Multimodal Physiological Signals Acquisition System And Its Application In Psychological Stress Assessment

People’s health is an important issue related to the national economy and people’s livelihood.At present,there are many characteristic physiological signal acquisition systems on the market.But there are still many problems,such as inability to collect data synchronously as well as transmit data at high speed in real time,expensive to sell it,not portable to use and unsuitable to promote for daily life.Therefore,to solve this problem,the paper designs a multi-modal physiological signal synchronous acquisition system based on EEG,ECG,respiration,EMG,Sp O2 and body temperature,and applies it to the evaluation of human psychological stress state.The specific work contents and research results are as follows:（1）In order to collect multimodal physiological signals synchronously,based on the conventional operational amplifier and ADC,the paper builds analog front-end circuit and data transmission circuit with separated components as the main component.The hardware circuit of amplification,filtering,analog-to-digital conversion and transmission of physiological signals is designed,and a portable and low-power multi-channel synchronous acquisition system is realized.（2）In order to eliminate the baseline drift,power frequency interference,physiological artifact and motion artifact,the paper applies wavelet denoising,adaptive filtering,sliding mean filtering and fast median filtering algorithm in the multi-mode physiological signal acquisition system designed by ourselves to eliminate the baseline drift,power frequency interference,physiological artifact and motion artifact in physiological signals automatically.In order to prove the effectiveness of the system to collect physiological signals,the rest data are collected by using the system and the MP 150 system.The comparison shows that the signals collected by the system and MP150 system are basically similar in waveform amplitude,phase and shape,and verify the effectiveness of the system.（3）In view of the limited transmission rate of Bluetooth and serial port,the paper designs USB type C and network port circuit,which realizes the high-speed and real-time transmission of data,and displays,stores and analyzes the transmitted data in PC application program in real time.（4）In order to further verify the application of multimodal physiological signal acquisition system in practice,the paper uses the system to study the relationship between human psychological stress and physiological signal.The system collects human physiological signals,extracts the features by linear analysis methods such as time domain,frequency domain,complexity,power spectrum and so on,classifies the collected single-mode data by multi classification support vector machine algorithm,and uses DS（Dempster Shafer）evidence theory algorithm to integrate the decision-making layer and comprehensively identify the psychological stress state.The results show that the classification accuracy of rest state is 93.75%,the classification accuracy of mild stress state is 87.5%,and the classification accuracy of high stress state is 90.62%.