METHOD FOR MONITORING AN ANALYTE, ANALYTE SENSOR AND ANALYTE MONITORING APPARATUS

• US 20160345873A1
• Filed: 05/29/2015
• Published: 12/01/2016
• Est. Priority Date: 05/29/2015
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Patel, Anuj M., Decke, Zachary, Liang, Bradley C.
• Granted Patent: US 10,575,767 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• 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 5/4839 combined with drug delivery
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps

Abstract

A method for monitoring an analyte within the body of a patient, an analyst sensor, and an analyte monitoring apparatus are presented here. In accordance with certain embodiments, the method for monitoring an analyte within the body of a patient includes implanting an analyte sensor at a sensor placement site in the patient. The analyte sensor includes a reference electrode, a counter electrode, a primary working electrode having a first structure, and an auxiliary working electrode having a second structure different from the first structure. The method includes communicating a primary signal from the primary working electrode and an auxiliary signal from the auxiliary working electrode to a processor. Further, the method includes monitoring the primary signal and the auxiliary signal with the processor to characterize a change in a physiological characteristic at the sensor placement site.

Claims

1. A method for monitoring an analyte within the body of a patient, the method comprising:

implanting an analyte sensor at a sensor placement site in the patient, the analyte sensor comprising a reference electrode;

a counter electrode;

at least one primary working electrode having a first structure; and

at least one auxiliary working electrode having a second structure different from the first structure;

communicating a primary signal from the primary working electrode and an auxiliary signal from the auxiliary working electrode to a processor; and

monitoring the primary signal and the auxiliary signal with the processor to characterize a change in a physiological characteristic at the sensor placement site.

2. The method of claim 1 wherein monitoring the primary signal and the auxiliary signal comprises sensing alterations in current at the primary working electrode and the auxiliary signal from the auxiliary working electrode and correlating the alterations in current with the change in the physiological characteristic.

3. The method of claim 1 wherein monitoring the primary signal and the auxiliary signal with the processor comprises characterizing a change in oxygen at the sensor placement site.

4. The method of claim 1 wherein the primary signal exhibits change in response to a decrease in tissue oxygen at the sensor placement site, and wherein the auxiliary signal exhibits a second change different from the first change in response to the decrease in tissue oxygen at the sensor placement site.

5. The method of claim 1 wherein the primary working electrode has a first electrochemical surface area, wherein the auxiliary electrode has a second electrochemical surface area less than the first electrochemical surface area, wherein the primary signal increases in response to a decrease in tissue oxygen at the sensor placement site, and wherein the auxiliary signal decreases in response to the decrease in tissue oxygen at the sensor placement site.

6. The method of claim 1 wherein monitoring the primary signal and the auxiliary signal with the processor comprises characterizing an increase in electroactive interferent concentration at the sensor placement site.

7. The method of claim 1 wherein the primary working electrode is adapted to provide measurements of glucose levels at the sensor placement site and wherein the auxiliary working electrode is adapted to provide measurements of an electroactive interferent at the sensor placement site.

8. The method of claim 1 wherein the primary working electrode is adapted to have a first response to an electroactive interferent, wherein the second working electrode is adapted to have a second response to the electroactive interferent different from the first response.

9. The method of claim 1 wherein each of the primary working electrode and the auxiliary working electrode includes a deposited metal layer, wherein the deposited metal layer forms an outer surface of the auxiliary working electrode, and wherein the primary working electrode includes a plated metal layer that is plated on the deposited metal layer and that forms an outer surface of the primary working electrode.

10. The method of claim 1 further comprising supplying a same operating voltage to the primary working electrode and the auxiliary working electrode.

11. The method of claim 1 further comprising supplying different operating voltages to the primary working electrode and the auxiliary working electrode.

12. An analyte sensor comprising:

a reference electrode;

a counter electrode;

at least one primary working electrode having a first structure; and

at least one auxiliary working electrode having a second structure different from the first structure.

13. The analyte sensor of claim 12 wherein the primary working electrode has a first electrochemical surface area and wherein the auxiliary electrode has a second electrochemical surface area less than the first electrochemical surface area.

14. The analyte sensor of claim 12 wherein the primary working electrode has a first electrochemical surface area, wherein the auxiliary electrode has a second electrochemical surface area less than the first electrochemical surface area, and wherein the primary working electrode and the auxiliary working electrode have a substantially same chemistry.

15. The analyte sensor of claim 12 wherein the analyte sensor is adapted to provide measurements of glucose levels at a sensor placement site, wherein the primary working electrode is adapted to exhibit a first response signal to a change in oxygen at the sensor placement site, and wherein the auxiliary working electrode is adapted to exhibit a second response signal different from the first response signal in response to the change in oxygen at the sensor placement site.

