Sheet, wearable device, bioelectrode, laminate for adhesion, and adhesion method

Abstract

[Problem] To provide a sheet or the like that has a less pronounced feeling of use when adhered to skin. [Solution] One aspect of the present invention provides a sheet having an adhesion surface that is used facing skin, said sheet including an elastomer and a light scattering material.

Description

Sheet, wearable device, bioelectrode, laminate for application, and application method

[0001] The present invention relates to a sheet, a wearable device, a bioelectrode, an adhesive laminate, and an application method.

[0002] In recent years, there has been active development of wearable devices that can be attached to the skin. In this regard, materials that are highly compatible with the skin have also been studied. For example, Patent Document 1 discloses a substrate for a wearable device that has heat insulating properties and moisture permeability.

[0003] Japanese Patent Application Laid-Open No. 2022-53560

[0004] However, the prior art has a problem in that the sheet leaves a feeling of use when applied to the skin.

[0005] In view of the above circumstances, the present invention provides a sheet or the like that reduces the sensation of use when applied to the skin.

[0006] According to one aspect of the present invention, there is provided a sheet having an attachment surface to be used facing the skin, the sheet including an elastomer and a light-scattering material.

[0007] According to the above aspect, a sheet or the like is provided that reduces the sensation of use when applied to the skin.

[0008] FIG. 1 is a cross-sectional view showing a sheet of the present embodiment. FIG. 2 is a cross-sectional view of a wearable device to which the sheet 1 is applied. FIG. 3 is a cross-sectional view of a bioelectrode to which the sheet 1 is applied. FIG. 4 is a cross-sectional view of an adhesive laminate to which the sheet 1 is applied. FIG. 5 is a conceptual diagram showing an example of an adhesive method according to the present embodiment. FIG. 6 is a view showing measurement results of glossiness and color analysis of a bioelectrode. FIG. 7 is a view showing measurement results of the stretchability of a bioelectrode. FIG. 8 is a view showing the results of a study on the conductivity of a bioelectrode. FIG. 9 is a view showing the results when a film is attached to the skin. FIG. 10 is a view showing the results of a sensory evaluation. FIG. 11 is a view showing the results of measuring electrooculography using a bioelectrode. FIG. 12 is a view showing the results of measuring myoelectric potential using a bioelectrode. FIG. 13 is a view showing the results of measuring brain potential using a bioelectrode.

[0009] Hereinafter, embodiments of the present invention will be described. Note that the various features shown in the following embodiments can be combined with each other. In addition, "~" in this specification means "above" through "below" unless otherwise specified.

[0010] The sheet of this embodiment is as follows: A sheet having an adhesive surface to be used facing the skin, the sheet including an elastomer and a light-scattering material. The layers constituting the sheet of this embodiment and uses thereof will be explained below with reference to the drawings as appropriate.

[0011] Fig. 1 is a cross-sectional view showing a sheet of this embodiment. The sheet 1 shown in Fig. 1 has an adhesive surface 11 that is used facing the skin. That is, the sheet 1 is used by being attached to the skin, but during use, the adhesive surface 11 of the sheet 1 may be attached to the skin, or the adhesive surface 11 may be attached to the skin via another layer. The sheet 1 shown in Fig. 1 also has an opposing surface 12 that faces the adhesive surface 11.

[0012] The thickness of this sheet 1 may be set appropriately depending on the application. On the other hand, since the sheet 1 is used by being attached to the skin as described above, it is preferable that the film thickness is set low. For example, the average film thickness of the sheet 1 may be 10 μm or less, 8 μm or less, 5 μm or less, or 3 μm or less. There is no particular lower limit to the average film thickness of the sheet 1, but an example is 100 nm or more.

[0013] The sheet 1 of this embodiment is characterized by containing an elastomer and a light-scattering material. Materials that can be contained in the sheet 1 will be described below.

[0014] Elastomer: In this embodiment, an elastomer refers to a polymeric substance having elasticity. This elastomer is typically a material that stretches when subjected to tension and returns to approximately its original length when the tension is released. Examples of this elastomer include hydrocarbon elastomers such as natural rubber, isoprene rubber, nitrile rubber (NBR), ethylene propylene rubber (EPDM), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), and styrene-butadiene-styrene (SBS) block polymers, as well as hydrogenated elastomers thereof; silicone elastomers; fluoroelastomers; urethane elastomers; acrylic elastomers; polyester elastomers; polyamide elastomers; and polyimide elastomers. These may be used alone or in combination. Alternatively, a composite elastomer in which two or more elastomers are chemically bonded may be used as the elastomer of this embodiment.

