External Charger for an Implantable Medical Device Having Alignment and Centering Capabilities

• US 20170361114A1
• Filed: 06/07/2017
• Published: 12/21/2017
• Est. Priority Date: 06/15/2016
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Aghassian, Daniel, Stouffer, Thomas W.
• Granted Patent: US 10,226,637 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61M 2205/8243 by induction
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: A61N 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/36125 Details of circuitry or electric components
• CPC Class Codes: A61N 1/36142 for improving safety
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01F 27/2823 Wires H01F27/2866 takes precedence
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils. The charging coil and one or more sense coils are preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the one or more sense coils are concentric with the charging coil and preferably formed in one or more traces of a circuit board. One or more voltages induced on the one or more sense coils can be used to determine whether the charging coil is (i) centered, (ii) not centered but not misaligned, or (iii) misaligned, with respect to the IMD being charged, which three conditions sequentially comprise lower coupling between the charging coil and the IMD. A charging algorithm is also disclosed that control charging dependent on these conditions.

Claims

1. An external charger for wirelessly providing energy to an implantable medical device (IMD), comprising:

a charging coil configured when energized by a drive signal to produce a magnetic field to wirelessly provide energy to the IMD as a coupled system;

at least one sense coil, wherein each at least one sense coil is configured to be induced by the magnetic field with an induced signal affected by a position of the charging coil with respect to the IMD; and

control circuitry configured to determine from at least one parameter determinable using each induced signal one of a plurality of positions of the charging coil with respect to the IMD, wherein the positions comprise whether the charging coil is (i) centered, (ii) not centered but not misaligned, and (iii) misaligned, with respect to the IMD.

2. The external charger of claim 1, wherein the at least one sense coil is concentric with the charging coil.

3. The external charger of claim 1, further comprising a user interface configured to indicate each of the determined positions to a user.

4. The external charger of claim 1, wherein the at least one parameter comprises a magnitude of at least one induced signal.

5. The external charger of claim 1, wherein the at least one parameter comprises a phase angle between at least one induced signal and the drive signal.

6. The external charger of claim 1, wherein the at least one parameter comprises a resonant frequency of the coupled system.

7. The external charger of claim 1,

wherein centered comprises a condition in which the coupling between the charging coil and the IMD is higher than a first coupling value,

wherein misaligned comprises a condition in which the coupling between the charging coil and the IMD is lower than or equal to a second coupling value lower than the first coupling value, and

wherein not centered but not misaligned comprises a condition in which the coupling between the charging coil and the IMD is greater than the second coupling value but less than or equal to the first coupling value.

8. The external charger of claim 1, further comprising an electronics module and a charging coil assembly coupled to the electronics module by a cable,

wherein the charging coil and the at least one sense coil are within the charging coil assembly, and

wherein the control circuitry is within the electronics module.

9. The external charger of claim 1, further comprising a circuit board, wherein the at least one sense coil is formed in one or more traces in the circuit board.

10. The external charger of claim 9, wherein the charging coil comprises a wire winding placed on a side of the circuit board.

11. The external charger of claim 9, wherein the charging coil comprises a wire winding, and wherein the circuit board is placed within the wire winding of the charging coil.

12. The external charger of claim 1, wherein the at least one sense coil comprises only one sense coil.

13. The external charger of claim 12,

wherein the control circuitry further includes a first threshold and a second threshold, and

wherein the control circuitry is configured to determine the one of a plurality of positions by comparing one of the at least one parameters to either or both of the first threshold and the second threshold.

14. The external charger of claim 13, wherein any one or more of the one parameter, the first threshold, and the second threshold are normalized to account for a power of the magnetic field.

15. The external charger of claim 1,

wherein the at least one sense coil comprises a first sense coil of a first radius and a second sense coil of a second radius larger than the first radius,

wherein the first sense coil is induced with a first induced signal, and

wherein the second sense coil is induced with a second induced signal.

16. The external charger of claim 15, wherein the control circuitry is configured to determine

from at least one first parameter determinable using the first induced signal whether the charging coil is centered,

from at least one second parameter determinable using the second induced signal whether the charging coil is misaligned, and

from the at least one first parameter and the at least one second parameter whether the charging coil is not centered but not misaligned.

17. The external charger of claim 16,

wherein the control circuitry further includes a first threshold and a second threshold,

wherein the control circuitry is configured to determine whether the charging coil is centered by comparing one of the at least one first parameters to the first threshold,

aligned by comparing one of the at least one second parameters to the second threshold, and

not centered but not misaligned by comparing one of the at least one first parameters and one of the at least one second parameters respectively to the first threshold and the second threshold.

18. The external charger of claim 17, wherein any one or more of the one first parameter, the one second parameter, the first threshold, and the second threshold are normalized to account for a power of the magnetic field.