Electrochemical analyte sensor
An electrochemical analyte sensor having conductive traces on a substrate is used to determine a level of analyte in in vitro or in vivo analyte-containing fluids. The electrochemical analyte sensor includes a substrate and conductive material disposed on the substrate, the conductive material forming a working electrode. In some sensors, the conductive material is disposed in recessed channels formed in a surface of the sensor. An electron transfer agent and/or catalyst may be provided to facilitate the electrolysis of the analyte or of a second compound whose level depends on the level of the analyte. A potential is formed between the working electrode and a reference electrode or counter/reference electrode and the resulting current is a function of the concentration of the analyte in the fluid.
1. A method of providing an electrochemical sensor, comprising:
providing a substrate;
disposing conductive material on a surface of the substrate to form a plurality of traces, at least one of the traces forming a working electrode;
disposing an electron transfer agent proximate the working electrode; and
disposing an enzyme proximate to the working electrode;
wherein at least two of the conductive traces are separated on the surface of the substrate by 150 μm or less, the separation preventing conduction between the plurality of formed traces on the substrate; and further
wherein at least 90% of the electron transfer agent remains disposed on the substrate for at least 24 hours after subcutaneous implantation of the sensor in a body fluid.
2. The method of claim 1 , wherein the plurality of conductive traces are separated on the surface of the substrate by 50 μm or less.
3. The method of claim 1 , further comprising disposing an analyte limiting layer proximate the working electrode.
4. The method of claim 1 , wherein the enzyme is non-leachably disposed proximate the working electrode.
5. The method of claim 1 , wherein the electron transfer agent is non-leachably disposed proximate the working electrode.
6. The method of claim 1 , wherein the surface of the substrate comprises a wide portion and a narrow portion, the narrow portion being configured for implantation into a patient.
7. The method of claim 6 , wherein the narrow portion has a width of about 0.5 mm or less.
8. The method of claim 1 wherein one or more of the plurality of the traces forms a counter electrode or a reference electrode or a reference/counter electrode, or one or more combinations thereof.
9. The method of claim 1 wherein the conductive material of the at least one trace forming the working electrode includes one of carbon, a conductive polymer, a metal or alloy, or a metallic compound.
10. The method of claim 9 wherein the metal or alloy includes gold or gold alloy.
11. The method of claim 1 wherein one of the plurality of traces is formed on the substrate using silver/silver chloride.
12. The method of claim 1 wherein at least 90% of the electron transfer agent remains disposed on the substrate for 72 hours after subcutaneous implantation of the sensor in the body fluid.
13. A method of providing an electrochemical sensor, comprising:
providing a substrate;
providing a conductive material disposed on a surface of the substrate to form a plurality of traces, at least one of the traces forming a working electrode;
disposing an electron transfer agent proximate the working electrode; and
disposing an enzyme proximate to the working electrode;
wherein the plurality of conductive traces are disposed on the surface of the substrate at a density, along a width of the substrate, of about 150 to 700 μm/trace or less, each of the plurality of traces on the substrate separated by a predetermined distance to prevent conduction between the traces on the substrate; and further
wherein at least 90% of the electron transfer agent remains disposed on the substrate for at least 24 hours after subcutaneous implantation of the sensor in a body fluid.
14. The method of claim 13 , wherein the density is 667 μm/trace or less.
15. The method of claim 13 , wherein the surface of the substrate comprises a wide portion and a narrow portion, the narrow portion being configured for implantation into a patient.
16. The method of claim 13 , further comprising disposing an analyte mass transport limiting layer proximate the working electrode.
17. The method of claim 13 , wherein the enzyme is non-leachably disposed proximate the working electrode.
18. The method of claim 13 wherein one or more of the plurality of the traces forms a counter electrode or a reference electrode or a reference/counter electrode, or one or more combinations thereof.
19. The method of claim 13 wherein the conductive material of the at least one trace forming the working electrode includes one of carbon, a conductive polymer, a metal or alloy, or a metallic compound.
20. The method of claim 19 wherein the metal or alloy includes gold or gold alloy.
21. The method of claim 13 wherein one of the plurality of traces is formed on the substrate using silver/silver chloride.
22. The method of claim 13 wherein at least 90% of the electron transfer agent remains disposed on the substrate for 72 hours after subcutaneous implantation of the sensor in the body fluid.