Simultaneous comparison of 1 gel with 4 dry electrode types for electrocardiography

We designed a spandex tank top with dry electrodes for continuous electrocardiogram (ECG) recording. This pilot study determined the best fabric, the best electrode types, sizes, and locations. Optimal electrodes provide high signal to artifact ratio (SAR) and reliability by meeting the following criteria: 1) low baseline shift, 2) high adhesion, 3) good physical stability, 4) large effective area, 5) thin with high flexibility (Luo et al 1992). We compared electrodes from three main groups: Ag/AgCl gel electrode, commercial conductive rubber and foam-metal based electrodes. Ag/AgCl gel electrodes are easy to apply, make good body contact and do not slip during the course of an experiment. We found that higher SARs are obtained when electrode area is increased (40 mm diameter) and the two dry measurement electrodes are located on convex areas (over chest muscle) rather than concave areas (over sternum), so the spandex will apply light pressure to the dry electrode to yield good electrode to skin contact. We experimentally validated findings with 24 subjects: 12 men and 12 women wearing the tank top with gel and dry electrodes, by monitoring movements imitating daily life while continuously recording their ECGs.