CONDUCTIVE PLASTIC STUD/EYELET WITH BASE HAVING AT LEAST ONE HOLE THEREIN

Abstract: A stud/eyelet (10) for a biomedical electrode is disclosed. The stud/eyelet (10) has at least one hole (18) in the base (12) to reduce manufacturing cost, provide increased surface contact with ionically conductive media, and to increase anchorage for the ionically conductive media.

Description: CONDUCTTVE PLASTIC STUD/EYELET WITH BASE HAVING AT LEAST ONE HOLE THEREIN Field ofthe Invention This invention relates to stud/eyelets for biomedical electrodes. Background ofthe Invention A stud/eyelet style biomedical monitoring electrode typically comprises a backing on which is coated a pressure sensitive adhesive to adhere the electrode to the skin and an ionically conductive gel or adhesive which serves as a bridge between the skin and an electronically conductive eyelet surface which is a planar disk-like component Attached to the eyelet and typically protruding through the backing is a post or stud which facilitates electrical connection ofthe electrode to the elctrocardigraph instrumentation. The stud/eyelet components may take two different forms. The first form is a "single-piece" construction where the stud and eyelet are molded together and inserted through the electrode backing. The second form is a "two-piece" construction where the stud and eyelet are mechanically assembled top and bottom through the backing during electrode manufacture. In certain procedures it is desirable that the stud/eyelet components be "radiolucent" - not obscuring the x-ray visualization ofthe tissue beneath them. In order to achieve radiolucency, the use of metal is avoided and either carbon- loaded conductive plastics or plastic articles overcoated with a thin layer of conductive metal are used. Carbon-loaded plastics can be expensive for electrode usage, resulting in a material cost of about one cent per electrode for 0.2 grams used in certain single piece constructions. Hence minimization of material use is desirable. A sponge or scrim is typically used to anchor the conductive gel or adhesive against the eyelet ensuring good electrical contact and preventing residue and transfer. Reliable adhesion ofthis sponge or scrim to the pressure sensitive adhesive ofthe backing may be difficult to achieve in the moist environment that the gel creates It also adds another component to the manufacture of an electrode increasing the cost Summary ofthe Invention The present invention provides an improved stud/eyelet that improves the means for securing the ionically conductive media (e.g., gel) that also reduces cost by eliminating components (e.g., sponge or scrim). For purposes ofthis invention, "stud/eyelet" can be either a two piece construction or a one piece construction. The present invention also provides an improved quality ofthe interface that the ionically conductive medium (gel or adhesive) forms with the stud/eyelet That interface is a major contributor to trace quality, because the interface of the electrode transduces ionic to electronic current The present invention also provides an improved electrode to recover from polarizing overloads Polarization occurs at the conductive media/eyelet interface when an extraneous external voltage is applied to the patient wearing the electrode (e.g , a defibrillation voltage) By increasing the contact area at the interface between conductive media and stud/eyelet, an electrode with improved trace quality and an ability to more rapidly and completely recover from polarization can be obtained One aspect ofthe invention comprises placing holes in the base of the stud/eyelet to reduce material costs while improving surface contact ofthe stud/eyelet with ionically conductive media in the biomedical electrode Advantages of the stud/eyelets ofthe present invention are 1) anchorage for conductive adhesives or gels that are cured against the stud/eyelets, 2) increased surface area of contact between the conductive gel and the stud/eyelet resulting in ii proved electrical performance, and 3) reduced use of materials in fabrication resulting in lower cost A further advantage is found in stud/eyelets where the eyelet comprises a conductive coating or plating, such that the holes provide an electrical connection between the face ofthe eyelet and the back ofthe base on the neck side ofthe stud/eyelet Another advantage is that the placement of an adhesive, such as a hot melt adhesive through holes in the stud/eyelet allows the stud/eyelet to be more securely anchored to a backing ofthe electrode, particularly if the holes are frustoconically shaped Thus, the invention includes a stud/eyelet for a biomedical electrode, comprising a base, a neck connected to the base, and a head connected to the neck, wherein the base has at least one hole therein. The invention also includes a biomedical electrode, comprising a nonconductive backing having an aperture, a stud/eyelet extending through the aperture wherein the stud/eyelet comprises a base, a neck connected to the base, and a head connected to the neck, wherein the base has at least one hole therein, and a field of conductive adhesive contacting the base Further features and advantages will become apparent from embodiments ofthe invention considered with reference to the following drawings Brief Description of Drawings Fig 1 illustrates a plan view of one embodiment ofthe stud/eyelet with holes in the base Fig 2 illustrates a top view ofthe embodiment of Fig 1 Fig. 3 illustrates a bottom view ofthe embodiment of Fig 1 Fig 4 illustrates a plan view of a second embodiment ofthe stud/eyelet Fig 5 illustrates a top view ofthe embodiment of Fig 4 Fig 6 illustrates a bottom view ofthe embodiment of Fig 4 Fig 7 illustrates a a plan view of a third embodiment ofthe stud/eyelet Fig 8 illustrates a top view ofthe embodiment of Fig 7 Fig 9 illustrates a bottom view ofthe embodiment of Fig 7 Fig 10 illustrates a plan view of a fourth embodiment ofthe stud/eyelet Fig 1 1 illustrates a top view ofthe embodiment of Fig. 10 Fig 12 illustrates a bottom view ofthe