Patent ID: 8704538

Claim:
A capacitance sensor assembly arranged to measure a pressure relative to a reference pressure, the capacitance sensor assembly comprising: a housing assembly including an opening having an inner radial wall extending along a radius from a longitudinal axis and defining a space within the housing; an electrode arrangement disposed within the housing and fixedly secured relative to the housing assembly; and a flexible diaphragm disposed within the housing and defining a first surface and an opposed second surface, the diaphragm further having (a) an active portion that is operative to flex in response to a pressure differential between the first surface and the second surface, and (b) a fixed portion having an outer radial perimeter that is fixed at one or more connections to the inner radial wall of the housing assembly; wherein the housing assembly supports the diaphragm and electrode arrangement in a spaced apart relationship with respect to one another such that the active portion of the diaphragm flexes relative to the electrode arrangement in response to a differential pressure applied to the opposed first and second surfaces of the diaphragm; and wherein the connections are configured to present a groove between the diaphragm and the inner radial wall of the housing assembly, wherein the diaphragm is connected to the inner radial wall of the housing assembly at an inner radial portion of the groove, wherein the groove is operative to relieve any stress on the active portion of the diaphragm under a condition of zero differential pressure.