[0015] The elastomer of this embodiment may contain a heteroatom in its chemical structure. Here, the heteroatom is, for example, selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, and a halogen atom. To give a more typical example, the elastomer of this embodiment preferably has a chemical bond containing a heteroatom in its chemical structure. That is, the elastomer of this embodiment preferably has, in its chemical structure, one or more bonds selected from the group consisting of an ether bond, a sulfide bond, an ester bond, a thioester bond, an amide bond, and a urethane bond. Among these, from the viewpoints of high availability and ease of imparting durability to the sheet 1 obtained, it is preferable that the elastomer of this embodiment contains a urethane bond in its chemical structure.

[0016] Light-Scattering Material The light-scattering material contained in the sheet 1 is a material that scatters light (changes the direction of travel of light) when light (particularly visible light) is incident on the sheet 1. By scattering light in this way, the presence of the sheet 1 becomes less noticeable when the sheet 1 is attached, and the feeling of use when attached to the skin can be reduced. Such a light-scattering material may be appropriately selected from known materials that can scatter light, and one example of a light-scattering material includes a metal oxide.

[0017] As the metal oxide, TiO ２ , SiO ２ , BaTiO ３ , ZnO, etc., but titanium oxide is preferred as the metal oxide because it is easily available and can scatter light efficiently.

[0018] Furthermore, the light-scattering material is preferably in a particulate form. This facilitates good dispersion within the sheet 1. More specifically, the light-scattering material may be particles whose particle diameter is controlled within a certain range. That is, the light-scattering material may be particles having a primary particle diameter of 5 nm or more, 8 nm or more, or 10 nm or more. By controlling the lower limit of the primary particle diameter of the light-scattering material in this manner, the appearance of the sheet 1 can be improved. The light-scattering material may be particles having a primary particle diameter of 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, 80 nm or less, or 50 nm or less. By controlling the upper limit of the primary particle diameter of the light-scattering material in this manner, the usability of the sheet 1 can be improved.

[0019] The content of the light-scattering material in the sheet 1 can be set as appropriate, but from the viewpoint of improving the balance between the appearance and mechanical properties of the sheet 1, it is preferably set in the range of 0.1 to 5 vol%, more preferably 0.3 to 4 vol%, and even more preferably 0.5 to 3 vol%, based on the total elastomer. It is also possible to add a known product containing a light-scattering material (e.g., a cosmetic product containing titanium oxide, such as foundation) to the elastomer. In this case, the amount of the light-scattering material to be added may be calculated based on the proportion of the light-scattering material contained in the product.

[0020] In addition, the sheet 1 may contain various other components within the scope of the present invention. Typically, the sheet 1 may further contain other components such as an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, a colorant, a release agent, a surface treatment agent, a flame retardant, and various fillers other than the above-mentioned components.

[0021] The sheet 1 can be obtained by mixing the various components described above and then forming the mixture into a sheet. The sheet forming method can be appropriately selected from known methods. Examples include spin coating, inflation, T-die, casting, calendaring, and extrusion.

[0022] The sheet 1 of this embodiment preferably has the following characteristics:

[0023] That is, when the adhesive surface 11 of the sheet 1 is attached to the skin and the gloss (Gloss Unit) of the surface (opposing surface 12) of the sheet 1 opposite the adhesive surface 11 is measured using a spectrophotometer at an incident angle of 60°, it is preferable that the measured value be 3.5 GU or less. By adopting such a configuration, the sheet 1 becomes less noticeable when attached to the skin.

[0024] This glossiness can be measured using, for example, a CM-26dG manufactured by Konica Minolta. The glossiness of the opposing surface 12 may be 3.2 GU or less, 3 GU or less, 2.8 GU or less, 2.5 GU or less, or 2.2 GU or less. By setting the glossiness within such a range, the above-described effects are more easily achieved. Meanwhile, the lower limit of the glossiness of the opposing surface 12 is not particularly limited, but an example is 1 GU or more.

[0025] In the above measurement, when the difference between the gloss (Gloss unit) of the facing surface 12 and the gloss (Gloss unit) of the skin to which the sheet is to be applied is calculated, the difference is preferably 2 GU or less, more preferably 1.8 GU or less, even more preferably 1.5 GU or less, particularly preferably 1.2 GU or less, even more preferably 1 GU or less, and particularly preferably 0.5 GU or less. By adopting such a configuration, the sheet 1 becomes even less noticeable when applied to the skin.

[0026] In the above measurement, when the ratio of the gloss (gloss unit) of the facing surface 12 to the gloss (gloss unit) of the skin to which the sheet is to be attached (gloss unit of facing surface 12 / gloss of skin) is calculated, it is preferably 2 or less, more preferably 1.8 or less, even more preferably 1.5 or less, particularly preferably 1.3 or less, and especially preferably 1.2 or less. By adopting such a configuration, the sheet 1 becomes even less noticeable when attached to the skin.

