Capacitive Electrocardiography: A Novel Perspective on Motion Artifacts and New Frontiers

The increasing prevalence of cardiovascular diseases in aging societies demands the adaptation of the healthcare system in the direction of prescreening and out-of-hospital monitoring. An unobtrusive alternative of the electrocardiogram (ECG), known as capacitive ECG, may help transform the diagnosis and treatment of patients with cardiovascular diseases. Although the capacitive ECG has been proposed for and tested in several applications like car seats and beds, various sources of electrical disturbances still deteriorate the ECG signal quality and restrict the feasibility of this technique. After laying the foundations for the modeling of motion artifacts, this work focuses on the heart's mechanical activity as a potential artifact origin, while demonstrating the influence of the cardiac vibrations on the capacitive ECG electrodes using impedance measurements. Afterward, the time-variant coupling impedance, the main mechanism leading to motion artifacts, is manipulated in a novel measurement modality aiming to utilize the tangible coupling impedance of cECG in an amplitude modulation scheme. Finally, a clinical trial is presented, where an existing capacitive ECG system was tested in a challenging subject profile, cardiac patients with implanted pacemakers, aiming to assess the limits of this technique in mobile healthcare monitoring.