Optical-based sensing devices

• US 6,711,423 B2
• Filed: 09/27/2001
• Issued: 03/23/2004
• Est. Priority Date: 08/26/1998
• Status: Expired due to Term

• Current Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Original Assignee: Sensors For Medicine and Science Incorporated
• Inventors: Colvin, Arthur E. Jr.
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): McCrosky, David J.
• Application Number:
  US09/963,798
• Publication Number:
  US 20020026108A1
• Time in Patent Office: 908 Days
• Field of Search: 600/316, 600/317, 600/302, 128/899, 427/2.13
• US Class Current: 600/317
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/6861 Capsules, e.g. for swallowing or implanting
• CPC Class Codes: G01N 2021/7773 Reflection
• CPC Class Codes: G01N 2021/7783 Transmission, loss
• CPC Class Codes: G01N 2021/7786 Fluorescence
• CPC Class Codes: G01N 21/552 Attenuated total reflection
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/648 using evanescent coupling or surface plasmon coupling for the excitation of fluorescence
• CPC Class Codes: G01N 21/77 by observing the effect on a chemical indicator
• CPC Class Codes: G01N 21/7703 using reagent-clad optical fibres or optical waveguides using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: Y10S 128/903 Radio telemetry

Abstract

An optical-based sensor for detecting the presence or amount of an analyte using both indicator and reference channels. The sensor has a sensor body with a source of radiation embedded therein. Radiation emitted by the source interacts with indicator membrane indicator molecules proximate the surface of the body. At least one optical characteristic of these indicator molecules varies with analyte concentration. For example, the level of fluorescence of fluorescent indicator molecules or the amount of light absorbed by light-absorbing indicator molecules can vary as a function of analyte concentration. In addition, radiation emitted by the source also interacts with reference membrane indicator molecules proximate the surface of the body. Radiation (e.g., light) emitted or reflected by these indicator molecules enters and is internally reflected in the sensor body. Photosensitive elements within the sensor body generate both indicator channel and reference channel signals to provide an accurate indication of the concentration of the analyte. Preferred embodiments are totally self-contained and are sized and shaped for use in vivo in a human being. Such embodiments preferably include a power source, e.g. an inductor, which powers the source of radiation using external means, as well as a transmitter, e.g. an inductor, to transmit to external pickup means the signal representing the level of analyte.

Claims

1. An optical-based sensor for determining the presence or concentration of an analyte in a medium, said sensor comprising:

an enclosed sensor body having an outer surface surrounding said sensor body;

a radiation source in said sensor body which emits radiation within said sensor body;

an indicator element having an optical characteristic that is affected by the presence or concentration of an analyte, said indicator element comprising indicator molecules contained within a liquid polymeric matrix, and said indicator element being positioned on said sensor body to receive radiation that travels from said radiation source, and which transmits radiation into said sensor body;

a photosensitive element located in said sensor body and positioned to receive radiation within the sensor body and which emits a signal responsive to radiation received from said indicator element; and

said sensor body being configured such that some of the radiation received by said photosensitive element is reflected internally within said sensor body before striking said photosensitive element.

2. The sensor of claim 1, wherein said indicator element is located in a recessed portion of said sensor body.

3. The sensor of claim 1, further comprising a cover layer which covers said liquid polymeric matrix and prevents the escape of said matrix.

4. The sensor of claim 3, wherein said cover layer has a tubular structure with an inside diameter closely matching an outermost diameter of said sensor body.

5. The sensor of claim 3, wherein said cover layer has a molecular weight cut-off that is smaller than a nominal molecular weight of said liquid polymer matrix.

6. The sensor of claim 3, wherein said cover layer is made of a dialysis membrane material.

7. The sensor of claim 3, wherein said cover layer is made of a biocompatible material.

8. The sensor of claim 1, wherein said liquid polymeric matrix comprises indicator molecules including 9-[[N-methacryloylaminopropyl-N-(o-boronobenzyl)amino]methyl] anthracene.

9. The sensor of claim 8, wherein said liquid polymeric matrix comprises a water-soluble-copolymeric solution of MAPTAC [3-(methacryloylamino)propyl]trimethylammonium chloride and 9-[[N-methacryloylaminopropyl-N-(o-boronobenzyl)amino]methyl] anthracene.

10. The sensor of claim 1, wherein said liquid polymerid matrix comprises a water-soluble compolymeric solution of 9-[N-[2-(5,5-dimethylborinan-2-yl)benzyl]-N-[2-(2-methacroyloxy-ethoxy)ethylamino]methyl]-10-[N-[2-(5,5-dimethylborinan-2-yl)benzyl]-N-[2-(2-hydroxyethoxy)ethylamino]methyl] anthracene and [2-(methacryloxy)ethyl]trimethyl-ammonium chloride.

11. The sensor of claim 1, wherein the optical characteristics of said indicator molecules vary as a function of the concentration of oxygen.

12. The sensor of claim 1, wherein said indicator molecules include light-absorbing indicator molecules.

13. The sensor of claim 1, wherein the optical characteristics of said indicator molecules vary as a function of the concentration of glucose.

14. The sensor of claim 1, wherein said indicator molecules include indicator molecules having an isosbestic point substantially at a particular wavelength and wherein a reference channel detects light substantially at the isosbestic wavelength.

15. The sensor of claim 1, wherein said indicator molecules interact with the radiation emitted by said radiation source by means of direct illumination.