ELECTRODE IMPEDANCE SPECTROSCOPY

• US 20120316454A1
• Filed: 06/10/2011
• Published: 12/13/2012
• Est. Priority Date: 06/10/2011
• Status: Active Grant

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Limited
• Inventors: Carter, Paul
• Granted Patent: US 11,083,391 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61F 11/04 Methods or devices for enabling ear patients to achieve auditory perception through physiological senses other than hearing sense, e.g. through the touch sense electronic stimulation of auditory nerves A61N1/36036
• CPC Class Codes: A61F 2/18 Internal ear or nose parts, e.g. ear-drums implants for middle ear ventilation or drainage A61F11/202
• CPC Class Codes: A61F 2002/183 Ear parts
• CPC Class Codes: A61F 2240/008 Means for testing implantable prostheses
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: A61N 1/36039 fitting procedures
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: H04R 2225/67 Implantable hearing aids or parts thereof not covered by H04R25/606
• CPC Class Codes: H04R 25/505 using digital signal processing
• CPC Class Codes: H04R 25/604 of acoustic or vibrational transducers

Abstract

Aspects of the present invention are generally directed to impedance spectroscopy in an active implantable medical device (AIMD) comprising a component with one or more electrodes. In an embodiment, the AIMD applies a signal at a plurality of frequencies using one or more of the electrodes. Measurements are then obtained for the applied signal to determine impedance(s) at the applied frequencies of the tissue in which the electrodes are located.

Claims

1. A method of operating an active implantable medical device (AIMD) comprising an electrode, the method comprising:

applying a measurement signal at a plurality of frequencies to a recipient of the AIMD using the electrode; and

performing, using the AIMD, a measurement, responsive to the measurement signal and indicative of an impedance of the electrode and tissue of the recipient, at each of the plurality of frequencies.

2. The method of claim 1, further comprising:

analyzing the measurement to determine location information regarding the electrode.

3. The method of claim 2, wherein the analyzing comprises:

analyzing the measurement to determine information regarding a proximity of the electrode to one or more tissue structures.

4. The method of claim 3, wherein the one or more tissue structures comprise a modiolus.

5. The method of claim 2, wherein the analyzing is performed during implantation of a component of the AIMD, wherein the component comprises the electrode.

6. The method of claim 5, further comprising:

repositioning the electrode during the implantation based on the location information.

7. The method of claim 5, further comprising

displaying on a device external to the AIMD the location information during the implantation.

8. The method of claim 7, wherein the displayed information comprises a curve computed using the measurement.

9. The method of claim 7, where the displaying comprises:

displaying the information on a heads-up display.

10. The method of claim 1, wherein the applying comprises:

applying a measurement signal at a first of the plurality of frequencies with a specified electrical characteristic using the electrode; and

applying a measurement signal at a second of the plurality of frequencies with the specified electrical characteristic using the electrode; and

wherein the performing comprises;

measuring a first impedance of the electrode and tissue in response to the measurement signal at the first of the plurality of frequencies; and

measuring a second impedance the electrode and tissue in response to the measurement signal at the second of the plurality of frequencies.

11. The method of claim 10, further comprising:

computing a curve using the first and second impedances; and

comparing the computed curve to one or more known curve patterns to identify the proximity of the electrode to one or more tissue structures.

12. The method of claim 11, wherein comparing comprises:

using a neural network in comparing the computed curve to one or more known curve patterns.

13. The method of claim 10, wherein the electrical characteristic is one of voltage and current.

14. The method of claim 1, wherein the AIMD is a cochlear implant.

15. The method of claim 14, wherein the measurement signal is applied by a signal generator of the AIMD that is configurable to apply at least one stimulation signal using the electrode to cause a hearing percept by the recipient.

