Design And Preparation Of PVDF And Blended Materials With Applications To Acoustic Devices

With technological progress and innovation,as an indispensable sensor in the IoTs,robots and smart devices,acoustic sensors have been continuously innovated and iterated.Due to the high performance and self-powered advantages,piezoelectric acoustic sensors have gradually become the most widely used acoustic sensors.Since the piezoelectric ceramics made from traditional piezoelectric sensors have problems of large size,difficult deformation,and high toxicity.the organic material polyvinylidene fluoride trifluoroethylene copolymer?PVDF-TrFE?,which is small in size,good in flexibility,and of high-piezoelectric properties,has become research hotspot in new acoustic sensor materials.In this paper,PVDF-TrFE piezoelectric films with excellent performance were prepared by process designing and parameter optimization.Based on this,an acoustic sensor with high accuracy,high sensitivity and high stability was fabricated.The main contents of this paper are as follows:?1?Process design and parameters optimization of PVDF-TrFE piezoelectric thin film preparation:in this chapter,the parameters invole the polarization conditions,film thickness and doping process in the preparation of PVDF-TrFE piezoelectric thin films,are explored and optimized In the polarization process,by designing and adjusting the gate voltage,source voltage,and polarization time parameters of the in-situ polarization system,PVDF-TrFE piezoelectric film with the best piezoelectric performance was obtained.The piezoelectric coefficient d₃₃ is up to 27.25 pC/N under the conditions of the gate voltage of 3.0 kV,the source voltage of 7.5 kV,and the polarization time of 10min.Through the research on the influence of the thickness of PVDF-TrFE piezoelectric film on its piezoelectric properties,it was proved that the PVDF-TrFE piezoelectric film at 30?m has the highest piezoelectric coefficient,and too thin or too thick films will affect the polarization effect.By doping 4.0wt%nano-SiO₂ during the doping process,the mechanical properties of PVDF-TrFE piezoelectric film are significantly improved.In addition,in this chapter,the thermal resistant properties of PVDF-TrFE piezoelectric thin films are also studied,and it is found that the highest resistance temperature of PVDF-TrFE piezoelectric thin films is as high as 130?,indicating the PVDF-TrFE film has good high-temperature performance.?2?preparation and performance research of acoustic sensor based on PVDF-TrFE piezoelectric film:In this chapter,an acoustic sensor is fabricated by using the PVDF-TrFE piezoelectric film made by the best process conditions and its performance on acoustic signals including sound intensity recognition,frequency recognition and sound source localization is characterized.In the sound intensity recognition Part,the produced acoustic sensors can respond to sound samples of different sound intensity signals,and the peak-to-peak response voltage is positively correlated with the sound intensity signal.In the sound source localization part,the arrayed acoustic device can determine the position of the sound source on the two-dimensional plane according to the amplitude of the voltage response of each part.In the frequency recognition part,the produced acoustic sensors can distinguish and identify all types of sound samples in the range of 20Hz²0kHz,with the relative error less than 1%.With the testing of musical instrument,human voice and animal sound samples,the PVDF-TrFE piezoelectric thin film acoustic sensor has been proved to have high accuracy,high sensitivity and high stability,indicating that it has broad application prospects and practical value.