Design And Implementation Of Wearable System For Human Physiological Signal Monitoring

With the improvement of living standards,people pay more attention to health issues,wearable medical monitoring equipment has been greatly developed in recent years,and flexible sensor front-end as an important part of wearable equipment has also received greater attention.The existing health monitoring equipment on the market has shortcomings such as large size,poor wearability,and high price.Therefore,designing and processing a portable flexible wearable human physiological signal monitoring system is of great significance to improve the application of health monitoring equipment.The system can monitor the two important physiological signals of human body’s electrocardiographic signal and pulse signal.And it communicates with the smartphone APP through the low-power Bluetooth system to realize the visual display of two physiological signals.The main contents of this thesis are as follows:（1）A flexible and stretchable metal dry electrode for ECG monitoring was designed and implemented.Firstly,the mechanism of ECG signal generation is studied,and the three-lead system is selected to monitor the human ECG signal.In view of the shortcomings of commercial gel electrodes that cannot be reused and easily cause human skin allergies,a flexible and stretchable metal dry electrode was designed and fabricated.The electrode uses the flexible material PDMS as the substrate,and sputtered gold serpentine island-bridge copper film as the conductive electrode.The processed flexible electrode can withstand 20%deformation without damage,and the contact impedance of the flexible ECG electrode is lower than the contact impedance of commercial Ag/AgCl electrodes at the same frequency,which can ensure the effective collection of human ECG signals.（2）A front-end flexible pressure sensor for pulse signal acquisition was designed and manufactured.The sensor consists of a sensitive layer and an interdigital electrode.The sensitive layer is made of a non-woven fabric coated with MXene.The metal interdigital electrode that has been magnetron sputtered gold is prepared by a laser etching process,and PI is used as a flexible substrate for the sensor.The test results show that the sensor has high sensitivity(S=0.465 kPa^-1),fast response（77 ms）and good anti-mechanical fatigue characteristics,which can realize the acquisition of pulse wave signals.（3）Flexible wearable systems are integrated and chartered.A monitoring system consists of ECG signal and pulse signal acquisition and back-end processing circuit is built,which realizes the monitoring and display functions of ECG and pulse weak signals.Based on the flexible stretchable metal dry electrode with low contact impedance and the flexible pressure sensor for high-sensitivity pulse signal acquisition,the ECG signal acquisition module circuit,pulse signal acquisition module circuit,main control circuit,power supply module and program processing system were designed,respectively.The weak human ECG and pulse signals extracted are filtered and amplified by the flexible front-end acquisition module,and then displayed on the mobile phone APP through wireless Bluetooth,and the human ECG and pulse signals are measured in real time.The human ECG signal and pulse signal acquisition system designed in this thesis has the advantages of low cost and convenient detection.It realizes the real-time monitoring of weak physiological signals on the mobile phone terminal,and is expected to be used in traditional Chinese medicine pulse diagnosis and wearable electronic equipments.