Dry electrode for collecting sleep electroencephalogram signals

Abstract

The utility model discloses a dry electrode for collecting sleep electroencephalogram signals, and belongs to the technical field of medical instruments. The non-inductive wearing electroencephalogram signal acquisition dry electrode comprises a vacuum chuck, an ultra-soft elastic layer, a conductive slurry substrate layer and a conductive coating from top to bottom, the vacuum suction cup is of a cap-shaped structure. The ultra-soft elastic layer is arranged in the vacuum chuck and is used for fixing the conductive slurry substrate layer, and the conductive coating is coated on the conductive slurry substrate layer through printing or printing. According to the electrode, the key sealing effect can be achieved by filling pores with a very small amount of conductive paste, suction cup pressure is transmitted through large flexible deformation of the ultra-soft elastic layer, the conductive coating is tightly attached to the scalp, impedance between the electrode and the scalp is greatly reduced, and signal noise is reduced. And the electrodes printed by the stretchable conductive ink have excellent elastic deformation capability, so that the stability of signals in the test process is ensured. The whole electrode is made of flexible, light and thin materials to achieve non-inductive wearing, and is suitable for being used at night or during long-term monitoring.

Description

Technical Field

[0001] The utility model relates to a dry electrode for collecting sleep electroencephalogram signals, belongs to the technical field of medical equipment, and relates to the construction and preparation of a biological electrode. Background Art

[0002] The incidence of sleep disorders is increasing. According to data released by the WHO, the global sleep disorder rate is as high as 27%. Sleep staging is the basis for the diagnosis of sleep disorders. Clinically, sleep staging is mainly identified by EEG signals in the forehead, central and occipital regions recorded by polysomnography. At present, the acquisition of sleep EEG signals mainly uses gold cup electrodes and conductive paste, that is, the wet electrode method, which has the advantages of low impedance and stable signals, but poor wearing comfort and cumbersome scalp treatment before and after the test, which is not suitable for long-term monitoring. Dry electrodes include invasive electrodes and non-invasive electrodes. The former requires microneedles to penetrate the stratum corneum, with low impedance but increased risk of secondary infection. Non-invasive dry electrodes are often made of conductive rubber, metal or other conductive materials, in the shape of a multi-claw comb, which is more convenient to use, but has high impedance, and the electrode hardness is large, so it is not comfortable to wear and is not suitable for long-term monitoring. Summary of the invention

[0003] In order to overcome the problems of high impedance of existing dry electrodes, poor wearing comfort during long-term monitoring and insufficient signal stability, the utility model proposes a non-contact wearable EEG signal collection dry electrode.

[0004] The technical solution of the utility model: a non-contact wearable EEG signal collection dry electrode, the dry electrode comprises a vacuum suction cup and a test electrode, the test electrode comprises an ultra-soft elastic layer, a conductive slurry base layer and a conductive coating;

[0005] The vacuum suction cup adopts a cap-shaped structure, and the circular ring base at the bottom is used for coating a sealing layer.

[0006] The conductive paste base layer is fixed on the super-soft elastic layer, and the conductive coating comprises a core electrode area and a conductor area, and the core electrode area and the conductor area are coated on the conductive paste base layer by printing or printing.

[0007] Specifically, the vacuum chuck and the test electrode may be connected as one body or may be independent components.

[0008] Specifically, the vacuum suction cup layer is a cap-shaped structure, consisting of a truncated cone shell with a closed top and a circular ring base. The truncated cone shell and the circular ring base are integrally formed, with a thickness of 0.5~1.5 mm, an outer diameter of the circular ring base of 12~20 mm, a width of the circular ring base of 2~5 mm, a height of the truncated cone of 3~5 mm, and is made of silicone or thermoplastic elastomer (TPE), with a hardness of Shore A 30~50 and an adsorption force of 1~3N. When in use, apply a thin layer of conductive paste, EEG paste or EEG coupling agent as a sealant layer on the circular ring base with a thickness of 0.05~0.1mm, then stick the circular ring base to the forehead, center, and occipital area, press the suction cup with your hand to expel the air, and use the vacuum adsorption effect to firmly adsorb the suction cup on the scalp surface, and then press the test electrode on the skin.

[0009] The ultra-soft elastic layer is made of Ecoflex platinum-cured silicone or polyether polyurethane foam sponge. The hardness is Shore00 10 ~ 40, the thickness is 1~2mm, and the diameter is 8~12mm. It is bonded to the conductive paste base layer. When the suction cup layer is pressed to expel air, it will be squeezed and deformed greatly, so that the conductive coating below it fits the skin more closely.

