Features of voltage pulse plethysmography

Measurement of tissue volume changes by voltage pulse plethysmography is being studied. In voltage pulse plethysmography short voltage pulses activate the bio-tissue and the characteristics of the transient process are measured. There are two possible implementations: with grounded bio-tissue and with grounded current sampling resistor. Measurement was carried out for both cases and the obtained wave-shapes for blood pulsations in the arteries and for respiration are presented. From the characteristics of measured voltage the parameters of equivalent circuit for electrode-skin interface with three elements are calculated for dry and gel-wetted electrodes.