Comparison of dry and wet electrodes for detecting gastrointestinal activity patterns from body surface electrical recordings

ObjectiveGastrointestinal motility patterns can be mapped via electrical signals measured non-invasively on the body surface. However, long-term monitoring ([≥] 24 hr) may be hindered by skin-irritation inherent with traditional Ag/AgCl pre-gelled ("wet") electrodes. Therefore, the aim of this work was to investigate the practical utility of using dry electrodes for GI body-surface electrical measurements. ApproachTo directly compare dry versus wet electrodes, we simultaneously recorded electrical signals from both types arranged in a 9 electrode (3 x 3) array during an {approx} 2.5 hr colonic meal-response study. Wavelet-based analyses were used to identify the signature post-meal colonic cyclic motor patterns. Signal quality was assessed for each electrode type through quantitative comparison of the dominant frequency, amplitude, signal-to-noise ratio (SNR), and signal energy vs time in the colonic frequency band. Blinded comparison of signal quality was carried out by four expert manual reviewers in order to assess the practical utility of each electrode type for identifying GI activity patterns. Main resultsDry electrodes recorded high-quality GI signals comparable to that of wet electrodes, with dominant frequency in the range 2.85 - 3.25 cpm; peak-peak amplitudes of 120 {+/-} 40 {micro}V, and SNR in the range 7.5 - 11 dB. The CWT colonic frequency band energy versus time correlation coefficient value was [≥] 0.71 for the majority of studies (6 out of 7) indicating very good agreement between dry and wet electrode signals overall. Whereas wet electrodes were rated by expert reviewers as having slightly better signal quality for identifying GI activity patterns, dry electrodes caused no skin irritation and were thus better-tolerated by all subjects. SignificanceDry electrodes are a viable option for long-term GI monitoring studies, offering a potentially more comfortable alternative to conventional wet electrode systems.