Design And Preparation Of Flexible Piezoelectric Sensor Based On PVDF And Hybrid System

With the rapid development of technologies such as the Internet of Things and Artificial Intelligence,technology products such as smart homes,smart robots,and biometrics are currently entering the market,and the demand for sensors in these products is increasing.Sensors based on organic piezoelectric materials such as polyvinylidene fluoride?PVDF?and its copolymers are self-powered,flexible and foldable,and have the characteristic of large area,which are widely used in pressure sensing,voice recognition,and electronic skin sensing fields.However,the piezoelectric performance of organic piezoelectric materials is not as good as that of inorganic ceramics.Therefore,we have incorporated inorganic nanoparticles into organic polymer piezoelectric materials to improve their piezoelectric performance.In order to improve the preparation efficiency of such organic piezoelectric materials,this article proposes to increase the polarization efficiency of the thin film by means of plasma polarization,which can be used to prepare the electronic skin of the wearable robot's touch,etc.,to meet the industry's demand for flexible sensors.This article studies the design and preparation of organic polymer piezoelectric material polyvinylidene fluoride and its copolymer-based piezoelectric sensors.The specific work is as follows:We explored the drying process of the film and used low-pressure room temperature drying technology to obtain a piezoelectric film with the best surface flatness and thickness uniformity.The surface of the film has no obvious pore-like defects.The crystal form of the film changed from?phase to?phase when annealed at140?.After being polarized in a plasma-based in-situ polarization system,the film exhibits excellent piezoelectric performance,with a piezoelectric coefficient of 27±2pC/N.The piezoelectricity of the film furtherly enhanced after dopping 0.1wt%hydroxyapatite into PVDF-TrFE,and the peak value of piezoelectric coefficient D₃₃reached 32 pC/N.Screen printing equipment was used to prepare metal Ag electrode of PVDF-TrFE film.The electrode has very high density and small resistivity.In addition,the binding force between the electrode and the film is strong,and the test result of the metal layer100 grid reaches 5B,which is better than the adhesion of Ag electrode prepared by magnetron sputtering after plasma activation treatment?4B?.The method of preparing electrodes by putting a Cu conductive tape on the film reduces the risk of conducting the upper and lower electrodes of the film to zero,which is the simplest method for preparing sensor electrodes.Self-powered wind speed and rain potential meteorological sensors based on PVDF-TrFE piezoelectric film can be used to sense the raindrop rate and frequency,and accurately measure the raindrop frequency with a detection error of less than 1%.In wind speed sensing,the output voltages reached 0.013 V and 0.03 V at low and high wind speeds,respectively.The stability of the sensor is still good after 100,000 cycles of testing,and the signal is not significantly attenuated.A 3×3-array piezoelectric sensor based on an arrayed electrode polyimide flexible circuit board with a single-electrode output structure can realize three-dimensional characterization of space forces.Capacitive piezoelectric composite sensors based on thin-film transistor arrays can be used to detect the surface topography with a resolution of 50 microns.The preparation of electrodes can realize the transformation from a capacitive sensor to a piezoelectric sensor,which can realize the grayscale display of the ultrasonic sound intensity distribution.