Two-Electrode ECG for Ambulatory Monitoring with Minimal Hardware Complexity.

Area of Science:

• Biomedical Engineering
• Signal Processing
• Wearable Technology

Background:

• Wearable electrocardiogram (ECG) devices require minimal hardware for battery-powered operation.
• Ground-free ECG measurements are susceptible to significant noise interference.
• Effective noise suppression is crucial for reliable ECG signal acquisition in wearable systems.

Purpose of the Study:

• To introduce and evaluate noise suppression techniques for a two-electrode, ground-free ECG system.
• To assess the suitability of these methods for wearable, battery-powered applications.
• To identify the most effective method for power-line noise reduction and hardware simplicity.

Main Methods:

• Development of a two-electrode, ground-free ECG acquisition system.
• Implementation and comparison of three distinct noise suppression methods.
• Experimental validation using a patient simulator and a living subject with the ADS1191 front-end.
• Analysis of Power Spectral Density (PSD) and current consumption.

Main Results:

• All three noise suppression methods demonstrated suitability for power-line noise reduction in simulator tests.
• Signal power at 50 Hz varied across methods for subject measurements (-28 dB, -24.8 dB, -26 dB).
• Post-processed ECG signals achieved quality comparable to traditional three-electrode systems.
• All proposed solutions exhibited low current consumption (<1.5 mA at 500 SPS), suitable for battery operation.

Conclusions:

• The developed two-electrode ground-free ECG system is effective for wearable applications.
• The first noise suppression method proved most effective in reducing power-line noise, minimizing current consumption, and simplifying hardware.
• High-quality ECG signals comparable to multi-electrode systems can be achieved with this simplified approach.