US Patent Number
A capsule pneumograph includes an electret microphone connected to a capsule chestpiece attached to a sleeping subject. The output of the microphone is connected to the input of a recorder or monitor in order to provide a system for the detection of respiratory movements in subjects during polysomnographic sleep monitoring. A tube connecting the capsule chestpiece to the microphone functions as a low pass filter to pass only low frequency signals in the range of respiratory movements from the chestpiece to the microphone.
University of Kentucky Research Foundation, Lexington, Ky.
Kraman, Steve S., "Simple Capsule Pneumograph" (1988). Internal Medicine Faculty Patents. 6.