Pressure actuated plethysmograph sensor - has crystal microphone for registering pressure changes of air bandage attached body of patient

摘要

This pressure plethysmograph employs a readily available body microphone with minor alterations for monitoring the pulse rate and the bloodcirculation. The microphone registers pressure changes of its enclosed air volume which is linked to an inflated bandage on the patient. The interior (18) of the readily available microphone (10) is made air tight by fitting a tube adaptor (17) which links the airspace (18) via a connector (20) to an inflated bandage (19). Pressure changs within this bandage are then converted into electrical signals by the piezoelectric crystal (14) on the diaphragm (11) of the microphone.