D.C. biopotential sensing electrode assemblies for apparatus for disease, injury and bodily condition screening or sensing

• US 5,660,177 A
• Filed: 10/17/1994
• Issued: 08/26/1997
• Est. Priority Date: 11/04/1991
• Status: Expired due to Fees

• Current Assignee: Biofield Corporation
• Original Assignee: Biofield Corporation
• Inventors: Barrett, Burke T., Faupel, Mark L., Stephens, John D., Nathanson, Seth D.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US08/325,085
• Time in Patent Office: 1,044 Days
• Field of Search: 128/639, 128/640, 128/641, 128/653.1, 128/644, 128/696, 606/12
• US Class Current: 600/382
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/2415 Measuring direct current [DC] or slowly varying biopotentials
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/259 using conductive adhesive means, e.g. gels

Abstract

A DC biopotential sensing electrode assembly is provided for an apparatus for sensing DC biopotentials present at the skin of a subject. The electrodes include an electroconductive medium for transmitting ions from the skin which has a chloride content within a range of from 6-15 grams per hundred grams of such medium. To reduce the corrosive effect of this electroconductive medium, each electrode includes only one metallic component, and to provide an electrode with a low AC impedance, this metal is uniformly coated upon nonmetallic sensor and terminal bodies with a coating thickness within a range of from 0.5 to 1.5 mil. To insure a complete electrical path through both the sensor and the terminal bodies, the nonmetallic portions are formed of conductive plastic.

Claims

1. A biopotential sensing electrode for contact with a skin surface of a human or animal subject and suitable for sensing DC biopotentials comprising:

an electrode sensing element,

an electrode terminal connected to said electrode sensing element to conduct an electrical potential therefrom, said electrode sensing element and electrode terminal each being formed from a nonmetallic, electrically conductive material to form a first electrically conductive path and coated with a uniform coating of silver having a thickness within a specified range of from 0.5 to 1.5 mil to form a second electrically conductive path, said nonmetallic electrically conductive material being formed of plastic, glass or a combination of both impregnated with carbon, said carbon being within a range of from 20 to 40% by weight of the nonmetallic conductive material, and

an electroconductive medium for contact with the skin surface of a subject contacting said electrode sensing element for relaying a biopotential from the skin surface of a subject to said electrode sensing element.

2. A biopotential sensing electrode for contact with a skin surface of a human or animal subject and suitable for sensing DC biopotentials comprising:

an electrode sensing element having a sensor body including a round disc having first and second substantially parallel opposed surfaces, and a mounting pin projecting centrally from the second surface of said disc, said disc having a diameter within a range of from 0.39 to 0.43 inches, the sensor body of said electrode sensing element being formed from an electrically conductive plastic, glass or a glass-plastic combination completely and uniformly coated with an electrically conductive silver/silver chloride coating, said coating having a thickness within a range of from 0.5 to 1.5 mil, said plastic, glass, or glass-plastic combination being impregnated with carbon to form an electrically conductive plastic-carbon, glass-carbon or plastic/glass carbon combination to provide a conductive path independent of said silver/silver chloride coating,

an electrode terminal connected to said electrode sensing element to conduct an electrical potential therefrom, said electrode sensing element and electrode terminal each being formed to include a first and a second electrically conductive path,

and an electroconductive medium for contact with the skin surface of a subject contacting the first surface of said round disc of said sensor body for relaying a biopotential from the skin surface of a subject to said electrode sensing element.

3. A biopotential sensing electrode assembly comprising:

a thin, flexible support sheet of electrical insulating material, said support sheet including an opening and an annular section extending around said opening, a plurality of separate radially extending legs extending outwardly from said annular section, said radially extending legs providing a flexible support for one or more biopotential sensing electrodes, and

biopotential sensing electrodes for contacting a subject mounted on said legs, each such biopotential sensing electrode including

an electrode sensing element including a sensor body with a sensor disc having first and second opposed surfaces and a mounting pin projecting from the second surface of said disc,

an electrode terminal connected to said electrode sensing element to conduct an electrical potential therefrom,

a flexible plastic sheet of liquid impervious barrier material positioned between said electrode terminal and said electrode sensing element, said barrier material being adhered to the second surface of said sensor disc to form a liquid seal and including an aperture through which said mounting pin projects,

a layer of flexible plastic material affixed to said sheet of barrier material, said layer of flexible plastic material having an aperture extending therethrough to form a well for receiving an electroconductive medium, the sensor disc of said electrode sensing element being positioned in said well, said sheet of barrier material extending outwardly from said sensor disc to close and seal a first end of said well, and an electroconductive medium for contacting a subject and transmitting a biopotential from the subject to said electrode sensing element, said electroconductive medium being received in said well in contact with the first surface of said sensor disc.