16. The analyte sensor of claim 12 wherein the analyte sensor is adapted to provide measurements of glucose levels in interstitial fluid, wherein the primary working electrode is adapted to exhibit a first response signal to a change in oxygen in the interstitial fluid, and wherein the auxiliary working electrode is adapted to exhibit a second response signal different from the first response signal in response to the change in oxygen in the interstitial fluid.

17. The analyte sensor of claim 12 wherein the primary working electrode includes a first enzyme, wherein the auxiliary working electrode includes a second enzyme, and wherein the first enzyme and the second enzyme are the same.

18. The analyte sensor of claim 12 wherein the primary working electrode is adapted to provide measurements of glucose levels at a sensor placement site and wherein the auxiliary working electrode is adapted to provide measurements of an electroactive interferent at the sensor placement site.

19. The analyte sensor of claim 12 wherein the primary working electrode is adapted to have a first response to an electroactive interferent, wherein the second working electrode is adapted to have a second response to the electroactive interferent different from the first response.

20. The analyte sensor of claim 12 wherein each of the primary working electrode and the auxiliary working electrode includes a deposited metal layer, wherein the deposited metal layer forms an outer surface of the auxiliary working electrode, and wherein the primary working electrode includes a plated metal layer that is plated on the deposited metal layer and that forms an outer surface of the primary working electrode.

21. The analyte sensor of claim 12 further comprising a power source, wherein the primary working electrode and the auxiliary working electrode are electrically connected to the power source.

22. An analyte monitoring apparatus comprising:

a base element adapted to secure the apparatus to the patient;

a piercing member coupled to and extending from the base element;

an electrochemical sensor for monitoring an electrochemical sensor placement site, wherein the electrochemical sensor is operatively coupled to the piercing member and comprises a reference electrode;

a counter electrode;

at least one primary working electrode having a first structure; and

at least one auxiliary working electrode having a second structure different from the first structure;

a sensor input capable of receiving signals from the electrochemical sensor; and

a processor coupled to the sensor input, wherein the processor is capable of characterizing one or more signals received from the electrodes of the electrochemical sensor.

23. The analyte monitoring apparatus of claim 22 wherein the primary working electrode is adapted to exhibit a first response to a physiological characteristic of the patient at the electrochemical sensor placement site, wherein the auxiliary working electrode is adapted to exhibit a second response to the physiological characteristic of the patient at the electrochemical sensor placement site, and wherein the processor is adapted to identify the physiological characteristic based on the signals received from the electrodes of the electrochemical sensor.

24. The analyte monitoring apparatus of claim 22 further comprising a substrate, wherein the reference electrode;

the counter electrode;

the primary working electrode; and

the auxiliary working electrode are coupled to the substrate.

25. The analyte monitoring apparatus of claim 22 wherein the primary working electrode is adapted to provide primary analyte measurements and wherein the auxiliary working electrode is adapted to provide auxiliary analyte measurements.

26. The analyte monitoring apparatus of claim 22 wherein the analyte monitoring apparatus is adapted to utilize interstitial fluid harvested from the skin.

27. The analyte monitoring apparatus of claim 22 wherein:

the primary working electrode is adapted to have a first response to an onset of a decline in tissue oxygen;

the second working electrode is adapted to have a second response to the onset of a decline in tissue oxygen; and

the processor is adapted to obtain information on tissue oxygen concentrations in the patient by comparing the signals received from the primary working electrode and the auxiliary working electrode so that the onset of the decline in tissue oxygen is characterized.

28. The analyte monitoring apparatus of claim 22 wherein:

the primary working electrode has a first electrochemical surface area and is adapted to have a first response to an onset of a decline in tissue oxygen;

the second working electrode has a second electrochemical surface area less than the first electrochemical surface area and is adapted to have a second response to the onset of a decline in tissue oxygen; and

the processor is adapted to obtain information on tissue oxygen concentrations in the patient by comparing the signals received from the primary working electrode and the auxiliary working electrode so that the onset of the decline in tissue oxygen is characterized.

29. The analyte monitoring apparatus of claim 22 wherein:

the primary working electrode is adapted to have a first response to an electroactive interferent;

the second working electrode is adapted to have a second response to the electroactive interferent; and

the processor is adapted to obtain information on electroactive interferent concentrations in the patient by comparing the signals received from the primary working electrode and the auxiliary working electrode so that an increase in electroactive interferent concentration is characterized.

30. The analyte monitoring apparatus of claim 22 wherein:

each of the primary working electrode and the auxiliary working electrode includes a deposited metal layer;

the deposited metal layer forms an outer surface of the auxiliary working electrode; and

the primary working electrode includes a plated metal layer that is plated on the deposited metal layer and that forms an outer surface of the primary working electrode.

31. The analyte monitoring apparatus of claim 22 further comprising a power source, wherein the primary working electrode and the auxiliary working electrode are electrically connected to the power source.