FI119908B - Sensor for saturation of biological voltage variation especially for the shell shell - Google Patents

Description

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Biological tension sensor especially for the scalp

FIELD OF THE INVENTION

The invention relates to measuring sensors. In particular, the invention relates to a sensor used for measuring biological voltage fluctuations on the surface of a human or animal body.

BACKGROUND OF THE INVENTION

10 Measurement of biological voltage variations in tissues (eg, EEG, electroencephalography, cerebral electrical function, ECG cardiac electrical function) is performed by placing sensors on the skin (e.g. The voltage variation of the EEG depicting brain function is typically 5-250 pV and the frequency range 1-70 Hz. EEG 15 measurements are made both in hospital wards and increasingly outside the ward. Measurement at the EEG Research Department is carried out by specialized personnel who are trained to use both measuring instruments and positioning sensors so that they are in the correct position, have good contact (impedance is sufficiently low) and remain stationary during the measurement. This is done using a variety of fastening systems, tapes, straps, nets, caps or elastic adhesive bonding mass.

Outside of the EEG research department, the measurement is prepared and performed by less trained staff, using a smaller set of equipment and focusing on a smaller set of questions. These include e.g. monitoring of neurological patients (reduced consciousness, epileptic seizure and its treatment, etc.) 25 in hospital outpatient clinic, monitoring, in-patient, intensive care unit, monitoring of EEG operation during surgery; to determine the depth of anesthesia and other measurements using the EEG signal, including sleep recordings sleep depiction, etc. in a hospital, research laboratory or at home. Similar situations occur when performing other biosignals (ECGs, sleep measurements).

Often only a few (e.g. 1-4) EEG measurement channels are used in these measurements, corresponding to 2-4-6 measurement points on the scalp. Keeping the electrodes in place and good skin contact (low impedance) are also crucial in these measurements for successful long-term measurement. These properties are easy to achieve in the hairless area of the forehead where the electrode can be glued but difficult in the scalp. Applying cup-like electrodes to the scalp requires skin cleansing eg. grease and mechanical preparation, slight mechanical scrubbing to remove dry and dead skin layer (epidermis), positioning of hair away from measuring electrode and attaching and holding electrodes of adhesive measuring paste or rubber net or cap.

The simplest EEG measurements can be done with a single measurement channel (anesthesia monitoring) 5 using a disposable electrode (commercially available, e.g., GE / Datex Entropy Electrode, Aspect Medical System Electrode) applied to the patient's forehead. Dual-channel EEG can also be measured with adhesive disposable electrodes in the forehead area or the ear area (earlobe, bony area behind the ear, or mastoid). However, there are situations where wider EEG measurement of the forehead area would provide clinically important additional information (epilepsy, localized brain damage, sleep measurements) and / or artefacts of various sources causing the forehead. Similarly, whenever there are more than three measurement points, a wider electrode alignment than the aforementioned hairless areas is desirable.

At present, if desired, long-term EEG electrode placement on the scalp scalp area is used either to attach electrode cups with an adhesive paste to a diameter of about 10 mm or the like. colloidal glue applied to the hair. A shorter measurement can be accomplished with a custom-made electrode cap with electrode cups attached to a resilient base material.

At electrode placement, the hair is turned aside at each measurement point, the skin is scraped off to remove a dry layer of epidermis containing corneal cells, and the electrode is pressed into the skin to obtain the desired good electrode contact. Good and stable measuring contact is achieved with a silver-silver chloride (Ag-AgCl) coated electrode, e.g. a silver chloride-coated cup electrode.

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If the electrode contact becomes poor during the measurement, the signal will be interfered and in most cases the electrode will have to be removed and reattached. In practice, this often means removing and reattaching all the electrodes, since the mesh must be removed at the same time. The described procedure complication often results in having to confine themselves to a forehead electrode placement unless trained nurses are available to do the electrode placement, which is not possible during on-call time, for example at night.