4. The biopotential sensing electrode assembly of claim 3 wherein said radially extending legs each include a first leg surface and a second leg surface parallel to and opposed to said first leg surface and at least one aperture extending through said flexible support sheet between said first and second leg surfaces, said electrode terminal is formed on the second leg surface of a radially extending leg and said sensing element mounting pin projects through said aperture from said first leg surface into contact with said electrode terminal.

5. A biopotential sensing electrode for contact with a skin surface of a human or animal subject and suitable for sensing DC biopotentials comprising:

an electrode sensing element formed from a nonmetallic, electrically conductive material forming a first electrode electrically conductive path, said nonmetallic electrically conductive material being entirely coated with a uniform external coating of an electrically conductive metal, said electrically conductive metal coating forming a second electrode electrically conductive path,

an electrode terminal formed from a nonmetallic, electrically conductive material forming a first terminal electrically conductive path, said nonmetallic electrically conductive material forming said terminal being entirely coated with a uniform external coating of the same conductive metal which coats said electrode sensing element to form a second terminal electrically conductive path, said electrode terminal being connected to said electrode sensing element to conduct an electrical potential therefrom, the conductive metal coating for both said electrode sensing element and said electrode terminal being of a thickness within a range of from 0.5 to 1.5 mil, and

an electroconductive medium for contact with the skin of a subject contacting said electrode sensing element for relaying a biopotential from the skin of a subject to said electrode sensing element.

6. The biopotential sensing electrode of claim 5 wherein said conductive metal is silver.

7. The biopotential sensing electrode of claim 6 wherein said silver coating is of a thickness of 1 mil.

8. The biopotential sensing electrode of claim 5 wherein said electrode sensing element includes a sensor body including a round disc having first and second, substantially parallel opposed surfaces, said first surface contacting said electroconductive medium and a mounting pin projecting centrally from the second surface of said disc.

9. The biopotential sensing electrode of claim 8 wherein said electrode terminal includes a terminal body having a button connector section having a first end and a second closed end, an annular skirt section extending outwardly from said first end of said button connector section, said terminal body having a chamber extending centrally of said button connector section from said second, closed end and opening at the first end, said chamber being dimensioned to receive and retain the mounting pin of said electrode sensing element, said button connector section having a round cross section, the cross section of the button connector section in a first area adjacent to said second end thereof being greater than the cross section of the button connector section in a second area including the rest of said button connector section, the cross section of said button connector section adjacent to said second end having a diameter of 0.151 inches or more.

10. The biopotential sensing electrode of claim 9 wherein the electrically conductive metal on said terminal body is a silver layer and the electrically conductive metal on said sensor body is formed by an inner layer of silver and an outer layer of silver chloride.

11. The biopotential sensing electrode of claim 10 wherein the said sensor and terminal bodies are formed of plastic, glass, or a glass-plastic combination, impregnated with a nonmetallic, electrically conductive material to form a second conductive path therethrough, said electrically conductive metal forming a first electrically conductive path.

12. The biopotential sensing electrode of claim 11 wherein said electrically conductive material is carbon, the carbon content of said carbon impregnated plastic, glass or glass-plastic combination being within a range of from 20-40% by weight.

13. The biopotential sensing electrode of claim 9 which includes a flexible sheet of a nonmetallic liquid impervious barrier material positioned between said electrode terminal and the second surface of the round disc of the sensor body of said electrode sensing element, said sheet of barrier material including an aperture through which said mounting pin projects to the chamber of said button section, the second surface of said round disc and the annular skirt section of said terminal body being engaged with said barrier material when said mounting pin is retained in said button section chamber.

14. The biopotential sensing electrode of claim 13 wherein a layer of flexible plastic material is affixed to said sheet of barrier material, said layer of flexible plastic material having a circular central aperture extending therethrough to form a well for receiving said electroconductive medium, the round disc of the sensor body of said electrode sensing element being centered in said circular central aperture, said sheet of barrier material extending outwardly from said round disc to close and seal a first end of said well.