16. The method of claim 14, wherein the cochlear implant comprises an extra-cochlear electrode and a stimulating lead assembly comprising the electrode and a plurality of other electrodes, wherein

the applying comprises:

applying the measurement signal using the electrode and the extra-cochlear electrode; and

wherein the method further comprises;

applying a second measurement signal at a plurality of frequencies to the recipient using one of the plurality of other electrodes and the extra-cochlea electrode; and

performing, using the AIMD, a second measurement responsive to the second measurement signal and indicative of an impedance of the one of the plurality of other electrodes and tissue of the recipient, at each of the plurality of frequencies.

17. The method of claim 14, wherein the analyzing is performed during implantation of a component of the AIMD comprising the electrode, wherein the analyzing determines whether a tip of the component has folded over the component.

18. The method of claim 1, further comprising:

analyzing the measurement to determine a fault regarding the AIMD.

19. The method of claim 1, where the applying and performing are performed for each of the plurality of frequencies using a frequency sweep.

20. The method of claim 19, wherein the plurality of frequencies of the frequency sweep comprise frequencies logarithmically spaced across a frequency range of the frequency sweep.

21. The method of claim 19, wherein the plurality of frequencies of the frequency sweep comprises a plurality of selected frequencies.

22. The method of claim 1, further comprising:

analyzing the measurement; and

adjusting one or more operating parameters of the AIMD based on the analysis.

23. The method of claim 1, further comprising:

analyzing the measurement to obtain information regarding the proximity of the electrode to one or more tissue structures; and

emitting an audible signal based on the analysis.

24. The method of claim 23, wherein a frequency of the audible signal is determined based on the analysis.

25. The method of claim 23, wherein audible signal comprises a series of tone bursts and wherein a frequency of the tone bursts is determined based on the analysis.

26. An active implantable medical device comprising:

a component comprising an electrode;

a signal generator configured to apply a signal using the electrode at a plurality of frequencies; and

a control circuit configured to perform a measurement, responsive to the signal, indicative of an impedance of the electrode and tissue of the recipient for each of the plurality of frequencies.

27. The active implantable medical device of claim 26, further comprising:

an interface configured to provide the measurement to an external device for analysis to determine location information regarding the electrode.

28. The active implantable medical device of claim 26, wherein the control circuit is configured to perform the measurement during surgically implantation of the component in the recipient, wherein the component comprises the electrode.

29. The active implantable medical device of claim 26, wherein the signal generator is configured to apply a signal at a first of the plurality of frequencies with a specified electrical characteristic using the electrode, and apply a signal at a second of the plurality of frequencies with the electrical characteristic using the electrode;

and

wherein the control circuit is configured to measure a first impedance of the electrode and tissue in response to the signal at the first of the plurality of frequencies and measure a second impedance of the electrode and tissue in response to the signal at the second of the plurality of frequencies.

30. The active implantable medical device of claim 29, wherein the electrical characteristic is one of voltage and current.

31. The active implantable medical device of claim 26, wherein the active implantable medical device is a cochlear implant.

32. The active implantable medical device of claim 31, wherein the component is a stimulating lead assembly.

33. The active implantable medical device of claim 32, wherein the stimulating lead assembly comprises the electrode and at least one other electrode;

and

wherein the signal generator is configured to apply a second signal at a plurality of frequencies using one of the plurality of other electrodes; and

wherein the control circuit is configured to perform a second measurement, responsive to the second signal, indicative of an impedance of the one of the plurality of other electrodes and tissue of the recipient at each of the plurality of frequencies.

34. The active implantable medical device of claim 31, wherein the measurement signal comprises a square shaped pulse.

35. The active implantable medical device of claim 26, wherein the control circuit is configured to analyze the measurement to determine a fault regarding the active implantable medical device.

36. A system for performing spectroscopy comprising:

an active implantable medical device (AIMD) comprising;

an electrode;

means for applying a measurement signal to a recipient using the electrode at a plurality of frequencies; and

means for performing, using the AIMD, a measurement, responsive to the measurement signal and indicative of an impedance of the electrode and tissue of the recipient for each of the plurality of frequencies.

37. The system of claim 36, further comprising:

means for analyzing the measurement to determine location information regarding the electrode.