Technique for design, and placement, of a subdermal Ag-Ag/Cl biopotential electrode

• US 20060161058A1
• Filed: 01/17/2006
• Published: 07/20/2006
• Est. Priority Date: 01/18/2005
• Status: Active Grant

• Current Assignee: John Richard Ives, Susan Elizabeth Phelan
• Original Assignee: John Richard Ives, Susan Elizabeth Phelan
• Inventors: Phelan, Susan Elizabeth, Ives, John Richard
• Granted Patent: US 7,643,861 B2
• Time in Patent Office: Days
• US Class Current: 600/373
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/296 for electromyography [EMG]

Abstract

A chronic subdermal silver-silver/chloride (Ag—Ag/Cl) electrode for the recording of biopotentials is disclosed. The electrode is comprised of an Ag—Ag/Cl distal end that is placed subdermally by various methods. The recording electrode is made of solid, multi-stranded or a ball of pure silver and the whole length of the electrode is insulated except for the distal end which is used for voltage recordation. The electrode can be placed subdermally by an introducer apparatus such as hypodermic or sewing needle, a split-cannula, a staple, or a suture. Once placed, the introducer apparatus can be removed leaving the recording wire/element in place. The recording electrode can be placed at any location on the body to record the local biopotential (EEG, EOG, EMG, EKG, etc). It can be left in place for hours, days, or weeks, as it will record without any further adjustment.

Claims

1. A subdermal silver-silver/chloride (“

Ag—

Ag/Cl”

) biopotential electrode comprising a pure multi-stranded or solid silver wire having proximal and distal ends;

wherein said wire is substantially coated with Telfon with said distal end Telfon-free;

said Telfon-free distal end being electrolysed with silver/chloride and wherein said proximal end of said wire is connected to a biopotential voltage recording means.

2. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, wherein said proximal end of said wire is either soldered or crimped to a connector for permitting external connection to said biopotential voltage recording means.

3. The subdermal Ag—

Ag/Cl biopotential electrode of claim 2, wherein said connector is insulated and sealed with heat-shrink tubing.

4. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, wherein an on-head preamplifier/multiplexer unit with mass connectors is used to record said biopotential voltage.

5. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, further comprising an introducer means to facilitate and to place said electrode in the subdermal space.

6. The subdermal Ag—

Ag/Cl biopotential electrode of claim 5, wherein said introducer is a hypodermic needle, a split-cannula, a staple or a suture.

7. The subdermal Ag—

Ag/Cl biopotential electrode of claim 6, wherein said hypodermic needle is a ⅝

″

, ultra thin-wall 25-gauge hypodermic needle.

8. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, wherein a 2″

piece of Teflon coated pure silver wire with an overall diameter of about 0.0045″

or 0.114 mm is used as the recording electrode wire.

9. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, wherein said Telfon-free distal end is approximately 3 to 4 mm in length.

10. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, wherein electrolysis of said Telfon-free distal end is conducted by placing said end in chlorine bath with a silver anode while 1.5 Volts is applied for about 15 minutes.

11. The subdermal Ag—

Ag/Cl biopotential electrode of claim 1, wherein said wire is chlorided with a silver salt to enable recordation of biopotential voltage at the site of placement for EEG, EOG, EKG, EMG applications.

12. The subdermal Ag—

Ag/Cl biopotential electrode of claim 6, wherein said hypodermic needle is the type having a hollow needle with a sharp end lumen and a slanted bevel for permitting penetration of the skin and for allowing said needle to carry in said electrode'"'"'s distal end hooked into said needle lumen with said wire runs along the outside sheath of said needle terminating in said connector.

13. The subdermal Ag—

Ag/Cl biopotential electrode of claim 11, wherein said hypodermic needle has a grip end opposite to the skin penetration end.

14. The subdermal Ag—

Ag/Cl biopotential electrode of claim 5, further comprising a protective cap for placement over the introducer means and said electrode.

16. A method of subdermally recording biopotential voltage of a subject by:

(i) inserting said distal end of said silver-silver/chloride (“

Ag—

Ag/Cl”

) biopotential electrode of claim 12 into said slanted lumen of said hypodermic needle;

(ii) folding back the coated portion of said wire along the outside sheath of said needle with one hand while holding the sheath of said needle with the other hand such that said wire is held between a finger and the thumb against the hub of the needle to permit the needle/wire assembly to be removed from the sheath without dislodging said wire'"'"'s distal end that is located in the slanted lumen of said needle;

(iii) pressing said needle against the skin of the subject and, with increase pressure, inserting said needle and distal end of said electrode subdermally just under the skin in the location where it is desired for recording the biopotential voltage; and

(iv) withdrawing said needle to leave said distal end of said electrode in place.

17. The method of subdermally recording biopotential voltage as claimed in claim 16, further comprising the step of applying a holding down adhesive on the surface of the skin to hold said wire and said distal end of said electrode securely in place.

18. The method of subdermally recording biopotential voltage as claimed in claim 17, wherein said adhesive is a tape, gauze, wrap or glue.

19. A self-contained, compact semi-automatic insertion unit for subdermally recording biopotential voltage of a subject, comprising a subdermal Ag—

Ag/Cl biopotential electrode of claim 1, an introducer means and an electrode connector for external connection to said unit for voltage recordation.

20. The self-contained, compact semi-automatic insertion unit of claim 19, wherein said introducer means comprises a protrusion or latching element or extension for permitting external gripping to facilitate placement of said electrode on the skin and allowing for said distal end of said electrode to be injected into the subdermal space.

21. The self-contained, compact semi-automatic insertion unit of claim 20, wherein a sewing type needle with a through hole or “

eye”

is used to hold said distal end of said electrode.

22. The self-contained, compact semi-automatic insertion unit of claim 21, wherein the length of said distal end is of a dimension sufficient to permit said end to be self extracted from said “

eye”

of said needle when said distal end is at the correct depth in the subdermal space.

23. The self-contained, compact semi-automatic insertion unit of claim 22, wherein activation of said protrusion or latching element permits direct insertion of said distal end of said electrode subdermally to a proper depth.

24. The self-contained, compact semi-automatic insertion unit of claim 20, wherein said unit is contained in a sterile, sealed package.

15. An apparatus for a subdermal silver-silver/chloride (“

Ag—

Ag/Cl”

) biopotential electrode comprising

(i) a pure multi-stranded or solid silver wire having proximal and distal ends;

wherein said wire is substantially coated with Telfon with said distal end Telfon-free;

said Telfon-free distal end being electrolysed with silver/chloride and wherein said proximal end of said wire is connected to a biopotential voltage recording means;

(ii) an introducer means to facilitate and place said electrode in the subdermal space; and

(iii) a protective cap for placement over the introducer means and said electrode.