WO2014020554A1

WO2014020554A1 - Device for measuring bioelectric signals, in particular signals recorded by electrodes

Info

Publication number: WO2014020554A1
Application number: PCT/IB2013/056286
Authority: WO
Inventors: Bernhard Wandernoth
Original assignee: Bernhard Wandernoth
Priority date: 2012-08-03
Filing date: 2013-07-31
Publication date: 2014-02-06
Also published as: DE212013000177U1; CH708652B1; CH706802A1

Abstract

A device for measuring bioelectric signals on a head of a human, in particular signals recorded by electrodes, wherein the electrodes are attached to one or more fixation elements, characterized in that the device is in the form of a holding device (1), which comprises a central element (3) which is cranially medially on a head and from which beam-like elements (2) extend away in such a way that electrodes (6, 6', 6'', 6''', 6'''') are fixed at the free ends of the respective beam-like elements, - wherein the beam-like elements (2) have a cannula-like design and are pre-bent in such a way that the electrodes (6, 6', 6'', 6''', 6'''') exert a contact pressure on the head, - wherein the beam-like elements (2) extend away from the central unit (3) in an arcuate manner and make contact with the head at least almost perpendicularly at the predetermined measurement point at the free end (5) of the electrodes (6, 6', 6'', 6''', 6'''') and - wherein the beam-like elements (2) only touch the head with the electrodes ( 6, 6', 6'', 6''', 6'''').

Description

Device for measuring bioelectric signals, in particular signals picked up by electrodes

Technical area

The invention relates to a device for measuring bioelectrical signals picked up by electrodes, the electrodes being attached to one or more fixing elements.

Background of the invention

Devices for the creation of electroencephalograms are known in many designs. For this purpose, electrode arrangements are suitable for

Attachment to a living being necessary to measure the bioelectric signals on the animal. Specially designed electrodes, so-called "EEG electrodes", are used to measure brain waves, in particular of a human, and are also known in various embodiments.

definitions

The term "EEG" is understood to mean electroencephalographies which are suitable for measuring, in particular, brain waves.

State of the art

The electrodes themselves are arranged in holders, which in turn are placed on a cap or a net-like structure on the subject's head become. Such caps or nets are often made of an elastic, preferably rubber-like material. The electrodes themselves are then fixed by clamping elements on this net-like structure. Such net-like structures, since they also contain metallic elements in particular, are perceived by the subject as very unpleasant, especially because they exert an increased pressure on the scalp. However, this increased pressure is necessary for the electrodes - preferably wet electrodes - to receive appropriate contact with the scalp. However, the pressure leads to possible obstruction of the circulation in the head and thereby the results obtained with the measurement can also be falsified. The attachment itself is done with a locally applied paste, cream or emulsion or a gel. This form is also perceived by the subject as very unpleasant.

For example, WO 2001/01 1857 A1 discloses an electrode arrangement. The holding means provided herein serve to secure the electrodes to the subject's scalp so as to provide the measurement

Attach electrode component fixed to the scalp at a defined location. The installation itself is very complex and complicated and requires a lengthy and time-consuming preparation phase.

From WO 2007/109745 A2 a headset is known, which can be arranged on a head of a subject. The headset consists of a very complex constructed, made of hard plastic holder element on which in

different defined locations electrodes can be attached. In this case, the headset is designed such that it extends away from the back of the head side arm-like to the head front and over the head holding elements, which are dimensioned such that when placing the headset, a corresponding contact pressure is present. The electrodes can preferably be clipped into holes provided at defined locations. Both dry and wet electrodes can be used. Alternatively, the electrode headset can be made of soft material, in which case additionally clamping elements must be present in order to ensure appropriate contact pressure of the electrodes on the scalp. The electrode headset, however, has a very complex structure and represents a very high difficulty, in particular in the production, since the corresponding

Contact pressure, in particular at the ends of the arm-like elements not, at least not permanently, can be provided. A corresponding material fatigue, especially when using plastic can lead to incorrect or not meaningful results.