15. The biopotential sensing electrode of claim 14 wherein said layer of flexible plastic material is substantially circular in configuration, said round disc of the sensor body of said electrode sensing element having a diameter within a range of from 0.39 to 0.43 inches, said layer of flexible plastic material having an outer diameter at least three times the diameter of said round disc.

16. The biopotential sensing electrode of claim 15 wherein said layer of flexible plastic material is a layer of plastic foam having a contact surface extending annularly of said well and spaced from the end of said well which is closed by said sheet of barrier material, said contact surface being coated with an adhesive acceptable for skin contact.

17. The biopotential sensing electrode of claim 16 wherein the diameter of said well is within a range of from a diameter equal to the diameter of the round disc of said sensor body to 11/2 times the diameter of said round disc.

18. The biopotential sensing electrode of claim 17 wherein a layer of open cell reticulated plastic foam is mounted in said well in contact with the first surface of the round disc of the sensor body, said reticulated foam layer being impregnated with said electroconductive medium.

19. The biopotential sensing electrode of claim 18 wherein said reticulated foam layer covers the first surface of said round disc of the sensor body, said reticulated foam layer extending outwardly from said well beyond the contact surface of said layer of flexible plastic material.

20. The biopotential sensing electrode of claim 19 wherein said reticulated open cell foam layer has a cell count within a range of from 35-45 cells per square inch.

21. The biopotential sensing electrode of claim 19 which includes a release liner provided to receive and retain said reticulated open cell foam layer and said electroconductive medium, said release liner having a adhesive release surface adhered to the adhesive on the contact surface of said layer of plastic foam and being formed with a cavity extending outwardly from a surface of said release liner opposite to said release surface, said cavity opening at said release surface and being positioned over the well in said layer of plastic foam to receive said reticulated foam layer and said electroconductive medium.

22. The biopotential sensing electrode of claim 21 wherein said cavity is formed of transparent or clear material to permit inspection of the electroconductive medium contained in said well and cavity.

23. The biopotential sensing electrode of claim 22 wherein said cavity is substantially circular with a diameter which is substantially equal to the diameter of said well.

24. A DC biopotential sensing electrode for contact with a skin surface of a human or animal subject comprising:

an electrode sensing element,

an electrode terminal connected to said electrode sensing element to conduct an electrical potential therefrom, said electrode sensing element and electrode terminal each being formed from a nonmetallic, electrically conductive material completely and uniformly coated with a metallic coating of the same noncorrosive metal, said metallic coating having a thickness within a range of from 0.5 to 1.5 mil, and constituting the only metallic component of said sensing electrode and

an electroconductive medium for contact with the skin surface of said subject contacting said electrode sensing element for transmitting a biopotential from the skin surface to said electrode sensing element, said electroconductive medium having a chloride content within a range of from 6-15 grams per hundred grams of electroconductive medium.

25. The biopotential sensing electrode of claim 24 wherein said metallic coating is silver.

26. The biopotential electrode of claim 25 wherein the silver coating on said electrode sensing element includes a uniform layer of silver chloride over a layer of silver.

27. A biopotential sensing electrode for contact with a skin surface of a human or animal subject and suitable for sensing DC biopotentials comprising:

an electrode sensing element which includes a sensor body including a round disc having first and second substantially parallel opposed surfaces, and a mounting pin projecting centrally from the second surface of said disc,

an electroconductive medium for contact with the skin surface of said human or animal subject contacting said electrode sensing element for relaying a biopotential from said skin surface of said human or animal subject to said electrode sensing element, said electroconductive medium contacting said first surface of said round disc, and

an electrode terminal connected to said electrode sensing element to conduct an electrical potential therefrom, said electrode terminal including a terminal body having a button connector section with a first end, a second closed end, and an annular skirt section extending outwardly from said first end of said button connector section, said button connector section having a round cross section, the cross section of the button connector section in a first area adjacent to the second end thereof being greater than the cross section of the button connector section in a second area of said button connector section which includes all of said button connector section with the exception of said first area, the round cross section of said button connector section in said first area having a diameter of 0.151 inches or more, said terminal body having a chamber extending centrally of said button connector section from said second closed end and opening at said first end, said chamber being dimensioned to receive and retain the mounting pin of said electrode sensing element, said electrode sensing element and electrode terminal each including a first and a second electrically conductive path and each including only one metallic component formed of the same electrically conductive metal.