Low-Noise and Cost-Effective Active Electrodes for Dry Contact ECG Applications

Abstract

Introduction. Active ECG electrodes for daily usable wearable electronics (glasses, headphones) enable making long-term cardiovascular disease diagnostics available to many people.Problem Statement. The methods of ECG recording become more accessible over the years. However, on the way to their general use, even in cases where only reliable registration of the R-wave of the ECG is important, there are certain difficulties associated with the need to apply special electrodes (eg, silver chloride ones) to certain parts of the body through wet pads and to perform specific actions. The problem is solved by using dry electrodes built into the usual devices. However, in this case, a low amplitude of the useful signal and a high contact resistance (for example, on the surface of the head) do not allow recording an ECG by conventional means.Purpose. The purpose of this research is to develop easy-to-use body ECG electrodes that may be built into everyday appliances.Materials and Methods. Active electrodes based on flexible conductive materials and high-quality operational amplifiers have been described. The main parameters of the electronic circuit have been obtained by model and experimental research. The parameters have been compared with the corresponding characteristics of commercial samples.Results. Prototype active ECG electrodes have been developed, created, and studied. The obtained results have shown that the dependence of the input reactance on the frequency plays an important role in terms of the final signal quality. For a low-amplitude ECG signal, the prototype has shown a signal-to-noise ratio that is higher by 4.7 dB than that for high-quality commercial electrodes.Conclusions. The designed electrodes may be used in body devices, on the body parts with a low amplitude of the useful signal and a high resistance of skin-electrode contact.