Research And Application Of Wearable Monitoring System Based On Barium Titanate Flexible Piezoelectric Sensor

Personal health wearable monitoring system has a wide range of applications in the field of health care.The wearable monitoring system consists of different types of sensors,transmission modules and power sources located in different parts of the body,which can be used to monitor physiological signals in real time(joint bending,plantar pressure and stride frequency,etc.).The pressure signal is the most commonly monitored signal in the exercise health monitoring of the human body.The measurement of the pressure signal in different parts of the human body can obtain rich physiological and pathological information,which has important research value for health monitoring,postoperative rehabilitation and sports training.Stability,comfort and sensitivity of wearable monitoring systems are of Paramount importance.Therefore,this paper takes the wearable monitoring system as the research object,and explores its accuracy,sensitivity and stability by preparing flexible piezoelectric sensors.Then the wearable monitoring system based on flexible piezoelectric sensors is designed and developed to realize multi-point pressure monitoring.In this study,a composite hydrogel with good piezoelectric properties was prepared by copolymerization of aminoated barium titanate with gelatin and oxidized chondroitin sulfate.By observing its microscopic morphology,mechanical properties and electro-mechanical response properties,we found that the composite piezoelectric hydrogel was a 3D porous network structure with good ductility and compressibility and low Young’s modulus.With precision digital multimeter graphics we tested under different external force output signal of the gel was carried out by finger/elbow bend Morse code sensor and signal detection experiments,the results show that the gel has the stable electric responsiveness,can the size of the response force,accurately and rapidly available in the material basis of flexible sensor.Based on the fabricated flexible piezoelectric sensor,we further develop a wearable monitoring system,and design a multi-channel analog switch circuit,charge amplification circuit,low-pass filter circuit,level lifting circuit,microcontroller minimum system,Bluetooth communication module,serial communication and system power supply circuit.This paper makes a detailed analysis and schematic design of the above circuits,laying a foundation for the establishment of the hardware platform of wearable monitoring system.The single-chip computer program is written in C language to realize the functions of multi-channel analog switch channel switching,data acquisition and conversion,filtering algorithm,Bluetooth data transmission and serial communication with the host computer.After completing hardware/software design,check and improve system design by debugging system.Finally,the piezoelectric hydrogel was encapsulated with a polyvinyl chloride/polyimide flexible substrate and combined with the wearable monitoring system developed by us to obtain a complete wearable flexible piezoelectric sensor monitoring system.Subsequently,we conducted experiments on gesture recognition,knee flexion Angle and plantar pressure distribution,all of which obtained stable data consistent with biomechanics,indicating that the wearable flexible monitoring system can be applied in disease diagnosis,rehabilitation treatment and movement guidance training,as well as virtual reality and artificial intelligence.