EP0255241A2 — Medical electrode

Claim 1

Independent Claim 206 words

A medical electrode adapted for providing electrical contact with a patient's skin comprising: a) a conductive member including means for connecting the medical electrode to an external electrical apparatus; and b) interfacing means comprising a solid sheet of a conductive viscoelastic hydrophilic gel, connected electrically with the conductive member, having a face adapted for interfacing electrically with and adhesively to the patient's skin, which sheet is more cohesive than it is adhesive to the patient's skin and is mechanically connected more firmly to the conductive member than it can be adhesively affixed to the patient's skin, thereby enabling concurrent removal of the conductive member and the sheet from the skin after use without leaving a noticeable residue on the skin, characterised in that the hydrophilic gel is a homogenous aqueous mixture, substantially free of unbound water, monomers and cross-linking agents, comprising (i) water; (ii) an amount dissolved in the water of a water soluble electrolyte effective to reduce the transverse electrical resistance of the sheet to an impedence at 60 Hz of less than 1,000 ohms, and iii) an amount dispersed uniformly throughout the water from about 2 to 35 wt% of a cross-linked polymer, effective to form with the water a tacky surfaced viscoelastic solid,

Claim 2

Dependent Claim 206 words

A medical electrode adapted for providing electrical contact with a patient's skin comprising: a) a conductive member including means for connecting the medical electrode to an external electrical apparatus; and b) interfacing means comprising a solid sheet of a conductive viscoelastic hydrophilic gel, connected electrically with the conductive member, having a face adapted for interfacing electrically with and adhesively to the patient's skin, which sheet is more cohesive than it is adhesive to the patient's skin and is mechanically connected more firmly to the conductive member than it can be adhesively affixed to the patient's skin, thereby enabling concurrent removal of the conductive member and the sheet from the skin after use without leaving a noticeable residue on the skin, characterised in that the hydrophilic gel is a homogenous aqueous mixture, substantially free of unbound water, monomers and cross-linking agents, comprising (i) water; (ii) an amount dissolved in the water of a water soluble electrolyte effective to reduce the transverse electrical resistance of the sheet to an impedence at 60 Hz of less than 1,000 ohms, and iii) an amount dispersed uniformly throughout the water from about 2 to 35 wt% of a cross-linked polymer, effective to form with the water a tacky surfaced viscoelastic solid,

Claim 3

Dependent Claim 129 words

which hydrophilic gel is produced by subjecting a liquid film of an agueous solution, having a viscosity of 2 ×10³ to 2,000 × 10³ cps, of the electrolyte and a water soluble polymer which is radiation crosslinkable having a weight average molecular weight from 0.05-10 × 10⁶ Daltons to an amount of high energy radiation effective to convert the liquid film to a sheet of the viscoelastic solid having an adhesive face which in the rolling ball tack test gives a rolling ball distance of less than about 10mm and an adhesion energy force in the Adhesion Energy Density Determination Test of about 2 to 80 g-cm/cm² which adhesive strength, whereby the sheet can be removed from a surface to which it is affixed without leaving a visible residue.

Claim 4

Dependent Claim 129 words

which hydrophilic gel is produced by subjecting a liquid film of an agueous solution, having a viscosity of 2 ×10³ to 2,000 × 10³ cps, of the electrolyte and a water soluble polymer which is radiation crosslinkable having a weight average molecular weight from 0.05-10 × 10⁶ Daltons to an amount of high energy radiation effective to convert the liquid film to a sheet of the viscoelastic solid having an adhesive face which in the rolling ball tack test gives a rolling ball distance of less than about 10mm and an adhesion energy force in the Adhesion Energy Density Determination Test of about 2 to 80 g-cm/cm² which adhesive strength, whereby the sheet can be removed from a surface to which it is affixed without leaving a visible residue.

Claim 5

Dependent Claim 27 words

A medical electrode according to claim 1 characterised in that the water, the cross-linked polymer and the electrolyte are substantially the sole constituents of the hydrophilic gel.

Claim 6

Dependent Claim 21 words

A medical electrode according to any of the preceding claims characterised in that the water soluble polymer comprises linear polyethylene oxide.

Claim 7

Dependent Claim 32 words

A medical electrode according to any of the preceding claims characterised in that the water soluble polymer has a weight average molecular weight of 0.5 × 10⁶ to 5 × 10⁶ Daltons.

Claim 8

Dependent Claim 23 words

A medical electrode according to any of the preceding claims characterised in that the hydrophilic gel contains immersed therein a low area-weight scrim.

Claim 9

Dependent Claim 29 words

A medical electrode according to any of the preceding claims characterised in that the electrolyte is a water soluble salt present in a concentration of 0.1 to 15 wt%.

Claim 10

Dependent Claim 17 words

A medical electrode according to claim 6 characterized in that the water soluble salt is magnesium acetate.

Claim 11

Independent Claim 107 words

A method for the production of skin interfacing member of a medical electode characterised in that it comprises the steps of subjecting a liquid film of an aqueous solution, having a viscosity of 2 × 10³ to 2,000 × 10³ cps, of an electrolyte and 2 to 35 wt% linear water soluble polymer which preferably has a weight average molecular weight of 0.05 × 10⁶ to 10 × 10⁶ Daltons to an amount of high energy radiation effective to convert the liquid film to a sheet of the viscoelastic adhesive solid and thereafter forming the thus produced film into a skin interfacing member of a medical electrode.

Claim 12

Independent Claim 107 words

A method for the production of skin interfacing member of a medical electode characterised in that it comprises the steps of subjecting a liquid film of an aqueous solution, having a viscosity of 2 × 10³ to 2,000 × 10³ cps, of an electrolyte and 2 to 35 wt% linear water soluble polymer which preferably has a weight average molecular weight of 0.05 × 10⁶ to 10 × 10⁶ Daltons to an amount of high energy radiation effective to convert the liquid film to a sheet of the viscoelastic adhesive solid and thereafter forming the thus produced film into a skin interfacing member of a medical electrode.

Claim 13

Independent Claim 28 words

A method of transmitting an electrical signal from the skin of a patient characterised in that it employs a medical electrode according to any of the preceding claims.

Claim 14

Independent Claim 27 words

A method of transmitting electrical energy to the skin of a patient characterised in that it employs a medical electrode according to any of the preceding claims.

Medical electrode

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