Effect of Dry Electrode Lead Spacing on ECG Signal Quality for Small Portable Devices

Advancements in wearable technology and home-based electrocardiogram (ECG) devices have enabled noninvasive periodic and continuous cardiac monitoring, improving accessibility to cardiac care. Traditional wet electrodes provide high signal quality but can be inconvenient due to difficulty of application, skin irritation, required disposables, and restrictions on daily activities. To address these challenges, this study explores a chest-based small form factor dry electrode ECG sensor system as a user-friendly alternative. This research evaluates the impact of dry electrode placement on ECG signal quality, comparing dry electrodes to gold-standard wet electrodes. Measurements were conducted across various lead separations, assessing signal integrity using Signal Quality Indices (SQI) and QRS complex detection accuracy via the Pan-Tompkins algorithm. Results indicate that increasing lead separation enhances QRS amplitude and signal quality, while narrow placements reduce signal strength. Despite amplitude variations, QRS detection remained highly accurate across all conditions, demonstrating the reliability of dry electrodes in beat detection. Findings support the feasibility of dry electrodes for small form factor home-based ECG monitoring, indicating that a lead separation of 85mm can lead to accurate detection of QRS complexes for 60s recordings if no significant motion artifacts are present. Future work should focus on optimizing electrode materials, refining placement strategies, and validating performance in real-world conditions, including motion artifacts and diverse patient populations.