Biomedical Detecting System For Micro-vibration Of Body Surface Based On Motion Sensors

Many human physical activities can produce weak vibration signals at body surface.Wearable biomedical sensor can detect the abnormalities of human body and provide timely warning as well as early diagnosis of related diseases via collecting these signals.Meanwhile,the rapid development of miniaturized and accurate motion sensors enables researchers to detect physiological signals at body surface noninvasively and continuously.At the same time,the maturity of Internet and wireless transmission technology provides more diversified methods for data storage and presentation.This paper targets for two specific micro vibration fields,which are fetal movements of pregnant women and radial pulse.Two different motion sensors have been selected for data collection.Low power Bluetooth technology has also been used in order to realize real-time monitoring of signals in the smart phones.The detailed work is as follow:Firstly,a real-time fetal movement monitoring system based on piezoelectric sensor array in the shape of honeycomb has been designed.This system uses seven piezoelectric sensors embedded in maternity belt to detect fetal movement in the pregnant woman's abdomen.The hardware circuit implements the filtering process,then the ADC module encapsuled in the Bluetooth chip is used to convert analog signals to digital signals.Finally,the data is transmitted to the mobile phone through radio module of Bluetooth chip to realize the animation display and data recording of fetal movement.Secondly,a pulse detection system placed at radial artery based on acceleration sensor has been designed.The system adopts the flexible circuit technology and collects the pulse signal of the radial artery through the MEMS accelerometer.By using I2 C protocol,the communication and control between the Bluetooth chip and the accelerometer has been realized.Then the data is transited to the mobile phone through Bluetooth to realize continuous and real-time monitoring of the radial artery pulse.While the system only uses a single acceleration sensor,it can realize more accurate pulse measurement without reference signal.Flexible circuit technology also makes it easy to integrate circuit board into wearable devices,making it possible to continuously measure pulses in real-time application.