DE212013000177U1 - Device for measuring bioelectric signals, in particular signals picked up by electrodes - Google Patents

Abstract

Device for measuring bioelectric signals on a human head, in particular signals picked up by electrodes, the electrodes being fixed to one or more fixing elements, characterized in that the device is a holding device (1) comprising a central element (3 ) extending cranially medially on a head away from the beam-like element (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 the free end (5) of the electrodes (6, 6 ', 6' ', 6' '', 6 '' '') on the provided measuring point at least na hezu vertically impinge and - wherein the bending beam-like elements (2) only with the electrodes (6, 6 ', 6' ', 6' '', 6 '' '') touching the head.

Description

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 assemblies are necessary for attachment to a living being, which measure the bioelectric signals on the animal. Particularly designed electrodes, so-called "EEG electrodes" serve to measure brain waves, in particular of a human. They 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. 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, from the WO 2001/011857 A1 an electrode arrangement known. The holding means provided herein serve to attach the electrodes to the scalp of the subject, so as to attach the measuring electrode member 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 the WO 2007/109745 A2 is a headset known that can be placed on a head of a subject. The headset consists of a very complex constructed, made of hard plastic holder element on which electrodes can be attached in different locations. 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 also be made of soft material, in which case additionally clamping elements must be present in order to ensure the corresponding contact pressure of the electrodes on the scalp. However, the electrode headset has a very complex construction and represents a very high difficulty, in particular in the production, since the corresponding contact pressures, in particular at the ends of the arm-like elements, can not be provided, at least not permanently. 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 pointed out in this prior art that it is necessary to provide the 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.

From the DE 10 2010 005 551 is a sensor system for non-invasive detection of electromagnetic signals on the human body, especially described 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 for performing a correct measurement is usually not given.

Also from the WO 2006/096135 A1 a device for measuring brain activity is 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, since in particular it is necessary to arrange the electrodes spring loaded 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 serve to measure brain activity at rest under laboratory conditions, the holding devices known to date for receiving the electrodes and thus for measuring the EEG brain waves are not suitable for carrying out measurements at work or during leisure time.

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. The wearing comfort should be perceived as pleasant for the test person.

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 preferably round in cross-section.

However, they can also have other cross-sections, so that different bending moments are necessary in different directions in order to carry out 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 bending apart happens automatically when putting on.

Bend 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 shape of the head and regardless of a defined tolerance of the touchdown point, there is always a minimum value of contact pressure of the electrode on the scalp, so that an appropriate result can be achieved in the measurement of the electrode currents. The bending mold is designed such that even during the placement process, the electrode slides on the scalp until it has reached the appropriate position. It has reached the appropriate position when the central element rests on the head surface. Then only by appropriate back and forth "sliding" the exact position can be determined. This means that the bending beam-like elements provide the necessary contact pressure, so that the electrode itself can be made very small and can be easily inserted at the free ends of the tubular elements.

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. However, if brain waves are examined outside of laboratory conditions, preferably only slight additional simple fixing elements are to be arranged, which fix the 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 ensures a simple plugging.

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 produces a corresponding well-being 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, an additional holding force can be activated by tightening a tensioning element or by folding it over from a corresponding folding mechanism.

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. As a result, it is possible either to transmit the data via a very long mobile cable without corresponding losses, for example via a serial data interface, and to evaluate these via a corresponding interface and a computer unit or also to transmit them to an interface without any hiccups. 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 described above, the bending beam-like formations are designed like a cannula so that cables can be guided from the central element to the electrodes within the cannula. The electrodes are fixedly connected at the free ends and arranged there captive. In order to allow the appropriate contact with the skin, a porous foam material in the form of a cap is slipped over the electrode head. In order to produce the electrical contact between the skin and the electrode head, preferably the head-like element is impregnated with a solution, preferably potassium chloride solution. 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. For example, this drop can be drawn from a suitable 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, starting from a central element cantilever-like element as a holder device, the bending beam-like elements are placed distally on the head and already exert by the construction when placing the corresponding contact pressure on the surface of the head so that the corresponding contact of the at provided electrodes is provided with the skin.

The design of the bending beam-like elements allows to design electrodes of different types, so that an optimal recording of the brain waves is possible even with appropriate head movement of the subject without artifacts or other interference.

