Design And Application Study Of Flexible Acoustic Sensor Array Based On Piezoelectric Polymer

With the gradual emergence of intelligence and the Web 3.0 as the main themes of the 21st century,acoustic sensors,as an important medium for information interaction,are also undergoing tremendous changes in constant updating and innovation trends.Capacitive acoustic sensors,which are the mainstream,are sweeping through all aspects of people’s daily lives and industrial equipment.However,due to the increasing demand for small size,flexibility,and wearable acoustic sensors in the intelligent era,the development of new materials is imperative.Based on organic polymer materials such as polyvinylidene fluoride-trifluoroethylene（PVDF-TrFE）,acoustic sensors have the advantages of flexibility,self-powered,and portable wearable,making them have great potential to replace traditional acoustic sensors.The thesis explains the preparation of PVDF-TrFE piezoelectric films by optimizing the process flow and improving polarization efficiency,and designs acoustic sensors for multi-domain applications based on the piezoelectric films.The specific research contents are as follows:（1）Based on the widely used process technology for preparing PVDF-TrFE piezoelectric films,the polarization process technology is optimized,and the piezoelectric films prepared by in-situ polarization show good performance through various characterization methods.By using in-situ polarization with an array of metal wires as the source electrode,the piezoelectric coefficient d₃₃ of the PVDF-TrFE piezoelectric film after polarization is 24±2 p C/N,and it is uniformly distributed.Using a 60 d B sound sample as the sound source,the performance of the PVDF-TrFE piezoelectric film is characterized by a sound testing platform,and the detection distance can reach about 25cm,and the response time for receiving sound vibration is about 0.021 s.In addition,the correlation coefficient between the sound frequency detected by the PVDF-TrFE piezoelectric film and the input sound signal frequency is 0.99,indicating a highly linear relationship.（2）Based on the PVDF-TrFE piezoelectric film,the acoustic sensor is applied to bionic ears,diagnosis of lung diseases,gas detection,and equipment fault monitoring.Based on the theoretical basis of human ear-conducted sound,an acoustic sensor for bionic ears is designed and fabricated with an array of piezoelectric film pixels as the core,which can extract sound frequency characteristics.In addition,the approximate location of the sound source can be displayed through a 3D effect map,which has a good sound source positioning function.At the same time,in the diagnosis of lung diseases,the sensor analyzes snoring and coughing sound samples,summarizes the acoustic characteristics of different diseases to establish a database,and realizes the rapid diagnosis of OSAHS and various lung diseases.For gas detection,the sound spectrum received by the acoustic sensor shows that different gases have different sound frequencies after passing through the sound chamber,and separating the corresponding spectra of mixed gases may make it a new type of gas detection instrument.In addition,in equipment fault detection,the sound spectrum of equipment that is not working properly is chaotic and complex,indicating that it will produce abnormal sounds such as noise compared to when it is working normally.Therefore,the acoustic sensor can obtain accurate results by comparing the spectral characteristics of the equipment’s normal operation and abnormal operation.Through examples of the multi-faceted applications of acoustic sensors,it can be demonstrated that PVDF-TrFE piezoelectric film acoustic sensors have good performance and enormous market value.