Research On PVDF Sensor Array For Wearable Devices

Because wearable devices are easy to use,more emphasis on user experience and environmental awareness,the way of human-computer interaction is developing from traditional equipment to wearable devices.As one of the most promising research directions in the field of human-computer interaction technology,gesture recognition technology is divided into two types:one is based on visual images,and the other one is based on motion sensors.Although the gesture recognition technology based on visual images is the mainstream technology in this field,its application is not that good due to the high cost and deep dependence on the environment.The gesture recognition technology based on motion sensors usually collect data by acceleration sensors and three axis gyro sensors.On one hand,however,this collection method can only obtain the position or coordinate information but not motion signals.On the other hand,gesture recognition requires not only time information but also spatial information,which can not be collected by a single sensor.To overcome these two disadvantages of the gesture recognition technology based on motion sensors,this paper puts forward an intelligent sensor array based on the PVDF piezoelectric thin film.The designed intelligent sensor array based on the PVDF piezoelectric thin film is suitable for wearable devices and can be used to collect wrist motion signals.The PVDF is a type of piezoelectric material with strong piezoelectricity,and also has the advantages of softness,light weight,good matching with human body.Based on the characteristics of wearable devices and piezoelectric properties of the PVDF,a sensor with a curved elastic backing,integrated sensor pretreatment circuit is presented in this paper for the measurement of wrist motion signals;According to the characteristics of the PVDF sensor,a test platform for sensor dynamic testing is built by using the loudspeaker;Thought the analysis of hand anatomy and kinematics,this paper proposes a scientific wrist sensor array structure and its signal pre-processing circuit,signal acquisition circuit and signal acquisition software design are completed;A rational gestures encoding rule is provided by studying gestures.In addition,the corresponding multi-channel sensor signals’ acquisition and real-time display platform are built under Windows system,and the gesture database is established based on this platform and the sensor array designed in this paper.The experimental results of the wrist motion signals show that the PVDF sensor array can collect,extract and output the multi-channel wrist motion signals,which can be as sufficient samples for gesture’s classification and identification in the future.