Research On Flexible Garment Pressure Sensor Based On PVDF Composite Membrane

At present,with the improvement of people's living standard and the rapid development of modern science and technology,people are no longer satisfied with the basic function of clothing in original,warm,beautiful,modesty,but getting more and more attention on its functionality and intelligent.In order to realize the intelligentization of textile and clothing,it is necessary to develop a wearable flexible sensor.Polyvinylidene fluoride(PVDF)is a new type of polymer sensing material with excellent piezoelectric properties.Meanwhile PVDF has the advantages of acid and alkali resistance,high mechanical strength,good chemical stability,etc.And PVDF has a large piezoelectric constant,wide frequency response,light weight,flexibility,ease of processing large area.Therefore,polyvinylidene fluoride is an excellent choice for the development of flexible sensors.Based on the existing research,this paper improved the preparation method of PVDF piezoelectric thin film,and successfully encapsulated it into sensor.The sensor was applied to the test of human knee force under moving state.The main work is as follows:(1)In this project,a PVDF composite membrane was designed,and PVDF filaments were prepared by melt spinning.The prepared filaments were integrated into the PVDF film,and a composite structure film based on PVDF wire and membrane was successfully prepared.The PVDF composite film and PVDF cast film were stretched and the crystal morphology was analyzed and compared.It was found that the content of ? crystal in PVDF composite film was significantly higher than that in common cast film.Based on this,the PVDF composite membrane was selected for making the sensor in the experiment.(2)The PVDF composite films were polarized after stretching,which make it has good piezoelectric properties and encapsulated into the piezoelectric sensor.Copper are used as the electrode of the sensor.The way of connection is hollow rivet and small chuck.This way of connection is strong and durable,and the direction of wire can be adjusted properly with the need of experiment,and it will not affect the film.(3)A set of piezoelectric testing devices was assembled by the project group to connect the sensor to a microcomputer through a charge amplifier.The static and dynamic responses of the sensor are tested respectively.It is found that the sensor can respond effectively to the change of external force,and the sensitivity is high.(4)The sensor was pasted on the front part of the human knee tendon and fixed on the kneecap.The piezoelectric response of the sensor in human knee joint was tested,and the bending state of the knee joint could be judged by analyzing the piezoelectric response curve.This research provides a certain reference for the application of flexible pressure sensors in textile and clothing.