Patent ID: 8142362
Filing Date: 2012-03-27
Classification: A61B

Abstract:
1. For measuring pressure of a sampled fluid within a biological structure, an implantable system comprising a plurality of housing portions having an overall coefficient of thermal expansion; an intermediary fluid having a coefficient of thermal expansion greater than the overall coefficient of thermal expansion of the plurality of housing portions; an external diaphragm including a first diaphragm portion having a first coefficient of thermal expansion, the first diaphragm portion positioned in the external diaphragm to contact the intermediary fluid when the external diaphragm is sealing the aperture with the pressure measuring system implanted in the biological structure, and a second diaphragm portion having a second coefficient of thermal expansion, the second diaphragm portion in juxtaposition with the first diaphragm portion; a chamber defined by the housing portions and the external diaphragm; and an aperture sealed by the external diaphragm to prevent passage of the intermediary fluid from the chamber through the aperture, apart from being sealed by the external diaphragm, the aperture otherwise in fluid communication with the chamber, the first diaphragm portion and the second diaphragm portion, shaped, sized, and positioned in the external diaphragm to cause the external diaphragm to expand away from the chamber to increase volume of the chamber when temperature of the intermediary fluid and the housing portions increases to substantially compensate for the difference between the coefficient of thermal expansion of the intermediary fluid and the overall coefficient of thermal expansion of the housing portions and geometrical configuration of the housing portions to allow the pressure level of the intermediary fluid to be substantially unaffected by changes in temperature of the intermediary fluid for conditions including over an operational range of the pressure measuring system.