Electromagnetic field source device with detection of position of secondary coil in relation to multiple primary coils

• US 6,366,817 B1
• Filed: 10/26/2000
• Issued: 04/02/2002
• Est. Priority Date: 05/03/1999
• Status: Expired due to Term

• Current Assignee: Abiomed, Inc. (Johnson & Johnson)
• Original Assignee: Abiomed, Inc. (Johnson & Johnson)
• Inventors: Kung, Robert T. V.
• Primary Examiner(s): Evanisko, George R.
• Application Number:
  US09/697,338
• Time in Patent Office: 523 Days
• Field of Search: 607/30, 607/32, 607/33, 607/60, 607/61, 128/903, 623/3.27
• US Class Current: 607/61
• CPC Class Codes: A61M 2205/8243 by induction
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/196 replacing the entire heart, e.g. total artificial hearts [TAH]
• CPC Class Codes: A61M 60/216 including a rotating member acting on the blood, e.g. impeller
• CPC Class Codes: A61M 60/247 Positive displacement blood pumps
• CPC Class Codes: A61M 60/873 specially adapted for wireless or transcutaneous energy transfer [TET], e.g. inductive charging
• CPC Class Codes: A61M 60/875 specially adapted for optimising alignment of external and implantable coils
• CPC Class Codes: A61M 60/876 Implantable batteries
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

An electromagnetic field source (EFS) for providing electromagnetic energy to a secondary coil, including two or more primary coils that each carry a time-varying current to produce an electromagnetic field, and a controller that selectively provides current to one or more primary coils based on their position with respect to the secondary coil. The secondary coil may be implanted in a human recipient and used to provide power for the operation of a medical device, such as an artificial heart or ventricular assist device. The invention also provides such a secondary coil and EFS, collectively referred to as a transcutaneous energy transfer (TET) device. The primary coils of the EFS or TET may be housed in furniture. For example, they may be housed in a bed mattress or mattress pad on which the recipient rests, or in a blanket for covering the recipient. The controller includes a proximity detector that identifies those primary coils that are closest to the secondary coil, and a current director that, responsive to the proximity detector, selectively directs time-varying currents through the closest primary coils. The controller may also include an orientation detector, coupled to the current director, that determines an orientation of the secondary coil with respect to the closest primary coils. In one implementation, the proximity detector identifies the quantity of closest primary coils utilizing a resonance frequency shift detector that detects a shift in inductance of one or more primary coils due to the proximity of the secondary coil.

Claims

1. A transcutaneous energy transmission (TET) device, comprising:

at least one secondary coil disposable within a patient and adapted to receive transcutaneous energy transmission;

a plurality of primary coils, each adapted to be placed outside a patient and constructed and arranged to carry a time-varying current to transmit transcutaneous energy to the secondary coil; and

a controller constructed and arranged to detect the position of the secondary coil relative to each of the plurality of primary coils and to selectively provide current to one or more of the plurality of primary coils based on the detected position of each primary coil with respect to the secondary coil.

2. The TET device of claim 1, wherein the controller comprises:

a proximity detector constructed and arranged to identify a quantity of the plurality of primary coils that are closest to the secondary coil; and

a current director, responsive to the proximity detector and electrically coupled to the plurality of primary coils, constructed and arranged to selectively direct time-varying currents through the closest primary coils.

3. The TET device of claim 2, wherein:

the proximity detector identifies the quantity of closest primary coils utilizing a pressure sensor.

4. The TET device of claim 2, wherein the proximity detector comprises a resonance frequency shift detector that detects a shift in inductance of one or more primary coils due to a proximity of the secondary coil.

5. The TET device of claim 1, wherein current director directs time-varying currents to flow through the closest primary coils so that each current flows in the same direction when the secondary coil is disposed in a plane predominantly parallel to the planes of the closest primary coils.

6. The TET device of claim 1, wherein current director directs time-varying currents to flow through the closest primary coils so that a current in each closest primary coil flows in a direction opposite to a direction of a current in an adjacent closest primary coil when the secondary coil is disposed in a plane predominantly perpendicular to the planes of the closest primary coils.

