Conductive adhesive and biomedical electrode

• US 4,554,924 A
• Filed: 09/04/1981
• Issued: 11/26/1985
• Est. Priority Date: 01/23/1980
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Engel, Michael R.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US06/299,570
• Time in Patent Office: 1,544 Days
• Field of Search: 128/639-641, 128/644, 128/798, 128/802, 128/803, 128/303.13, 252/500
• US Class Current: 600/391
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/259 using conductive adhesive means, e.g. gels
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61N 1/0456 Specially adapted for transcutaneous electrical nerve stimulation [TENS]
• CPC Class Codes: A61N 1/0492 Patch electrodes A61N1/0412, A61N1/0428 take precedence
• CPC Class Codes: C08F 222/102 of dialcohols, e.g. ethylene glycol di(meth)acrylate or 1,4-butanediol dimethacrylate
• CPC Class Codes: C09J 4/00 Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16

Abstract

A disposable biomedical electrode is disclosed wherein the electrically-conductive material between the electrode plate and the skin comprises a swellable, conformable, cohesive, hydrophilic, electrically-conductive adhesive formed by an improved solventless process. The adhesive precursor comprises a polyhydric alcohol, a non-ionic unsaturated free radically polymerizable material, a free radical initiator, a crosslinking agent and an ionizable salt. The adhesive precursor is polymerized after coating onto the electrode plate or releasable transfer sheet, preferably by exposure to ultraviolet radiation.

Claims

1. In an ECG electrode comprising an electrode plate having an upper surface and a lower skin-directed surface, means for electrically-connecting said electrode plate to the lead wire of an electrocardiograph, and a layer of an electrically-conductive pressure-sensitive adhesive on the lower surface of electrode plate, the improvement wherein said adhesive comprises a nonionic swellable, conformable, cohesive, dermally-non-irritating hydrophilic synthetic cross-linked acrylic acid polymer;

polyhydric alcohol which is liquid at about 20°

C.; and

an ionizable salt in an amount effective to render said adhesive electrically-conductive;

said polymer being polymerized and cross-linked after formation into said layer to form a continuous covalently-bonded network throughout said layer.

2. The electrode according to claim 1 wherein said ionizable salt contains a halide ion.

3. The electrode according to claim 2 wherein said halide ion is chloride.

4. The electrode according to claim 3 wherein said salt is potassium chloride.

5. The electrode according to claim 1 wherein said polyhydric alcohol comprises from about 10 to about 90 parts per weight of said adhesive.

6. The electrode according to claim 5 wherein said polyhydric alcohol is glycerol.

7. The electrode according to claim 1 wherein said adhesive further comprises a tackifier selected from the group consisting of polyacrylic acid and soluble salts thereof.

8. The electrode according to claim 1 wherein said electrode plate comprises a layer of metal foil.

9. The electrode according to claim 8 wherein said metal is tin.

10. The electrode according to claim 1 wherein said electrode plate comprises a non-woven web having metallic silver vapor-coated on the lower surface thereof.

11. In a biomedical electrode comprising an electrode plate having an upper surface and a lower skin-directed surface, said electrode plate having means for electrical connection to a lead wire of an electro-medical device, and a layer of an electrically-conductive pressure-sensitive adhesive on said lower surface of said electrode plate for enhancing electrical connection with the skin, the improvement wherein said adhesive layer comprises a swellable, dermally-nonirritating, conformable, cohesive, hydrophilic polymer formed by the in situ photo-polymerization of an adhesive precursor comprising

(1) a water-soluble polyhydric alcohol which is a liquid at about 20°

C.;

(2) acrylic acid

(3) a photo-initiator soluble in said polyhydric alcohol;

(4) a crosslinking agent of a multifunctional unsaturated free radically-polymerizable material soluble in said polyhydric alcohol; and

(5) an ionizable salt in an amount effective to render said conductive material electrically conductive;

whereby said adhesive layer is a continuous covalently bonded network throughout said adhesive layer.

12. The essentially dry biomedical electrode according to claim 11 wherein the photo-initiator is benzildimethylketal.