Importance

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Abstract

A pressure regulator integrated in a sandwich of pyrex and silicon wafers. A first integrated valve comprising a silicon wafer in which there is etched a cavity so as to leave a flexible membrane of silicon is sandwiched between two other wafers which are usually pyrex. One of the pyrex wafers has a resistor pattern etched thereon in a location such that the resistor pattern is enclosed by the walls of the cavity when the pyrex wafer is bonded to the silicon wafer. The other pyrex wafer has a valve seat etched adjacent to the membrane in the silicon wafer. The cavity is filled with a fluid which, when heated, raises the vapor pressure in the cavity so as to cause the membrane to flex and change the spacing between the membrane and the valve seat thereby regulating flow. A second integrated valve has the same structure. One of these valves is coupled to a high pressure source and the other is coupled to a low pressure sink. Both valves are coupled to an output channel which has a capacitive pressure sensor integrated therein. Signals from this pressure sensor are used to control the energy applied to the resistors in the first and second valves to vary the area of the channels through the two valves coupling the output channel to the high pressure and low pressure sources.

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First Claim