Electrochemical sensing apparatus with in situ calibration
First Claim
1. A chemically sensitive probe for taking measurement of the chemical properties of biological fluids in vivo with in vivo recalibration, comprisinga closed tube having a wall with a fixed opening to admit fluid to be tested,an electrochemical sensor assembly affixed to the inside wall of said tube covering said opening to define therewith a sensing chamber, andmeans defining an infusion channel in said tube for flooding said sensor assembly with a known fluid for calibration during which the fluid to be tested is temporarily expelled through said opening.
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Abstract
An in vivo electrochemical monitoring device is formed by a catheter-like member which terminates in a closed end having a wall with a fixed opening to admit fluid to be tested, such as blood in an artery. An electrochemical sensor, such as an ISFET device for monitoring the concentration of a particular ion in blood, is mounted inside the tube at a fixed location below the opening preferably a larger sensing chamber. an infusion channel in the tube is arranged to flood the sensor with a fluid of known chemical properties so that the sensor output can be calibrated. Under pressure the calibration fluid expels the test fluid out of the tube or chamber via the fixed opening. A method of constructing a suitable chamber on an ISFET wafer is also disclosed.
150 Citations
14 Claims
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1. A chemically sensitive probe for taking measurement of the chemical properties of biological fluids in vivo with in vivo recalibration, comprising
a closed tube having a wall with a fixed opening to admit fluid to be tested, an electrochemical sensor assembly affixed to the inside wall of said tube covering said opening to define therewith a sensing chamber, and means defining an infusion channel in said tube for flooding said sensor assembly with a known fluid for calibration during which the fluid to be tested is temporarily expelled through said opening.
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9. An electrochemical sensing cell for a chemically sensitive probe for taking measurement of the chemical properties of biological fluids in vivo with in vivo recalibration comprising
a wafer comprising an ISFET with a chemically sensitive surface area, a body affixed on top of said wafer having a central recess formed in the adjacent face thereof encompassing said chemically sensitive area and defining therewith a sensing chamber, a port extending from said chamber through said body to admit fluid to be tested, and a calibration channel through said wafer leading to said chamber to flood said chemically sensitive area with a known fluid for calibration during which said fluid to be tested is expelled through said port.
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12. A chemically sensitive probe for taking measurement of the chemical properties of biological fluids in vivo with in vivo recalibration, comprising
a catheter, means defining an enclosed sensing chamber inside the distal end of said catheter, a chemically sensitive electrical device disposed in said chamber at a fixed location, first port means defined through an outside wall of said catheter for admitting bodily fluid into said chamber for testing, second port means for admitting calibration fluid to said chamber, and duct means carried within said catheter for supplying said chamber with calibration fluid via said second port thereby expelling bodily fluid from said chamber via said first port during recalibration of said device.
Specification