Multiple implant communications with adjustable load modulation based on received signal amplitudes

Patent metadata

Field	Value
Publication number	US-10925489-B2
Application number	US-201916580985-A
Country	US
Kind code	B2
Filing date	Sep 24, 2019
Priority date	Feb 8, 2017
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

A medical system and method of communicating between a telemetry controller and medical devices is provided. Coupling coefficients between a primary coil of the telemetry controller and secondary coils of the medical devices differ from each other. A primary carrier signal is applied to the primary coil, thereby respectively inducing secondary carrier signals on the secondary coils. An amplitude of the secondary carrier signal is measured on each of the secondary coils. The envelope of each secondary carrier signal is modulated in accordance with data, thereby inducing modulation of the envelope of the primary carrier signal for the implanted medical devices. The secondary carrier signal envelopes are modulated based on the measured amplitudes of the respective secondary carrier signals.

First claim

What is claimed is:

1. An implantable medical device for communicating with a telemetry controller having a primary coil on which a primary carrier signal is applied, comprising:
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;
an amplitude detector configured for measuring a voltage of the secondary carrier signal across the secondary coil;
a voltage-to-current converting circuit configured for selecting a magnitude of a modulation of the secondary carrier signal by converting the measured voltage of the secondary carrier signal to a load current associated with the secondary coil in accordance with an inversely varying relationship with the measured voltage of the secondary carrier signal; and
a modulator configured for applying the selected modulation magnitude to the secondary carrier signal envelope by modulating the load current in accordance with data, thereby inducing an amplitude modulation of an envelope of the primary carrier signal.

2. The implantable medical device of claim 1 , wherein the measured voltage of the secondary carrier signal comprises a peak voltage of the secondary carrier signal.

3. The implantable medical device of claim 1 , wherein the voltage-to-current converting circuit is an analog voltage-to-current converting circuit.

4. The implantable medical device of claim 1 , further comprising a rectifier configured for rectifying and regulating the secondary carrier signal for powering circuitry within the implantable medical device.

5. The implantable medical device of claim 1 , further comprising a biocompatible casing containing the secondary coil, amplitude detector, voltage-to-current converting circuit, and modulator.

6. The implantable medical device of claim 1 , wherein the voltage-to-current converting circuit is a digital voltage-to-current converting circuit, the implantable medical device further comprising an analog-to-digital (A/D) converter configured for converting the measured voltage of the secondary carrier signal into a digital voltage value for input into the digital voltage-to-current converting circuit, and a digital-to-analog (D/A) converter configured for converting a digital current value output by the digital voltage-to-current converting circuit into the load current.

7. The implantable medical device of claim 1 , wherein the data is physiological data of a patient, the implantable medical device further comprising at least one sensor configured for acquiring the physiological data from the patient.

8. The implantable medical device of claim 1 , wherein the data is operational status data of the implantable medical device.

9. A method of communicating between a telemetry controller and a medical device implanted within a patient, the telemetry controller having a primary coil, and the medical device having a secondary coil, the method comprising:
generating data by the implanted medical device;
applying a primary carrier signal having an envelope to the primary coil, thereby respectively inducing a secondary carrier signal having an envelope on the secondary coil;
measuring a voltage of the secondary carrier signal across the secondary coil;
selecting a magnitude of a modulation of the secondary carrier signal by converting the measured voltage of the secondary carrier signal to a load current associated with the secondary coil in accordance with an inversely varying relationship with the measured voltage of the secondary carrier signal;
applying the selected modulation magnitude to the secondary carrier signal envelope by modulating the load current in accordance with the data generated by the implanted medical device, such that the primary carrier signal envelope is amplitude modulated; and
amplitude demodulating the modulated primary carrier signal envelope to acquire the data from the implanted medical device.

10. The method of claim 9 , wherein the telemetry controller is external to the patient.

11. The method of claim 9 , wherein the measured voltage of the secondary carrier signal comprises a peak voltage of the secondary carrier signal.

12. The method of claim 9 , 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.

13. The method of claim 12 , wherein an amplitude of the threshold level is between a minimum and a maximum of the modulated primary carrier signal envelope.

14. The method of claim 13 , wherein the amplitude of the threshold level is centered between the minimum and the maximum of the modulated primary carrier signal envelope.

15. The method of claim 9 , wherein the measured voltage is converted to the load current in an analog fashion.

16. The method of claim 9 , wherein converting the measured voltage of the secondary carrier signal to a load current comprises transforming the measured voltage of the secondary carrier signal into a digital voltage value, converting the digital voltage value into a digital current value, and transforming the digital current value into the load current.

17. The method of claim 9 , wherein the generated data is physiological data acquired from the patient by the implantable medical device.

18. The method of claim 9 , wherein the generated data is operational status data of the implantable medical device.

19. A method of manufacturing an implantable medical device, comprising:
(a) selecting a uniform value for an amplitude modulation induced on a primary signal envelope;
(b) selecting a coupling coefficient value between a primary coil and a secondary coil;
(c) applying a fixed alternating current (AC) signal to the primary coil, thereby respectively inducing a secondary signal on the secondary coil for the selected coupling coefficient value;
(d) determining an amplitude of the secondary signal for the coupling coefficient value;
(e) determining an amplitude of a modulating signal for modulating an envelope of the secondary signal in a manner that induces an amplitude modulation on the primary coil that is substantially equal to the selected uniform amplitude modulation value;
(f) correlating the determined amplitude of the secondary signal and the determined amplitude of the modulating signal to create a data point;
(g) repeating steps (b)-(f) for different coupling coefficient values to create a plurality of data points;
(h) deriving a relationship between the respective amplitudes of the secondary signal and the modulating signal from the plurality of data points; and
(i) manufacturing the implantable medical device having the secondary coil and processing circuitry configured for outputting the modulating signal in response to an input of a measured amplitude of a secondary carrier signal induced on the secondary coil in accordance with the derived relationship, such that an envelope of the secondary carrier signal is modulated.

20. The method of claim 19 , wherein the amplitude of the modulating signal is determined by adjusting the modulating signal until the amplitude modulation induced on the primary signal envelope is substantially equal to the selected uniform amplitude modulation value.

21. The method of claim 19 , wherein steps (c)-(e) are simulated.

22. The method of claim 19 , wherein steps (c)-(e) are actually performed.

Assignees

• The Alfred E Mann Foundation For Scient Research

Inventors

• Lee Edward K F
• Suri Harshit R

Classifications

• A61B5/7228 Primary

  Signal modulation applied to the input signal sent to patient or subject; Demodulation to recover the physiological signal · CPC title

• A61B2562/12

  Manufacturing methods specially adapted for producing sensors for in-vivo measurements · CPC title

• A61N1/37288

  Communication to several implantable medical devices within one patient · CPC title

• A61N1/3727

  characterised by the modulation technique · CPC title

• H04L27/18

  Phase-modulated carrier systems, i.e. using phase-shift keying (H04L27/32 takes precedence) · CPC title