SPINAL CORD STIMULATOR SYSTEM

• US 20150180271A1
• Filed: 03/10/2015
• Published: 06/25/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Cirtec Medical Corp.
• Original Assignee: Globus Medical, Inc.
• Inventors: Angara, Raghavendra, Khalil, Saif, Curtis, Miles, Biele, Christopher, Fellmeth, Daniel
• Granted Patent: US 9,887,574 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/0553 Paddle shaped electrodes, e.g. for laminotomy
• CPC Class Codes: A61N 1/36071 Pain
• 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 1/37235 Aspects of the external programmer
• CPC Class Codes: A61N 1/3752 Details of casing-lead connections
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

A wireless charger for automatically tuning an optimum frequency to inductively charge a rechargeable battery of an implantable pulse generator (IPG) that generates spinal cord stimulation signals for a human body is provided. The charging coil in the charger is wirelessly coupled to a receiving coil of the IPG to charge the rechargeable battery. An optimization circuit detects a reflected impedance of the charging coil through a reflected impedance sensor, and select an optimum frequency of a charging signal supplied to the charging coil based on the detected reflected impedances of a plurality of charging frequencies in a selected frequency range. Advantageously, the optimum charging frequency provides a more efficient way to charge the IPG'"'"'s rechargeable battery.

Claims

1. A wireless charger for automatically tuning an optimum frequency to inductively charge a rechargeable battery of an implantable pulse generator (IPG) that generates spinal cord stimulation signals for a human body, the wireless charger comprising:

a charging coil adapted to be wirelessly coupled to a receiving coil of the IPG to charge the rechargeable battery;

a reflected impedance sensor coupled to the charging coil to detect a reflected impedance of the charging coil;

an optimization circuit coupled to the reflected impedance sensor and adapted to select an optimum frequency of a charging signal supplied to the charging coil based on the detected reflected impedances of a plurality of charging frequencies in a selected frequency range.

2. The wireless charger of claim 1, wherein the optimization circuit includes a microcontroller programmed to receive the detected reflected impedances of the plurality of charging frequencies.

3. The wireless charger of claim 1, wherein the optimization circuit periodically repeats the selection of the optimum frequency at a selected time interval.

4. The wireless charger of claim 1, wherein the optimization circuit sweeps the plurality of charging frequencies in the selected frequency range from one end to the other at a selected interval to obtain the detected reflected impedances.

5. The wireless charger of claim 1, wherein the optimization circuit selects, as the optimum frequency, the charging frequency that results in the detected reflected impedance representing the highest peak-to-peak voltage of the charging coil.

6. The wireless charger of claim 1, wherein the reflected impedance sensor includes a current sensor coupled in series with the charging coil.

7. The wireless charger of claim 1, wherein the reflected impedance sensor includes a transformer having a primary winding in series with the charging coil and a secondary coil coupled to the primary coil.

8. The wireless charger of claim 1, wherein the reflected impedance sensor includes:

a current sensor coupled in series with the charging coil for detecting the voltage across the charging coil; and

a rectifier to rectify the output of the current sensor such that an output of the rectifier represents a rectified voltage level of the charging coil.

9. The wireless charger of claim 1, further comprising:

a class-E amplifier adapted to generate a charging signal for the charging coil;

a current limiter connected between a power supply and the class-E amplifier to limit the current supplied to the class-E amplifier below a threshold value.

10. A method for a wireless charger to automatically tune an optimum frequency to inductively charge a rechargeable battery of an implantable pulse generator (IPG) that generates spinal cord stimulation signals for a human body, the method comprising:

applying a plurality of charging frequencies in a selected frequency range to a charging coil;

detecting a reflected impedance of the charging coil for each applied charging frequency;

selecting an optimum frequency of the charging coil based on the detected reflected impedances of the plurality of charging frequencies.

11. The method of claim 10, further comprising receiving the detected reflected impedances of the plurality of charging frequencies by a microcontroller, wherein the microcontroller selects the optimum frequency based on the received impedances.

12. The method of claim 10, further comprising periodically repeating the applying, detecting and selecting steps at a selected time interval.

13. The method of claim 10, wherein the step of applying includes sweeping the plurality of charging frequencies in the selected frequency range from one end to the other at a selected interval to obtain the detected reflected impedances.

14. The method of claim 10, wherein step of selecting includes selecting, as the optimum frequency, the charging frequency that results in the detected reflected impedance representing the highest peak-to-peak voltage of the charging coil.

15. The method of claim 10, wherein the step of detecting includes detecting the reflected impedance values from a current sensor coupled in series with the charging coil.

16. The method of claim 10, wherein the step of detecting includes detecting the reflected impedance values from a transformer having a primary winding in series with the charging coil and a secondary coil coupled to the primary coil.

17. The method of claim 10, wherein step of detecting includes detecting the reflected impedance values from a rectifier that rectifies the output of a current sensor coupled in series with the charging coil.

18. The method of claim 10, further comprising limiting the current supplied to a class-E amplifier below a threshold value, the current limiter connected between a power supply and the class-E amplifier applying the plurality of charging frequencies to the charging coil.