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US4023562A
Expired / Lapsed
US
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Miniature pressure transducer for medical use and assembly method
Assignee: Case Western Reserve University
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Filing: 1975-09-02
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Granted: 1977-05-17
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Expires: 1995-09-02
Abstract
Abstract A fluidtight, hermetically sealed, miniature transducer adapted to be inserted into the human body and useful for directly monitoring internal fluid or pneumatic pressures within the human body is disclosed. Semiconductor strain gauge elements constituting a piezoresistive bridge are formed by diffusion on the surface of one side of an integral flexible, rectangular, silicon diaphragm area of a single crystal silicon base. A single crystal silicon cover is eutectically bonded to the base by a metallic laminate seal. The base, cover, and seal define an evacuated fluidtight chamber containing the strain gauge elements. Electrical conductors, which include diffused conductor paths under an insulating oxide layer, extend from the piezoresistive bridge to contact pads outside the fluidtight chamber. The contact pads can be connected to a readout device for electrically measuring the pressure differential between the evacuated chamber and fluid external to the transducer as a function of time.
Inventors
- 👤 Jaroslav Hynecek
- 👤 Wen H. Ko
- 👤 Eugene T. Yon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 18:43
CPC Classifications
G; G01; G01L; G01L19/00; G01L19/0061; A; A61; A61B; A61B5/00; A61B5/03; G01L9/00; G01L9/0041; G01L9/0051; G01L9/0052; G01L9/0054
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
130 words
A transducer for measuring fluid or pneumatic pressure comprising a semiconductor base member, at least a portion of said base member being a thin flexible diaphragm, a piezoresistive bridge formed on a surface of a side of said diaphragm, said bridge having at least one electrical parameter which changes in response to flexing of said surface of said diaphragm, a cover member, a seal bonding said cover member to said base member, said members and said seal defining a fluidtight chamber containing said piezoresistive bridge, and electrical conductor means extending from said piezoresistive bridge to a point external to said fluidtight chamber, said conductor means including diffused conductor paths on said base member where said conductor means passes from said fluidtight chamber to said point external to said fluidtight chamber.
Claim 2
Dependent Claim
130 words
A transducer for measuring fluid or pneumatic pressure comprising a semiconductor base member, at least a portion of said base member being a thin flexible diaphragm, a piezoresistive bridge formed on a surface of a side of said diaphragm, said bridge having at least one electrical parameter which changes in response to flexing of said surface of said diaphragm, a cover member, a seal bonding said cover member to said base member, said members and said seal defining a fluidtight chamber containing said piezoresistive bridge, and electrical conductor means extending from said piezoresistive bridge to a point external to said fluidtight chamber, said conductor means including diffused conductor paths on said base member where said conductor means passes from said fluidtight chamber to said point external to said fluidtight chamber.
Claim 3
Dependent Claim
23 words
A transducer according to claim 1, wherein said base member and said cover member have generally identical thermal coefficients of expansion and contraction.
Claim 4
Dependent Claim
12 words
A transducer according to claim 2, wherein said fluidtight chamber is evacuated.
Claim 5
Dependent Claim
22 words
A transducer according to claim 3, wherein said seal and said base member are separated by a layer of electrical insulation material.
Claim 6
Dependent Claim
18 words
A transducer according to claim 4, wherein said insulation material covers said piezoresistive bridge and said conductor paths.
Claim 7
Dependent Claim
128 words
A transducer for measuring fluid or pneumatic pressure comprising a single crystal, silicon base member with an integral flexible diaphragm, a diffused piezoresistive bridge formed on a surface of said diaphragm, said bridge having at least one electrical parameter which changes in response to the deformation of said surface of said diaphragm, a single crystal, silicon cover member, a laminate seal bonding said cover member to said base member, said members and said seal defining an evacuated fluidtight chamber containing said piezoresistive bridge, and electrical conductor means extending from said piezoresistive bridge to a point external to said fluidtight chamber, said conductor means including diffused conductor paths on said base member where said conductor means passes from said fluidtight chamber to said point external to said fluidtight chamber.
Claim 8
Dependent Claim
128 words
A transducer for measuring fluid or pneumatic pressure comprising a single crystal, silicon base member with an integral flexible diaphragm, a diffused piezoresistive bridge formed on a surface of said diaphragm, said bridge having at least one electrical parameter which changes in response to the deformation of said surface of said diaphragm, a single crystal, silicon cover member, a laminate seal bonding said cover member to said base member, said members and said seal defining an evacuated fluidtight chamber containing said piezoresistive bridge, and electrical conductor means extending from said piezoresistive bridge to a point external to said fluidtight chamber, said conductor means including diffused conductor paths on said base member where said conductor means passes from said fluidtight chamber to said point external to said fluidtight chamber.
Claim 9
Dependent Claim
11 words
A transducer according to claim 6, wherein said diaphragm is rectangular.
Claim 10
Dependent Claim
16 words
A transducer according to claim 7, wherein said diaphragm has a rectangle ratio of approximately 3:1.
Claim 11
Dependent Claim
27 words
A transducer according to claim 6, wherein said laminate seal includes at least one metal alloy which eutectically bonds said cover member and said base member together.
Claim 12
Independent Claim
134 words
A method of assembling a pressure transducer comprising the steps of: forming a piezoresistive bridge and diffused conductor paths on the surface of one side of a generally planar semiconductor base member, at least a portion of said base member being a thin flexible diaphragm, said bridge having at least one electrical parameter which changes in response to flexing of diaphragm; electrically connecting said piezoresistive bridge to one end of said diffused conductor paths; forming a cup-shaped cover member, said cup member being composed of semiconductor material identical to that of the base member; and eutectically bonding said members together with a metallic alloy seal such that said piezoresistive bridge is enclosed in a fluidtight evacuated chamber with said conductor paths extending from said fluidtight chamber to a point external to said fluidtight chamber.
Claim 13
Independent Claim
134 words
A method of assembling a pressure transducer comprising the steps of: forming a piezoresistive bridge and diffused conductor paths on the surface of one side of a generally planar semiconductor base member, at least a portion of said base member being a thin flexible diaphragm, said bridge having at least one electrical parameter which changes in response to flexing of diaphragm; electrically connecting said piezoresistive bridge to one end of said diffused conductor paths; forming a cup-shaped cover member, said cup member being composed of semiconductor material identical to that of the base member; and eutectically bonding said members together with a metallic alloy seal such that said piezoresistive bridge is enclosed in a fluidtight evacuated chamber with said conductor paths extending from said fluidtight chamber to a point external to said fluidtight chamber.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-16 | 1980-11-15 | 1981-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-16 | 1984-11-15 | 1985-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-16 | 1988-11-15 | 1989-05-17 | $7700.00 | Window Closed / Lapsed |