[0027] From another perspective, it is preferable that the coefficient of dynamic friction of the surface opposite to the attachment surface 11 (opposing surface 12), measured using a finger model tactile contactor under conditions of a load of 50 g, a sweep speed (measurement speed) of 10 mm / s, and a sweep distance (measurement distance) of 10 mm, be equal to or less than 1. By adopting such a configuration, the feeling of use when the sheet 1 is attached to the skin is further reduced.

[0028] This dynamic friction coefficient can be measured using, for example, a TL201 manufactured by Trinity Lab Co., Ltd. The "finger model tactile contactor" is a contactor with a hardness equivalent to that of a fingertip, with a measurement surface textured to resemble a fingerprint, and is available as a product of Trinity Lab Co., Ltd. The dynamic friction coefficient of the opposing surface 12 may be 0.9 or less, 0.8 or less, 0.7 or less, or 0.65 or less. Setting the value within these numerical ranges makes it easier to achieve the above-mentioned effects. Meanwhile, the lower limit of the dynamic friction coefficient of the opposing surface 12 is not particularly limited, but an example is 0.1 or more.

[0029] Next, the use of the sheet 1 will be described. Fig. 2 is a cross-sectional view of a wearable device to which the sheet 1 is applied. The wearable device 100 shown in Fig. 2 includes the sheet 1 and a device 2A attached to the sheet 1. The device 2A may be any of various electrical elements, such as a display, a transistor, a secondary battery, a solar cell, or various sensors.

[0030] As described above, the sheet 1 can be attached to the skin via the attachment surface 11. Therefore, the wearable device 100 shown in FIG. 2 can also be attached to the skin (worn on the skin) via the attachment surface 11 of the sheet 1. Note that although the wearable device 100 shown in FIG. 2 has a structure in which the device 2A is provided on the opposing surface 12, the location where the device 2A is attached is not limited to this. For example, the device 2A may be disposed on the attachment surface 11 side of the sheet 1, or the device 2A may be disposed within the membrane of the sheet 1. Note that when the device 2A is disposed on the attachment surface 11 side, it is sufficient that the sheet 1 be attached to the skin via an area of ​​the attachment surface 11 where the device 2A is not provided.

[0031] The sheet 1 of this embodiment may be used to form a bioelectrode. Fig. 3 is a cross-sectional view of the bioelectrode to which the sheet 1 is applied. The bioelectrode 150 shown in Fig. 3 includes the sheet 1 and an electrode 2B attached to the sheet 1.

[0032] The electrode 2B may contain a predetermined electrode material in its structure. The electrode material may be metal nanowires; carbon materials such as carbon black, carbon nanotubes, and graphene; or conductive organic materials. The electrode 2B may also be formed by dispersing these electrode materials in a predetermined binder. The binder used for the electrode 2B is preferably a highly flexible material, and the materials listed above as elastomers may be used.

[0033] The metal nanowires described above may be composed of various metals. Examples of metals that can form metal nanowires include gold, silver, copper, and titanium. When applying metal nanowires to the electrode 2B, it is preferable to perform a process to precipitate metal species between the metal nanowires so as to bond the metal nanowires together. Specifically, after obtaining a shaped object containing metal nanowires on the sheet 1, it is preferable to perform the following process. The shaped object here is typically formed by applying ink in which the metal nanowires are dispersed. That is, it is preferable to immerse the shaped object formed on the sheet 1 in a solution containing a metal salt, and then perform a process to reduce the metal salt. By performing this process, the metal salt is converted into a metal species that bonds the metal nanowires in the shaped object together. As a result, it becomes easier to obtain an electrode 2B with appropriate mechanical strength for use as a bioelectrode. In this specification, this process of bonding the metal nanowires together is sometimes referred to as a "welding process." Furthermore, the metal ions contained in the solution may be ions corresponding to the same metal as the metal constituting the metal nanowires, or ions corresponding to a metal different from the metal constituting the metal nanowires. Furthermore, prior to forming a shaped object by applying ink in which metal nanowires are dispersed onto the sheet 1, the sheet 1 may be subjected to a surface treatment. For example, the sheet 1 may be subjected to an oxidation treatment (O ２ The sheet 1 may be subjected to a plasma treatment, which may improve the polarity of the surface of the sheet 1.

[0034] The shape of the metal nanowires can be set as appropriate, but for example, the average diameter may be in the range of 10 to 100 nm, or in the range of 15 to 80 nm, and the average length of the metal nanowires may be in the range of 10 to 100 μm, or in the range of 15 to 80 μm.

[0035] The conductive organic material may include one or more organic materials selected from the group consisting of polythiophene, polypyrrole, polyaniline, and polybenzodifurandione.