[0010] The conductive paste base layer is a polymer material film with certain flexibility, specifically, the material film is medical grade polyethylene, polypropylene, polyvinyl alcohol, polyurethane film, with a thickness of 0.05~0.2mm, and has good adhesion to the conductive paste. Its size and shape are consistent with the conductive coating.

[0011] The conductive coating is coated on the conductive paste base layer by printing, printing, etc. through screen printing, dispensing machine, inkjet printer, brush coating machine, scraper coating machine, etc. The conductive paste is composed of conductive filler, water, binder and additives. The conductive filler is a mixture of one or more fillers selected from silver powder, graphene, carbon nanotubes, carbon black, poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonic acid) PEDOT / PSS, and the binder is a resin or a mixture of several resins selected from polyurethane, acrylic resin, and silicone resin that have greater elasticity after curing into a film. Additives include defoaming agents, dispersants, and leveling agents. The thickness of the conductive coating is 10~30 microns, and the square resistance is less than 50Ω / sq. The conductive coating includes a core electrode area that directly contacts the skin and a wire area for connecting an external measuring device, such as Figure 3 As shown in the figure, the core electrode area can be in any shape, such as round, square, rectangular, regular hexagon, etc., with an area of ​​60~200mm 2 The wire is 20~30mm long and 1~3mm wide. The core electrode area directly contacts the skin, the tail of the wire area is connected to the DuPont cold terminal, and the wire and the cold terminal are encapsulated except for the male pin. The encapsulation can be brushed with ecoflex, three-proof glue, etc., and then the DuPont male pin is connected to the external test line.

[0012] Beneficial effects of the utility model:

[0013] (1) A very small amount of conductive paste fills the gaps between the scalp, hair and suction cup, which plays a key sealing role and ensures that the air in the suction cup is completely expelled. The suction cup pressure is transmitted through the flexible large deformation of the ultra-soft elastic layer, so that the conductive coating can be tightly attached to the scalp, greatly reducing the impedance between the electrode and the scalp and reducing signal noise.

[0014] (2) The electrodes made of stretchable conductive paste have excellent elastic deformation ability, which ensures a close fit with the scalp. This deformation ability also ensures that the electrodes always fit closely with the skin during the test, ensuring signal stability.

[0015] (3) The thickness of the conductive paste base layer and the conductive coating is extremely small, and the ultra-soft elastic layer and the vacuum suction cup layer are very soft, making them non-conductive to wear and suitable for use at night or for long-term monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a schematic diagram of the structure of a dry electrode for collecting EEG signals without being worn.

[0017] Figure 2 It is a front view of the conductive paste base layer.

[0018] Figure 3 It is a top view of the conductive paste base layer.

[0019] Figure 4 is a front view of the conductive coating.

[0020] Figure 5 is a top view of the conductive coating.

[0021] Figure 6 It is a schematic diagram of electrode distribution in the process of using electrodes to monitor sleep EEG signals in an embodiment of the utility model.

[0022] In the figure, 1. vacuum suction cup layer; 2. ultra-soft elastic layer; 3. sealing layer; 4. conductive paste base layer; 5. conductive coating; 5-1. wire area; 5-2. DuPont cold terminal. DETAILED DESCRIPTION

[0023] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0024] In order to make the advantages of the embodiments of the utility model clearer, the advantages of the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the described embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Figure 1 The schematic diagram of the structure of a non-contact wearable EEG signal collection dry electrode is shown. In the figure, the non-contact wearable EEG signal collection dry electrode includes a vacuum suction cup 1 and a test electrode, and the test electrode includes an ultra-soft elastic layer 2, a conductive paste base layer 4 and a conductive coating 5; the vacuum suction cup 1 adopts a cap-shaped structure, and the circular ring base at the bottom is used to apply the sealing layer 3. The conductive paste base layer 4 is bonded to the ultra-soft elastic layer 2, and the conductive coating 5 includes a core electrode area and a wire area. The core electrode area and the wire area are coated on the conductive paste base layer 4 by printing or printing. The core electrode area adopts a circular shape, and the size and shape of the conductive paste base layer are consistent with the conductive coating.

[0026] The thickness of the conductive paste base layer 4 is 0.1 mm, the thickness of the conductive coating 5 is 20 μm, the square resistance is 10 Ω / sq, and the area of ​​the core electrode region is 100 mm 2 The wire length in the wire area is 25 mm and the width is 2 mm.

