Sensor with layered electrodes

• US 20070173711A1
• Filed: 09/23/2005
• Published: 07/26/2007
• Est. Priority Date: 09/23/2005
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Shah, Rajiv, Gottlieb, Rebecca
• GRANTED PATENT: US 7,725,148 B2
• Time in patent office: 0 Days
• US Class Current: 600/347
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/0017 transmitting optical signals transmission by light H04B10/00
• 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: A61B 5/6848 Needles
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: C23C 14/20 on organic substrates
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: G01N 27/307 Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 27/4166 measuring a particular property of an electrolyte
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A thin film sensor, such as a glucose sensor, is provided for transcutaneous placement at a selected site within the body of a patient. The sensor includes several sensor layers that include conductive layers and includes a proximal segment defining conductive contacts adapted for electrical connection to a suitable monitor, and a distal segment with sensor electrodes for transcutaneous placement. The sensor electrode layers are disposed generally above each other, for example with the reference electrode above the working electrode and the working electrode above the counter electrode. The electrode layers are separated by dielectric layer.

Claims

1. A flexible analyte sensor comprising:

a base layer;

a first electrode layer disposed on the base layer and including a first electrode;

a first insulative layer disposed on the first electrode layer, wherein said first insulative layer leaves at least a portion of the first electrode exposed;

a second electrode layer disposed on the first insulative layer and including a second electrode; and

a second insulative layer disposed on the second electrode layer, wherein said second insulative layer leaves at least a portion of the second electrode exposed.

2. The flexible analyte sensor of claim 1, further comprising a third electrode layer disposed on the second insulative layer and including a third electrode.

3. The flexible analyte sensor of claim 2, further comprising a third insulative layer disposed on the third electrode layer, wherein said third insulative layer leaves at least a portion of the third electrode exposed.

4. The flexible analyte sensor of claim 1, wherein the first electrode layer is disposed directly on the base layer without any intervening layers.

5. The flexible analyte sensor of claim 1, wherein the first insulative layer is disposed directly on the first electrode layer without any intervening layers.

6. The flexible analyte sensor of claim 1, wherein the second electrode layer is disposed directly on the first insulative layer without any intervening layers.

7. The flexible analyte sensor of claim 1, wherein the second insulative layer is disposed directly on the second electrode layer without any intervening layers.

8. The flexible analyte sensor of claim 1, wherein the second electrode layer is laterally offset from the first electrode layer, and wherein the third electrode layer is laterally offset from the second electrode layer.

9. The flexible analyte sensor of claim 2, wherein the second electrode layer is directly above the first electrode layer, and wherein the third electrode layer is directly above the second electrode layer.

10. The flexible analyte sensor of claim 2, wherein the first, second and third electrodes are in a staggered configuration.

11. The flexible analyte sensor of claim 1, wherein the thickness of the sensor is about 25 microns.

12. The flexible analyte sensor of claim 1, wherein the thickness of each electrode layer is less than about 5000 angstroms and each insulative layer is about 5 microns.

13. The flexible analyte sensor of claim 2, wherein one of the electrodes is a counter electrode, one of the electrodes is a reference electrode, and one of the electrodes is a working electrode.

14. The flexible analyte sensor of claim 1, wherein at least one of the first electrode and the second electrode comprises one or more compounds selected from the group consisting of gold and chrome.

15. The flexible analyte sensor of claim 14, wherein the reference electrode is plated with one or more compounds selected from the group consisting of silver and silver chloride.

16. The flexible analyte sensor of claim 14, wherein at least one of the counter electrode and the working electrode is plated with platinum black.

17. The flexible analyte sensor of claim 2, wherein the first electrode layer further includes a first conductive trace leading from the first electrode to a first conductive pad adapted to electrically couple to sensor electronics, the second electrode layer further includes a second conductive trace leading from the second electrode to a second conductive pad adapted to electrically couple to sensor electronics, and the third electrode layer further includes a third conductive trace leading from the third electrode to a third conductive pad adapted to electrically couple to sensor electronics.

18. An analyte monitoring system comprising:

the flexible analyte sensor of claim 17;

sensor electronics electrically connected to the first, second and third conductive pads;

an analyte monitor; and

wherein the sensor electronics and the analyte monitor are adapted to communicate with one another.

19. The analyte monitoring system of claim 18, wherein the sensor electronics and the analyte monitor are adapted to communicate wirelessly with one another.

20. The analyte monitoring system of claim 19, wherein the type of wireless communication is selected from the group consisting of radio frequency, infrared, WiFi, ZigBee and Bluetooth.

21. The flexible analyte sensor of claim 2, wherein at least one of the base layer, the first insulative layer, the second insulative layer, and third insulative layer includes polyimide.

22. The flexible analyte sensor of claim 2, further comprising an enzyme layer including glucose oxidase disposed over the first, second and third electrodes.

23. The flexible analyte sensor of claim 22, wherein the enzyme layer further includes albumin.

24. The flexible analyte sensor of claim 22, further comprising a glucose limiting membrane disposed over the enzyme layer.

