US3631850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pressure transducer apparatus for microhemocirculation studies
Assignee: United States Department of the Navy
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Filing: 1969-11-13
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Granted: 1972-01-04
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Expires: 1989-11-13
Abstract
Abstract The transducer has a closed chamber or pressure dome formed of a flat base having a diaphragm portion and sidewalls that converge into a central opening by which it is coupled to a tube or microcannula which, preferably, is a flexible polyethylene tube having a tip or needle at its end for insertion into microvessels. A pressure transmitting fluid characterized by having a high wettability, low surface tension and physiological compatibility fills the pressure dome and the tube so that circulatory pressure changes are transferred to the diaphragm to cause diaphragm displacement. A sensor is responsively coupled to the diaphragm to detect the displacements and provide the data for the microhemocirculatory studies. A greatly improved frequency response of the transducer is achieved by minimizing the volume of the chamber, the preferred chamber volume being no greater than about 0.25 cc. Also, the internal diametric area of the cannula or tube preferably is no greater than about 0.28 mm. Improved operation results when the design parameters of the transducers are based upon the following relationship: IN WHICH K is a dimensionless proportionality constant having a value of about 3.789 X 10 6.
Inventors
- 👤 Joseph Emile Levasseur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:09
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/021; A61B5/0215
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
149 words
A pressure transducer of a type adapted to be inserted into microvessels having a size range of 5-30 microns for conducting microhemocirculatory studies comprising: a closed chamber formed with a flat base having a diaphragm portion and with sidewalls converging into a central opening, a microcannula having a tip externally sized for insertion into said microvessels and having its bore communicating with said chamber through said opening, a pressure-transmitting fluid body filling said chamber and cannula, and a sensor responsively coupled to said base diaphragm for detecting diaphragm displacements produced by volume changes of said fluid body due to circulatory pressure variations, said chamber volume being no greater than about 0.25 cc. and the internal diametric area of the cannula being no greater than about 0.28 mm., and the diaphragm area and volume displacement being selected in accordance with the circulatory inputs to be studied and the sensor characteristics.
Claim 2
Dependent Claim
149 words
A pressure transducer of a type adapted to be inserted into microvessels having a size range of 5-30 microns for conducting microhemocirculatory studies comprising: a closed chamber formed with a flat base having a diaphragm portion and with sidewalls converging into a central opening, a microcannula having a tip externally sized for insertion into said microvessels and having its bore communicating with said chamber through said opening, a pressure-transmitting fluid body filling said chamber and cannula, and a sensor responsively coupled to said base diaphragm for detecting diaphragm displacements produced by volume changes of said fluid body due to circulatory pressure variations, said chamber volume being no greater than about 0.25 cc. and the internal diametric area of the cannula being no greater than about 0.28 mm., and the diaphragm area and volume displacement being selected in accordance with the circulatory inputs to be studied and the sensor characteristics.
Claim 3
Dependent Claim
32 words
The transducer of claim 1 wherein the design parameters are based upon the following relationship: in which K is a dimensionless proportionality constant having a value of about 3.789 X 10 6.
Claim 4
Dependent Claim
38 words
The transducer of claim 2 wherein said fluid of the pressure-transmitting body is a bile salt solution characterized by having a surface tension about one-half that of an aqueous solution of sodium chloride and by being physiologically inert.
Claim 5
Dependent Claim
18 words
The transducer of claim 3 wherein said solution is 0.001 molar sodium taurocholate in 0.9 percent sodium chloride.
Claim 6
Dependent Claim
133 words
An improved pressure transducer for microhemocirculation studies of microvessels having a size range of 5-30 microns, the transducer being of a type having a conelike cavity formed of a flat base and sidewalls projecting angularly of the base toward an apex, the cavity being filled with a pressure-transmitting fluid and its flat base inCluding a diaphragm exposed to said fluid for dynamically transmitting fluid pressure variations to a sensor, said cavity further being in fluid communication with a microbore needle having a bore diametric area of no greater than about 0.28 mm. and adapted to be directly exposed to vascular pressure variations, said improvement comprising: a cavity in which said sidewalls project at an angle of between 1.5*-2.5* and the normal volume of said cavity is in the order of 0.025 cubic centimeters.
Claim 7
Dependent Claim
133 words
An improved pressure transducer for microhemocirculation studies of microvessels having a size range of 5-30 microns, the transducer being of a type having a conelike cavity formed of a flat base and sidewalls projecting angularly of the base toward an apex, the cavity being filled with a pressure-transmitting fluid and its flat base inCluding a diaphragm exposed to said fluid for dynamically transmitting fluid pressure variations to a sensor, said cavity further being in fluid communication with a microbore needle having a bore diametric area of no greater than about 0.28 mm. and adapted to be directly exposed to vascular pressure variations, said improvement comprising: a cavity in which said sidewalls project at an angle of between 1.5*-2.5* and the normal volume of said cavity is in the order of 0.025 cubic centimeters.
Claim 8
Dependent Claim
41 words
The improved pressure transducer of claim 5 wherein the fluid in said cavity and microbore is a bile salt solution characterized by having a surface tension about one-half that of an aqueous solution of sodium chloride and by being physiologically inert.
Claim 9
Dependent Claim
18 words
The improvement of claim 6 wherein said solution is 0.001 molar sodium taurocholate in 0.9 percent sodium chloride.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |