Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
  • A61B5/25—Bioelectric electrodes therefor
  • A61B5/251—Means for maintaining electrode contact with the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
  • A61B5/25—Bioelectric electrodes therefor

Definitions

• a medical electrode A medical electrode
• the invention concerns a medical electrode for picking up electric signals from a person's skin.
• the electric signals to be picked up comprise ECG signals originating from the heart EEG signals originating from the brain, and EMG signals originating from nerve and muscle activity in the person etc.
• Such electrodes comprise a sensor for picking up the elec ⁇ tric signals, and the sensor is attached in electric con ⁇ nection with the person's skin. The attachment frequently takes place by adhering the sensor to the person's skin, a contact medium in the form of an electrically conducting gel or an electricly conducting adhesive being necessary between the sensor and the skin.
• Other electrode types have a sensor with a tip which pierces the upper layer of the skin to directly contact the intercellular fluid of the skin. Electric signals picked up are conveyed from the sensor via an electric conductor to an output terminal on the electrode.
• the output terminal may be in the form of an electric plug or the like.
• the electric signals picked up are weak, typically of the order of 1 mV or less, and if the sensor of the electrode moves with respect to the person's skin, this, as shown by experience, may give rise to artifacts or false signals, which may be considerably greater than the signals to be measured. It is therefore of great importance that the sensor of the electrode does not move during the measure ⁇ ment.
• An important cause of such movements of the sensor of the electrode is that the person moves. In bed-confined patients this problem is less pronounced, but in case of e.g. work medical and sport medical studies the person frequently performs very violent movements, and a tug at - 2 -
• an electrode wire can cause the above-mentioned artifacts and can possibly cause the electrode to be pulled of com ⁇ pletely.
• US 4 503 860 describes an electrode where the wire of the electrode is provided with means to attach the wire at a distance from the sensor, thereby relieving the conductor mechanically.
• the conductor is tight between the attach ⁇ ment point and the sensor, so that a tug at the electrode wire will be transferred to the sensor of the electrode and cause the above-mentioned artifacts.
• US 4 653 502 shows a medical electrode with associated ad ⁇ hesive elements for attaching the wire of the electrode at a distance from the sensor, thereby relieving the cable mechanically.
• this electrode has the same draw ⁇ back as mentioned above.
• US 3 547 104 likewise shows a medical electrode having means for relieving the wire of the electrode, the wire being attached to the person's skin at a distance from the sensor.
• a loop is formed between the sensor and the attachment point when the elec ⁇ trode is applied to the person's skin, so that movements at the attachment point are not transferred to the sensor.
• the electrode cable is an ordinary, flexible wire, and it is clear that the staff has to ensure that the electrode cable, when mounted, will have a sufficiently large loop that can compensate for the movements to which the attachment point is subjected owing to pulls at the elec ⁇ trode cable.
• the object of the invention is to provide a medical elec ⁇ trode having a built-in pull relief, and where movements at the attachment point are not transferred to the sensor of the electrode so that the electrode of the invention may be used for studying persons in motion, e.g. work and sports medical studies for picking up electric signals from the skin on a person's body or head.
• the wire of the electrode is given such a shape with bends that the wire has a length between the sensor and the attachment point of the electrode which is greater than the direct distance between the sensor and the attachment point and is thereby capable of permitting and compensating for mutual move ⁇ ments between the sensor and the attachment point, without such movements loading the sensor to cause the said arti ⁇ facts.
• fig. 1 shows an electrode according to the invention shown from the side which in use faces the person
• fig. 2 shows the electrode of fig. 1 in a stretched state
• fig. 3 is an exploded view of the electrode of fig. 1.
• the medical electrode in figs. 1 and 2 consists of a flex ⁇ ible carrier sheet 10 which is cut or punched from a web of a suitable plastics sheet so that the electrode gets the contour shown.
• the carrier sheet 10 has applied to it a web 11 of an electrically conducting material which ex ⁇ tends in the entire length of the carrier sheet.
• the con ⁇ ducting web is applied to the carrier sheet in a known manner, e.g. by silk screen printing with an electrically conducting paste containing silver particles.
• the conduct- ing web is wide at one end of the electrode so that it covers an end portion of the carrier sheet 10 in the entire width of the carrier sheet and forms a sensor 12.
• the sensor 12 is covered in a known manner by a contact medium in the form of a layer of a conducting adhesive 16 or a contact gel having at least the same extent as the sensor 12.
• the self-adhesive tape 13 is arranged such that the sensor 12 is disposed completely within the periphery of the self-adhesive tape 13.
• the self-adhesive tape 13 and the possibly adhering contact medium on the sensor 12 enable the sensor 12 of the electrode to be connected electrically with a person's skin in a known manner, so that electric signals may be picked up from the person's skin.
• the electric conductor web 11 is widened at the end of the electrode opposite the sensor 12 so that it here covers an end portion of the carrier sheet 10 in the entire width of the carrier sheet, thereby forming an output terminal 14.
• Electric signals, which have been picked up by the sensor 12 are conveyed by the electrically conducting web 11 to the output terminal 14 from which the electric signals may be picked up and passed on to measuring and recording equipment in a known manner.
• the conductor web 11 is covered by a layer of ensulating lacquer 18 between the sensor 12 and the output terminal 14, which lacquer 18 protects the conductor 11 electrically and mechanically, but does not prevent electric contact to the sensor 12 and the output terminal 14.
