Mks Instruments, Inc.

John A Denner

Paul D Lucas

Kristen Dodds Weight

Chris P Grudzien

Richard A Benson

Jeff Lischer

A pressure transducer assembly includes a first body, a second body, a diaphragm, and an electrode. The diaphragm is mounted between the first and second bodies. The first body and the diaphragm form a first chamber. The second body and the diaphragm form a second chamber. The electrode is disposed in the first chamber. A portion of the diaphragm flexes in a first direction in response to pressure in the first chamber being greater than pressure in the second chamber. A portion of the diaphragm flexes in a second direction, opposite the first direction, in response to pressure in the second chamber being greater than pressure in the first chamber. A capacitance between the electrode and the diaphragm is representative of a difference between the pressures in the first and second chambers. In some embodiments, the electrode is suspended from a hub and spoke mounting. In some embodiments the electrode is entirely metallic. In other embodiments, the electrode includes a ceramic disk with a conductive film formed on the disk and the disk is coupled to the housing with a ceramic rod. In some embodiments, the transducer also has a low thermal coefficient of expansion member connected to the housing for reducing warping in response to temperature changes. In additional embodiments, the disk includes a groove that reduces the effects of temperature variations on a ceramic electrode.

Capacitive based pressure sensor design

The disclosed pressure transducer assembly includes metallic body, a diaphragm, a metallic plate, an insulator, and a conductor. The body defines an interior cavity. The diaphragm is mounted in the body and divides the interior cavity into a first chamber and a second chamber. A portion of the diaphragm flexes in a first direction in response to a pressure in the first chamber being greater than a pressure in the second chamber, and that portion of the diaphragm flexes in a second direction opposite the first direction in response to the pressure in the second chamber being greater than the pressure in the first chamber. The metallic plate is fixed to the metallic body in one of the first and second chambers. The insulator is also disposed in that chamber and is fixed to the metallic plate. The conductor is disposed on the insulator. The diaphragm and the conductor are characterized by a capacitance. The capacitance is representative of a difference between the pressures in the first and second chambers.

Capacitive pressure transducer with improved electrode support

A single fluid-pressure transducer unit, of the type in which sensed electrical capacitance is varied in accordance with electrode deflections induced by pressure changes, is rendered capable of characterizing a wide range of pressures extending from near-vacuum to atmospheric levels, with the aid of a distinctive composite-electrode capsule which interacts uniquely with a conventional type of sheet-metal diaphragm. While sensing relatively low pressures, the exhibited capacitance of the transducer is essentially that appearing between the diaphragm and a nearby electrode carried by the capsule, but, at or near atmospheric pressure, the diaphragm physically engages and deflects that electrode, which is elastically deformable, causing it to vary a further capacitance appearing between that deformable electrode and a companion stationary electrode which is also part of the capsule.

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Lynn, MA, United States of America

John A Denner