GB2341104A

GB2341104A - A medical electrode

Info

Publication number: GB2341104A
Application number: GB9920660A
Authority: GB
Inventors: Thomas Bassoe
Original assignee: Medicotest AS
Current assignee: Medicotest AS
Priority date: 1998-09-01
Filing date: 1999-09-01
Publication date: 2000-03-08
Anticipated expiration: 2019-09-01
Also published as: GB2341104B; GB9920660D0; DE29915267U1

Abstract

A medical electrode for picking up electrical signals from a person's skin comprises a carrier sheet 10 having an Ag/AgCl sensor 12 with a sponge 18 with an electrically conductive gel 19 in contact with the Ag/AgCl sensor 12 and a ring of adhesive foam material 16 with a skin-friendly adhesive around the sponge 13 with the gel 19. A web 11 of electrically conductive carbon based material electrically connects the sensor to an output. The carrier sheet of the electrode has an elongated shape with a relatively wide 22 end at the sensor and the adhesive foam material and a relatively narrow end 23 at the output, and the carrier sheet has a constriction 24 between the wide end and the narrow end. A removable protective sheet 20 with a cavity 21 to partially receive the porous material with the gel covers the electrode. The output may have a rivet or stud type connector 25.

Description

2341104 A medical electrode The invention relates to a medical electrode

for picking up electrical signals from a person's skin. Such elec- trodes are available in many variants and for use under many different conditions.

The present electrode is particularly useful for recording rest ECG. The invention will be described below with reference to the drawings, in which figure 1 is an exploded view of the structure of a first embodiment of electrodes according to the invention, figure 2 is an exploded view of the structure of a second embodiment of electrodes according to the invention, figure 3 is a schematic view of a carrier sheet with the various steps in the production of electrodes in the first and second embodiments of the invention, and figure 4 is a view of the carrier sheet of figure 3 seen from the opposite side and with additional steps in the production of electrodes in both embodiments of the in vention.

Figure 1 shows the structure of a tab electrode, while figure 2 shows the structure of a fitting electrode. The difference between the two embodiments will appear from the following.

The electrodes of figures 1 and 2 both have a carrier sheet 10 preferably of PET, whose one side has applied thereto an electrically conductive web 11 of carbon based material. one end of this web has applied thereto a layer of Ag/AgCl based material 12, which serves as a sensor 2 and is in electrical connection with the conductive web 11. The upper side of the carrier sheet 10 has applied thereto a layer of colour 13 which leaves an elongated window 14 through which the carbon based web 11 is vis ible, whereby the window 14 appears in black. The colour 13 is preferably selected to be other than black. A layer of foam material 16, preferably PE foam, is adhered to the carrier sheet and covers part of the conductor web 11 with the protective layer 15 between the foam layer 16 and the sheet. The protective layer may be a layer of lacquer or a separate double-adhesive sheet. The foam layer 16 has a layer of skin- friendly adhesive on the free side to attach the electrode to a person's skin. The foam layer 16 has a central circular opening 17 so that the foam layer does not cover the Ag/AgC1 sensor 12. The circular opening 17 accommodates a porous material 18, preferably a sponge of polyurethane foam on polyether basis, with a small amount of electrolytically conductive material 19, preferably a wet gel, which has been ab- sorbed by the sponge. The wet gel 19 gives good electrical contact with the person's skin. A protective sheet 20 having a circular cavity 21 covers the entire one side of the electrode, and the sponge 18 with gel is partly received in the cavity 21.

Figure 4 shows the carrier sheet of figure 3 seen from the opposite side, and is shown here die-cut ready for use. The die-cut electrodes have an elongated shape with a relatively wide, round end 22 at the sensor 12 and the adhesive foam material 16 and a relatively narrow, round end 23 opposite the wide end. The carrier sheet has two V-shaped notches 24 between the ends.

The foregoing is common to the tab electrode of figure 1 and the fitting electrode of figure 2.

3 In figures 2, 3 and 4, the fitting electrodes have a coupling head 25 formed by two metal parts 25a and 25b which are riveted together and make electrical contact with the conductor web 11. The metal part 25b of the rivet is covered by an electrically insulating protective sheet 28, which causes the rivet to be electrically insulated from the person's skin in use. The coupling head 25 mounts a contact device 26 with a duct 27 for the reception of a banana plug, from which the electrical signals are passed on to recording apparatus. The contact device 26 is described in greater detail in Danish Patent No. 150 841 corresponding to US Patent No. 4 865 566.

The electrical signals are passed from the tab electrodes to recording apparatus by a wire having a crocodile clip or the like which is clamped on to the free end of the conductor web 11 at the narrow end.

Figures 3 and 4 show a carrier sheet 10 having a row of tab electrodes to the left and a row of fitting electrodes to the right. In practice, either the one or the other type of electrodes will preferably be manufactured on the same carrier sheet.

The shape of the carrier sheet with a relatively wide end and a relatively narrow end with a constriction between these ends gives the electrode a good stability, so that any impacts in the form of pulls in the connected wire are transferred to the sensor of the electrode only to a limited extent, thereby obviating measuring errors and artifacts. The combination of a relatively small Ag/AgC1 sensor and a carbon based conductor web gives an economically attractive structure which also gives a reliable technical function.

4

Claims

CLAIMS:

1. A medical electrode for picking up electrical signals from a person's skin and comprising a carrier sheet hav ing an Ag/AgC1 sensor with a porous material with an electrically conductive gel in contact with the Ag/AgC1 sensor and a ring of adhesive foam material with a skinfriendly adhesive around the porous material with the gel, and having an output for connection to recording ap- paratus as well as a web of electrically conductive carbon based material which electrically connects the sensor to the output, wherein the carrier sheet of the electrode has an elongated shape with a relatively wide end at the sensor and the adhesive foam material and a relatively narrow end at the output, said carrier sheet having a constriction between the relatively wide end and the relatively narrow end, and a removable protective sheet with a cavity to partially receive the porous material with the gel.

2. A medical electrode according to claim 1, c h a r a c t e r i z e d in that the output is formed by a free end section of the web of carbon based material for the connection of an electrical wire with a crocodile clip, and that the electrically conductive gel is a wet gel.

3. A medical electrode according to claim 1, c h a r a c t e r i z e d in that the relatively narrow end is a ball head riveted on the carrier sheet so that the ball head is in electrical contact with the web of carbon based material.

4. A medical electrode substantially as herein described with reference to and as shown in Figs. 1, 3 and 4 or Figs. 2, 3 and 4 of the accompanying drawings.