MULTIPLE IMPLANT COMMUNICATIONS WITH ADJUSTABLE LOAD MODULATION USING MODULATION INDICES

• US 20180256030A1
• Filed: 02/28/2018
• Published: 09/13/2018
• Est. Priority Date: 03/07/2017
• Status: Active Grant

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: LEE, EDWARD K. F., SURI, HARSHIT R.
• Granted Patent: US 10,568,513 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61F 2/583 Hands; Wrist joints
• CPC Class Codes: A61F 2/72 Bioelectric control, e.g. myoelectric
• CPC Class Codes: A61F 2002/705 Electromagnetic data transfer for implantable prostheses A61F2250/0002
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04Q 2209/40 using a wireless architecture
• CPC Class Codes: H04Q 2209/88 Providing power supply at the sub-station
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A medical system and method of communicating between a telemetry controller and a plurality of medical devices implanted within a patient is provided. Communication links are respectively established between the telemetry controller and the implanted medical devices. The communication links are respectively amplitude modulated by the implanted medical devices at modulation levels using load modulation. Received signal strength indicators (RSSIs) of the amplitude modulated communication links for the implanted medical devices are measured. A variation of the RSSIs is decreased by modifying, based on the measured RSSIs, at least one modulation level at which the respective at least one communication link is amplitude modulated by the respective implanted medical device(s).

Claims

1. A medical system, comprising:

a plurality of implantable medical devices; and

a telemetry controller configured for establishing communication links between the implantable medical devices and the telemetry controller;

wherein the implantable medical devices are configured for amplitude modulating the communication links at modulation levels; and

wherein the telemetry controller is further configured for respectively measuring received signal strength indicators (RSSIs) of the amplitude modulated communication links, and decreasing a variation of the RSSIs by commanding, based on the measured RSSIs, at least one of the implantable medical devices to modify the respective at least one modulation level at which the respective at least one communication link is amplitude modulated.

2. The medical system of claim 1, wherein the telemetry controller is configured for decreasing the variation of the RSSIs by:

determining the lowest one of the RSSIs;

selecting one of the implantable medical devices not associated with the lowest RSSI; and

commanding the selected implantable medical device to modify the respective modulation level to an equalizing modulation level, such that the RSSI of the communication link amplitude modulated at the new modulation level by the selected implantable medical device matches the lowest RSSI.

3. The medical system of claim 2, wherein the telemetry controller is configured for commanding the selected implantable medical device to modify the respective modulation level to the equalizing modulation level by decrementing the respective modulation level by a predetermined amount at least one time.

4. The medical system of claim 2, wherein telemetry controller is configured for commanding the selected implantable medical device to modify the respective modulation level to the equalizing modulation level by approximating a modulation level at which the RSSI of the respective communication link amplitude modulated at the approximated modulation level by the selected implantable medical device is likely to match the lowest RSSI.

5. The medical system of claim 2, wherein the telemetry controller is configured for commanding the selected implantable medical device to modify the respective modulation level to the equalizing modulation level by:

measuring the RSSI of the communication link amplitude modulated at the modified modulation level by the selected implantable medical device;

comparing the measured RSSI with the lowest RSSI; and

repeating the modulation level modifying, RSSI measuring, and RSSI comparison functions until the RSSI of the amplitude modulated communication link between the telemetry controller and the selected implantable medical device matches the lowest RSSI.

6. The medical system of claim 2, wherein the telemetry controller is further configured:

for selecting another one of the implantable medical device not associated with the lowest RSSI; and

commanding the other selected implantable medical device to modify the respective modulation level to another equalizing modulation level, such that the RSSI of the communication link amplitude modulated at the other equalizing modulation level by the selected implantable medical device matches the lowest RSSI.

7. The medical system of claim 6, wherein the telemetry controller is configured for repeating the implantable medical device selection and modulation level modification functions for all remaining ones of implantable medical devices not associated with the lowest RSSI.

8. The medical system of claim 2,

wherein the implantable medical devices are configured for initially amplitude modulating the communication links at maximum modulation levels;

and

wherein the telemetry controller is configured for commanding the selected implantable medical device to modify the respective modulation level to the equalizing modulation level by reducing the respective maximum modulation level to the respective equalizing modulation level.

9. The medical system of claim 1, wherein amplitude modulating the at least one communication link by the at least one implantable medical device at the respective at least one modified modulation level results in substantial uniformity between the RSSIs.

