D.C. biopotential sensing electrode and electroconductive medium for use therein

• US 5,823,957 A
• Filed: 07/27/1995
• Issued: 10/20/1998
• Est. Priority Date: 10/17/1994
• 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:
  US08/508,206
• Time in Patent Office: 1,181 Days
• Field of Search: 128/639-641, 128/644, 607/153, 252/500, 252/518, 252/519, 252/518.1, 252/519.1, 600/372, 600/386, 600/395-397, 600/391, 600/392
• US Class Current: 600/397
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/259 using conductive adhesive means, e.g. gels
• CPC Class Codes: A61B 5/266 containing electrolytes, conductive gels or pastes

Abstract

A DC biopotential sensing electrode assembly is provided for an apparatus for sensing DC biopotentials present at the skin of a subject. An electroconductive medium for transmitting ions from the skin which has a chloride ion content within a range of from 6-15 grams per hundred grams of such medium is formulated for use with the electrode. 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 preassembled biopotential sensing electrode for contact with a skin surface of a human or animal subject and suitable for sensing DC biopotentials which includes an electrode sensing element, an element terminal connected to said electrode sensing element to conduct an electrical potential therefrom,

said electrode sensing element being 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,

said electrode terminal being 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

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,

said electroconductive medium having a chloride content within a range of from 6 to 15 g chloride ion per 100 g of electroconductive medium.

2. The biopotential sensing electrode of claim 1 wherein said 6 to 15 g chloride ion includes sodium chloride, potassium chloride and calcium chloride.

3. The biopotential sensing electrode of claim 2 wherein said electrode sensing element and said electrode terminal are electrically conductive and are formed from materials which are corrosion resistant in sodium chloride, potassium chloride and calcium chloride.

4. The biopotential sensing electrode of claim 1 wherein said conductive metal is silver.

5. The biopotential electrode of claim 4 wherein the silver coating on said electrode sensing element includes a uniform layer of silver chloride over a layer of silver.

6. The biopotential sensing electrode of claim 5 wherein said electroconductive medium has a sodium ion content within a range of from 1.4 to 3.2 grams sodium ion per hundred grams of electroconductive medium.

7. The biopotential sensing electrode of claim 6 wherein said electroconductive medium has a potassium ion content within a range of from 1.5 to 7 grams potassium ion content per one hundred grams of electroconductive medium.

8. The biopotential sensing electrode of claim 7 wherein the potassium ion content of said electroconductive medium is equal to or greater than the sodium ion chloride content thereof.

9. The biopotential sensing electrode of claim 1 wherein said electroconductive medium has a pH within a range of 4 to 6.5.

10. An electroconductive medium for a preassembled DC biopotential electrode for contacting the skin of a subject and relaying a D.C. biopotential therefrom to an electrode sensing element comprising

chloride in an amount to provide said electroconductive medium with a chloride ion content within a range of from 6 to 15 g chloride ion per 100 g of electroconductive medium, said chloride including sodium chloride, potassium chloride and calcium chloride,

a thickener;

and

water.

11. The electroconductive medium of claim 10 which includes water in an amount equal to 63.4 grams or more per 100 grams of electroconductive medium.

12. The electroconductive medium of claim 11 which includes a paraben preservative.

13. The electroconductive medium of claim 11 in the form of a gel.

14. The electroconductive medium of claim 13 wherein the potassium ion content is equal to or greater than the sodium ion content thereof.

15. The electroconductive medium of claim 14 wherein the potassium ion content is within a range of from 4 to 7 g potassium ion per 100 g of electroconductive medium.

16. The electroconductive medium of claim 15 where said potassium ion content is greater than both said sodium ion content and calcium ion content.

17. The electroconductive medium of claim 16 wherein said thickener includes Hydroxyethyl Cellulose.

18. The electroconductive medium of claim 17 having a pH within a range of 4 to 6.5.

19. The electroconductive medium of claim 11 in the form of a cream.

20. The electroconductive medium of claim 19 wherein the sodium ion content is greater than the potassium ion content.

21. The electroconductive medium of claim 20 wherein said 6-15 g chloride ion includes sodium chloride, potassium chloride and calcium chloride in an amount sufficient to form 7.6-9.06 g chloride per 100 g of cream.

22. The electroconductive medium of claim 20 wherein said thickener includes Propylene Glycol.

23. The electroconductive medium of claim 22 wherein said thickener includes mineral oil.

24. The electroconductive medium of claim 23 which includes a paraben preservative.

25. The electroconductive medium of claim 24 which has a conductivity within a range of from 22,000 to 50,000 micromhos.

26. The electroconductive medium of claim 19 wherein the sodium ion content is within a range of from 2.25 to 3.2 g sodium ion per 100 g of electroconductive medium.

27. The electroconductive medium of claim 26 wherein the potassium ion content is within a range of from 1.5 to 2 g potassium ion per 100 g of electroconductive medium.

28. The electroconductive medium of claim 27 having a conductivity within a range of from 22,000 to 50,000 micromhos.

29. The electroconductive medium of claim 10 having a sodium ion content within a range of from 1.4 to 3.2 g sodium ion per 100 g of electroconductive medium.

30. The electroconductive medium of claim 29 having a potassium ion content within a range of from 1.5 to 7 g potassium ion per 100 g of electroconductive medium.

31. The electroconductive medium of claim 10 having a pH within a range of 4 to 6.5.

32. The electroconductive medium of claim 10 wherein the sodium ion content is greater than the potassium ion content.

33. A preassembled 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 material completely and uniformly coated with a metallic coating of the same metal, said metallic coating being noncorrosive in sodium chloride, potassium chloride and calcium chloride and of a thickness within a range of from 0.5 to 1.5 mil, 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, said chloride content including sodium chloride, potassium chloride and calcium chloride, the electroconductive medium further including water and a thickener.

34. The D.C. biopotential sensing electrode of claim 33 wherein said electroconductive medium is a gel having a potassium ion content which is equal to or greater than a sodium ion content, the potassium ion content of said gel being within a range of from 4 to 7 g potassium ion per 100 g of electroconductive medium.

35. The D.C. biopotential sensing electrode of claim 34 wherein said thickener includes Hydroxyethyl Cellulose.

36. The D.C. biopotential sensing electrode of claim 35 wherein said electroconductive medium has a pH within a range of 4 to 6.5.

37. The D.C. biopotential sensing electrode of claim 33 wherein said electroconductive medium is a cream having a sodium ion content greater than a potassium ion content.

38. The D.C. biopotential sensing electrode of claim 37 wherein said thickener includes Propylene Glycol.