Study On The Fabrication And Properties Of BZT-0.5BCT/PVDF Based High-sensitivity Flexible Piezoelectric Sensor

In recent years,with the increasing popularity of intelligent products in people's daily life,flexible and wearable electronic products used to monitor human physiological health and daily activities have attracted more and more attention.The development of flexible pressure sensors with multi-function,high sensitivity,fast response and low cost has important practical significance in medical,healthcare,exercise,health monitoring and human-computer interaction.The purpose of this study is to prepare high-performance flexible piezoelectric sensors with high sensitivity and rapid response.The flexible piezoelectric sensor based on composite nanofiberwas fabricated using inorganic piezoelectric material barium zirconium titanate calcium(Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)Ti O₃,shorter form is BZT-0.5BCT)as filler and organic piezoelectric material polyvinylidene fluoride(PVDF)as a matrix.However,the traditional thin films based on inorganic/organic composite piezoelectric materials have poor crystallization performance,low piezoelectric performance and poor sensor sensing performance of their prepared piezoelectric sensors.Therefore,by exploring the electrospinning process and introducing inorganic piezoelectric material barium zirconate titanate calcium(BZT-0.5BCT)to improve the piezoelectric properties of PVDF matrix.A series of pure PVDF nanofibers and BZT-0.5BCT/PVDF composite nanofibers were prepared by electrospinning technology,and wearable flexible piezoelectric sensors with cross-finger electrode structure were prepared using piezoelectric nanofibers.The main work and innovations of this paper are as follows:(1)A series of PVDF nanofibers with different spinning voltage and drum speed were prepared by electrospinning method,and a series of PVDF nanofibers flexible piezoelectric sensors with different drum speed were prepared.The spinning voltage and drum speed play a positive role in promoting the crystallization performance of PVDF nanofibers and the relative content of piezoelectric?phase,and the content of piezoelectric phase can reach82.83%.The maximum output voltage of the sensor can reach 2.236V,the maximum sensitivity can reach 0.9609V/N,the response time is 100ms,the minimum detection limit is2.5mg,and the high stable voltage output can still be maintained in the test within 600s.It shows high sensitivity to the breathing behavior and bending of human limbs,and has the ability to detect movement and physiological signals such as finger bending and distinguishing different breathing modes in real time.(2)A series of BZT-0.5BCT/PVDF composite nanofibers with different mass fraction BZT-0.5BCT nanoparticles prepared by electrospinning.Then,a series of composite nanofiber flexible piezoelectric sensors were prepared.With the continuous addition of BZT-0.5BCT,the crystallization properties of PVDF based composite nanofibers and the relative content of piezoelectric?phase have been promoted in varying degrees.The piezoelectric?phase content reached the highest 92.1%when the BZT-0.5BCT nanoparticle content was 20wt%.Under this condition,the output voltage of the sensor is up to 6.3699V,sensitivity is up to 2.8174V/N,response time is 50ms and in 600s cycle impact test can still maintain its high stable voltage output.Compared to pure PVDF nanofiber sensors,sensitivity and maximum output voltage of the PVDF based composite nanofiber sensor increased by three times,while the response time was halved.And the composite nanofiber flexible piezoelectric sensors also showed greater sensitivity to detect movement and physiological signals in real time,such as bending and breathing behavior,has great application prospect and development potential in wearable devices such as medical health,disease diagnosis and exercise monitoring.