Polygraphic belt with force-sensing expander for physiological tests on cosmonauts.

To study cardiorespiratory and neuromotor functions in cosmonauts a novel belt with embedded polygraphic sensors and a force sensing expander were developed. The sensors are: a three-electrode ECG/impedance plethysmographic system to capture cardiac and respiratory activity, two triaxial accelerometers to record limb micromotions and an IR reflex-sensor to detect peripheral pulse waves. The expander consists of an elastic cable in series with a load cell to measure the extension force and to adjust the extensions by visual feedback. The cable stiffness was chosen rather high (150-200 N/m) in order to induce involuntary limb oscillations at higher extension levels. The equipment was tested in MIR spaceflights and is projected for physiological tests on the ISS.