One prior art solution is a spring electrode (Sleep Sense, USA, Spring EEG electrode # 5025), or virtually a steel wire spiral which is opened by a special tool 35 by mechanical stretching prior to insertion of the skin contact. When the opening mechanism is detached, the steel wires squeeze the hair vigorously and the electrode sticks to the hair. In this way, the electrode remains attached without rubber bands and glue. However, for the electrode, the skin is treated and the electrode paste is applied as in cup electrodes. If the electrode contact deteriorates, disconnect it. The scalp is then re-prepared and the electrode repositioned using a special tool.

SUMMARY OF THE INVENTION

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The object of the invention is to reduce the problematic situations caused by the poor skin contact of the electrodes and, thus, the difficult electrode repositioning and fixing procedures required.

The object of the invention is achieved by an electrode structure in which the actual contact surface of the measuring area / measuring surface facing the human or animal body surface, i.e. the skin, is designed so that it can be easily inserted through the hair layer between the scalp and its mechanical properties. skin to improve contact. The measuring surface 15 of the electrode consists of the contact surface of the electrode and the space between the pattern defined by the contact surface structures when the electrode is pressed against the skin. As the name implies, the contact surface of the electrode connects the sensor to the skin either directly through contact or through, for example, a electrically conductive and possibly adhesive substance, such as an electrode paste, cast on the skin / contact surface.

A measuring transducer according to the invention for measuring biological electrical voltages on the surface of a human or animal body, for example for measuring brain electrical activity (EEG) in the scalp or other signal in the hairy area, characterized in that the transducer has an intermittent space between and comprising up to 90% of the measuring surface, allowing the hair, hair, or other projections of the body surface to settle in said space.

The method of measuring biological electrical voltages according to the invention 30 is characterized by: providing such a sensor for measuring biological electrical voltages, positioning the sensor in contact with a skin or electrically conductive material cast on the skin, and rubbing the sensor against the skin to remove the skin contact surface and touch.

The electrode is reasonably simple in manufacturing and structure, inexpensive, suitable for attachment either by the tape / cap method or by adhesive-like electrode paste. The electrode can be exposed to functional skin contact without the use of tools. The electrode is also suitable for single use. The electrode is particularly suitable for EEG measurements, but it can also be used to measure other biological voltage variations such as cardiac electrical ECG, muscle electrical EMG, eye electrical EOG. The structures of the contact surface contained in the measuring surface of the electrode 5, and in particular the angular and peripheral portions thereof, create a scratching surface which, by moving the electrode, advantageously performs mechanical treatment of the skin surface layer without removing the electrode from skin contact.

In one embodiment of the invention, the electrode comprises a metal wire bent to an ellipse, 10 cylindrical or spiral in cross section, to which is attached a measuring cable of an EEG measuring device amplifier. A hospital staff member performing an EEG measurement places the electrode at the desired location on the scalp of the test hair. She drains the electrode paste from the gel soap and mechanically, using reciprocating motions, scratches the scalp with gentle pressure, pressing it against the skin. He secures the electrode with a flexible 15 strap. He determines the skin resistance of the electrode with the special EEG measuring device impedance measurement used. If it is worse than required by the device, he will repeat the scratching and perform other appropriate skin cleansing methods (including degreasing with a solvent such as alcohol) to reduce impedance. He then begins the EEG measurement.

In another embodiment of the invention, the electrode includes a collar portion surrounding the electrode to form a cup-like structure around the hollow metal portion of the electrode. A large amount of gel-like electrode paste is drained into the cup-like structure to maintain the quality of the measurement. The structure gradually directs the electrode paste into the measuring range to replace the drying and volatile gel-like electrode paste. In the embodiment 25, the electrode paste does not need to be repeatedly repeated, which requires special skill and can cause measurement artifact, but the once-drained material is sufficient for a long time, e.g., for long-term patient measurement of high quality. If the electrode is attached to an area where there is no hair or hair, it can be glued with an adhesive tissue (tape) passing over the electrode, in which case the electrode paste remains inside the hollow electrode structure and allows long-term measurement of the electrode paste in contact. The elastic structure of the cylindrical wire of the electrode and the uneven discontinuous surface of the skin allow it to be further rubbed with small reciprocal movements to further reduce the measurement resistance between the electrode and the skin. In one embodiment, the hospital or research and perform measurements that can be used to treat the patient.