[0036] The electrode 2B may be a patterned electrode. The patterning of the electrode 2B may be achieved by a known method. For example, a pattern may be formed by printing the above-mentioned electrode material by a predetermined printing method. Examples of the printing method include an inkjet method. Alternatively, a pattern may be formed by obtaining a shaped object containing metal nanowires and then subjecting the shaped object to an etching process or laser processing.

[0037] The thickness of the electrode 2B can be set as appropriate, but may be, for example, in the range of 10 nm to 10 μm. The thickness of the electrode 2B may be set depending on the type of electrode 2B, and when the electrode 2B is formed from the metal nanowires described above, the thickness is, for example, 0.1 μm to 1 μm. When the electrode 2B is formed from the carbon material described above, the thickness is, for example, 10 nm to 10 μm. When the electrode 2B is formed from the conductive organic material described above, the thickness is, for example, 10 nm to 10 μm.

[0038] As described above, the sheet 1 can be attached to the skin via the attachment surface 11. Therefore, the bioelectrode 150 shown in FIG. 3 can also be attached to the skin (worn on the skin) via the attachment surface 11 of the sheet 1. Note that although the bioelectrode 150 shown in FIG. 3 has a structure in which the electrode 2B is provided on the opposing surface 12, the location where the electrode 2B is attached is not limited to this. For example, the electrode 2B may be disposed on the attachment surface 11 side of the sheet 1, or the electrode 2B may be disposed within the membrane of the sheet 1. Note that when the electrode 2B is disposed on the attachment surface 11 side, it is sufficient that the sheet 1 be attached to the skin via a region of the attachment surface 11 where the electrode 2B is not provided.

[0039] By attaching the bioelectrode 150 to the skin in this manner, it is possible to acquire various biosignals from the subject to which the bioelectrode 150 is attached. Typically, the bioelectrode 150 can acquire (measure) biosignals such as an electrooculogram, an electrocardiogram, an electromyogram, an electrocutaneous potential, an electroencephalogram, and a heart rate.

[0040] Next, an adhesive laminate using the sheet 1 and an application method using this adhesive laminate will be described. FIG. 4 is a cross-sectional view of the adhesive laminate using the sheet 1. The adhesive laminate 200 shown in FIG. 4 comprises the sheet 1 and a release film 3 that is located on the opposite side of the adhesive surface 11 of the sheet 1 and is exposed to the outside. The adhesive laminate 200 shown in FIG. 4 is described as comprising a device 2A. In the adhesive laminate 200, an electrode 2B may be provided instead of or in addition to the device 2A. From this perspective, the adhesive laminate 200 may comprise a wearable device 100 that includes the sheet 1 as shown in FIG. 2 and a release film 3 that is located on the opposite side of the adhesive surface 11 of the sheet 1 and is exposed to the outside. Specific uses of such an adhesive laminate 200 will be described with reference to the drawings.

[0041] 4, a release film 3 is provided on the outermost layer to facilitate the application of the sheet 1. Such a release film 3 is usually removed after the application of the sheet 1 is completed.

[0042] The thickness of the release film 3 may be appropriately set depending on the ease of application, etc. For example, the average thickness of the release film 3 may be in the range of 1 to 50 μm, 3 to 40 μm, or 5 to 30 μm.

[0043] The release film 3 may be removed by various methods. In one embodiment, the release film 3 is mechanically peeled off after the application operation. Alternatively, the release film 3 may be dissolved and removed with a solvent (including water and organic solvents) after the application operation. The embodiment in which the release film 3 is removed with a solvent will be described in detail below.

[0044] That is, assuming a system in which the release film 3 is removed by water, the release film 3 may be an embodiment containing a water-soluble polymer. Such a water-soluble polymer may be appropriately selected from various materials. Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, etc. Among these, from the viewpoint of realizing high performance as the release film 3, it is preferable that the release film 3 contains polyvinyl alcohol (hereinafter sometimes abbreviated as PVA). Note that PVA here is generally obtained by saponifying polyvinyl acetate. Note that the degree of saponification can be appropriately set depending on the application, etc.

[0045] Next, a description will be given below of an application method using such an adhesive laminate 200. That is, the application method of this embodiment includes the steps of preparing the adhesive laminate 200, applying the sheet 1 while facing the application surface 11 of the sheet 1 to the skin of the application target, and removing the release film 3.

[0046] This application method will be described with reference to FIG. 5. FIG. 5 is a conceptual diagram illustrating an example of the application method according to this embodiment. First, the adhesive laminate 200 shown in FIG. 4 is prepared, and then the application surface 11 (the surface opposite to the side where the release film 3 is present) of the adhesive laminate 200 is applied to the skin SK (see FIG. 5( a)). Next, water-soaked fibers or the like (referred to as "water W" for convenience) are brought into contact with the release film 3 exposed on the surface (see FIG. 5( b)). As described above, if the release film 3 contains a water-soluble polymer, the release film 3 is dissolved and removed by the water W, resulting in the sheet 1 (wearable device 100) being applied to the skin SK (see FIG. 5( c)). This adhesive laminate 200 can also be used when applying a bioelectrode 150, which is a combination of the sheet 1 and an electrode 2B, to the skin.

