21 mV/Hz.The sensor with a length of 25 mm has a frequency sensitivity of up to 0.22 mV/Hz.When the output frequency of the signal generator is 400 Hz and the drive voltage of the exciter is 3V,the amplitude of the output voltage of the sensor with a length of 50 mm is 133.81 mV,and the amplitude of the output voltage of the sensor with a length of 25 mm is 118.60 mV.