Deformable inductor having a liquid magnetic core

• US 10,553,342 B2
• Filed: 07/13/2016
• Issued: 02/04/2020
• Est. Priority Date: 07/13/2016
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Inventors: Lazarus, Nathan S., Meyer, Christopher D.
• Primary Examiner(s): Chan, Tszfung J
• Application Number:
  US15/209,115
• Publication Number:
  US 20180019049A1
• Time in Patent Office: 1,301 Days
• Field of Search: 336200, 336232
• CPC Class Codes: H01F 1/44 of magnetic liquids, e.g. ferrofluids particles in a bonding agent H01F1/28, H01F1/36, H01F1/37
• CPC Class Codes: H01F 27/022 Encapsulation
• CPC Class Codes: H01F 27/24 Magnetic cores

Abstract

A deformable inductive device includes an elastomer material having at least one deformable electrode and a liquid magnetic core formed in the elastomer material and containing a magnetic liquid. Depending on the device'"'"'s configuration, the deformable element may be embedded in, attached to, or in close proximity with the liquid magnetic core. In some embodiments, the deformable inductive device may be configured as an inductor, solenoid, or transformer and the deformable electrode is at least partially embedded in the liquid magnetic core, for instance. In another embodiment, the deformable inductive device may be configured as part of a wireless power transfer system which includes a coil and a magnetic backplane having the liquid magnetic core with the coil being attached to or in close proximity to the magnetic backplane.

Claims

1. A passive, deformable inductive device comprising:

an elastomer material;

at least one deformable electrode at least partially embedded in the elastomer material; and

a liquid magnetic core formed in the elastomer material and containing a magnetic liquid,

wherein both the liquid magnetic core and the at least one deformable electrode are not actively-deformed with ordinary operation of the device yet are configured so as to be readily elastic at greater than ±

5% strain and maintain operability of the device.

2. The device of claim 1, wherein the deformable inductive device is configured as an inductor, solenoid, or transformer with the at least one deformable electrode is positioned proximate to the liquid magnetic core such that (i) electrical current flowing in the at least one deformable electrode induces magnetic flux in the liquid magnetic, and/or (ii) changing magnetic flux in the liquid magnetic induces electrical current flowing in the at least one deformable electrode.

3. The device of claim 1, wherein the deformable inductive device is part of a wireless power transfer system comprising a coil and a magnetic backplane which includes the liquid magnetic core with the coil being attached to or in close proximity to the magnetic backplane.

4. The device of claim 1, wherein the elastomer material comprises a polymer or plastic material.

5. The device of claim 4, wherein the polymer comprises natural rubber or a silicone material.

6. The device of claim 1, wherein the magnetic liquid comprising a fluid having magnetic particles dispersed within.

7. The device of claim 6, wherein the fluid comprises mineral oil.

8. The device of claim 1, wherein the magnetic particles have a size on the order of 10 nm.

9. The device of claim 1, wherein the magnetic liquid comprises a ferrofluid or magnetorheological fluid.

10. The device of claim 6, wherein the magnetic particles are formed of iron, nickel, cobalt and/or an alloy thereof, or carbonyl iron.

11. The device of claim 6, wherein the magnetic particles are generally spherical particles or platelets.

12. The device of claim 1, wherein the deformable electrode comprises at least one deformable conductive trace or at least one coil having one or more turns.

13. The device of claim 12, wherein the at least one deformable conductive trace is 500 nm thick and 100 μ

m wide.

14. The device of claim 1, wherein the deformable electrode comprises at least one deformable channel containing a containing a liquid conductor.

15. The device of claim 14, wherein the liquid conductor comprises a liquid metal, flowable elastomer or polymer having conductive particles intermixed therein, or a fluid solution containing an ionic conductor or electrolyte.

16. The device of claim 15, wherein the liquid metal comprises Galinstan, eutectic gallium/indium, or mercury.

17. The device of claim 1, wherein the stretchable inductive device is configured to be elastically deformable from −

50% strain to 100% strain.

18. A method for forming the deformable inductive device of claim 1, comprising the steps of:

preparing a mold, the mold including a removable element which will form the liquid magnetic core in the elastomer material;

casting elastomer material into the mold;

removing the removable element; and

filling the void in the elastomer material left by the removable element with the magnetic liquid.

19. The device of claim 1, wherein the device is configured to generate a flow of the magnetic liquid in the liquid magnetic core.

20. A passive, deformable inductive device comprising:

an elastomer material;

a liquid magnetic core formed in the elastomer material and comprising at least one channel containing a ferroliquid; and

a deformable electrode at least partially embedded in the elastomer material,

wherein both the liquid magnetic core and the deformable electrode are not actively-deformed with ordinary operation of the device yet are configured so as to be readily elastic at greater than ±

5% strain and maintain operability of the device.