GB1299449A - Conductive gel pads - Google Patents

Abstract

1299449 Electrodes MINNESOTA MINING & MFG CO 17 Dec 1969 [18 Dec 1968] 61547/69 Heading A5R An electrically conductive pad for facilitating the transfer of electrical signals from the skin of a patient to an electrode is conformable to the surface of the patient's skin and. comprises a carrier having conductive hydrogel carried thereby, the hydrogel being lightly adherent to the skin but sufficiently cohesive to enable residue-free removal from the skin. The pad may comprise a porous matrix, of for example rayon, cotton, cellulose acetate, cheese-cloth, or plastics sponge or foam, impregnated with hydrogel which is exposed on opposed major surfaces of the matrix. Such pads may be sealed in impermeable envelopes separably connected together and wound on a roll. An alternative pad comprises a cavity 34 formed between an impermeable upper layer 18, of for example aluminium foil, and a release liner 24, the cavity 34 being filled with hydrogel 20 or with a porous web impregnated with hydrogel, the pad being secured to the skin by adhesive 22 around the edge of the pad after removal of the liner 24 and being connected to electrical apparatus by a wire 26. Alternative pads of similar form to that shown in Fig. 5 may be connected to an electrode by a wire or fastener (44), Fig. 6 (not shown), which contacts the hydrogel and extends to the exterior of the pad, or by a male conductive snap-fastener on the pad which engages a female fastener on the electrode, Fig. 7 (not shown). The hydrogel may comprise a mixture of polyvinyl alcohol, sodium borate decahydrate, a fungicide and at least 70% by weight water, or a mixture of 1.8% by weight guar gum, 0.18% by weight sodium borate decahydrate and a solution of fungicide in water of 0.1% by weight fungicide concentration, or a mixture of 2.0% sodium chloride, a solution of agar in water of 1% by weight agar concentration, and a solution of fungicide in water of 0.1% by weight fungicide concentration.