Sensor head for use with implantable devices

• US 20050103625A1
• Filed: 12/22/2004
• Published: 05/19/2005
• Est. Priority Date: 07/27/2001
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Shults, Mark C., Brauker, James H., Tapsak, Mark A., Rhodes, Rathbun
• Granted Patent: US 7,471,972 B2
• Time in Patent Office: Days
• US Class Current: 204/403.110
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: C12Q 1/002 Electrode membranes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• CPC Class Codes: G01N 33/48707 by electrical means G01N33/49, G01N33/493 take precedence
• CPC Class Codes: G01N 33/48785 Electrical and electronic details of measuring devices for physical analysis of liquid biological material not specific to a particular test method, e.g. user interface or power supply

Abstract

The present invention provides a sensor head for use in an implantable device that measures the concentration of an analyte in a biological fluid which includes: a non-conductive body; a working electrode, a reference electrode and a counter electrode, wherein the electrodes pass through the non-conductive body forming an electrochemically reactive surface at one location on the body and forming an electronic connection at another location on the body, further wherein the electrochemically reactive surface of the counter electrode is greater than the surface area of the working electrode; and a multi-region membrane affixed to the nonconductive body and covering the working electrode, reference electrode and counter electrode. In addition, the present invention provides an implantable device including at least one of the sensor heads of the invention and methods of monitoring glucose levels in a host utilizing the implantable device of the invention.

Claims

1. A sensor for use in a glucose measuring device, the sensor comprising:

a non-conductive body;

a first electrode and a second electrode, wherein each of the electrodes passes through the non-conductive body, forming an electrochemically reactive surface at one end of the sensor and an electronic connection at another end of the body, wherein an electrochemically reactive surface area of the second electrode is greater than an electrochemically reactive surface area of the first electrode; and

a multi-region membrane covering the first electrode and the second electrode, wherein the multi-region membrane comprises an immobilized enzyme domain comprising an enzyme in at least a portion thereof, and wherein the electrochemical reactive surface area of the second electrode is situated at a location distant from the enzyme.

2. The sensor of claim 1, wherein a portion of the multi-region membrane covering the second electrode further comprises an additional domain capable of selectively blocking glucose from an area over the electrochemically reactive surface of second electrode.

3. The sensor of claim 1, wherein the immobilized enzyme domain is positioned only over the first electrode.

4. The sensor of claim 1, wherein the multi-region membrane comprises an oxygen antenna domain.

5. The sensor of claim 1, wherein the multi-region membrane comprises a first region distant from the electrochemically reactive surfaces, a second region less distant from the electrochemically reactive surfaces and a third region adjacent to the electrochemically reactive surfaces.

6. The sensor of claim 1, wherein the first region comprises a cell disruptive domain distant from the electrochemically reactive surfaces and a cell impermeable domain less distant from the electrochemically reactive surfaces.

7. The sensor of claim 5, wherein the second region includes a glucose exclusion domain that does not substantially cover the electrochemically reactive surface of the first electrode.

8. The sensor of claim 5, wherein the third region comprises an immobilized enzyme domain distant from the electrochemically reactive surfaces and an electrolyte-containing domain adjacent to the electrochemically reactive surfaces.

9. The sensor of claim 5, wherein the third region further comprises a resistance domain more distant from the electrochemically reactive surfaces than the immobilized enzyme domain.

10. The sensor of claim 5, wherein the first region is permeable to oxygen and glucose.

11. The sensor of claim 5, wherein the second region is permeable to oxygen and interferes with glucose transport across the membrane, further wherein the second region does not cover the electrochemically reactive surface of the first electrode.

12. The sensor of claim 1, wherein the multi-region membrane comprises a first region distant from the electrochemically reactive surfaces and a further region adjacent to the electrochemically reactive surfaces.

13. The sensor of claim 12, wherein the first region comprises a cell disruptive domain distant from the electrochemically reactive surfaces and a cell impermeable domain less distant from the electrochemically reactive surfaces.

14. The sensor of claim 12, wherein the further region comprises an immobilized enzyme domain distant from the electrochemically reactive surfaces and an electrolyte-containing domain adjacent to the electrochemically reactive surfaces.

15. The sensor of claim 12, wherein the further region further comprises a resistance domain more distant from the electrochemically reactive surfaces than the immobilized enzyme domain.

16. The sensor of claim 12, wherein the further region comprises a portion positioned over only the second electrode that reduces the consumption of oxygen above the second electrode.

17. The sensor of claim 1, wherein the non-conductive body is made of plastic or polymer.

18. The sensor of claim 1, wherein the first electrode is made of platinum.

19. The sensor of claim 1, wherein the electrochemically reactive surface area of the second electrode is greater than or equal to about two times the electrochemically reactive surface area of the first electrode and is less than or equal to about 10 times the electrochemically reactive surface area of the first electrode.