Implantable sensor electrodes and electronic circuitry

• US 6,809,507 B2
• Filed: 12/28/2001
• Issued: 10/26/2004
• Est. Priority Date: 10/23/2001
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Choy, David, Shah, Rajiv, Morgan, Wayne A., Gord, John C.
• Primary Examiner(s): Deb, Anjan
• Assistant Examiner(s): Dole, Timothy J.
• Application Number:
  US10/034,338
• Publication Number:
  US 20030076082A1
• Time in Patent Office: 1,033 Days
• Field of Search: 324/71.1, 324/658, 324/666, 324/670, 324/676, 324/680, 324/717, 600/300, 600/301, 307/2, 307/60, 204/403.14
• US Class Current: 324/71.1
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: G01R 27/14 Measuring resistance by measuring current or voltage obtained from a reference source G01R27/16, G01R27/20, G01R27/22 take precedence

Abstract

An electronic circuit for sensing an output of a sensor having at least one electrode pair and circuitry for obtaining and processing the sensor output. The electrode pair may be laid out such that one electrode is wrapped around the other electrode in a U-shaped fashion. The electronic circuitry may include, among other things, a line interface for interfacing with input/output lines, a rectifier in parallel with the line interface, a counter connected to the line interface and a data converter connected to the counter and the electrode pair. The data converter may be a current-to-frequency converter. In addition, the rectifier may derive power for the electronic circuit from communication pulses received on the input/output lines.

Claims

1. An electronic circuit for sensing an output of a sensor, the electronic circuit comprising:

a substrate;

at least two electrode pairs formed on a first surface of the substrate for sensing a parameter, each electrode pair having a first electrode and a second electrode, wherein the first electrode of each electrode pair wraps at least partially around the second electrode of its electrode pair; and

circuitry for processing the parameter,

wherein a layout of the at least two electrode pairs minimizes cross coupling between at least one electrode of a first electrode pair and at least one electrode of a second electrode pair.

2. The electronic circuit of claim 1, wherein the first electrode of each electrode pair wraps around the second electrode of its electrode pair in a U-shaped fashion.

3. The electronic circuit of claim 1, wherein the first electrode of each electrode pair wraps around the second electrode of its electrode pair by surrounding three sides of the second electrode.

4. The electronic circuit of claim 1, further comprising a reference electrode for setting a reference voltage for the at least two electrode pairs.

5. The electronic circuit of claim 4, wherein the reference voltage set on the reference electrode is about 0.5 volts.

6. The electronic circuit of claim 1, wherein the circuitry comprises

a line interface for interfacing with input/output lines;

a rectifier in parallel with the line interface;

a counter connected to the line interface; and

a data converter connected to the counter and the at least two electrode pairs.

7. The electronic circuit of claim 6, further comprising control logic connected to the counter and the line interface.

8. The electronic circuit of claim 7, wherein the control logic comprises

a state machine;

and

a state decoder connected to the state machine.

9. The electronic circuit of claim 7, wherein the control logic comprises a microprocessor.

10. The electronic circuit of claim 6, wherein the rectifier transfers power from communication pulses to a capacitor.

11. The electronic circuit of claim 10, wherein the capacitor powers the electronic circuit using power stored from the communication pulses.

12. The electronic circuit of claim 6, wherein the data converter is an analog-to-digital converter.

13. The electronic circuit of claim 6, wherein the data converter is a voltage-to-frequency converter.

14. The electronic circuit of claim 6, wherein the data converter is a current-to-frequency converter.

15. The electronic circuit of claim 14, wherein an output of the current-to-frequency converter is scaled using a prescaler before connecting to the counter.

16. electronic circuit of claim 15, wherein the prescaler is a divide-by-16 prescaler.

17. The electronic circuit of claim 6, wherein the circuitry further comprises

a temperature sensor for reading a temperature of an environment;

and

a voltage reference for applying a voltage to a reference electrode.

18. The electronic circuit of claim 6, further comprising switched capacitor circuits for use as resistors in the electronic circuit.

19. The electronic circuit of claim 1, wherein the parameter sensed by the at least two electrode pairs is a physiological parameter.

20. The electronic circuit of claim 19, wherein the physiological parameter sensed is glucose.

21. The electronic circuit of claim 19, wherein the physiological parameter sensed is oxygen.

22. The electronic circuit of claim 1, wherein at least one of the first electrode and the second electrode is electroplated.

23. The electronic circuit of claim 1, wherein the first electrode is coplanar with the second electrode.

24. The electronic circuit of claim 1, wherein the first electrodes of the at least two electrode pairs are electronically coupled to each other.

25. The electronic circuit recited in claim 1, further comprising a spacer covering the at least two electrode pairs.

26. The electronic circuit recited in claim 25, wherein the spacer includes an area for containing a biomolecule such that the biomolecule is located adjacent to at least one of the at least two electrode pairs.

27. The electronic circuit recited in claim 26, wherein the biomolecule is a glucose oxidase enzyme.

28. The electronic circuit recited in claim 26, wherein the spacer comprises a material that is permeable to oxygen and is not permeable to the biomolecule.

29. The electronic circuit recited in claim 1, wherein the first electrodes of each pair have a U-shape including an open end, the at least two electrode pairs being formed on the first surface of the substrate such that the open ends face in opposing directions.

30. The electronic circuit of claim 1, further comprising a reference electrode separating the at least two electrode pairs.

31. The electronic circuit of claim 30, wherein the reference electrode is substantially rectangular.

32. The electronic circuit of claim 1, wherein the reference electrode is disposed substantially perpendicularly to at least one electrode of each of the at least two electrode pairs.

33. An electronic circuit for sensing an output of a sensor, the electronic circuit comprising:

a substrate;

at least two electrode pairs formed on a first surface of the substrate for sensing a parameter, each electrode pair having a first electrode and a second electrode, wherein the first electrode of each electrode pair wraps at least partially around the second electrode of its electrode pair;

circuitry for processing the parameter, and

a reference electrode for setting a reference voltage for the at least two electrode pairs,

wherein a layout of the first electrode and the second electrode minimizes cross coupling between the first electrode and the second electrode, and

wherein the reference electrode is formed between the at least two electrode pairs.

34. An electronic circuit for sensing an output of a sensor, the electronic circuit comprising:

a substrate;

at least two electrode pairs formed on a first surface of the substrate for sensing a parameter, each electrode pair having a first electrode and a second electrode, wherein the first electrode of each electrode pair wraps at least partially around the second electrode of its electrode pair;

circuitry for processing the parameter, and

a reference electrode for setting a reference voltage for the at least two electrode pairs,

wherein a layout of the first electrode and the second electrode minimizes cross coupling between the first electrode and the second electrode,

wherein the reference electrode is disposed between and separates the at least two electrode pairs, and

wherein the first electrode of each of the at least two electrode pairs separates the reference electrode and the second electrode of each of the at least two electrode pairs.

35. The electronic circuit of claim 34, wherein the reference electrode is rectangular.

36. The electronic circuit of claim 34, wherein the second electrode is rectangular.

37. The electronic circuit of claim 36, wherein the reference electrode is perpendicular to the second electrode.

38. The electronic circuit of claim 34, wherein the second electrode is disposed within the boundaries of the first electrode.

39. The electronic circuit of claim 38, wherein the second electrode is substantially parallel with at least one leg of the first electrode.

40. The electronic circuit of claim 34, wherein the reference electrode is disposed perpendicularly to the second electrode of each of the at least two electrode pairs.