In order to ensure a corresponding contact pressure, it is also noted in this prior art that it is necessary that

To provide electrodes with a corresponding contact pressure. This is achieved by the fact that the electrodes are spring-loaded. This means that the contact pressure is not provided by the electrode headset itself, but by the electrodes themselves. The headset thus has only the function of holding the electrodes in the corresponding positions.

DE 10 2010 005 551 describes a sensor system for non-invasive detection of electromagnetic signals on the human body, in particular on the head. The corresponding measuring electrodes, which are each designed as a dry electrode and are coupled to a processing device, have a headset system in which centrally extending arm-like support arms extend away, each of which has an electrode disposed at its end. In addition, the device has centrally starting and side arms extending to the side, at the free end of centrally extending support arms wegerstrecken having at their free ends electrodes.

In the housing, the processing unit is arranged and it is preferably located in the central region of the top of the head. The arrangement, however, requires that the subject does not move, otherwise the electrodes may slip relative to their measurement point and so no useful result can be achieved. In addition, the arrangement has a great weight, which just leads to a slipping is quite possible. In addition, the necessary Contact pressure of the electrodes to perform a correct measurement usually not given.

Also from WO 2006/096135 A1 is a device for measuring the

Brain activity known. The device itself is cap-shaped. In the head center, a band extends from the back of the head to the forehead and from which further bands extend vertically away. At the respective ends of the bands electrodes are arranged, which are arranged spring-loaded. This system is very complex, especially since it is necessary to

Spring loaded to arrange electrodes at the free ends of the belt-like structure. For this purpose, it is necessary that the band-like structure has a high rigidity, so that the spring force can be exercised.

Since nowadays not only brainwave measurements are used to measure brain activity in the resting state under laboratory conditions, the holding devices known to date are suitable for receiving the electrodes and thus for

Measurement of EEG brain waves not to perform measurements at work or during leisure.

Object of the invention

The object of the invention is to provide a holding device for receiving the electrode and thus for carrying out measurements of brain waves, which is easy to produce and with little effort. Of the

Comfort should be perceived as comfortable for the subject.

Solution of the task

The solution of the problem is provided by the characterizing features of claim 1. Advantages of the invention

The essential idea of the invention is to provide a holding device which is simply placed on a subject's head without having to use any further fastening and fixing means. The holding device essentially comprises a central element, from which extend bending beam-like elements away, the free ends of each arrive at a head of a person to the plant. The bending beam-like elements are designed such that they rest with a defined contact pressure, regardless of the shape of the head on the surface of the head. The contact pressure is at least about 0.75 N in size.

In order to bring this contact pressure, which is necessary in particular to bring electrodes into contact with the surface of the head, it is provided that the respective star-shaped elements that form the center of the central element be specially designed. The special design is that they consist of a tubular hollow-walled body in the rule, which is specially shaped depending on the respective contact point on the head. The form provides that the one end in the central element fixed, that is fixed and immovable, with the free end extending like a beam to the contact point. In this case, this can assume a corresponding arc-shaped structure, so that either the free end tangentially to the head surface or perpendicular or almost perpendicular to the head surface comes to rest. The hollow-walled cantilever-like elements are thus in cross section

preferably round.

However, they can also have other cross sections, so that in

different directions different bending moments are necessary to perform corresponding deflections of the free ends. This also implies that different restoring forces are possible in different directions. The hollow-walled structure is therefore used to guide, starting from the central element within the cantilever-like element, electrical cables or the like, which are closed together with the electrodes arranged at a free end. The elements are designed so that it is not necessary to use a shielded cable. The tubular structure of the elements provides this shielding. Furthermore, this structure provides protection for the cable itself so that it is not accidentally destroyed. Preferably, the bending beam-like elements are metal tubes which are formed on its inside electrically insulating. They are usually made of spring steel-like material, so that when placing the fixture on the head, first the free ends must be slightly bent apart until they reach the appropriate attachment to the defined points. The

Bend apart happens automatically when putting on. Bending beam-like elements, which are formed as metal tubes, extending from a centrally located on the head central element, to the discharge point at the head, where the electrode attaches. In order for the electrode to be able to absorb the corresponding brain currents, a defined contact pressure of the electrode is necessary. Different Anpresstechniken are known from the prior art. In particular, in the way that the electrodes themselves are spring loaded. For this purpose, it is necessary that the arrangement on which the electrode is arranged, is designed so stiff that no bending takes place due to the contact pressure and the contact pressure is actually applied to the scalp. Compared to the prior art, the present invention takes a different approach. The electrode is located immediately at the free end of the tube and can be considered as an integral part of the tube. The metal tube itself is preferably made of a resilient material and fixed to the central element. By a corresponding bending shape, the bending beam-like element is designed such that at its free end, regardless of the head shape, always a certain contact pressure, which exceeds a certain size, is present. This ensures that regardless of the head shape and regardless of one defined tolerance of the touchdown point, there is always a minimum value of contact pressure of the electrode on the scalp, so that a proper result in the measurement of the electrode currents can be achieved. The

Bending form is designed such that already during the placement process, the electrode on the scalp long slides until it has reached the appropriate position. It has reached the appropriate position when the central element rests on the head surface. Then the precise position can only be determined by corresponding reciprocating carriages. "This means that the bending beam-like elements provide the necessary contact pressure so that the electrode itself can be made very small and simply inserted at the free ends of the tubular elements can be.

Due to the special design of the holding device, there is the advantage that fixing devices are not necessary if the subject is preferably examined under laboratory conditions. Will, however

Brain currents examined outside of laboratory conditions, preferably only minor additional simple fixing elements are to be arranged, which the

Fix holding device on the head immovably. The fixing elements, but only serve to fix the holding devices in place. They are not designed and also not necessary that the corresponding contact pressure of the electrodes is achieved with this fixing device. Marking elements dictate which orientation the holding device must have on the head in the distal arrangement. This is a simple one

Plugging guaranteed.

For the subject, the postponement of placing the holding device does not feel - as in comparison to the prior art - uncomfortable, but rather he feels this as a light head massage, which in turn

corresponding well-being produced in the subject. Thus, the invention provides that the bending beam-like elements are designed such that the contact pressure of the electrodes arranged at the free ends to the scalp is the same everywhere. Due to the low weight and small size of the electrodes, head movements that are intentionally or unintentionally exerted by the subject do not exhibit artifacts in the encephalogram.

A development may provide that at least one of the bending beam-like elements is designed such that it additionally has a corresponding holding force. This holding force can then be triggered only after placement distally on the head in the arrangement on the head by inducing a corresponding fixing movement. In addition, by tightening a clamping element or by folding over a corresponding

Folding mechanism an additional holding force can be activated.

Another essential advantage of a further development of the invention provides that both the preamplifier necessary for the electrodes and the analog-digital converter are already preferably arranged in the region of the central element. The so-called front-end electronics is thus already accommodated in the holding device, so that the signals recorded by the brain waves are not analog, as is the case in the prior art, but can already be transmitted digitally. This makes it possible, either over a very movable long cable without corresponding losses the data

For example, to transmit via a serial data interface and evaluate them via a corresponding interface and a computer unit or these also without a hitch to transfer to an interface. Thus, the interface has only the task of providing a galvanic isolation to the computer, which is necessary for an accurate measurement and on the other hand to adapt the data format accordingly. Thus, a conventional from the prior art simple and adapted for each individual case evaluation can be used.

The bending beam-like formations also allow different use of electrode heads, in particular of wet electrodes at the respective free ends. As already described above, the bending beam-like formations are formed like a cannula, so that within the cannula cable from the

Central element can be guided to the electrodes. The electrodes are fixedly connected at the free ends and arranged there captive. To allow the appropriate contact with the skin is a porous

Foam material in the form of a cap slipped over the electrode head. In order to establish the electrical contact between the skin and the electrode head, the head-like element is preferably with a solution, preferably

Potassium chloride solution soaked. The head is preferably soft and porous and thus gives a very pleasant contact on the skin.

So that the corresponding measurement result is little distorted, the inner wall of the cannula is isolated. An inner insulation can be done for example by paint or enamel.

An optimal electrode constellation with regard to the electrochemical properties envisages using a chlorinated silver wire which is in a saturated potassium chloride solution. So that the liquid does not leak, a gel is used, which has the formation of a polymerized potassium chloride.

Another embodiment provides for the electrode head to be designed in such a way that the silver wire guided in the cannula is adhesively bonded at the free end so that no liquid can enter the cannula. There, the silver wire is stripped and wrapped around the insulated cannula. Subsequently, the cannula end is coated with a drop of silver or silver chloride. This drop can be used for

Example be drawn from a corresponding melt. Preferably, the ends of the cannula are configured such that, at least over a defined distance, it is coated with a noble-ray tube.

Alternatively, it can also be provided that initially a silver-conductive adhesive is used, which is then coated by the silver or silver chloride droplet.

Thus, the invention provides, outgoing from a central element

bending beam-like element to form as a holder device, wherein the bending beam-like elements are placed distally on the head and exercise by the construction during placement already the corresponding contact pressure on the surface of the head so that the corresponding contact of the electrodes located at the free ends is provided with the skin. The formation of the bending beam-like elements allows for, electrodes

different design, so that an optimal recording of

Brain currents even with appropriate head movement of the subject without artifacts or other interference is possible. Further advantageous embodiments will become apparent from the following description, the claims and the drawings.

Drawings:

Show it:

Fig. 1 is a schematic perspective view of the

holding device according to the invention; Fig. 2 is a perspective view of the holding device

placed on a human head; Fig. 3 is a side view of the holding device mounted on a head according to FIG. 2;

4 shows a further view of the holding device according to FIG. 2;

5 is a rear view of the holding device according to FIG.

2;

Fig. 6 is a schematic representation of the holding device according to

Fig. 1 for identification of the respective electrodes;

7 is an enlarged view of the holding device,

in particular for the representation of the central element of the holding device;

Fig. 8 is a schematic representation of the first

Embodiment of an electrode for the embodiments of the holding device shown in Figures 1 to 7. Fig. 9 shows a second embodiment of an electrode for in

Fig. 1 to 7 illustrated embodiments of

Holder;

Fig. 1 0 a third embodiment of an electrode for in

Fig. 1 to 7 illustrated embodiments of

Holder;

Fig. 1 1 shows a fourth embodiment of an electrode for in

Fig. 1 to 7 illustrated embodiments of

Holder. Description of the embodiments

In FIGS. 1 to 6, the holding device 1 according to the invention is shown in perspective. The holding device 1 consists of a variety of

bending beam-like elements 2, which extend centrally from a central element 3 star-shaped away and are formed differently long depending on the corresponding position on the head. The one end 4 of the respective bending beam-like element 2 is fixedly arranged on the central element 3, whereas the other free end 5 is provided with an electrode 6. The bending beam-like element 2 is preferably formed like a cannula, so that the electric wires not shown in detail in the drawings of the central element 3 to the free ends 5 and 6 electrodes are feasible.

The holding device 1 is placed cranially medially on the head of a subject, so that the central element 3 is preferably arranged medially cranial (as explicitly shown in Fig. 5). From here extend the

corresponding bending beam-like elements 2 to the respective measuring points or electrodes 6 in order to measure the brain waves generated in the brain.

Preferably, the free ends 5 are bent toward the head, so that already by the cranial medial placement first the bending beam-like elements 2 must be spread. As a result, the necessary contact pressure of the electrodes 6 at the head is advantageously achieved.

If the corresponding position, as described above, achieved and the

Central element 3 sits on the cranial medial on the skull, pressing the bending beam-like elements 2 to the respective measuring points of the skull. Preferably, the bending beam-like elements 2 are designed and dimensioned such that all electrodes 6 at the free ends 5 the same

Have contact pressure on the skull. This is achieved in particular. that the bending beam-like elements 2 extend arcuately away from the central element 3 and are preferably bent more strongly at free ends 5, in comparison to the remaining part of the element. By pointing from the head bow shape is a corresponding

Pretension generated, which affects in a contact pressure on the scalp. In particular, the last region of the free end 5 is bent more strongly, whereby it is achieved that the free end, namely the electrode can lie flat on the scalp. A lateral tilting of the electrode is thereby excluded.

With regard to the production, the bending beam-like element 2 is precisely defined for each discharge point on the head. The length of the central element 3 must also already be precisely matched with respect to the corresponding pre-bend so that a precise contact of the electrode can be made at the discharge point.

Only with the proper positioning of the holding device 1, the optimum contact pressure at the respective electrodes is provided. Advantageously, the subject or the one who places the device on the subject receives an optical or acoustic signal. In particular, the nasenbein 1 5 applying electrode 6 ^{1 5} shows the achievement of the appropriate position.

From the central element 3, the respective wires 7 guided in the cannulas, in this case preferably silver wires, are led to the corresponding measuring station (not shown here in detail).

As a further development, it is provided that the holding device 1 already comprises a preamplifier and a corresponding analog-to-digital converter 9. The entire "front-end electronics" is thus in the inventive

Holding device 1 housed. The thus generated at the electrodes 6

Signals thus arrive with minimal losses directly to the preamplifier and the corresponding analog-to-digital converter 9, so that they then digitally over thin cable can be connected in the formation of a data interface with an interface electronics. This interface electronics only has the task to provide the galvanic isolation between a computer provided for evaluation and to adapt the data format accordingly for the evaluation.

Alternatively, the data can be transmitted wirelessly. An appropriate power supply provides the necessary energy. In FIG. 6 and FIG. 7, for example, a cavity 1 6 is shown, in which the front-end electronics could be arranged.

Different embodiments of electrodes 6 'to 6 "" are shown in FIGS. 8 to 11. These electrodes 6 'to 6 "" can each be applied to the embodiment of the holding device 1 shown in FIGS. 1 to 7.

In Fig. 8 is a fixedly connected to the bending beam-like element 2

Electrode head 1 7 of an electrode 6 'shown. This electrode head 1 7 is part of the bending beam-like element 2 and has an exchangeable cap-like element 1 0, which can be plugged onto the electrode head in the direction of arrow 1 1. The cap-like element 10 is soft and porous and is preferably impregnated with potassium chloride solution in order to produce the electrical conductivity between the skin on the outer wall 1 2 of the cap-like element 10 and the electrode head 17. An isolated one

Silver wire 1 3 extends inside the cannula-like element 2 up to the central element 3 (shown in FIGS. 1 to 7),

The cap-like element 10 is interchangeable as required and preferably biocompatible. 9 shows a second exemplary embodiment of an embodiment of an electrode 6 '' for the holding device according to the invention as shown in FIGS 1 to 7. The electrode configuration shown here is designed with respect to its electrochemical property such that it has a chlorinated silver wire 1 3, which is arranged in a saturated potassium chloride solution 20. In order that the liquid does not leak within the hollow body into the bending beam-like elements 2, a gel 1 9, which is preferably a polymerized potassium chloride, is used for a sealing.This polymerized potassium chloride is a solidified polyacrylamide The silver wire is hermetically sealed about 1 cm behind the end of the cannulated element, whereby the occlusion is hydrophobic, so that the potassium chloride can not penetrate to the outside.The front part of the silver wire is abis polished and electrolytically chlorinated. This front part is completed with the previously described polymerized potassium chloride 20.

Again, it is envisaged, as shown in Fig. 8 cap-like element 1 0 impregnated soaked with potassium chloride. A major advantage of these embodiments is that no set times must be calculated and also the "drifting" of the measurement result is avoided, in addition to sufficient

Concentration of the potassium chloride solution of the Anderson potential is suppressed. A further embodiment provides that, in contrast to FIG. 9, in FIG. 10, the silver wire 1 3 is glued and insulated at the end of the cannula-like element

(Reference numeral 22), so that no liquid in the bending beam-like

Element 2 can penetrate. The free silver wire 1 3 is stripped and wound around the insulated cannula-like element, the free end of the

Canule-like element is additionally provided with a stainless steel tube 1 8 at least in the region of the electrodes. Subsequently, the free end of the cannula with a drop, at least with a layer 21 of silver or silver chloride overdrawn. For example, this drop may be from a corresponding one

Melt be pulled.

In contrast to FIG. 10, in FIG. 11, the embodiment provides that, instead of the drop of silver chloride, first of all a silver-epoxy layer 23 is used, which encloses the free end of the electrode. Subsequently, an enclosure with a layer 21 of a silver drop then takes place.

The basic idea of the invention is to use the electrodes in such a way that they can be used as dry electrodes. Will a corresponding coating, as in

Fig. 8 and 1 0 is proposed, provided, they can be used as wet electrodes. The latter show in practice a much better

Contact readiness.

E N G L I S H E S T E

1, 1 'holding device

2 cantilever-like elements

3 central element

4 free end

5 free ends

6 electrode

6 '- 6 ""' electrode

6 ¹⁵ electrode

7 wire

8th

9 analog-to-digital converter

10 cap-like element

11 arrow direction

12 outer wall

13 silver wire

14

15 nose bone

16 cavity

17 electrode head

18 stainless steel pipe

19 gel

20 potassium chloride solution

21 shift

22 canular element

23 silver epoxy layer

Claims

1 . Device for measuring bioelectric signals on a head of a

People, in particular signals, which are received by electrodes, wherein the electrodes are attached to one or more fixing elements, characterized in that the device is a holding device (1) comprising a central element (3), the cranial medial on a Head extending from the bending beam-like elements (2), such that at the free ends of the respective electrodes (6, 6 ', 6 ", 6"', 6 "") are fixed

wherein the bending beam-like elements (2) are formed like a cannula and are pre-bent such that the electrodes (6, 6 ', 6 ", 6"', 6 "") exert a contact pressure on the head,

wherein the bending beam-like elements (2) extend arcuately away from the central unit (3) and impinge at least approximately perpendicular to the free end (5) of the electrodes (6, 6 ', 6 ", 6"', 6 "") at the intended measuring point and

wherein the bending beam-like elements (2) only with the electrodes (6, 6 ', 6 ", 6"', 6 "") touch the head.

2. Apparatus according to claim 1, characterized in that the electrodes (6, 6 ', 6 ", 6"', 6 "") are wet electrodes.

3. A device according to claim 1, characterized in that the electrodes (6, 6 ', 6 ", 6"', 6 "") are dry electrodes.

4. Device according to one of the preceding claims, characterized in that the bending beam-like elements (2) are tubular, wherein in the tubular embodiment, a silver wire (1 3) is arranged as a power line between the electrode and the central unit (3). Device according to one of the preceding claims, characterized in that the free end of the bending beam-like element (2) by the electrode (6, 6 ', 6 ", 6"', 6 "") is sealed.

Apparatus according to claim 5, characterized in that the free end of the electrode (6, 6 ', 6 ", 6"', 6 "") is provided with a silver drop.