US5528452A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitive absolute pressure sensor
Assignee: Case Western Reserve University
•
Filing: 1994-11-22
•
Granted: 1996-06-18
•
Expires: 2014-11-22
Abstract
Abstract A capacitive absolute pressure sensor. The sensor includes a substrate having an electrode deposited thereon and a diaphragm assembly disposed on the substrate. As pressure increases, the diaphragm deflects, touches the electrode (in the touch mode), and changes the capacitance of the sensor. The changed capacitance is sensed to thus sense pressure changes. A buried feedthrough is used to sense the change in a capacitance in a chamber under the diaphragm and thus determine the pressure sensed. A vacuum in the chamber is maintained by proper selection of a thickness of a sensing electrode and an insulating layer, exposition thereof to a thermal cycle, and the hermetic bonding of the diaphragm assembly to the substrate.
Inventors
- 👤 Wen H. Ko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 06:08
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0072; G01L9/0073
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
190 words
A capacitive pressure sensor comprising: a substrate having 1) an electrode disposed thereon, 2) a first portion and a second portion spanned by the electrode, and 3) an insulating layer disposed over the electrode in the first portion only; a diaphragm assembly on the substrate including a frame structure and a dividing wall defining a first region, across which a diaphragm is disposed, and a second open region; and, the first and second regions being arranged on the substrate such that 1) the first portion of the substrate is aligned with the first region and the diaphragm so the diaphragm, the substrate, the dividing wall, and corresponding frame structure defining the first region, form an evacuated chamber and 2) the second portion of the substrate is aligned with the second open region to facilitate access to the electrode, the dividing wall generally separating the first and second regions and contacting the insulating layer on the electrode in the first portion, the insulating layer and the electrode being of a predetermined thickness and, the insulating layer deforming around the electrode to seal and maintain a vacuum state in the evacuated chamber.
Claim 2
Dependent Claim
190 words
A capacitive pressure sensor comprising: a substrate having 1) an electrode disposed thereon, 2) a first portion and a second portion spanned by the electrode, and 3) an insulating layer disposed over the electrode in the first portion only; a diaphragm assembly on the substrate including a frame structure and a dividing wall defining a first region, across which a diaphragm is disposed, and a second open region; and, the first and second regions being arranged on the substrate such that 1) the first portion of the substrate is aligned with the first region and the diaphragm so the diaphragm, the substrate, the dividing wall, and corresponding frame structure defining the first region, form an evacuated chamber and 2) the second portion of the substrate is aligned with the second open region to facilitate access to the electrode, the dividing wall generally separating the first and second regions and contacting the insulating layer on the electrode in the first portion, the insulating layer and the electrode being of a predetermined thickness and, the insulating layer deforming around the electrode to seal and maintain a vacuum state in the evacuated chamber.
Claim 3
Dependent Claim
33 words
The sensor as set forth in claim 1 wherein the frame structure and the dividing wall are dimensioned such that the sensor withstands large external forces, pressures, and temperature extremes thereby maintaining stability.
Claim 4
Dependent Claim
20 words
The sensor as set forth in claim 1 wherein the predetermined thickness of the insulating layer is approximately 0.3-3.0 microns.
Claim 5
Dependent Claim
19 words
The sensor as set forth in claim 1 wherein the predetermined thickness of the electrode is approximately 0.1-0.3 microns.
Claim 6
Dependent Claim
15 words
The sensor as set forth in claim 1 wherein the evacuated chamber has a capacitance.
Claim 7
Dependent Claim
19 words
The sensor as set forth in claim 5 wherein the capacitance changes as pressure is exerted on the diaphragm.
Claim 8
Dependent Claim
19 words
The sensor as set forth in claim 6 wherein the pressure causes the diaphragm to touch the insulating layer.
Claim 9
Dependent Claim
23 words
The sensor as set forth in claim 1 wherein the electrode comprises chromium and platinum thereby providing good adhesion to the insulating layer.
Claim 10
Dependent Claim
30 words
The sensor of claim 1 wherein the diaphragm is deflected to touch the insulating layer as a function of pressure imposed on the diaphragm whereby touch mode operation is realized.
Claim 11
Dependent Claim
17 words
The sensor of claim 9 wherein the sensor has a linear operating range in a touched region.
Claim 12
Dependent Claim
22 words
The sensor of claim 10 wherein the sensor withstands overload pressure as a result of being deflected to touch the insulating layer.
Claim 13
Dependent Claim
26 words
The sensor of claim 11 wherein output voltage in a non-linear region is suppressed such that the linear operating range corresponds to a desired pressure range.
References Cited (Backward Citations)
US4838088A
Cited
US5241864A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-06-18 | 1999-12-18 | 2000-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-18 | 2003-12-18 | 2004-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-18 | 2007-12-18 | 2008-06-18 | $7700.00 | Window Closed / Lapsed |