Suppression of Artifacts in Biomeasurement System by Pneumatic Filtering

The pneumatic biomeasurement system is a noninvasive, constraint-free method for monitoring the heartbeat, respiration and other vital signs of a person in bed. Body microvibrations transmitted through the bed cushion act on the air in a thin air mattress under the cushion. Changes in air pressure synchronized with the microvibrations are detected by a pressure sensor. However, the high sensitivity of the sensor results in output saturated with body motion artifacts. This paper describes a novel method for pneumatic filtering of these artifacts. A theoretical model was developed as the basis for designing a pneumatic filter to reduce body motion artifacts. The validity of the proposed high-pass filtering method was examined through experiments.