Evanescent Catheter System

• US 20080275325A1
• Filed: 12/01/2005
• Published: 11/06/2008
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: Hamamatsu University School of Medichine
• Original Assignee: National University Corporation Kumamoto University
• Inventors: Yamamoto, Seiji, Terakawa, Susumu, Miyakawa, Atsuo, Doi, Matsuyuki
• Granted Patent: US 8,208,982 B2
• Time in Patent Office: Days
• US Class Current: 600/368
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: G01N 21/648 using evanescent coupling or surface plasmon coupling for the excitation of fluorescence

Abstract

An evanescent catheter system is provided as a system having a structure of a tip portion of an optical fiber capable of securely measuring a fluorescence intensity or fluorescence spectrum of a substance around a catheter tip, without being hindered by optical absorption of hemoglobin in erythrocytes in blood, and being capable of calculating an existing amount of a fluorescence-emitting substance existing in an evanescent light generating part. A protecting layer 22 and a cladding 23 are removed from an upper semicircular part of a core 24 at a tip of a catheter 21 to expose the core 24. An optical filter 26 and a photodiode 28 are located opposite to a lower semicircular part. When excitation light 29 is incident, evanescent light 25 is generated on the upper semicircular part of the core 24 and a fluorescent substance generates emits fluorescence 30. An interference filter 26 filters out the excitation light and only the fluorescence 30 reaches the photodiode 28, an output intensity of which is guided to the outside to permit a measuring device to measure an existing amount of the fluorescent substance.

Claims

1. An evanescent catheter system adapted to place in blood an optical fiber obtained by removing a cladding layer to expose a core layer, to generate evanescent light, to detect fluorescence from a fluorescent substance excited by the evanescent light, and to measure an existing amount of the substance in the blood on the basis of a fluorescence intensity,

wherein substantially a half of the cladding covering the core is removed at a columnar tip of the optical fiber whereby the evanescent light is generated on an upper columnar surface of the core, and

wherein an optical filter for transmitting the fluorescence in a predetermined wavelength region is located on a lower columnar surface of the core exposed by removing the cladding layer, a light receiving element is located on a back side of the optical filter, and the light receiving element detects the fluorescence from the fluorescent substance.

2. An evanescent catheter system comprising a first optical fiber for transmitting excitation light, and a second optical fiber for receiving fluorescence, and adapted to place in blood an optical fiber obtained by removing a cladding layer of the first optical fiber to expose a core layer, to generate evanescent light, to receive fluorescence from a fluorescent substance excited by the evanescent light, by the second optical fiber, and to measure an existing amount of the substance in the blood on the basis of a fluorescence intensity,

wherein substantially a half of the cladding layer covering the core is removed at a columnar tip of the first optical fiber whereby the evanescent light is generated on an upper columnar surface of the core, and

wherein a reflecting mirror is located in the second optical fiber opposed to the core resulting from the removal of substantially the half of the cladding, and the reflecting mirror reflects the fluorescence from the fluorescent substance to guide the fluorescence to an output end of the second optical fiber.

3. An evanescent catheter system adapted to place in blood an optical fiber obtained by removing a cladding layer to expose a core layer, to generate evanescent light, to detect fluorescence from a fluorescent substance excited by the evanescent light, and to measure an existing amount of the substance in the blood on the basis of a fluorescence intensity,

wherein the cladding layer is removed from an entire circumference of the core at a columnar tip of the optical fiber, an inclined surface is formed from a top toward a root of a tip of the core part from which the cladding layer is removed, and a reflecting mirror is located on the inclined surface to generate the evanescent light on a columnar upper surface of the cladding-removed core, and

wherein the reflecting mirror reflects the fluorescence from the fluorescent substance to guide the fluorescence to an output end of the optical fiber.

4. An evanescent catheter system adapted to place in blood an optical fiber obtained by removing a cladding layer to expose a core layer, to generate evanescent light, to detect fluorescence from a fluorescent substance excited by the evanescent light, and to measure an existing amount of the substance in the blood on the basis of a fluorescence intensity,

wherein substantially a half of the cladding covering the core is removed at a columnar tip of the optical fiber, the evanescent light is generated on a columnar upper surface of the core exposed after the removal of the cladding, and a large number of reflecting mirrors are arranged so as to be inclined at a predetermined inclination angle relative to the optical axis, on a lower columnar surface of the cladding-removed core,

whereby the large number of reflecting mirrors reflect the fluorescence from the fluorescent substance to guide the fluorescence to an output end of the optical fiber.

5. An evanescent catheter system adapted to place in blood an optical fiber obtained by removing a cladding layer to expose a core layer, to generate evanescent light, to detect fluorescence from a fluorescent substance excited by the evanescent light, and to measure an existing amount of the substance in the blood on the basis of a fluorescence intensity,

wherein the core part from which the cladding layer is removed at a columnar tip of the optical fiber, is formed in such a conical shape as to make a predetermined angle relative to the optical axis,

whereby the evanescent light is generated on a surface of the core part of the conical shape, and

wherein the core part of the conical shape reflects the fluorescence from the fluorescent substance to guide the fluorescence to an output end of the optical fiber.

6. An evanescent catheter system adapted to place a tip of an optical fiber in blood, to generate evanescent light, to detect fluorescence from a fluorescent substance excited by the evanescent light, and to measure an existing amount of the substance in the blood on the basis of a fluorescence intensity,

wherein a protecting layer of the cladding layer is removed from a columnar tip of the optical fiber and the core in the cladding layer is formed in a spiral shape,

wherein excitation light leaking from the core of the spiral shape reaches a columnar surface of the cladding layer to generate the evanescent light on the columnar surface of the cladding layer, and

wherein the core part of the spiral shape reflects the fluorescence from the fluorescent substance to guide the fluorescence to an output end of the optical fiber.