Parameter optimization in voltage pulse plethysmography

Abstract

Measurement optimization is being studied when short voltage pulses are stimulating bio-tissue and the transient process is sampled in order to measure the tissue volume changes. The measurement sensitivity depends on the ratio of the sampling instant to the time constant of the transient process, (T/τ) and on the ratio of the current sensing resistance to the resistance of the electrode-skin interface (R0/RSX). With variations of R0/RSXand T/τ the sensitivity changes from negative to positive values, while it equals zero for certain R0/RSXand T/τ ratios. The sensitivity is greater when positive while than negative but it depends on T/τ and R0/RSX. For negative sensitivity, T and R0can be chosen to maximize the sensitivity and minimize its variations.