Research On Systems And Methods For Fabric Dry Electrode Performance Evaluation

At present,wearable health care equipment due to real-time monitoring of elderly and cardiovascular disease in patients with physiological indicators widely used in various countries and regions.Fabric dry electrode relative to the current medical institutions commonly used disposable electrodes,with a soft texture,breathable performance and easy to combine the advantages of clothing,very popular with the researchers.However,the existence of dynamic noise in practical applications will affect the measurement of physiological signals of fabric dry electrodes.Therefore,the researchers have been analyzing the dynamic noise mechanism of the interface between the dry electrode and the human skin,thus improving the performance of the electrode.Due to the continuous changes in human physiological electrical:signals,the electrode directly on the human skin to measure the low repeatability,so there is no instrument can be more realistic to simulate the electrode and skin contact between the state.In this paper,we first develop a dynamic performance evaluation system for bioelectrode dry electrode.The system consists of three parts:skin simulator,pressure controller,data acquisition and system control.Skin simulator can simulate the human skin characteristics,divided into active and passive simulation module,compared to the passive module,active module add a ECG signal generator,import ECG signal inside the skin simulator,so more real Simulate the human body;the pressure controller function is to precisely control the pressure between the electrode and the simulated skin;the data acquisition and system control section can save the collected data for analysis.Ten different electrodes were made to quantitative analyze the relationship of the electrode and skin contact interface change parameter(Electrode and skin pressure,relative velocity and displacement)and measurement parameters(impedance spectrum,dynamic and static open circuit voltage,ECG signal),thus reduce the dynamic noise of the electrode/skin interface.The CV coefficients of the three groups were 4.02%,5.05%and 4.35%,respectively.The maximum CV of the peak time,voltage amplitude and noise amplitude of the ECG signal was obtained by experimentally verifying the stability and repeatability of the instrument Values were 9.28%,7.58%and 7.96%,indicating that the instrument reproducibility is better.The results show that the relative velocity and pressure between the electrode and the skin are strongly negative linear correlation with the dynamic open-circuit voltage change,that is,the dynamic noise,the minimum correlation coefficients were 0.84 and 0.81,the relative motion and dynamic noise were strongly positive linear correlation,the minimum correlation coefficient was 0.87,the pressure between the electrode and the skin and the peak time offset in the ECG signal was negative linear And the correlation coefficients were 0.79 and 0.8 respectively.Finally,the difference between the impedance spectrum of ten electrodes,the dynamic and static open circuit voltage and the collected ECG signal is analyzed.The results show that the characteristics of different electrodes are combined with the charge transfer process of electrode and skin interface.It is found that 2V-60s-Ag/Agcl electrode has the best performance,and the peak time offset of the original ECG signal is only 0.002s,the noise amplitude is the smallest 0.0037mV,the most suitable as the electrode extracting human physiological electrical signal.