Identifying Optimal Electrodermal Activity Locations in the Torso for Wearable Belt Monitors: Preliminary Results

Electrodermal activity (EDA) is traditionally taken from locations like the fingers, palms, or even the sole of the foot. These areas provide ideal signals but are easily corrupted by movement, limiting the practical acquisition of the signal during most activities. The torso could potentially offer an alternative location for EDA recording that negates the effect of such movements while preserving the information the signal holds. In this work, we collected EDA recordings from 10 subjects across five different locations (finger, sternum, lower pectoralis, hip, spine) while they were exposed to cognitive and physical stressors (Stroop task and cold pressor task respectively). Several EDA indices were derived from the EDA corresponding to each task and compared across all the locations using the finger data as reference. We found significant differences between stressor and baseline for the pectoral location when observing the time-varying index of sympathetic activity (TVSymp), in addition to the spine location when observing the spectral index of sympathetic activity based on EDA (Sympn). This corresponds with similar activation of the same indices captured by the fingers. Low correlation was found between locations for each metric. Additional work modifying subject hydration, electrode type, and signal filtering is required to identify an ideal torso location for EDA.