[0047] Furthermore, it may be provided in the following aspects.

[0048] (1) A sheet having an adhesive surface that faces the skin, the sheet comprising an elastomer and a light-scattering material.

[0049] (2) The sheet according to (1) above, wherein when the adhesive surface of the sheet is attached to the skin and the gloss (Gloss Unit) of the surface of the sheet opposite the adhesive surface is measured using a spectrophotometer at an incident angle of 60°, the measured value is 3.5 GU or less.

[0050] (3) The sheet according to (1) or (2) above, wherein the coefficient of dynamic friction of the surface opposite the adhesive surface is 1 or less, as measured using a finger model tactile contactor under conditions of a load of 50 g, a sweep speed of 10 mm / s, and a sweep distance of 10 mm.

[0051] (4) The sheet according to any one of (1) to (3) above, wherein the average thickness is 10 μm or less.

[0052] (5) The sheet according to any one of (1) to (4) above, wherein the light-scattering material contains a metal oxide.

[0053] (6) The sheet according to (5) above, wherein the metal oxide is titanium oxide.

[0054] (7) The sheet according to any one of (1) to (6) above, wherein the light scattering material is particles having a primary particle size of 5 to 500 nm.

[0055] (8) A wearable device comprising the sheet described in any one of (1) to (7) above and a device attached to the sheet.

[0056] (9) A bioelectrode comprising the sheet according to any one of (1) to (7) above and an electrode attached to the sheet.

[0057] (10) The bioelectrode according to (9) above, wherein the electrode is a shaped object containing metal nanowires, and the metal nanowires are bonded to each other in the shaped object by metal species produced by a reduction treatment.

[0058] (11) A laminate for application, comprising a sheet according to any one of (1) to (7) above, and a release film on the opposite side of the sheet from the application surface, the release film being exposed to the outside.

[0059] (12) The adhesive laminate according to (11) above, wherein the release film contains PVA (polyvinyl alcohol).

[0060] (13) A method of application, comprising the steps of preparing the adhesive laminate described in (11) above, applying the sheet with the adhesive surface facing the skin of the application target, and removing the release film. Of course, the present invention is not limited to this.

[0061] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0062] [Materials Used] In this example, the following materials were used as the elastomer and light-scattering material. Elastomer: Hydrogenated styrene-based thermoplastic elastomer (SEBS; manufactured by Asahi Kasei Corporation, Tuftec (registered trademark) H1051) Light-scattering material 1: Titanium oxide "ST-01" (manufactured by Ishihara Sangyo Kaisha) Light-scattering material 2: Titanium oxide "ST-21" (manufactured by Ishihara Sangyo Kaisha) Light-scattering material 3: Titanium oxide "ST-31" (manufactured by Ishihara Sangyo Kaisha) Light-scattering material 4: Titanium oxide "ST-41" (manufactured by Ishihara Sangyo Kaisha) Light-scattering material 5: Titanium oxide "Sigma-Aldrich 637254-50G" (manufactured by Merck; anatase-type TiO with a primary particle size of 25 nm or less) ２ )

[0063] [Film Formation] First, a toluene solution of the above-mentioned elastomer (SEBS) was prepared. Next, a PVA layer was formed on an OTS-treated glass substrate, and the upper layer of the PVA layer (the surface opposite to the surface contacting the glass substrate) was spin-coated with a toluene solution of the elastomer, followed by annealing to obtain an elastomer / PVA / glass substrate laminate. The elastomer / PVA laminate was then peeled off from the glass substrate. In this example, it was confirmed that this laminate could be applied to human skin by contacting the elastomer with human skin and dissolving the PVA exposed on the surface with water. Furthermore, the gloss evaluation below was performed with the sheet attached to human skin. The film formation conditions for obtaining each SEBS film thickness were as shown in Table 1 below.

[0064]

[0065] [Evaluation 1 when using light-scattering material] Sheets containing light-scattering material were obtained by employing the conditions for forming a film of "300 nm" among the film-forming conditions described above, and further adding the light-scattering material shown below to the elastomer solution used. The amount of light-scattering material added was adjusted to 1 vol% relative to the total elastomer. Furthermore, the glossiness of the surface of each sheet was measured using a Konica Minolta CM-26dG spectrophotometer. The spectrophotometer was used under the conditions of an incident angle of 60°, and gloss units were measured as glossiness. The results are shown in Table 2. In this measurement, glossiness was also measured on skin without a sheet attached, and the measured value was "1.73 GU."

