Development of a Solid-State Impedance Plethysmograph for Research in a Space Environment

摘要

A new solid-state impedance plethysmograph utilizing a constant current source was designed, built, and tested. The report presents the design philosophy, the circuitry, the final configuration of the device, and the technics for its proper alignment. The circuit detects a 1% impedance change centered on basal body impedance levels between 100 ohms and 15 kilohms. Although normally operated at 100 kHz, the circuit will operate at various frequencies, and it will accommodate either the bipolar or tetrapolar electrode configuration. Circuit performance was confirmed by taking thoracic impedance measurements on a human subject. (Author)