US4589287A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Strain gauge for medical pressure measurements
Assignee: American Hospital Supply Corp
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Filing: 1984-09-17
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Granted: 1986-05-20
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Expires: 2004-09-17
Abstract
Abstract A disposable strain gauge pressure sensor providing reliable electrical isolation even at defibrillation voltages in the measurement of biological fluid pressures is produced by floatingly mounting a glass plate on a closed cell, fluid-impervious foam pad within a firm but not totally rigid plastic housing. The glass plate has a thin glass diaphragm integrally formed therein which carries the strain gauge element. Openings in the foam pad and the housing allow a fluid contained in a fluid dome on the outside of the housing to bathe the side of the glass diaphragm opposite that on which the strain gauge element is mounted. The glass plate, foam pad, and housing are bonded together in fluid-tight relationship so that fluid cannot reach anything within the housing other than the glass diaphragm. The housing is preferably transparent to allow observation of the diaphragm during operation.
Inventors
- 👤 Duane D. Dickens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:23
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0051; A; A61; A61B; A61B5/00; A61B5/02; A61B5/021; A61B2562/00; A61B2562/02; A61B2562/0261
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
125 words
A strain gauge for measuring the pressure of biological fluids, comprising: (a) a non-rigid housing including fluid receiving means, a generally planar support surface, and walls surrounding said support surface; (b) said support surface having an opening therein communicating with said fluid receiving means; (c) a closed cell foam pad secured in fluid-tight relationship to said support surface and having an opening therein communicating with said support surface opening; and (d) a sensor plate secured in fluid-tight relationship to said foam pad in spaced relation to said walls, said sensor plate having a glass diaphragm formed therewith, said glass diaphragm being in communication with said foam pad opening on one side thereof and having a strain gauge element applied thereto on the other side thereof.
Claim 2
Dependent Claim
125 words
A strain gauge for measuring the pressure of biological fluids, comprising: (a) a non-rigid housing including fluid receiving means, a generally planar support surface, and walls surrounding said support surface; (b) said support surface having an opening therein communicating with said fluid receiving means; (c) a closed cell foam pad secured in fluid-tight relationship to said support surface and having an opening therein communicating with said support surface opening; and (d) a sensor plate secured in fluid-tight relationship to said foam pad in spaced relation to said walls, said sensor plate having a glass diaphragm formed therewith, said glass diaphragm being in communication with said foam pad opening on one side thereof and having a strain gauge element applied thereto on the other side thereof.
Claim 3
Dependent Claim
19 words
The strain gauge of claim 1, in which said foam pad is positioned in spaced relationship to said walls.
Claim 4
Dependent Claim
31 words
The strain gauge of claim 1, in which said openings and fluid receiving means together define a fluid chamber to allow fluids in said fluid chamber to bathe said glass diaphragm.
Claim 5
Dependent Claim
55 words
The strain gauge of claim 1, further including: (e) cable means for connecting said sensor means to external apparatus, said cable means having strain relief means integrally formed therewith; (f) said housing including clamp means cooperating with said strain relief means to hold said cable means in a fixed position with respect to said housing.
Claim 6
Dependent Claim
37 words
The strain gauge of claim 4, in which said sensor plate further includes circuit board means bonded to said glass plate, said circuit board means being electrically connected to said strain gauge means and said cable means.
Claim 7
Dependent Claim
34 words
The strain gauge of claim 1, further comprising fluid inlet and outlet means associated with said fluid receiving means to fill said fluid receiving means with a fluid whose pressure is to be measured.
Claim 8
Dependent Claim
43 words
The strain gauge of claim 6, in which said fluid receiving means is a transparent fluid dome positioned on the outside of said housing in fluid-tight relationship to said outside of said housing, and adjacent said support surface opening for fluid communication therewith.
Claim 9
Dependent Claim
18 words
The strain gauge of claim 1, in which said foam pad opening is larger than said glass diaphragm.
Claim 10
Dependent Claim
33 words
The strain gauge of claim 1, in which said foam pad is on the order of 0.5 to 1.3 mm in thickness, and has a density on the order of 6 to 30.
Claim 11
Dependent Claim
23 words
The strain gauge of claim 1, in which said foam pad is about 0.8 mm thick and has a density of about 6.
Claim 12
Dependent Claim
12 words
The strain gauge of claim 1, in which said housing is transparent.
References Cited (Backward Citations)
US4274423A
Cited
US4373397A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |