Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-05-04
2001-01-09
Nasser, Robert L. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S488000, C073S730000
Reexamination Certificate
active
06171253
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to pressure sensors, and, more specifically, to through-flow pressure sensors.
Many types of pressure sensors are available for measuring pressure of a fluid flowing through a conduit. These sensors vary in complexity and operation and their affect on the fluid flow therethrough. The fluid may be compressible gas or incompressible liquid which may flow under laminar or turbulent flow conditions.
In the medical field pertaining to living patients, pressure sensing of bodily fluids introduces the additional requirement of patient safety. For example, the measurement of blood pressure must not damage the blood itself or form clots therein which are detrimental to patient health.
Artificial heart pumps are being developed in the exemplary form of a Left Ventricular Assist Device (LVAD) which assists damaged hearts. Typical artificial heart pumps are configured for varying blood flowrate, frequency, and pressure as required to meet the typical demands placed on the heart which change in response to work efforts. It is therefore desirable to control the heart pump by sensing blood pressure in the body. However, blood pressure must be measured without adversely affecting blood flow or causing damage or clotting thereof.
Furthermore, the sensing of blood pressure, in particular, requires high accuracy or resolution to precisely control the artificial heart pump. Blood pressure is typically measured in millimeters of mercury (Hg), with a blood pressure sensitivity of 1 mm Hg (0.02 psi) being desirable.
Accordingly, it is desired to provide an improved through-flow pressure sensor for use in precisely measuring pressure of a fluid, such as blood, without adversely affecting the flow thereof.
BRIEF SUMMARY OF THE INVENTION
A pressure sensor includes a tube for channeling a fluid therethrough. A seat is disposed in an outer surface of the tube, with a diaphragm at the bottom thereof. The diaphragm is planar, and blends at its perimeter coextensively with an arcuate inner surface of the tube. A gauge is mounted in the seat above the diaphragm for measuring flexure thereof under pressure of the fluid inside the tube.
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Bullister Edward Theodore
d'Entremont Peter Richard
APEX Medical, Inc.
Conte Francis L.
Nasser Robert L.
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