Abbott Laboratories Corporation

Bruce M Fieggen

Dana K Lewis

Todd W Hubbard

Jeffrey B Yim

Michael A Sexton

Lori D Melkerson

Linda Sawyer

A method and apparatus are provided for detecting and compensating for a kink in an optical fiber. A distal sensor (11) monitors a level of a parameter in an environment in which the distal sensor is immersed. The distal sensor is disposed at a tip of the optical fiber (17) and the optical fiber conveys green light signals and near infrared (NIR) light signals to and from the distal sensor. A photodetector (59') records the signal and reference values for the green light signals and the NIR light signals conveyed by the optical fiber at consecutive data points. A microcontroller (42) is electronically coupled to the photodetector and receives the signal and reference values for the green light signals and the NIR light signals. A kink in the optical fiber is detected when a change between NIR signal values recorded at a pair of consecutive data points recorded by the photodetector is greater than a predetermined threshold. After the kink is detected, a true level of the parameter in the environment is calculated that compensates for the kink. More specifically, a true green signal value is determined based on a linear relationship between green and NIR signal values recorded at the pair of consecutive data points. The true green signal value is then used to calculate the true level of the parameter. In an alternative embodiment of the present invention, a warning is issued when the kink is detected and monitoring of the level of the parameter is discontinued.

Method and apparatus for detecting and compensating for a kink in an

A bundle of fiber-optic sensors that resist breakage, for use in measuring pH, CO.sub.2, and O.sub.2 concentration, and a method of making the same. Three otpical fibers are enclosed in a common polyimide sheath and extend parallel to one another toward a distal end of the sensor, where they are bonded together in a mutually supportive array. At the distal end of one of these optical fibers is disposed a pellet comprising a CO.sub.2 analyte indicator molecule codissolved within a polymer matrix. A thin reflective surface of gold foil is provided on the pellet such that incident light transmitted through the optical fiber and polymer matrix is reflected back into the optical fiber. The CO.sub.2 polymer matrix absorbs light of a given wavelength to an extent dependent upon the level of CO.sub.2 present. Similarly, on the distal end of a second optical fiber is disposed a pH pellet comprising a pH analyte indicator matrix with a thin reflective gold foil attached for reflecting light that has passed through the pH analyte indicator matrix back into the optical fiber. The pH analyte indicator matrix absorbs light of a given wavelenth to an extent dependent upon the hydrogen ion concentration (pH level) of a surrounding fluid. The third optical fiber is used for measuring oxygen concentration. An O.sub.2 indicator matrix covers the distal ends of at least two of the three optical fibers; however, at least a portion of the pH optical fiber and the pH pellet are free of the O.sub.2 indicator matrix, which is hydrophobic. The oxygen indicator matrix phosphoresces for an interval of time that decreases in proportion to the surrounding oxygen gas concentration. The phosphorescent and reflected light signals are transmitted to light detectors through the optical fibers for comparison to reference signals, so that the analyte concentrations can be determined.

Configuration fiber-optic blood gas sensor bundle and method of making

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Edmonds, WA, United States of America

Bruce M Fieggen