Flexible polymeric dry electrodes for the long-term monitoring of ECG

In this paper, we present a novel polymeric dry electrode that (1) changes its shape in a way that supports the electrode's contact with the skin and (2) that does not cause skin irritations or allergic reactions. For a polymeric substrate of electrodes, we have used the elastomer poly(dimethylsiloxane), which is known to be inexpensive, biocompatible, and amenable to micro-molding, and to have excellent gas and water permeability. We have established a process by which one can deposit a metal layer on the PDMS substrate, etch the electrode patterns chemically and with good resolution, and package the electrode so that it is easily wearable on the forearm. We measured the impedance according to the frequency change and compared the results with those of Ag/AgCl electrodes. Afterward, we measured the ECG signal and investigated possible artifacts caused by motion. For the feasibility of long-term monitoring, we examined the influence of surface electrodes on the skin after 7 days of ECG monitoring. In conclusion, our PDMS-based dry electrode measured the ECG signals with comparatively good fidelity, but showed better skin compatibility after long-term tests. We expect that our method for the production of PDMS-based dry electrodes will be broadly applicable to the field of ubiquitous biosignal monitoring.