Two-Electrode ECG for Ambulatory Monitoring with Minimal Hardware Complexity

Abstract

This article introduces a two-electrode ground-free electrocardiogram (ECG) with minimal hardware complexity, which is ideal for wearable battery-powered devices. The main issue of ground-free measurements is the presence of noise. Therefore, noise suppression methods that can be employed for a two-electrode ECG acquisition system are discussed in detail. Experimental measurements of a living subject and patient simulator are used to investigate and compare the performance of the three proposed methods utilizing the ADS1191 analogue front-end for biopotential measurements. The resulting signals recorded for the simulator indicate that all three methods should be suitable for suppressing power-line noise. The Power Spectral Density (PSD) of the signals measured for a subject exhibits differences across methods; the signal power at 50 Hz is −28, −24.8, and −26 dB for the first, second, and third method, respectively. The digital postprocessing of measured signals acquired a high-quality ECG signal comparable to that of three-electrode sensing. The current consumption measurements demonstrate that all proposed two-electrode ECG solutions are appropriate as a battery-powered device (current consumption < 1.5 mA; sampling rate of 500 SPS). The first method, according to the results, is considered the most effective method in the suppression of power-line noise, current consumption, and hardware complexity.

Human Body–Electrode Interfaces for Wide-Frequency Sensing and Communication: A Review

“…External interferences such as AC mains near to a biopotential signal measurement system can capacitively couple current to the human body and to the measurement circuit [ 90 , 91 ]. Figure 16 depicts an ECG measurement system showing the coupling of currents from AC main lines to the human body and to the ECG measurement circuit.…”

“…The magnitude of this noise signal, , is proportional to the coupling currents, , , contact impedance of electrode-A ( ), contact impedance of electrode-B ( ) and their mismatches. can be calculated as follows [ 90 , 92 , 93 ]. …”

“…External interferences can also cause common mode-induced noise in biopotential signal measurements [ 90 ]. In Figure 16 , the current , coupled from the AC mains to the body through the parasitic capacitor, , can modulate the body potential, , at 50/60 Hz with respect to the earth’s ground.…”

Design of Smart Steering Wheel for Unobtrusive Health and Drowsiness Monitoring

“…The electrode placed on the right leg provides the return path for common-noise reduction. This type of noise reduction is known as driven-right-leg (DRL) circuit [ 36 , 37 ]. Alternatively, the right leg electrode can be connected to the signal ground to reduce noise from the surroundings.…”

Prototype Development of Continuous Remote Monitoring of ICU Patients at Home

“…Several researchers demonstrated that three-electrode ECGs provide an approximately 98% and 74% sensitivity and specificity respectively for distinguishing between native and pathological heart electrical activity [7,8]. Branko Babusiak et al shown low powered two-electrode ECG system that may be used for the analysis of the electrical activity of the heart [9]. The three electrodes (lead-II) were used to acquire the ECG signal to monitor the electrical activity of the heart.…”