Further advantageous embodiments will become apparent from the following description, the claims and the drawings.

Drawings:

Show it:

1 a schematic perspective view of the inventive holding device;

2 a perspective view of the holding device mounted on a human head;

3 a side view of the holding device placed on a head according to 2 ;

4 another view of the holding device according to 2 ;

5 a rear view of the holding device according to 2 ;

6 a schematic representation of the holding device according to 1 for identification of the respective electrodes;

7 an enlarged view of the holding device, in particular for the representation of the central element of the holding device;

8th a schematic representation of the first embodiment of an electrode for in 1 to 7 illustrated embodiments of the holding device;

9 a second embodiment of an electrode for in 1 to 7 illustrated embodiments of the holding device;

10 a third embodiment of an electrode for in 1 to 7 illustrated embodiments of the holding device;

11 A fourth embodiment of an electrode for in 1 to 7 illustrated embodiments of the holding device.

Description of the embodiments

In the 1 to 6 is in perspective the inventive holding device 1 shown. The holding device 1 consists of a variety of cantilever-like elements 2 that is central to a central element 3 extend star-shaped away and are formed differently long depending on the corresponding position on the head. The one end 4 the respective bending beam-like element 2 is at the central element 3 fixed, whereas the other free end 5 with an electrode 6 is provided. The bending beam-like element 2 is preferably formed like a cannula, so that the electrical leads not shown in the drawings of the central element 3 to the free ends 5 or electrodes 6 are feasible.

The holding device 1 is placed cranially medially on the head of a subject, so that the central element 3 preferably arranged cranially medially (as explicitly in 5 shown). From here, the corresponding bending beam-like elements extend 2 to the respective measuring points or electrodes 6 to measure the brain waves generated in the brain.

Preferably, the free ends 5 bent to the head, so that already by the cranial medial touch down the bending beam-like elements 2 have to be spread. This advantageously the necessary contact pressure of the electrodes 6 reached at the head.

The corresponding position, as described above, reached and the central element 3 sits cranial medial on the skull, press the bending beam-like elements 2 to the respective measuring points of the skull.

Preferably, the bending beam-like elements 2 designed and dimensioned so that all electrodes 6 at the free ends 5 have the same contact pressure on the skull. This is achieved in particular by the fact that the bending beam-like elements 2 arcuate from the central element 3 extend away and preferably at free ends 5 are more bent, compared to the rest of the element.

By pointing from the head arch form a corresponding bias is generated, which affects in a contact pressure on the scalp. In particular, the last area of the free end 5 is more bent, which ensures that the free end, namely the electrode can lie flat on the scalp. A lateral tilting of the electrode is thereby excluded.

In terms of manufacture, the deflection beam-like element is for each discharge point on the head 2 exactly defined. The length of the central element 3 It must also be precisely tuned with respect to the corresponding pre-bend, so that a precise concern of the electrode at the discharge point can be made.

Only with the proper positioning of the holding device 1 the optimum contact pressure is provided at the respective electrodes. Advantageously, the subject or the one who places the device on the subject receives an optical or acoustic signal. Especially those on the nasal bone 15 attaching electrode 6 ¹⁵ shows the achievement of the proper position.

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

As a further development it is provided that the holding device 1 already a preamplifier and a corresponding analog-to-digital converter 9 includes. The entire "front-end electronics" is thus in the inventive holding device 1 accommodated. The thus on the electrodes 6 generated signals thus reach with minimal losses directly to the preamplifier and the corresponding analog-to-digital converter 9 so that they can then be digitally connected via a thin cable 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 6 and 7 is for example a cavity 16 represented in which the front-end electronics could be arranged.

In the 8th to 11 are different embodiments of electrodes 6 ' to 6 '''' shown. These electrodes 6 ' to 6 '''' can each be to the in the 1 to 7 illustrated embodiment of the holding device 1 Find application.

