Capacitance Manometers and Methods of Making Same

• US 20090255342A1
• Filed: 04/10/2008
• Published: 10/15/2009
• Est. Priority Date: 04/10/2008
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Grudzien, Chris P.
• Granted Patent: US 7,757,563 B2
• Time in Patent Office: Days
• US Class Current: 73/724
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

A capacitance manometer comprises: a flexible diaphragm including a first electrode structure; an electrode structure including second and third spaced-apart electrode structures secured relative to the diaphragm so as to establish a capacitance between the first electrode structure and the second electrode structure and a capacitance between the first electrode structure and the third spaced-apart electrode structure, wherein the capacitances between the first electrode structure and each of the second and third electrode structures change with changes in differential pressure placed on opposite sides of the flexible diaphragm; and a thick film dielectric material disposed between the first electrode and each of the second and third spaced-apart electrode structures so as to increase the gain in capacitance of the manometer without decreasing the distance between the first electrode structure and each of the second and third electrode structures and without increasing the stroke of the flexible diaphragm, while preventing the first electrode structure from shorting with either the second or third electrode structure in response to over pressurization conditions.

Claims

1. A capacitance manometer comprising:

a flexible diaphragm including a first electrode structure;

an electrode structure including second and third spaced-apart electrode structures secured relative to the diaphragm so as to establish a capacitance between the first electrode structure and the second electrode structure and a capacitance between the first electrode structure and the third spaced-apart electrode structure, wherein the capacitances between the first electrode structure and each of the second and third electrode structures change with changes in differential pressure placed on opposite sides of the flexible diaphragm; and

a thick film dielectric material disposed between the first electrode and each of the second and third spaced-apart electrode structures so as to increase the gain in capacitance of the manometer without decreasing the distance between the first electrode structure and each of the second and third electrode structures, and without increasing the stroke of the flexible diaphragm, while preventing the first electrode structure from shorting with either the second or third electrode structure in response to over pressurization conditions.

2. A manometer according to claim 1, wherein the dielectric material is a coating disposed on the second and third electrode structures, between the diaphragm and the second and third electrode structures.

3. A manometer according to claim 2, wherein the coating includes a plurality of layers of the dielectric material.

4. A manometer according to claim 2, wherein the coating is uniform in thickness.

5. A manometer according to claim 1, wherein the second electrode is a center electrode and the third electrode is a ring electrode concentric with and spaced from the center electrode.

6. A manometer according to claim 5, wherein the dielectric material is disposed between the diaphragm and the center electrode and between the diaphragm and the ring electrode, and omitted between diaphragm and the space in between the center electrode and the ring electrode so as to minimize inter capacitance effects relating to the dielectric material.

7. A manometer according to claim 1, wherein the dielectric material is in contact with and seals the second and third electrode structures and is selected so as to protect the second and third electrodes from corrosive materials introduced in the manometer.

8. A manometer according to claim 1, wherein the second and third electrodes are coplanar with one another and in parallel with the first electrode structure when the diaphragm is in the zero position.

9. A manometer according to claim 1, wherein the dielectric material is chosen so as to increase the base capacitance and full scale capacitance of the manometer.

10. A manometer according to claim 1, wherein the dielectric material has a thickness greater than 1 micron.