PRESENTATION OF THE PATTERNS

The invention will now be described in more detail with reference to the accompanying figures. Figure 1 shows a first embodiment of the invention in which patient measurement of EEG is performed. Figure 2 illustrates another embodiment of the invention where long-term measurement is performed.

Figure 3 is a flowchart of a method for measuring biological electrical voltages with a measuring transducer according to the invention delivered to a hospital or other site.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Figure 1 shows a first preferred embodiment of an electrode according to the invention. In Figure 1, the EEG electrode (1) consists of, for example, a silver-plated or silver wire / ribbon or a metal chip (2) (e.g. 0.3-3.0 mm thick) twisted or machined into a 15-flattened round or oval or flattened cylindrical shape ( 20mm, depth 2-20mm, height 2-20mm). The total contact surface of the electrode is discontinuous and consists of a metal measuring surface and a portion between the measuring surface. The contact surface of the electrode contacts the skin, aligning it with the shape of the skin. The electrode is secured to the skin (3) by a flexible strap which holds it mechanically against the skin. Between the skin and the contact surface of the electrode 20 is an electrically conductive paste, or electrode paste (4). The skin surface layer is thus in contact with the electrode. The skin has been scraped with an electrode wire to reduce the measurement impedance at the start of the measurement.

The silver wire has a connector (10) and a conductor (11) attached to the EEG amplifier (12). 25 The signal produced by the amplifier is used in patient diagnostics.

The helical structure allows the electrode to settle between the hairs (5) and the electrode strands to reach the surface of the skin, forming a discontinuous contact surface of the electrode with respect to the skin.

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The measuring surface, i.e. the total area defined by the wires forming the contact surface and the "blank" areas between them, and within it, respectively, becomes sufficiently large when there is a sufficient number of threads. The total number of threads and their mutual distance (from the contact surface), either standardized or variable, determine the proportion of the contact surface 35 to the total measuring surface; if the threads in the contact surface are close to each other, the contact surface may comprise e.g. 90% of the total measuring surface, while increasing the thread spacing or reducing the number of threads while maintaining the length, the relative proportion of the contact surface will eventually decrease e.g. 50%, 30% or 25%.

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The spacing between the contact surfaces of the measuring surface allows the hair or skin of the scalp to be positioned so that the contact surface is positioned against the skin and said hair and hair are outside the contact surface. This solution is reducing impedance.

The electrode is mechanically robust so that it can be moved to perform an important mechanical treatment of the skin surface layer (epidermis) with small reciprocal movements, scratching the surface of the skin. The electrode measuring surface may have a straight, concave or convex shape according to the shape of the underlying skin or scalp. The cylindrical or spiral electrode structure is resilient 10, suitable for being under, e.g., a stretchable strap against the skin without causing pressure stress. The strap may be wide, pressing the entire electrode structure, or may have a protrusion, groove, pins, protrusions, or irregularities that attach the electrode to a stretchable strap or web of straps or an elastic cap, e.g., to the skin of the scalp. A glue-stiff electrode paste or colloidal adhesive 15 may also be applied over the electrode to cure the electrode and measuring surface to the skin when cured. If the electrode is placed in an area where there is no hair or hair, it can be fixed with an adhesive surface fabric (tape, elastic adhesive fabric, etc.) over the electrode.

The electrode material may be wire, chip or other metal-coated material 20 (artificial material such as plastic). The cylindrical, spiral, and concave or convex shape suitable for the unevenness of the measuring surface is achieved by making the electrode by twisting, bending, braiding, casting or otherwise mechanically molding. The twisted cylindrical shape makes the structure elastic, whereby the mechanical attachment of the electrode to the skin using stretchable straps, hats, tape, etc. is reliable, with the elastic structure resting evenly against the skin. The surface material is, for example, silver (Ag), the surface film of which is silver chloride (AgCl) and is therefore advantageous in measurement technology.

The measuring electrode is connected to the measuring electronics using a connector or wire. The measuring electrode may also be directly attached (integrated) to the measuring electronics or a part thereof directly attached to the patient's skin or scalp by the attachment methods described.