10. The medical system of claim 9, wherein the variation of the RSSIs is less than 50%.

11. The medical system of claim 9, wherein the variation of the RSSIs is less than 20%.

12. The medical system of claim 1;

wherein the implantable medical devices are further configured for respectively stored modulation indices that respectively set the modulation levels at which the implantable medical devices amplitude modulate the communication links; and

wherein the telemetry controller is further configured for commanding the at least one implantable medical device to modify the respective at least one modulation level by commanding the at least one implantable medical device to modify the respective at least one modulation index.

13. The medical system of claim 1,

wherein the implantable medical devices are further configured for generating data and sequentially amplitude modulating the communication links with the data by the implantable medical devices after the variation of the RSSI has been decreased;

and

wherein the telemetry controller is further configured for amplitude demodulating the communication links to acquire the data from the implantable medical devices.

14. The medical system of claim 13, wherein the data is physiological data acquired from the patient by the implantable medical devices.

15. The medical system of claim 13, wherein the data is operational status data of the implantable medical devices.

16. The medical system of claim 1,

wherein the telemetry controller comprises:

a primary coil; and

a coil driver configured for applying a primary carrier signal having an envelope to the primary coil; and

each of the implantable medical devices comprises;

a secondary coil on which a secondary carrier signal having an envelope may be induced in response to the application of the primary carrier signal on the primary coil, thereby establishing the respective communication link between the implantable medical device and the telemetry controller; and

an uplink modulator configured for amplitude modulating the secondary carrier signal envelope at the respective modulation level, thereby inducing an amplitude modulation of the primary carrier signal envelope on the primary coil.

17. The medical system of claim 16,

wherein the telemetry controller further comprises:

an amplitude detector configured for detecting a peak-to-peak amplitude of the induced amplitude modulations of the primary carrier signal envelope;

control circuitry configured for determining the RSSIs from the detected peak-to-peak amplitudes, and generating at least one command based on the measured RSSIs; and

a downlink modulator configured for amplitude modulating the primary carrier signal envelope on the primary coil with the at least one command, thereby inducing an amplitude modulation of the secondary carrier signal envelope, encoded with the respective command, on the secondary coil of the at least one implantable medical device; and

each of the at least one implantable medical device further comprises;

a downlink demodulator configured for amplitude demodulating the modulated secondary carrier signal envelope to acquire the respective command; and

control circuitry configured for modifying the respective modulation level in accordance with the respective command.

18. The medical system of claim 17,

wherein each of the implantable medical devices is configured for generating data, and the uplink modulator of each implantable medical device is configured for amplitude modulating the secondary carrier signal envelope on the secondary coil with the respective data, thereby inducing an amplitude modulation of the primary carrier signal envelope, encoded with the data, on the primary coil of the telemetry controller;

and

wherein the telemetry controller further comprises an uplink demodulator configured for amplitude demodulating the modulated primary carrier signal envelope to acquire the data.

19. The medical system of claim 18, wherein the uplink demodulator is configured for amplitude demodulating the modulated primary carrier signal envelope by:

detecting the modulated primary carrier signal envelope; and

comparing the detected modulated primary carrier signal envelope to a threshold level.

20. The medical system of claim 19, wherein the amplitude of the threshold level is between a minimum and a maximum of the modulated primary carrier signal envelope.

21. The medical system of claim 20, wherein the amplitude of the threshold level is centered between the minimum and the maximum of the modulated primary carrier signal envelope.

22. The medical system of claim 16, wherein each of the implantable medical devices further comprises a rectifier configured for rectifying and regulating the secondary carrier signal on the respective secondary coil for powering circuitry within the respective implantable medical device.

23. The medical system of claim 16, wherein the uplink modulator of each of the implantable medical devices is configured for load modulating the respective secondary carrier signal envelope on the respective secondary coil.

24. The medical system of claim 1, wherein the telemetry controller is an external telemetry controller.

25. A method of communicating between a telemetry controller and a plurality of medical devices implanted within a patient, comprising:

respectively establishing communication links between the telemetry controller and the implanted medical devices;

respectively amplitude modulating the communication links by the implanted medical devices at modulation levels;

respectively measuring received signal strength indicators (RSSIs) of the amplitude modulated communication links for the implanted medical devices; and

decreasing a variation of the RSSIs by modifying, based on the measured RSSIs, at least one modulation level at which the respective at least one communication link is amplitude modulated by the respective at least one implanted medical device.

26. The method of claim 25, wherein decreasing the variation of the RSSIs comprises:

determining the lowest one of the RSSIs;

selecting one of the implanted medical devices not associated with the lowest RSSI;

modifying the respective modulation level to an equalizing modulation level, such that the RSSI of the communication link amplitude modulated at the new modulation level by the selected implantable medical device matches the lowest RSSI.

27. The method of claim 26, wherein modifying the respective modulation level to the equalizing modulation level comprises decrementing the respective modulation level by a predetermined amount at least one time.

