Analysis of Skin-Electrode Impedance Using Concentric Ring Electrode

Abstract

A significant contributor to artefact generation in surface electromyography (sEMG) and, functional electrical stimulation (FES) intensity is the skin-to-electrode impedance (Z(S/E)). While using electrolytic gels may initially lower Z(S/E), the impedance may not remain stable. It can vary over time due to changes in underlying structures such as sweat glands and physical deformations due to movements. An experiment seeking to identify major factors in the reduction of Z(S/E), and therefore mitigate these artefacts, was performed by varying a series of control factors on the concentric ring electrode (CRE). Unlike conventional disc electrodes, CREs have small surface areas which may exacerbate Z(S/E) changes. The factors tested were electrode material, electrode size, skin preparation, and surface pressure. This work analyzes how these factors in their various combinations effect changes in Z(S/E) and suggests protocols for improving recording or stimulation with CREs via lowered and consistent Z(S/E).

A Novel Intrabody Communication Transceiver for Biomedical Applications

“…The value of Z ES is represented by a series of three impedances consisting of electrode metal impedance, gel impedance, and skin layer impedances which include epidermis and subdermal impedances. According to Besio et al [56], in the suitable contact between electrode and skin surface, the amount of Z ES is less than 10 kΩ. To achieve the value of Z ES in this study, port 1 of Mini VNA Pro is directly connected to the on-body transmitter electrodes via the connecting cable.…”

A Comparative Evaluation of Sonomyography, Electromyography, Force, and Wrist Angle in a Discrete Tracking Task

“…EMG is an inherently random, nonstationary and nonlinear signal that is susceptible to interference from socket movement and sweat-related skin impedance changes (Besio and Prasad 2006;Alemu et al 2003). It is also difficult when using surface EMG to discriminate the activity of deep muscles from that of more superficial ones (De Luca 2002), limiting the potential for multi-DOF control.…”

Site-to-site variation of muscle activity and sensitivity in the human anterior temporalis muscle: Implications for contingent stimulation

“…Adequate electrode adhesion to the skin is important for maintaining EMG signal quality and sensory threshold to electrical stimulation. Skin abrasion, electrolytic gel interfaces and pressure on the electrode surface have been recommended to reduce impedance and hold the electrode in place [30]. This study showed that impedance and sensory threshold was higher at the posterior area compared to the anterior and middle areas.…”

“…The electrode-skin impedance is one of the main elements of artefact in surface EMG recording and electrical stimulation intensity [30,31]. The skin at the temple over the AT muscle was divided into nine sites which were a 3x3 grid in this study.…”