Since Summer 2021 the well-known special electrolyte for galvanic skin response (GSR) or electrodermal activity (EDA) recordings, TD-246, is no longer available, leaving a severe gap as no other commercial isotonic electrolyte seems to be available. Easycap GmbH therefore put its effort into developing and evaluating an alternative of equal quality. This gel, called EDALYT, is now available.
EDALYT is a non-drip, non-staining, water-soluble electrolyte gel with 0.5% salinity. It underwent quantitative and qualitative evaluation by recording GSR simultaneously from adjacent TD-246-filled and EDALYT-filled pairs of electrodes fixed to the muscle bellies of the left and right index and middle finger phalanges (see figure below). The numerical values recorded with EDALYT were very similar to those recorded with TD-246 (see figure below), and qualitatively the signals of both gels clearly showed the same standard GSRs to typical provocations (Valsalva maneuver, listening to jokes), but also suppressed or absent GSRs over scar tissue, and similar artifact profiles over dry skin.
Left: Electrode placement (Fig.1). Right: Signal of TD-246, EDALYT, and difference (Fig. 2).
Due to the limited data base, our results up to now should be seen more as proof-of-principle tests than comprehensive evaluations. Therefore, before using EDALYT instead of TD-246 in an ongoing experiment each lab should make their own independent signal quality checks and comparisons. Nonetheless, we are confident that for new experiments, EDALYT will yield results equally reliable and valid as if done with TD-246.