28. The method of claim 26, wherein modifying the respective modulation level to the equalizing modulation level comprises approximating a modulation level at which the RSSI of the respective communication link amplitude modulated at the approximated modulation level by the selected implantable medical device is likely to match the lowest RSSI.

29. The method of claim 26, wherein modifying the respective modulation level to the equalizing modulation level comprises:

measuring the RSSI of the communication link amplitude modulated at the modified modulation level by the selected implantable medical device;

comparing the measured RSSI with the lowest RSSI; and

repeating the modulation level modifying, RSSI measuring, and RSSI comparison steps until the RSSI of the amplitude modulated communication link between the telemetry controller and the selected implantable medical device matches the lowest RSSI.

30. The method of claim 26, further comprising:

selecting another one of the implanted medical device not associated with the lowest RSSI; and

modifying the respective modulation level to another equalizing modulation level, such that the RSSI of the communication link amplitude modulated at the other equalizing modulation level by the selected implantable medical device matches the lowest RSSI.

31. The method of claim 30, further comprising repeating the implanted medical device selection and modulation level reduction steps for all remaining ones of implanted medical devices not associated with the lowest RSSI.

32. The method of claim 26,

wherein the communication links are initially amplitude modulated by the implanted medical devices at maximum modulation levels;

and

wherein the respective modulation level is modified to the equalizing modulation level by reducing the respective maximum modulation level to the respective equalizing modulation level.

33. The method of claim 25, wherein modifying the at least one modulation level results in a substantial uniformity between the RSSIs.

34. The method of claim 33, wherein the variation of the RSSIs is less than 50%.

35. The method of claim 33, wherein the variation of the RSSIs is less than 20%.

36. The method of claim 25, further comprising:

storing modulation indices in the respective implanted medical devices;

wherein the communication links are respectively amplitude modulated by the implanted medical devices in accordance with modulation indices; and

wherein modifying the at least one modulation level comprises modifying the respective at least one modulation index.

37. The method of claim 25, wherein the telemetry controller sends at least one command to the at least one implanted medical device to modify the at least one modulation level.

38. The method of claim 25, further comprising:

generating data by the implanted medical devices;

sequentially amplitude modulating the communication links with the data by the implanted medical devices after the variation of the RSSI has been decreased; and

amplitude demodulating the communication links by the telemetry controller to acquire the data from the implanted medical devices.

39. The method of claim 38, wherein the data is physiological data acquired from the patient by the implantable medical devices.

40. The method of claim 38, wherein the data is operational status data of the implantable medical devices.

41. The method of claim 25,

wherein the telemetry controller has a primary coil and each of the medical devices has a secondary coil;

wherein the communication links between the implanted medical devices and the telemetry controller are established by applying a primary carrier signal having an envelope to the primary coil, thereby respectively inducing a secondary carrier signal having an envelope on each of the secondary coils; and

wherein the communication links are amplitude modulated by the implanted medical devices by sequentially amplitude modulating each of the secondary carrier signal envelopes on the secondary coils, thereby inducing an amplitude modulation of the primary carrier signal envelope on the primary coil for the implanted medical devices.

42. The method of claim 41, wherein coupling coefficients between the primary coil and the secondary coils differ from each other.

43. The method of claim 41, wherein the telemetry controller sends at least one command to the at least one implanted medical device to modify the at least one modulation level by amplitude modulating the primary carrier signal envelope on the primary coil with the at least one command, thereby inducing an amplitude modulation of the at least one secondary carrier signal envelope, encoded with the at least one command, on the at least one secondary coil of the at least one implanted medical device.

44. The method of claim 41, further comprising:

generating data by the implanted medical devices;

sequentially amplitude modulating the secondary carrier signal envelopes on the respective second coils with the data after the variation of the RSSIs has been decreased, thereby inducing an amplitude modulation of the primary carrier signal envelope, encoded with the data, on the primary coil for the implanted medical devices; and

amplitude demodulating the modulated primary carrier signal envelope to acquire the data from the implanted medical devices.

45. The method of claim 44, wherein amplitude demodulating the modulated primary carrier signal envelope comprises:

detecting the modulated primary carrier signal envelope; and

comparing the detected modulated primary carrier signal envelope to a threshold level.

46. The method of claim 45, wherein the amplitude of the threshold level is centered between a minimum and a maximum of the modulated primary carrier signal envelope.

47. The method of claim 41, further comprising generating power for each of the implanted medical devices from the respective secondary carrier signal.

48. The method of claim 41, wherein amplitude modulating each of the secondary carrier signal envelopes comprises load modulating each of the secondary carrier signal envelopes.