embodiment of Fig 10 Fig 13 illustrates a plan view of a fifth embodiment ofthe stud/eyelet Fig 14 illustrates a top view ofthe embodiment of Fig 13 Fig 15 illustrates a bottom view ofthe embodiment of Fig 13 Fig 16 illustrates a plan view of a sixth embodiment ofthe stud/eyelet Fig 17 illustrates a top view ofthe embodiment of Fig 16 Fig 18 illustrates a top view ofthe embodiment of Fig 16 Fig 19 is a cross-sectional view of a biomedical electrode Embodiments ofthe Invention Fig 1 shows a stud/eyelet 10 having a base 12, a neck 14, and a head 16 with a plurality of holes 18 extending through the base 12 Holes 18 are orthogonal to the bottom plane of base 12 and are of substantially constant diameter Figs 2 and 3 show the top view and bottom views, respectively, ofthis embodiment Fig 4 shows a stud/eyelet 30 having a base 32, a neck 34, and a head 36 with a plurality of holes 38 extending through the base 32 Holes 38 are orthogonal to the plane of base 32 and are of substantially constant diameter except for recesses extending on the top ofthe base 32 to the outer perimeter ofthe base 32 Figs 5 and 6 show the top view and bottom views, respectively, ofthis embodiment Fig 7 shows a stud/eyelet 50 having a base 52, a neck 54, and a head 56 with a plurality of holes 58 extending through the base 52 Holes 58 are orthogonal to the bottom plane of base 52 and are frustroconical in shape with the wider diameter adjacent the top plane ofthe base 52 Figs 8 and 9 show the top view and bottom views, respectively, ofthis embodiment Fig 10 shows a stud/eyelet 70 having a base 72, a neck 74, and a head 76 with a plurality of grooves 78 (i e , holes that contact the perimeter ofthe base 72) extending through the base 72 at the perimeter of base 72 Grooves 78 are orthogonal to the plane of base 72 and are frustroconical in shape with the wider diameter adjacent the top plane ofthe base 72 Figs 11 and 12 show the top view and bottom views, respectively, ofthis embodiment Fig 13 shows a stud/eyelet 90 having a base 92, a neck 94, and a head 96 with a stepped-back rim 98 extending from the top plane of base 92 adjacent neck 94 Figs 14 and 15 show the top view and bottom views, respectively, ofthis embodiment Fig 16 shows a stud/eyelet 1 10 having a base 1 12, a neck 1 14, and a head 1 16 with a stepped-back rim 1 18 extending from the top plane of base 112 adjacent neck 1 14 and also with a plurality of holes 128 extending through the base 1 12 Holes 128 are orthogonal to the bottom plane of base 1 12 and are of substantially constant diameter This embodiment combines the embodiments of Fig 1 and Fig 13 Figs 17 and 18 show the top view and bottom views, respectively, ofthis embodiment Each ofthe embodiments ofthe present invention can be combined with any other embodiment ofthe present invention in order to provide the advantages ofthe present invention described above The scope ofthe present invention is not limited to the embodiments or their combinations described herein The geometries of holes, grooves or rims can vary as needed For example, holes can be curved or angular Each ofthe six embodiments described and shown in the Figs 1-18 provides decreased use of expensive materials, increased surface area for contact with ionically conductive media, and increased sites of anchorage ofthe ionically conductive media By allowing the ionically conductive media to penetrate into those embodiments with holes during electrode manufacture, better interfacial contact results, yielding better electrical properties This penetration also provides anchorage ofthe gel against the eyelet, eliminating the need for a scrim or sponge Penetration may be facilitated by providing channels allowing for air to escape as illustrated in Fig 4 Certain conductive gels or adhesives may get better anchorage by being cured into holes which are wider at the top than the bottom as illustrated in Fig 7 Usefulness ofthe Invention Stud/eyelets ofthe present invention can be used in biomedical electrodes for a variety of purposes A typical biomedical electrode construction is shown in Fig 19 in cross-section Electrode 130 has a nonconductive backing 132 having an opening 133 though which stud/eyelet 134 (in the embodiment of Fig 1) protrudes to provide a point of electrical connection to biomedical instrumentation Covering stud/eyelet 134 and backing 132 is a field 136 of conductive adhesive A release liner 138 protects the field 136 prior to use Backing 132 can be made of any suitable insulator construction as disclosed in U S Pat No 5,012,810 (Strand et al) Eyelet 135 can be a plastic, metallic plated eyelet (such as an ABS plastic eyelet silver-plated and chlorided and commercially available from Micron Products of Fitchburg, MA or Select Engineering of Fitchburg, MA) For an additional appreciation ofthe scope ofthe invention, the claims follow

Claims: What is claimed is: 1. A stud/eyelet for a biomedical electrode, comprising: a base, a neck connected to the base, and a head connected to the neck, wherein the base has at least one hole therein. 2. The stud/eyelet of Claim 1, wherein each hole is of substantially constant diameter 3. The stud/eyelet of Claim 1, wherein each hole is frustroconical 4 The stud/eyelet of Claim 1, wherein each hole is angular 5 The stud/eyelet of Claim 1, wherein each hole is curved. 6 The stud/eyelet of Claim I , wherein at least one hole contacts a perimeter ofthe base to form a groove. 7 A biomedical electrode, comprising: a nonconductive backing having an aperture; a stud/eyelet of claims 1-6 extending through the aperture; and a field of conductive adhesive contacting the base. 8. The biomedical electrode of Claim 7, wherein at least one hole contacts a perimeter ofthe base to form a groove. 9. The biomedical electrode of Claim 7, wherein the stud/eyelet is secured to the backing using adhesive in at least one hole.

Inventors: CARIM HATIM M, KANTNER STEVEN S, CARIM, HATIM, M., KANTNER, STEVEN, S.
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1996
Main classification: A61B5
IPC codes: A61B5, A61N1