A direct comparison of wet, dry and insulating bioelectric recording electrodes

TLDR

Alternatives to conventional wet electrodes are sought for prolonged biomedical recordings. The study quantitatively compares wet, dry, and insulating electrodes on impedance, static interference, and motion artefact. Measurements were taken simultaneously in the same environment, comparing dry and insulating electrodes to wet ones under non‑stationary electric fields and motion artefact. Dry and insulating electrodes performed comparably to wet electrodes, showing 40 dB and 34 dB lower interference and eventually lower artefact levels by 8.2 dB and 6.8 dB, refuting concerns about their reliability.

Abstract

Alternatives to conventional wet electrode types are keenly sought for biomedical use and physiological research, especially when prolonged recording of biosignals is demanded. This paper describes a quantitative comparison of three types of bioelectrode (wet, dry and insulating) based on tests involving electrode impedance, static interference and motion artefact induced by various means. Data were collected simultaneously, and in the same physical environment for all electrode types. Results indicate that in many situations the performance of dry and insulating electrodes compares favourably with wet electrodes. The influence of non-stationary electric fields on shielded dry and insulating electrode types was compared to wet types. It was observed that interference experienced by dry and insulating electrode types was 40 dB and 34 dB less than that experienced by wet electrode types. Similarly, the effect of motion artefact on dry and insulating electrodes was compared to wet types. Artefact levels for dry and insulating electrodes were significantly higher than those for wet types at the beginning of trials conducted. By the end of the trial periods artefact levels for dry and insulating types were lower than wet electrodes by an average of 8.2 dB and 6.8 dB respectively. The reservations expressed in other studies regarding the viability of dry and insulating electrodes for reliable sensing of biosignals are not supported by the work described here.