Improved configuration fiber-optic blood gas sensor bundle and method of making

摘要

A bundle of fiber-optic sensors that resist breakage, for use in measuring pH, CO₂, and O₂ concentration, and a method of making the same. Three optical fibers (15,17,19) are enclosed in a common polyimide sheath (13) 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 (21) comprising a CO₂ analyte indicator molecule codissolved within a polymer matrix (22). A thin reflective surface of gold foil (20) 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 CO₂ polymer matrix absorbs light of a given wavelength to an extent dependent upon the level of CO₂ present. Similarly, on the distal end of a second optical fiber is disposed a pH pellet (25) comprising a pH analyte indicator matrix with a thin reflective gold foil (24) 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 wavelength 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 O₂ indicator matrix (27) 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 O₂ 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.