Measuring skin-electrode impedance variation of conductive textile electrodes under pressure

Electrocardiogram (ECG) is the first bio-signal physicians use to diagnose cardiovascular diseases, since any kind of heart abnormality reflects on it. ECG electrodes play an important role in collecting this signal. One type of ECG electrodes which is recently getting more popular, especially due to its user friendly features compared to traditional Ag/AgCl electrodes, is conductive textile. Similar to any other type of electrode, conductive textile is associated with skin-electrode interface impedance located between the body (source of signal) and ECG monitoring device, thus affecting the recorded ECG quality. In this paper, we measure the skin-electrode impedance of conductive textile electrodes under various pressure levels, because in some applications ECG electrode is located under a blood pressure cuff and therefore it is under pressure when the cuff is inflated. We show that in fact under pressure the impedance decreases, resulting in a higher quality ECG measurement.