Compound metal analyte sensor

• US 20050004438A1
• Filed: 06/16/2004
• Published: 01/06/2005
• Est. Priority Date: 06/16/2003
• Status: Active Grant

• Current Assignee: Konamite Limited
• Original Assignee: Isense Corporation
• Inventors: Sass, Richard G., Ward, W. Kenneth
• Granted Patent: US 7,146,202 B2
• Time in Patent Office: Days
• US Class Current: 600/345
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• 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: Y10T 29/49 Method of mechanical manufacture

Abstract

A sensing element adapted to, at least in part, be inserted into a mammalian body. The sensing element is made up of a core of a structurally robust metal and a plated portion made of an electrochemically active metal conjoined to at least a portion of the core. This sensing element may be used as part of a method for the continuous or intermittent monitoring of an analyte within a mammalian body. The method includes inserting at least a portion of the sensing element into the mammalian body and measuring any electric current produced by at least of portion of the sensor.

Claims

1. A sensing element adapted to be, at least in part, inserted into a mammalian body, said sensing element comprising:

(a) a core of a structurally robust material; and

(b) a layer of electrochemically active metal substantially circumferentially applied to at least a portion of said core.

2. The sensor of claim 1 wherein said electrochemically active metal is a noble metal.

3. The sensor of claim 1 wherein said structurally robust metal is stainless steel.

4. The sensor of claim 1 wherein said structurally robust metal is tantalum.

5. The sensor of claim 2 wherein said noble metal is gold.

6. The sensor of claim 2 wherein said noble metal is platinum.

7. The sensor of claim 2 wherein said noble metal is palladium.

8. The sensor of claim 1 wherein said core is round in cross-section and wherein said electrochemically active metal is applied to said core circumferentially.

9. The sensor of claim 1, further being biocompatible and flexible so that it may be implanted into a mammal for at least 24 hours.

10. The sensor of claim 1, further being rigid and sharp so that it can briefly pierce the skin and be brought into contact with body fluid for a measurement process lasting less than 3 minutes.

11. The sensor of claim 1 wherein said core and said layer are parts of a drawn filled tube that has been cut to an appropriate length.

12. The sensor of claim 1 wherein said core is round in cross-section.

13. A method for the measuring the concentration of an analyte within a mammalian body having body fluids, comprising:

(a) providing a sensor having;

(i) a core of structurally robust material; and

(ii) a layer of electrochemically active metal applied to at least a portion of said core;

(b) placing at least a portion of said sensor into contact with said body fluid; and

(c) measuring any electric current produced by said at least of portion of said sensor and forming a measurement of analyte concentration based on said current measurement.

14. The method of claim 13 wherein said electrochemically active metal is a noble metal.

15. The method of claim 14 wherein said noble metal is gold.

16. The method of claim 13 wherein said structurally robust metal is stainless steel.

17. The method of claim 13 wherein said structurally robust metal is tantalum.

18. The method of claim 13 wherein said at least a portion of said sensor remains inserted for at least 24 hours and produces a multiplicity of analyte measurements.

19. The method of claim 13 wherein said at least a portion of said sensor remains inserted for less than 3 minutes.

20. The method of claim 19 wherein said at least a portion of said sensor provides a single measurement only.

21. The method of claim 19 wherein said at least a portion of said sensor is withdrawn from said mammalian body before a measurement is formed and wherein a measurement is formed using retained body fluid after said at least a portion of said sensor is withdrawn.

22. A method of producing a sensing element having good structural and electrochemical properties, said method comprising:

(a) providing a core of a structurally robust metal; and

(b) applying a layer of an electrochemically active metal onto at least a portion of said core.

23. The method of claim 22 wherein said electrochemically active metal is a noble metal.

24. The method of claim 22 wherein said noble metal is gold.

25. The method of claim 22 wherein said structurally robust material is stainless steel.

26. The method of claim 22 wherein said structurally robust material is tantalum.

27. The method of claim 22 wherein plasma vapor deposition is used in the step of applying a layer of an electrochemically active metal onto at least a portion of said core.

28. The method of claim 27 wherein said core is passivated directly before said plasma vapor deposition.

29. The method of claim 22 wherein said step of applying a layer of an electrochemically active metal onto at least a portion of said core is performed by electroplating.

30. The method of claim 29 wherein said electroplating is performed in a bath having a current density of less than 40 amps/ft².

31. The method of claim 29 wherein a strike of an intermediate metal is applied to said structurally robust metal prior to said step of applying a layer of an electrochemically active metal onto at least a portion of said core.

32. The method of claim 31 wherein said intermediate metal is gold.

33. The method of claim 31 wherein said intermediate metal is chrome.

34. The method of claim 22 wherein said step of applying a layer of an electrochemically active metal onto at least a portion of said core is performed by cladding the core with a foil of said electrochemically active metal.