• the carrier sheet 10 On a portion of its length the carrier sheet 10 has an expansion 15, which here has an approximately square shape with rounded corners.
• the expansion 15 is provided with a layer of adhesive which is disposed over the entire sur ⁇ face of the expansion 15 and over part of the conductor web 11.
• the adhesive may be applied in a liquid form or may be a piece of soft self-adhesive tape 17 with adhesive on both sides.
• the electrode is supplied in the shape which is shown in fig. 1, and the adhesive faces of the tape 13 and the ex ⁇ pansion 15 are provided in a known manner with a protec- tive layer, which is removed before the electrode is used.
• the sensor 12 of the electrode is applied to the point or the person's skin where it is desired to pick up electric signals, and the expansion 15 is adhered to the person's skin at a distance from the sensor 12, so that the elec- trode has its relaxed or rest shape shown in fig. 1.
• the expansion 15 is attached to the person's skin by means of the adhesive on the expansion 15, and any load, e.g. in the form of pull forces from an electric wire connected to the output terminal 14, will hereby be transferred to the patient's skin, and the expansion 15 hereby serves as a mechanical relief of forces from the output terminal 14.
• the carrier sheet 10 of the elec ⁇ trode is punched or cut of a web of sheet, and the elec- trode is shown in fig. 1 in the position which it automa ⁇ tically assumes, and it will appreciated that the elec ⁇ trode is flat here and is positioned in a plane.
• the carrier sheet extends between the sensor 12 and the expan ⁇ sion or relief 15 as an elongate strip with an S-shaped course having three rectilinear portions 10a, 10c and lOe, which are interconnected in series by means of inter ⁇ mediate curved portions 10b and lOd.
• the recti ⁇ linear portions 10a, 10c and lOe are mutually parallel, and the curved portions 10b and lOd are semicircular. It is noted that at their respective transitions lOf, lOg to the portion of the carrier sheet 10 on which the piece of - 6 -
• the tape 13 is adhered and the relief 15, respectively, the rectilinear portions 10a and lOe form an obtuse angle with the longitudinal axis of the electrode, i.e. the angular change is less than 90°.
• the mentioned protective layers are removed from the tape 13 and the area of relief 15, and the sensor 12 is placed on the point where electric signals are to be picked up, and the area of relief 15 is likewise adhered to the skin.
• the electrode Owing to the S-shaped course of the carrier sheet between the sensor 12 and the relief 15, the electrode is capable of compensating for mutual movements between the sensor 12 and the relief 15. Such movements may be caused by pull forces transferred from a wire which is connected to the output terminal 14, and this pull will be absorbed com ⁇ pletely by the relief 15, since this is adhered to the person's skin.
• Fig. 2 shows the electrode in a state where the attachment point of the sensor 12 and the attachment point of the relief 15 have moved apart from each other, and the S-shaped carrier sheet of the electrode will then stretch to compensate for the mutual movement between sensor and relief.
• the electrode is also capable of compensating for a compression where the sensor 12 and the relief approach each other.
• the transitions lOf and lOg from the S-shaped portion of the carrier sheet to the carrier sheet near the sensor 12 and to the relief 15, respectively, constitute an angular change of less than 90°, so that obtuse angles are formed here.
• the deformation of the S-shaped carrier sheet of the electrode shown in fig. 2 is effective right up to the transitions lOf, lOg, which would not be the case if the transitions had formed right or even acute angles. Obtuse angles in the transitions cause the mate- rial to be less twisted and thus less loaded here, than if the angles were right or acute.
• the transitions lOf, lOg are here shown with abrupt bends having relatively small radia of curvature, but the radius of curvature may also be made larger.
• the S-shaped course of the carrier sheet is positioned within width limits corresponding to the width of the self-adhesive portion 13.
• the S-shaped bends will not overlap either and thus will not interfere with each other.
• the part of the carrier sheet which compensates for mutual movements of the sensor 12 and the relief 15 is shaped as a substantially rectilinear strip which is folded upon itself by one or preferably two folds.
• Such an embodiment has the same advantages for the user as the embodiment shwon, but it is more expensive to manufacture because of the necessity of folding operations which are avoided in the embodiment shown.
• the part of the elec- trode which compensates for mutual movements is shaped as a helical twist with just a few turns.
• This embodiment too, has the same advantages for the user as the embodi ⁇ ment shown, but also this is more expensive to manufac ⁇ ture.
• a plurality of electrodes may be combined to a set by using a common piece of self-adhesive tape of a suitable size instead of individual pieces of tape 13 for each individual electrode, so that the tape accomodates the desired number of sensors arranged at the desired dis- tance.
• the relief 15 may be provided as a through relief in such an embodiment, so that the relief hereby connects all the electrodes of the set.

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• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Medical Informatics (AREA)
• Biophysics (AREA)
• Pathology (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Physics & Mathematics (AREA)
• Molecular Biology (AREA)
• Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
• Electrotherapy Devices (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (1)

Citations (5)

• 1994
  • 1994-04-26 DK DK048194A patent/DK48194A/da not_active Application Discontinuation
• 1995
  • 1995-04-25 JP JP7527291A patent/JPH10503661A/ja active Pending
  • 1995-04-25 WO PCT/DK1995/000170 patent/WO1995028877A1/en active Application Filing
  • 1995-04-25 DE DE19581635T patent/DE19581635T1/de not_active Withdrawn
  • 1995-04-25 AU AU23433/95A patent/AU2343395A/en not_active Abandoned
• 1996
  • 1996-10-24 GB GB9622237A patent/GB2302286A/en not_active Withdrawn

Patent Citations (5)

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