Figure 2 illustrates another preferred embodiment of the invention. In the figure, the material around the electrode cylinder (20) is, for example, a plastic collar (21) which forms a "cup" when the electrode is positioned against the scalp. The electrode is thus hollow and the electrode paste (22) drained into the "cup" 35 gradually contacts between the skin (23) and the electrode, preventing the skin electrode contact from drying and impedance deterioration during measurement. The dish-like hollow shape allows a large amount of pasta to be used, for example, for long-term measurement.

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The collar portion may be an integral part of the electrode or removable and reattached. In addition to plastic, the material of the collar member may be of other elastic electrode shape or metal film. The collar portion may be part of an electrode attachment system such as straps and a cap that presses the electrode against the skin. The collar then forms with the belt or cap 5 a more closed container in which the electrode paste is retained without evaporation. When the measuring electrode is placed in an area free of hair or hair, the corresponding vessel-like structure can be achieved by placing a larger adhesive surface tissue (tape, stretchable elastic fabric, etc.) over the cylindrical hollow discontinuous surface sensor which secures the electrode to the skin evaporates the electrode paste from the electrode and allows 10 long-term measurements. The attachment tip allows for the mass of the lower surface of the discontinuous elastic electrode to be rubbed against the skin, which is advantageous in reducing the measurement resistance of the skin surface layer.

Figure 3 shows a flow chart of a third preferred embodiment of the invention. Measuring electrodes 30 according to the invention are provided to a hospital or research facility. When care staff 15 wishes to perform patient measurement, measuring electrodes are placed on test subject 31. This is done as detailed in Figure 2 by positioning the electrode on the scalp and abrasion the skin. The method is characterized in that the fastening and quality assurance procedures described in Figure 2 are easy to learn and perform and inexpensive when using a measurement, e.g., in an emergency department where no trained personnel 20 are available to perform the measurement. In particular, the steps involved in using the invention to keep the impedance of the electrode low during measurement will make diagnostic examination with the described measurement electrode easier and more reliable than conventional techniques. This will improve the reliability and diagnostic quality of the result. The measuring signal 32 recorded through the measuring electrodes is used to monitor the condition of the patient or subject and to perform any treatment.

Claims (6)

A measuring transducer (1, 20) having a measuring surface including a space between the electrode contact surface and the structures of the contact surface for measuring biological electrical voltages on a human or animal body surface, for example brain electrode (EEG) activity on the scalp or other hairy area. the contact surface to be positioned against the body surface of the sensor is discontinuous, consisting of parallel longitudinal wire elements and comprises up to 90% of the 10 measurement surfaces, allowing hair (5), hair or other projections of the body surface to settle in said discontinuous space. Measuring sensor according to Claim 1, characterized in that it further comprises a collar part or an edge (21) which together form a vessel-like hollow structure and hold the electrode paste (4, 22) or gel inserted into the electrode in a cuplike manner and release it only to the measuring surface. The measuring sensor according to claim 1, characterized in that the contacting dimension of the measuring sensor 20 is additionally a width of 2-20mm, a length of 2-20mm, a height of 2-20mm suitable for application to the scalp or other skin, and the lower surface is shaped the measuring surface of the electrode may be straight or concave or convex to the surface of the skin or scalp to be measured. Measuring sensor according to Claim 1, characterized in that the surface of the measuring and contacting surface of the measuring sensor is also uneven in detail so that it can scratch the surface layer of the skin and thereby improve the measuring contact (impedance) during or later during measurement. but without breaking or damaging it. 30 Measuring sensor according to claim 1, characterized in that the top surface of the measuring sensor is further shaped to include means for receiving, for example, an elastic strap, a net, a hat, an adhesive cloth, a tape or an adhesive or curable elastic conductive material 35 mechanically on the scalp or skin. Λ% 5 Measuring sensor according to Claim 1, characterized in that the measuring sensor is further shaped in such a way that it can have a connector to which the measuring cable (11) is attached or can be directly connected to the measuring cable or measuring electronics (12).