PRESSURE TRANSDUCERS
First Claim
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1. A blood pressure transducer comprising:
- a housing having an opening;
a flexible diaphragm mounted in said opening, said housing being adapted for source of fluid pressure to be exposed to said diaphragm;
a pair of strain-sensitive elements comprised of the same piezoresistive material, each of said elements having two spaced pads, the pads of each element being interconnected by a reduced neck portion, said neck portions being spaced from and parallel to a plane of symmetry and being of substantially the same dimension and shape, said pads of each element being joined together at contiguous faces;
a layer of electrically insulating material between the contiguous faces of each pad;
means for affixing one of said pads in one element to a portion of said diaphragm and for affixing the other pad in said element to said housing, whereby flexure of said diaphragm causes compression in the reduced neck portion of one element and tension in the reduced portion of the other; and
electrodes electrically connected to the pads of each of said elements on opposite sides of said reduced neck portions.
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Abstract
A novel miniature blood pressure transducer is described including a catheter tip transducer implantable in an artery or vein. The transducer employs a novel strain gauge for converting blood pressure pulsations into measurable electrical signals. The strain gauge is formed of two strain sensitive elements composed of a piezoresistive material. The strain occurring in each element is concentrated in separate reduced neck portions. The reduced neck portions are substantially parallel to each other and are of substantially the same dimension. Force supplied to the strain gauge results in placing one reduced neck portion in tension while placing the other reduced neck portion in compression.
45 Citations
4 Claims
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1. A blood pressure transducer comprising:
- a housing having an opening;
a flexible diaphragm mounted in said opening, said housing being adapted for source of fluid pressure to be exposed to said diaphragm;
a pair of strain-sensitive elements comprised of the same piezoresistive material, each of said elements having two spaced pads, the pads of each element being interconnected by a reduced neck portion, said neck portions being spaced from and parallel to a plane of symmetry and being of substantially the same dimension and shape, said pads of each element being joined together at contiguous faces;
a layer of electrically insulating material between the contiguous faces of each pad;
means for affixing one of said pads in one element to a portion of said diaphragm and for affixing the other pad in said element to said housing, whereby flexure of said diaphragm causes compression in the reduced neck portion of one element and tension in the reduced portion of the other; and
electrodes electrically connected to the pads of each of said elements on opposite sides of said reduced neck portions.
- a housing having an opening;
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2. A blood pressure transducer comprising:
- a generally cylindrical catheter tip having a tip end and a shank end, said catheter tip having one flattened side, the interior of said catheter tip forming a sealed compartment;
a diaphragm being mounted in the flattened side of said catheter tip, said diaphragm being exposed on one side of said sealed compartment;
a pair of strain-sensitive elements of the same piezoresistive material joined together at a common plane, each of said elements having two spaced pads, the pads of each element being interconnected by a reduced neck portion, said neck portions being spaced from and parallel to a plane of symmetry and being of substantially the same dimension and shape, said pads of each element being joined together at contiguous faces along said plane of symmetry;
a layer of electrically insulating material between the contiguous faces of each pad;
means for securing one of said pads in one element to a portion of said diaphragm And for securing the other pad in said one element to said catheter tip, whereby flexure of said diaphragm causes a compression in the reduced neck portion of one element and a tension in the reduced neck portion of the other element;
electrodes electrically connected to the pads of each of said elements on opposite sides of said reduced neck portions;
a flexible cable secured to the shank end of said catheter tip, the flexible cable providing a fluid passage from a source of reference pressure to the sealed compartment within said catheter tip; and
electrical conductors within said flexible cable, said conductors being electrically insulated from each other and being connected to respective ones of said electrodes.
- a generally cylindrical catheter tip having a tip end and a shank end, said catheter tip having one flattened side, the interior of said catheter tip forming a sealed compartment;
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3. A blood pressure transducer comprising:
- a conduit adapted to carry the fluid whose pressure is to be measured, said conduit having an opening in the wall structure thereof;
a flexible diaphragm mounted in said opening in the wall structure of said conduit, said diaphragm being adapted to flex in response to pressure variations in the fluid to be carried in said conduit;
a pair of strain-sensitive elements of the same piezoresistive material, each of said elements having two spaced pads, the pads of each element being interconnected by a reduced neck portion, said neck portions being spaced from and parallel to a plane of symmetry and being of substantially the same dimension and shape, said pads of each element being joined together at contiguous faces;
a layer of electrically insulating material between contiguous faces of each pad;
means for securing one of said pads in one element to a portion of said diaphragm and for securing the other pad in said one element to said conduit, whereby flexure of said diaphragm causes a compression in the reduced neck portion of one element and a tension in the reduced neck portion of the other element;
electrodes electrically connected to the pads of each of said elements on opposite sides of said reduced neck portions.
- a conduit adapted to carry the fluid whose pressure is to be measured, said conduit having an opening in the wall structure thereof;
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4. A blood pressure transducer comprising:
- a pressure housing having two compartments separated by a bulkhead, the pressure housing having fittings for respectively connecting a first and second source of fluid pressure to be measured to said compartments, the bulkhead having a passageway extending from one compartment to the other;
a diaphragm formed in said passageway;
a pair of strain-sensitive elements of the same piezoresistive material, each of said elements having two spaced pads, the pads of each element being interconnected by a reduced neck portion, said neck portions being spaced from and parallel to a plane of symmetry and being of substantially the same dimension and shape, said pads of each element being joined together at contiguous faces;
a layer of electrically insulating material between contiguous faces of each pad;
means for securing one of said pads in one element to a portion of said diaphragm and for securing the other pad in said one element to said bulkhead, whereby flexure of said diaphragm in response to the differential pressure between said first and second fluid sources causes compression in the reduced neck portion of one element and tension in the reduced neck portion of the other element; and
electrodes in electrical connection to the pads of each element on opposite sides of said reduced neck portion.
- a pressure housing having two compartments separated by a bulkhead, the pressure housing having fittings for respectively connecting a first and second source of fluid pressure to be measured to said compartments, the bulkhead having a passageway extending from one compartment to the other;
Specification
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Current AssigneeHuntly Drummond Millar
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Original AssigneeHuntly Drummond Millar
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InventorsMillar, Huntly Drummond
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Primary Examiner(s)Albritton, C. L.
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Application NumberUS05/274,874Time in Patent Office364 DaysField of Search338/4,2,3,5,42 73/88.5SD,88.5R,398ARUS Class Current338/4CPC Class CodesA61B 2562/0247 Pressure sensorsA61B 2562/0261 Strain gaugesA61B 5/0215 by means inserted into the ...A61M 2025/0002 with a pressure sensor at t...G01L 9/0052 of piezoresistive elements ...