25. The flexible analyte sensor of claim 24, wherein the glucose limiting membrane comprises poly.

26. The flexible analyte sensor of claim 24, wherein the glucose limiting membrane comprises a silane.

27. The flexible analyte sensor of claim 26, wherein the silane is polydimethylsiloxane.

28. The flexible analyte sensor of claim 24, further comprising a hydrophilic membrane over the glucose limiting membrane.

29. An analyte monitoring system comprising:

the flexible analyte sensor of claim 24;

sensor electronics electrically connected to the first, second and third conductive pads;

an analyte monitor; and

wherein the sensor electronics and the analyte monitor are adapted to communicate with one another.

30. The analyte monitoring system of claim 29, wherein the sensor electronics and the analyte monitor are adapted to communicate wirelessly with one another.

31. The analyte monitoring system of claim 30, wherein the type of wireless communication is selected from the group consisting of radio frequency, infrared, WiFi, ZigBee and Bluetooth.

32. The flexible analyte sensor of claim 3, wherein the first electrode layer is disposed directly on the base layer without any intervening layers, the first insulative layer is disposed directly on the first electrode layer without any intervening layers, the second electrode layer is disposed directly on the first insulative layer without any intervening layers, the second insulative layer is disposed directly on the second electrode layer without any intervening layers, the third electrode layer is disposed directly on the second insulative layer without any intervening layers, and the third insulative layer is disposed directly on the third electrode layer without any intervening layers.

33. The flexible analyte sensor of claim 32, wherein the second electrode layer is directly above the first electrode layer, the third electrode layer is directly above the second electrode layer, and the first, second and third electrodes are in a staggered configuration.

34. The flexible analyte sensor of claim 33, wherein the thickness of the sensor is about 25 microns.

35. An analyte monitoring system comprising:

the flexible analyte sensor of claim 33;

sensor electronics electrically connected to the first, second and third conductive pads;

an analyte monitor; and

wherein the sensor electronics and the analyte monitor are adapted to communicate with one another.

36. The analyte monitoring system of claim 35, wherein the sensor electronics and the analyte monitor are adapted to communicate wirelessly with one another.

37. The flexible analyte sensor of claim 33, wherein the flexible analyte sensor is adapted to sense a current representative of the amount of glucose in the body of a patient.

38. The flexible analyte sensor of claim 1, wherein the flexible analyte sensor is adapted to sense a current representative of the amount of glucose in the body of a patient.

39. A method of making a flexible analyte sensor, the method comprising:

providing a base layer;

forming a first electrode layer on the base layer, wherein the first electrode layer includes a first electrode;

forming a first insulative layer on the first electrode layer;

forming a second electrode layer on the base layer, wherein the second electrode layer includes a second electrode; and

forming a second insulative layer on the second electrode layer.

40. The method of claim 39, wherein the providing a base layer includes spin coating polyimide onto a rigid substrate.

41. The method of claim 39, wherein the forming a first electrode layer includes surface sputtering a chrome-based layer on the base layer.

42. The method of claim 41, wherein the forming a first electrode layer further includes surface sputtering a gold-based layer on the chrome-based layer.

43. The method of claim 39, wherein the forming a first insulative layer includes spin-coating polyimide onto the second electrode layer.

44. The method of claim 39, wherein a first aperture is formed in the first insulative layer to expose at least a portion of the first electrode.

45. The method of claim 44, wherein the first aperture is formed by a photoresist process.

46. The method of claim 39, further comprising depositing platinum black on one or more of the first and second electrodes.

47. The method of claim 39, further comprising:

forming a third electrode layer, wherein the third electrode layer includes a third electrode; and

forming a third insulative layer above the third electrode layer.

48. The method of claim 47, further comprising depositing one or more compounds selected from the group consisting of silver and silver chloride on the third electrode.

49. The method of claim 48, further comprising forming a glucose oxidase layer above the second electrode layer, wherein the glucose oxidase layer coats at least a portion of the first electrode and the second electrode.

50. The method of claim 49, further comprising vapor cross-linking the glucose oxidase layer.

51. The method of claim 49, wherein the glucose oxidase layer includes albumin.

52. The method of claim 49, further comprising forming an adhesion promoter layer above the glucose oxidase layer.

53. The method of claim 49, further comprising forming a glucose limiting membrane over the glucose oxidase layer.

54. The method of claim 53, wherein the glucose limiting membrane comprises at least one compound selected from the group consisting of polyoxypropylene-diamine and a silane.

55. The method of claim 53, further comprising forming a hydrophilic layer over the glucose limiting membrane.

56. The method of claim 39, wherein the forming the first electrode layer further includes forming a first conductive trace leading from the first electrode to a first conductive pad adapted to electrically connect to sensor electronics, and the forming the second electrode layer further includes forming a second conductive trace leading from the second electrode to a second conductive pad adapted to electrically connect to sensor electronics.

57. The method of claim 56, wherein the sensor electronics are adapted to communicate by a wire to a monitor.

58. The method of claim 56, wherein the sensor electronics are adapted to communicate wirelessly to a monitor.

59. The method of claim 58, wherein the wireless communication is selected from the group consisting of radio frequency, infrared, WiFi, ZigBee and Bluetooth.