[0027] The conductive paste base layer 4 is made of medical grade polyethylene film; the conductive coating 5 is coated on the conductive paste base layer 4 with a metal-based conductive paste by an inkjet printer. The vacuum suction cup 1 is made of silicone with a hardness of Shore A 40 and an adsorption force of 2 N. The vacuum suction cup has a thickness of 1 mm and a height of 4 mm. The outer diameter of the ring base is 15 mm and the width is 3 mm. The super soft elastic layer is made of polyether polyurethane foam sponge. The hardness of the super soft elastic layer is Shore 00 25, the thickness is 1.5 mm, and the diameter is 10 mm.

[0028] The conductive paste formula used in this embodiment is: 40wt% micron silver powder, 40% deionized water, 15wt% water-based modified TPU resin, Shanghai Oudi carbon black dispersant OCD-314 (0.5wt%), BASF (Corning) water-based defoamer A10 (1wt%) and BYK-333 leveling agent (3.5wt%).

[0029] When in use, apply a thin layer of conductive paste on the base of the ring as a sealant layer 3 (such as Figure 1As shown in the figure, the thickness is 0.07mm. Place the test electrodes at the test points corresponding to the forehead, central and occipital test areas. Then stick the disc part on the skin below the test electrode. Press the suction cup with your hand to expel the air in it, and use the vacuum adsorption effect to firmly adsorb the suction cup on the scalp surface. The core electrode area directly contacts the skin, and the tail of the wire area is connected to the DuPont cold terminal 5-2 (as shown in the figure). Figure 5 As shown in the figure), the wire and the cold terminal except the male pin are packaged (as shown in the figure). Figure 5 As shown), the package is coated with three-proof glue, and then the DuPont male pin is connected to the external test line.

[0030] In order to detect the benefits of the dry electrode of this embodiment for monitoring sleep EEG signals, the inventors used a standard polysomnography (PSG) with four electrodes for testing, including the dry electrode of this embodiment, the gold cup electrode originally configured by PSG, the hydrogel electrode and the five-claw conductive polymer dry electrode provided by other laboratories. The original gold cup electrode and the other three electrodes were used to monitor the sleep status of healthy subjects simultaneously, that is, the original gold cup electrode was used to record the EEG (F3, C3, O1) signals of the left hemisphere of the subject's brain during sleep in each test, and the dry electrode, hydrogel electrode and five-claw polymer electrode of this embodiment respectively recorded the EEG (F4, C4, O2) signals of the right hemisphere of the subject's brain during sleep. The reference electrodes were all the contralateral mastoid (M1 / M2). The distribution of electrodes during the test was as follows: Figure 6 As shown, the signal acquisition process adopts conventional methods in the art.

[0031] The preparation of the conductive hydrogel used in this example refers to the following references: [1] Mao Jie, Dai Jingbo, Zhou Junhui, et al. Preparation and performance study of polyvinyl alcohol / ethylene glycol / graphene oxide / polyaniline conductive composite hydrogel [J]. Materials Reports, 2021, 35(24): 24172-24176.

[0032] The polyvinyl alcohol conductive hydrogel and its electrode were prepared with reference to the above literature. The specific steps were as follows: 1 g polyvinyl alcohol, 300 μL aniline, and 0.5 mL 3 mol / L HCl were added to a mixed solution of 9 mL H2O and ethylene glycol in a ratio of 1:1, heated at 90°C for 2 h, and cooled to 0°C. 0.765 g ammonium persulfate was dissolved in 1 mL deionized water and cooled to 0°C. After the two solutions were mixed, they were frozen at -20°C for 8 h and thawed at 25°C for 12 h to obtain the desired polyvinyl alcohol conductive hydrogel, which was directly attached to the scalp and tested after connecting the wires.

[0033] The conductive polymer used in this example was prepared according to the literature: [2]KIM T, PARK J, SOHN J, et al. Bioinspired, Highly Stretchable and Conductive Dry Adhesives Based on 1D-2DHybrid Carbon Nanocomposites for All-inone ECG Electrodes[J]. ACS Nano, 2016, 10(4): 4770-4778.

