Research On Technology And Application Of Non-contact ECG Detection

As the most frequent chronic diseases,cardiovascular disease has the characteristics of high outbreak rate,low awareness rate and low control rate.For cardiovascular disease,the early prevention and early diagnosis are necessary,and the electrocardiogram is the main basis for the prevention and diagnosis of cardiovascular disease.However,the wet electrodes commonly used in clinical electrocardiogram detection need been contacted with the skin tightly,and long-term continuous use is likely to cause skin allergies and reduce patient compliance.In recent years,non-contact electrocardiogram(ECG)detection technology has developed rapidly,and the noncontact electrodes used by it can obtain accurate ECG without contacting the skin.This technology has great development potential in long-term ECG monitoring and meets the medical needs for early prevention and early diagnosis of cardiovascular disease.Based on the above background,this paper discusses the research on technology and application of non-contact ECG detection.It mainly explores the single lead system design of non-contact ECG,common mode interference suppression of non-contact ECG,and motion artifact suppression of non-contact ECG and lead-off detection.The main results are as follow:1.An analog front-end circuit design with ultra-high input impedance for noncontact ECG detection has been proposed.Based on this circuit,a single-lead system of non-contact ECG with high integration is developed,which can effectively collect a high-quality non-contact ECG signal through the clothes with one-millimeter thickness under two the states of rest and motion.2.The common mode interference caused by the power supply line in non-contact ECG detection has been studied.By establishing an equivalent circuit model of the common mode interference of the ECG detection equipment by the power supply line,a new suppression method,named ‘noise neutralization method',is proposed to suppress the common mode interference and its pseudo difference mode components.In the case where the electrode area is limited and the skin-electrode interface impedance mismatch is unavoidable,it has better interference suppression ability than the traditional capacitive driven-right-leg method.3.Based on the generation mechanism of motion artifacts,the motion artifacts caused by the accumulation of triboelectric charges in non-contact ECG detection have been studied.By analyzing the decay model of the accumulated charge on the conductive fabric electrode,it is found that with the appropriate amount of free water content,the free water evaporation path(FWEP)can become the main path of the charge decay,which can accelerate the decay process of the charge.A controllable conductive fabric electrode humidification design is proposed,which can effectively suppress motion artifacts in both low relative humidity and high relative humidity environments.4.The lead-off detection technology,which is essential in the practical application of non-contact ECG detection,has been studied.Based on the existing direct-current(DC)lead-off detection principle,a DC lead-off detection model for analog front-end with a virtual driven-right-leg circuit has been established,and a DC lead-off detection method for two-electrode configuration is proposed.The proposed method has been well verified in ECG acquisition and lead-off detection of bike-sharing.