Validating Differential Dermal Potentials for Use in Real-Time Human Condition Monitoring

In the present pandemic scenario, it is of great importance to have reliable schemes for monitoring the human condition. The aim of this study is to validate the differential dermal potential in terms of the standard endosomatic electrodermal activity (EDA) and determine its usability in real-time applications. The differential dermal potential signal is passively acquired across the intermediate phalanges of the middle and index fingers of the hand or feet of human subjects. A physiological basis for these signals is proposed at the outset of this study. In this study, the signal is acquired from the left hand and is compared with two corresponding standard endosomatic EDA signals that are acquired simultaneously from the same two fingers. The experimental data is acquired while the subjects undergo a change of posture and then settle into a restful static condition. Thereafter, these signals are analyzed to determine their settling time as well as their autocorrelation, statistical, and spectral characteristics. It is found that the differential dermal potential signal is a stable passive signal with low settling time. It is strongly correlated with the difference of the two underlying standard endosomatic EDA signals, though not identical to it. The information in this signal, as obtained from the various characteristics, are interpretable and reliable. The findings in this study validate that this signal can be effectively used for monitoring the human condition.