[0034] Doped conductive polymers and their electrodes were prepared with reference to the above literature: 7 g of polydimethylsiloxane (PDMS) (70 wt%), 1.5 g of carbon nanotubes and 1.5 g of graphene powder (15 wt%: 15 wt%) were pre-mixed manually, then placed in a stirrer and stirred and dispersed at a speed of 2,000 r / min for 5 min, PDMS curing agent (hydrogen-containing polydimethylsiloxane, with a mass ratio of 1:10 to PDMS) was added, and stirred again under the same conditions for 20 min. A 5-claw electrode was pressed into a film mold, fixed to the scalp with medical tape, and connected to the wire for measurement.

[0035] The experimental results are as follows:

[0036] (1) After the electrodes are connected, the test data displayed by the standard polysomnography monitor are recorded, and the impedances of the four electrodes in the monitored area are compared. The impedance of the dry electrode in this embodiment is the lowest, all less than 10 kΩ, the impedance of the original gold cup electrode is about 15 kΩ, the impedance of the hydrogel electrode and the five-claw polymer electrode exceeds 50 kΩ, and some samples even exceed 100 kΩ;

[0037] (2) After the test, the original gold cup electrode and the dry electrode provided in this embodiment had clear and stable signals with little noise. The signals remained stable during the 10-hour sleep experiment. The hydrogel electrode and the five-claw polymer electrode had large noise and unstable signals, and some of them were intermittently interrupted. The data stability of the hydrogel electrode dropped sharply after the test exceeded 1 hour, and the noise signal had interfered with the normal signal, making it impossible to extract and analyze the normal signal.

[0038] (3) The signals collected by the dry electrode of this embodiment and the standard gold cup electrode were respectively used for automatic sleep staging and compared with the manual labeling results. The average accuracy of the former on 5 healthy subjects was 86%, and the average accuracy of the original gold cup electrode was 84%. Due to data stability and wearing comfort issues, the hydrogel electrode and the five-claw polymer electrode could not complete all data collection and the accuracy could not be known.

[0039] (4) Subjective experience: the original gold cup electrode requires a large amount of conductive paste to be applied to the hair, and the hair needs to be washed immediately after the test. The other three electrodes do not require hair washing after the test. The main structure of the original gold cup electrode is made of metal material. Although it is small in size, it still has a strong foreign body sensation. The hydrogel electrode and the dry electrode of this embodiment are softer in material and comfortable to wear. The hydrogel electrode feels cool and slippery after wearing. The dry electrode of this embodiment is lighter in weight, has better fit, and is more comfortable. The five-claw conductive polymer electrode is large in size and hard, and is extremely uncomfortable to wear. Some subjects refused to wear it or asked to stop wearing it during the test.

Claims

1. A dry electrode for collecting sleep EEG signals, characterized in that: The dry electrode comprises a vacuum chuck and a test electrode, wherein the test electrode comprises an ultra-soft elastic layer, a conductive slurry base layer and a conductive coating; The vacuum suction cup adopts a cap-shaped structure, and the circular ring base at the bottom is used for coating the sealing layer; The conductive paste substrate layer is fixed on the ultra-soft elastic layer, and the conductive coating layer includes a core electrode area and a conductor area, and the core electrode area and the conductor area are coated on the conductive paste substrate layer by printing or printing; The thickness of the conductive paste base layer is 0.05~0.2 mm, the thickness of the conductive coating is 10~30 microns, the square resistance is less than 50Ω / sq, and the area of ​​the core electrode area is 60~200 mm 2 The wire length in the wire area is 20~30 mm and the width is 1~3 mm.

2. A dry electrode for collecting sleep EEG signals according to claim 1, characterized in that: The conductive paste base layer uses medical-grade polyethylene, polypropylene, polyvinyl alcohol, and polyurethane film; The conductive coating is coated on the conductive paste base layer by using metal-based, carbon-based or PEDOT:PSS conductive paste through screen printing, dispensing machine, inkjet printer, brush coating machine or doctor blade coating machine.

3. The dry electrode for collecting sleep EEG signals according to claim 1, characterized in that: The core electrode area is circular, square, rectangular or regular hexagonal.

4. A dry electrode for collecting sleep EEG signals according to any one of claims 1 to 3, characterized in that: The vacuum suction cup is made of silicone or TPE with a hardness of Shore A 30~50 and an adsorption force of 1~3 N. The thickness of the vacuum suction cup is 0.5~1.5 mm, the height is 3~5 mm, the outer diameter of the ring base is 12~20 mm, and the width of the ring base is 2~5 mm. The ultra-soft elastic layer is made of ecoflex or polyether polyurethane foam sponge, the hardness of the ultra-soft elastic layer is shore 00 10~40, the thickness is 1~2 mm, and the equivalent diameter is 8~12 mm.

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