[0066]

[0067] When the state of the sheet attached to the skin was visually confirmed, the sheet was not noticeable when attached to the skin for Examples 1 to 5. In other words, by setting the gloss level as described above, it is possible to reduce the noticeable appearance when the sheet is worn.

[0068] [Evaluation 2 when using light-scattering material] A sheet was obtained by employing the conditions for forming a film of "300 nm" among the film-forming conditions described above, and further adding light-scattering material 5 to the elastomer solution used. The amount added here was also adjusted to 1 vol% relative to the total elastomer. The dynamic friction coefficient of this sheet was measured under conditions of a load of 50 g, a sweep speed of 10 mm / s, and a sweep distance of 10 mm. The dynamic friction coefficient was measured using a TL201 manufactured by Trinity Lab Co., Ltd.

[0069] As a result, the dynamic friction coefficient when the light-scattering material was added was 0.61. When a sheet was produced using SEBS without adding the light-scattering material, the dynamic friction coefficient of the sheet was 1.8, confirming that the dynamic friction coefficient decreases when the light-scattering material is added. From this, it is expected that the addition of the light-scattering material will reduce the feeling of use when the sheet is attached to the skin.

[0070] [Fabrication of Bioelectrode] In this example, a bioelectrode using a sheet was fabricated as follows. First, a toluene solution with the same composition as in Example 1 was prepared. A PVA layer was formed on an OTS-treated glass substrate, and a toluene solution of elastomer was spin-coated on the top layer of the PVA layer (the side opposite to the surface contacting the glass substrate). Annealing was then performed to obtain an elastomer / PVA / glass substrate laminate. The thickness of the elastomer layer was set to 200 nm.

[0071] Meanwhile, silver nanowire ink (AW030-μL, diameter: 25-35 nm, length: 40-60 μm, 1 wt % (solvent: isopropyl alcohol)) manufactured by Zhejiang KEC-Chuang High-Tech Materials Co., Ltd. (China) was prepared, and the silver nanowire ink was mixed with isopropyl alcohol in a ratio of 15 / 100 (v / v).

[0072] The outermost surface (elastomer layer) of the laminate was cleaned with a Tergeo plasma cleaner (50 W, 1 min, O ２ The elastomer was treated with a gas (5 sccm) and then spin-coated with diluted silver nanowire ink at 1000 rpm for 60 seconds. This formed a silver nanowire layer on the elastomer surface. The performance of the silver nanowire layer was improved by performing a welding process. Specifically, a 1 mM silver nitrate ethanol solution was spin-coated onto the formed silver nanowire layer, causing silver ions to float at the intersections of the silver nanowires. The silver ions were then reduced by dripping ascorbic acid, a reducing agent. The reduced and precipitated silver welded the intersections of the silver nanowires (bonding between the silver nanowires). This welding process was performed three times. The specific conditions for the welding process were as follows: dripping a 1 mM silver nitrate ethanol solution and spin-coating at 1000 rpm for 60 seconds; then dripping a 1 mM ascorbic acid ethanol solution and leaving it for 1 minute; and then spin-coating at 1000 rpm for 60 seconds. In the above example, this process was repeated three times, thereby forming a bioelectrode 1 having an electrode formed on the outermost layer.

[0073] [Bioelectrode Sheet Resistance] Regarding the above-mentioned bioelectrode 1, the specific influence of different silver nanowire concentrations on the electrode performance was investigated. As described above, in addition to the silver nanowire ink diluted to 15 / 100 (v / v), various bioelectrodes were fabricated by setting the dilution degrees of the silver nanowire ink to 20 / 100 (v / v), 25 / 100 (v / v), and 30 / 100 (v / v) (these were designated bioelectrodes 2 to 4). For each bioelectrode, the electrode was cut into a 76 × 52 mm ２ The sheet resistances measured for bioelectrodes 1 to 4 were 167.77 Ω / Sq, 111.57 Ω / Sq, 66.16 Ω / Sq, and 38.85 Ω / Sq, respectively.

[0074] [Glossiness of Bioelectrodes] Using a Bioskin Plate P001-001 manufactured by Beaulux, which has a color, roughness, and softness similar to human skin, the color and glossiness of the bioelectrodes 1 to 4 obtained above were measured. Specifically, after transferring the bioelectrodes 1 to 4 to the Bioskin Plate, the color and glossiness of the thin film surface were evaluated using a spectrophotometer CM-26dG manufactured by Konica Minolta. The difference in glossiness (ΔG) and color difference were obtained by comparing the measured value after the thin film was applied with the initial measured value without the thin film applied.

