Direct current conditioning to reduce the electrical impedance of the electrode to skin contact in physiological recording and stimulation

TL;DR

This paper presents a method using direct current to lower electrode-skin impedance, improving contact quality for physiological recording and stimulation, with effects lasting several hours.

Contribution

The study introduces a novel DC conditioning technique to reduce skin-electrode impedance, enhancing electrophysiological recording and stimulation reliability.

Findings

Impedance drops by 10-30% immediately after DC treatment.

Effects last for several hours with electrolyte paste.

DC conditioning improves electrode contact stability.

Abstract

Direct and alternating current iontophoresis and electro-osmosis methodologies have provided new methods of transcutaneous drug delivery. A byproduct of such methods is lowering the electrical impedance of the electrode to skin contact, as conductive ions permeate the stratum corneum, the primary resistive layer of the skin. We developed a method for adapting iontophoresis to condition the electrode to skin contact, both for electrophysiological recording and electrical stimulation of body tissues. By utilizing direct current to treat electrodes with high impedance we show the effectiveness of iontopheresis as a driving force for permeation of ionic electrolyte into the skin barrier. We applied direct current (DC) levels of 50 {\mu}A to electrodes on the human head for 30 seconds with paste (Nihon Kohden Elefix) electrolyte. Typically immediately after DC treatment conditioning there was an impedance drop of 10-30%. The effect was lasting over several hours, with the paste electrolyte. These results demonstrate the feasibility of DC conditioning to reduce the set time of electrolytic solutions and to maintain good skin contact during extended recording or stimulation sessions.