In 8th is one with the bending beam-like element 2 firmly connected electrode head 17 an electrode 6 ' shown. This electrode head 17 is Part of the bending beam-like element 2 and has a replaceable cap-like element 10 on the electrode head in the direction of the arrow 11 is pluggable. The cap-like element 10 is soft and porous and is preferably soaked with potassium chloride solution to increase the electrical conductivity between the on the outer wall 12 of the cap-like element 10 adjacent skin and the electrode head 17 manufacture. An isolated silver wire 13 extends within the cannula-like element 2 to the central element 3 (shown in the 1 to 7 )

The cap-like element 10 is interchangeable as needed and preferably biocompatible.

In 9 is a second embodiment of an embodiment of an electrode 6 '' for the inventive holding device according to the 1 to 7 shown. The electrode formation shown here is designed with regard to its electrochemical property such that it is a chlorinated silver wire 13 which is in a saturated potassium chloride solution 20 is arranged. So that the liquid is not within the hollow body in the bending beam-like elements 2 leaking, a gel becomes a seal 19 which is preferably a polymerized potassium chloride. This polymerized potassium chloride is a polyacrylamide filled with solid potassium chloride or a saturated potassium chloride solution. The silver wire is hermetically sealed approx. 1 cm behind the end of the cannulated element, whereby the closure is hydrophobic, so that the potassium chloride can not escape to the outside. The front part of the silver wire is stripped and galvanically chlorinated. This front part is with the previously described polymerized potassium chloride 20 completed.

Also here is provided, as in 8th illustrated cap-like element 10 impose impregnated with potassium chloride.

A significant advantage of these embodiments is that no set times must be calculated and also the "drifting" of the measurement result is avoided, which is additionally suppressed at sufficient concentration of the potassium chloride solution of the Anderson potential.

Another training provides that unlike 9 , in 10 the silver wire 13 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 13 is stripped and wrapped around the insulated cannula-like element, with the free end of the cannula-like element additionally with a stainless steel tube 18 is provided at least in the region of the electrodes. Subsequently, the free end of the cannula with a drop, at least one layer 21 made of silver or silver chloride. This drop can be drawn, for example, from a corresponding melt.

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

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 8th and 10 is proposed, provided, they can be used as wet electrodes. The latter show a much better contact in practice.

LIST OF REFERENCE NUMBERS

1, 1 '

holder

2

 bending beam-like elements

3

 central element

4

 free end

5

 free end

6

 electrode

6'-6 '' '' '

 electrode

6 ¹⁵

 electrode

7

 wire

8th

9

 Analog to digital converter

10

 cap-like element

11

 arrow

12

 outer wall

13

 silver wire

14

15

 nasal bone

16

 cavity

17

 electrode head

18

 stainless steel tube

19

 gel

20

 Potassium chloride solution

21

 layer

22

 canula-like element

23

 Silver epoxy layer

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2001/011857 A1 [0005]
• WO 2007/109745 A2 [0006]
• DE 102010005551 [0008]
• WO 2006/096135 A1 [0010]

Claims (6)

Device for measuring bioelectric signals on a human head, in particular signals picked up by electrodes, the electrodes being fixed to one or more fixing elements, characterized in that the device comprises a holding device ( 1 ), which is a central element ( 3 ), which extends cranially medially on a head from the cantilever-like elements ( 2 ), such that at the free ends of the respective electrodes ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) are fixed - whereby the bending beam-like elements ( 2 ) are cannulated and are pre-bent such that the electrodes ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) exert a contact pressure on the head, - whereby the bending beam-like elements ( 2 ) arcuately from the central unit ( 3 ) and to the free end ( 5 ) of the electrodes ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) impinge at the intended measuring point at least almost vertically and - wherein the bending beam-like elements ( 2 ) only with the electrodes ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) touch the head. Device according to claim 1, characterized in that the electrodes ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) Are wet electrodes. Device according to claim 1, characterized in that the electrodes ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) Are dry electrodes. Device according to one of the preceding claims, characterized in that the bending beam-like elements ( 2 ) are tubular, wherein in the tubular formation a silver wire ( 13 ) as a power line between the electrode and the central unit ( 3 ) is arranged. Device according to one of the preceding claims, characterized in that the free end of the bending beam-like element ( 2 ) through the electrode ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) is sealed. Device according to claim 5, characterized in that the free end of the electrode ( 6 . 6 ' . 6 '' . 6 ''' . 6 '''' ) is provided with a silver drop.

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