[0075] Figure 6 shows the gloss and color analysis results for bioelectrodes. In this measurement, color analysis was performed under different silver nanowire dilution conditions, with measurements divided into three RGB components: red, green, and blue. As shown in Figure 6, the values ​​for each color of bioelectrodes 1 to 4 changed as follows: red decreased by 0.17, 0.5, 1.03, and 1.04; green decreased by 0.3, 1, 1.17, and 1.29; and blue decreased by 0.18, 0.64, 0.51, and 0.45. Using the same experimental method, the gloss difference was 0.44, 0.46, 0.65, and 1.53, respectively.

[0076] [Stretchability of Bioelectrode] To measure the stretchability of the bioelectrode, the bioelectrode 1 on OTS glass was cut into small pieces measuring 10 mm x 5 mm and fixed to a measuring device with double-sided tape together with a thick SEBS layer obtained by the drop-cast method. A fine mist was sprayed from a spray bottle to dissolve the PVA layer on the top of the bioelectrode. The bioelectrode 1 was pulled in the longitudinal direction at a speed of 0.5 mm / s, and the stretchability of the bioelectrode 1 was measured using an LCR meter ZM2376 (manufactured by NF Corporation).

[0077] Figure 7 shows the results of measurements of the stretchability of the bioelectrode. The bioelectrode 1 fabricated under a dilution condition of 15 / 100 (v / v) maintained high stretchability of 60% or more, achieving performance exceeding that of human skin. Furthermore, even when stretched 40% under these conditions, the resistance value remained below 1000 Ω.

[0078] [Consideration of the conductivity of bioelectrodes] In this section, we investigated the conductivity of the bioelectrodes by using a TiO ２ The effect of adding TiO was investigated in detail. First, two OTS glass substrates were prepared, and PVA was spin-coated onto these substrates at 500 rpm for 60 seconds. Then, the substrates were annealed at 100°C for 3 minutes. After annealing, SEBS H1051 (toluene, 20 mg / ml) was applied to one substrate, and SEBS H1051 (20 mg / ml) and TiO were applied to the other substrate. ２ The substrates were spin-coated with a solution containing 1.5 vol% silver nanowires and annealed at 100°C for 30 minutes. Each substrate was then spin-coated with a 15 / 100 (v / v) diluted silver nanowire ink at 1000 rpm for 60 seconds, and then left to stand in a fume hood for 5 minutes to promote solvent evaporation. Three cycles of welding were then performed.

[0079] Fig. 8 shows the results of an investigation into the conductivity of bioelectrodes. ２ The sample containing TiO ２ The difference in the stretch rate was only 2% compared to the sample not containing TiO ２It was revealed that the welding treatment had almost no effect on the stretch rate of the sample containing the compound. Furthermore, under the same concentration conditions, the sample without welding treatment had a stretch rate of less than 20%, while the sample with welding treatment reached 60%. This result revealed that the welding treatment had a significant effect on the stretch rate of the sample.

[0080] [Evaluation of Bioelectrodes, etc.] Next, various evaluations of bioelectrodes, etc. were carried out. At the start of the experiment, the initial state of the skin of 20 volunteers was recorded in detail, and when a film (resin sheet or bioelectrode) was attached, the gloss value (CM-26dG manufactured by Konica Minolta), transepidermal water evaporation (Cutometer DUAL MPA580 manufactured by Integral), tactile sensation (TL201Tt manufactured by Trinity Lab), and epidermal temperature (N543 manufactured by Nikkiso Thermo) were measured in comparison with the initial state. Figure 9 shows the results when the film was attached to the skin. In this evaluation, five different types of film were evaluated. Specifically, PVA only, SEBS, and SEBS + TiO ２ , SEBS + TiO ２ In Figure 9, SEBS + TiO ２ The results for +AgNW are labeled "This work." Specifically, each film was prepared by coating on OTS glass. The film was peeled off from the OTS glass, and a tissue containing the PVA layer was placed over the film. The film was then placed on the skin of a volunteer. The film was carefully applied to ensure complete adhesion to the skin and no wrinkles or bubbles were formed. When evaluating a PVA-only film, the film was covered with the water-soaked tissue and most of the film was removed before the sensory evaluation. To prevent water from affecting the film's stealth properties, the film was allowed to dry for 10 minutes after transfer.

[0081] Thereafter, a series of sensory evaluations were conducted to evaluate the skin sensation after wearing the film. Here, the sensory evaluations were conducted according to the following items.

[0082] (1) Stealth Two to three volunteers worked together to carry out the following procedure. Environments with different light sources were designed, including natural light (D65 standard light source), room light, and strong light (using a flashlight). Under these three light sources, the volunteers located the film on the back of their own hand and the back of the other volunteer's hand, and evaluated the film's stealthiness. The stealthiness evaluation table was rated from 1 to 4 as follows: 1: Very visible 2: Somewhat visible 3: Slightly visible 4: Invisible Note that Figure 10 shows the evaluation results as "Invisibility Own Sensation" and "Invisibility Other's Sensation."