7. The TET device of claim 2, wherein the quantity of the closest primary coils identified is a predetermined number.

8. The TET device of claim 2, wherein the quantity of the closest primary coils identified is based on a size of the secondary coil.

9. The TET device of claim 2, wherein the proximity detector comprises an optical sensor.

10. The TET device of claim 2, wherein the proximity detector comprises a mechanical sensor.

11. The TET device of claim 2, wherein the proximity detector comprises an electromagnetic transmission detector.

12. The TET device of claim 2, wherein the quantity of the closest coils is two.

13. The TET device of claim 2, wherein the proximity detector determines an approximate distance between one or more of the closest primary coils and the secondary coil, and the current director increases the currents through the closest primary coils when the proximity detector determines that the distance is greater than a nominal threshold value.

14. The TET device of claim 2, wherein the current director includes a power adjuster for adjusting the amount of current directed to the closest primary coils.

15. The TET device of claim 2, wherein the current director includes a current direction determiner for determining the directions of current supplied to two or more closest primary coils.

16. The TET device of claim 2, wherein the current director means includes a primary coil selector for selecting primary coils to receive the current.

17. The TET device of claim 1, wherein each of said plurality of primary coils comprises a phase and a size adapted to optimize coupling with the secondary coil.

18. The TET device of claim 1, wherein each of the primary coils is disposed in a plane substantially parallel to, including the same plane as, a plane of each of the other primary coils.

19. The TET device of claim 1, wherein the primary coils are disposed in two or more substantially parallel planes, including:

a first plane having one or more first-plane primary coils that, when energized, generate electromagnetic fields having one or more dead zones; and

a second plane having at least one second-plane primary coil positioned with respect to the one or more first-plane primary coils to generate, when energized, at least one electromagnetic field encompassing the one or more dead zones.

20. The TET device of claim 1, wherein the primary coils are disposed in two or more substantially parallel planes, including:

a first plane having two or more mutually adjacent first-plane primary coils; and

a second plane having at least one second-plane primary coil positioned with respect to the two or more mutually adjacent first-plane primary coils so that the projection of a magnetic center of the second-plane primary coil on the first plane is approximately equidistant from magnetic centers of each of the two or more mutually adjacent first-plane primary coils.

21. The TET device of claim 1, wherein the primary coils are disposed in two or more substantially parallel planes, including:

a first plane having four mutually adjacent primary coils positioned with respect to each other in a roughly square arrangement; and

a second plane having one primary coil including a second plane primary coil geometric center, the second plane primary coil positioned so that the projection of the second plane primary coil geometric center on the first plane is approximately centrally located among the four first plane primary coils.

22. The TET device of claim 1, further comprising one or more articles of furniture housing the plurality of primary coils.

23. The TET device of claim 1, further comprising a cardiac assist device electrically coupled to the secondary coil.

24. A cardiac-assist device comprising:

a pumping means; and

a transcutaneous energy transmission (TET) device electrically coupled to the pumping means, comprising;

a secondary coil implanted in a subject and adapted to receive transcutaneous energy transmission;

a plurality of primary coils, each adapted to be placed outside a subject and constructed and arranged to carry a time-varying current to transmit transcutaneous energy to the secondary coil; and

a controller constructed and arranged to detect the position of the secondary coil relative to each of the plurality of primary coils and to selectively provide current to one or more of the plurality of primary coils based on the detected position of each primary coil with respect to the secondary coil.

25. The cardiac-assist device of claim 24, wherein:

the pumping means includes an artificial heart.

26. The cardiac-assist device of claim 24, wherein:

the pumping means includes a ventricular-assist device.

27. The cardiac-assist device of claim 24, wherein the controller comprises:

a proximity detector constructed and arranged to identify a quantity of the plurality of primary coils that are closest to the secondary coil; and

a current director, responsive to the proximity detector and electrically coupled to the plurality of primary coils, constructed and arranged to selectively direct time-varying currents through the closest primary coils.

28. The cardiac-assist device of claim 24, wherein a phase and size of said plurality of primary coils is selected to optimize coupling with the secondary coil.