Fabrication Of PVDF Piezoelectric Thin Film Senor

Clothes can not only keep warm,aesthetic and personality,but also have function of senses.If sensors,electrodes and conductor can be fully integrated in the garment, it can monitor the change of external and internal environment,such as Physiological parameters,body motion.Those garments are called as "Smart clothes".In this work, the results from testing polyvinylidene fluoride(PVDF) thin film sensor were reported and pre-circuit was designed.Smart clothes,which are very flexible,embedded with sensors,must be made by soft material.PVDF piezoelectric film is a novel polymer sensing flexible material with piezoelectric characteristics.This character has been satisfied the different measurement requirements.With high piezoelectric constants,flexible,light,easy to processing and wide frequency response,PVDF thin film was made as sensors with some advantages,such as simple structure,quick respond and simple pre-circuit.The process of making the PVDF sensors and the experience of testing the character of the PVDF sensors were reported in this paper.(1) The PVDF sensors have been designed by using the integral characteristics of PVDF piezoelectric film.The processes of making sensor include shaping,cutting, modifying the edge,setting electrode and outer layer protection.(2) The pre-circuit consists of charge amplifier circuit,negative feedback voltage amplifier circuit and Low-pass filter circuit.Charge amplifier circuit is the most important in the pre-circuit,which will directly effect on the signals.(3) The value of the integral capacitor C_f and the feedback Resistor R_f in the charge amplifier circuit have been determined by the experiments.It has been shown by experimentation that the system noise can be reduced and the signal distorting be avoided.(4) The signal produced by the PVDF sensors under the different condition were analyzed and the character of the PVDF sensors were measured by data acquisition device.PVDF sensors were embedded in the glove to monitor movement of fingers' joint.It has been proved that the PVDF sensors and data processing system can quickly record the movement of human body.Monitoring movement of fingers joint has been completed by the pre-circuit modified and the magnitude-frequency characters in bending deformation of the PVDF sensors were discussed.We can recognize movement of body through the clothes integrated with the PVDF sensors.