Magnetic coil for pulsed electromagnetic field

• US 5,951,459 A
• Filed: 08/29/1997
• Issued: 09/14/1999
• Est. Priority Date: 08/29/1997
• Status: Expired due to Fees

• Current Assignee: Orthosoft LLC (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Orthosoft LLC (Zimmer Biomet Holdings, Inc.)
• Inventors: Blackwell, Lyman L.
• Primary Examiner(s): Lacyk, John P.
• Application Number:
  US08/920,870
• Time in Patent Office: 746 Days
• Field of Search: 600/9-15
• US Class Current: 600/13
• CPC Class Codes: A61F 7/007 characterised by electric heating
• CPC Class Codes: A61F 7/034 Flameless
• CPC Class Codes: A61N 2/02 using magnetic fields produced by coils, including single turn loops or electromagnets A61N2/12 takes precedence

Abstract

A portable electronic PEMF apparatus comprises a PEMF coil, power supply, and electronic switching means contained therein. The power supply along with the switching means provide periodic electric power to the PEMF coil. The PEMF coil comprises multiple turns of a conductive wire around a core with an elongated cross section. The core comprises a magnetic shield layer of materials such as mu metal or soft iron. The power supply comprises a battery, a regulated voltage source and unregulated voltage source from the battery and electronic switching circuit, powered by the regulated voltage, for electrically connecting the unregulated voltage source to the coil. The electronic switching circuit is tuned to periodically provide power to the coil at a frequency to generate a non-inverting, varying electromagnetic field from the coil.

Claims

1. A therapeutic coil for pulsed electromagnetic field comprising,

a core having a bottom surface and a top surface defining a thickness, a first side edge portion and a second side edge portion defining a height, and a first end portion and second end portion defining a width;

and

an electrically conductive wire wound a plurality of turns around the first end portion, the bottom surface, the second end portion and the top surface, to form a coil comprising a plurality of loops, each loop having at least two dimensions wherein a first dimension is at least 5 times as great as a second dimension.

2. The therapeutic coil of claim 1 wherein said core comprises a pliant material shaped to conform to an exterior conformation of a patient'"'"'s body.

3. The therapeutic coil of claim 1 wherein said core further comprises a magnetic shielding material at least partially disposed between said bottom surface and said top surface.

4. The therapeutic coil of claim 3 wherein said magnetic shielding material is selected from the group consisting of soft iron, iron-silicon alloys, nickel iron alloys, magnet steel, chromium magnet steels, tungsten magnet steel, cobalt magnet steels, comol, indalloy, remalloy, alnico alloy, ceramic, mu metal, and combinations thereof.

5. The therapeutic coil of claim 1 wherein said electrically conductive wire is an insulated wire.

6. The therapeutic coil of claim 1 wherein said electrically conductive wire is between about 18 gauge to about 40 gauge.

7. The therapeutic coil of claim 1, wherein said electrically conductive wire is wound a plurality of turns sufficient to provide said coil with an inductance of between about 80 to about 200 milli-Henrys.

8. The therapeutic coil of claim 1 wherein said coil has an electrical resistance of less than about 100 ohms.

9. The therapeutic coil of claim 1 further comprising a capacitor, electrically connected to said coil in parallel, to form a LC circuit with a Q factor of about 2 to about 5.

10. The therapeutic coil of claim 1, further comprising a fastening means to affix said coil to an affected area of a patient.

11. The therapeutic coil of claim 10, wherein said fastening means is a hook and loop fastener.

12. The therapeutic coil of claim 1 further comprising heating means for applying heat to a body part in proximity to said coil.

13. The therapeutic coil of claim 12 wherein said heating means is an electrical resistance heater.

14. The therapeutic coil of claim 12 wherein said heating means is a chemical heater.

15. A pulsed electromagnetic field generator comprising, a coil comprising one or more core each with a bottom surface and a top surface defining a thickness, a first side edge portion and a second side edge portion defining a height, and a first end portion and second end portion defining a width, and an electrically conductive wire wound a plurality of turns around the first end portion, the bottom surface, the second end portion and the top surface, to form a coil comprising a plurality of loops, each loop having at least two dimensions wherein a first dimension is at least 5 times as great as a second dimension;

a battery for applying a current said coil to generate said magnetic field;

a solid state switching circuit connected between said battery and said PEMF coil for controlling current flow from said battery to said coil; and

control circuit means connected to said solid state switching circuit for operating said solid state switching circuit at a frequency to prevent an inversion of the magnetic field.

16. The pulsed electromagnetic field generator of claim 15 said generator being portable.

17. The pulsed electromagnetic field generator of claim 15, wherein said control circuit means comprises an oscillator circuit.

18. The pulsed electromagnetic field generator of claim 17, wherein said oscillator circuit comprises at least one 555 timer chips.

19. The pulsed electromagnetic field generator of claim 15, wherein said control circuit means comprise a microcontroller circuit.

20. The pulsed electromagnetic field generator of claim 15 further comprising a regulated power supply having a ground, an unregulated input, and a regulated output connection for supplying regulated power to said control circuit means, said ground connected to a ground terminal of said battery, said unregulated input connected to a positive terminal of said battery, and said output connected to a power input of said control circuit means.

21. The regulated power supply of claim 20 further comprising a resistor and a zener diode, and a light emitting diode connected between the unregulated input and ground of the regulated power supply for monitoring voltage supply and generating a signal indicative of when the apparatus is in operation.

22. The pulsed electromagnetic field generator of claim 15 further comprising means for connecting an external power source to said circuit.

23. The pulsed electromagnetic field generator of claim 15 further comprising automatic shutoff means to limit operation of said pulsed electromagnetic field generator for about 10 to about 60 minutes.