[0083] (2) Breathability Volunteers were asked to wear the film for 10 minutes, and the amount of transepidermal water evaporation from the skin to which the film was attached was measured using a TEWAMETER. This was compared with the initial data to determine whether the film had changed during wear. Then, the subject was evaluated for whether they felt a strong sense of stuffiness at the site where the film was worn. The breathability evaluation table was rated from 1 to 4 as follows: 1: Very bad 2: Bad 3: Good 4: Very good. Note that Figure 10 shows the evaluation results as "Breathability."

[0084] (3) Tactile Sensation Volunteers were instructed to lightly touch their own skin with their fingers. They touched the film and their skin to feel the difference between the two, and evaluated the tactile sensation of the film. After the volunteers evaluated the film attached to their own skin, they cooperated with other volunteers to touch the location of the film attached to the other volunteers and evaluated whether they could feel the difference in the tactile sensation between the film and bare skin. The tactile sensation evaluation table was rated from 1 to 4 as follows: 1: Different from skin 2: Slightly different from skin 3: Slightly different from skin 4: Same as skin Note that Figure 10 shows the evaluation results as "Tactile Own Sensation" and "Tactile Other's Sensation."

[0085] (4) Warm / Cold Sensation After measuring the temperature of bare skin using Nikkiso Thermo N543, a film was attached and measurements were taken at the same location, and any change in skin temperature with or without the film was recorded. After recording, a volunteer lightly touched the surface of the film three times. It was observed whether the film generated heat with slight friction. The warm / cold sensation evaluation table was rated from 1 to 4 as follows: 1: A clear change in temperature 2: A noticeable change in temperature 3: A slight change in temperature 4: No change in temperature Note that Figure 10 shows the evaluation results as "Warmth / Coldness Sensation."

[0086] Figure 10 shows the results of the sensory evaluation. The results revealed that the scores for "invisibility" were higher for others than for the volunteers. It is possible that the psychological effects of the volunteers influenced the evaluation.

[0087] [Application of Bioelectrodes to Biosignal Measurement] Finally, to confirm the applicability of the developed bioelectrode, we performed biosignal measurements. Specifically, we measured electrooculography, electromyography, and electroencephalography using the Miyuki Giken Polymate Pocket MP208. Electrooculography (EOG) records the position and movement of the eyeball by measuring the potential difference between the retina and cornea through electrodes placed around the eye. In such cases, bioelectrodes must be attached to the face, which can affect the subject's appearance and lead to resistance to wearing them. Furthermore, this can lead to psychological pressure due to privacy leaks, affecting the accuracy of measurement results. However, the bioelectrode of this example (bioelectrode 1) can solve these problems. Its low visibility and presence make it undetectable to the wearer, and it is undetectable to third parties. When designing the bioelectrode system, we used extremely thin copper connection wires covered with an insulating layer to connect the bioelectrode to the biosignal analysis device. To improve the connectivity between the connection wire and the bioelectrode (bioelectrode 1) and prevent signal noise contamination, the surface of bioelectrode 1 was coated with a 45 nm thick, 1 mm x 1 mm diameter wire. ２A gold electrode sheet was vapor-deposited onto the electrode. During the attachment process, the gold electrode sheet was covered over the copper connection wire. A computational filter was introduced to reduce noise and ensure clear signals during signal transmission and consistency. Figure 11 shows the results of electrooculography (EOG) measurements using a bioelectrode. Figure 11 also shows the relationship between the corneal position of the eye and the measured potential during writing. Furthermore, this example also collected other biosignals, such as electromyography (EMG) and electroencephalography (EEG). Figure 12 shows the results of electromyography measurements using a bioelectrode. Figure 13 shows the results of electroencephalography measurements using a bioelectrode. As these figures demonstrate, the bioelectrode of this example is expected to be applicable in a variety of fields.

[0088] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0089] 1: Sheet, 2A: Device, 2B: Electrode, 3: Release film, 11: Adhesive surface, 12: Opposing surface, 100: Wearable device, 150: Bioelectrode, 200: Adhesive laminate, SK: Skin, W: Water

Claims

1. A sheet having an application surface to be placed against the skin, the sheet comprising an elastomer and a light-scattering material.

2. A sheet according to claim 1, wherein when the adhesive surface of the sheet is attached to the skin and the gloss (Gloss Unit) of the surface of the sheet opposite the adhesive surface is measured using a spectrophotometer at an incident angle of 60°, the measured value is 3.5 GU or less.

3. A sheet according to claim 1 or 2, in which the dynamic friction coefficient of the surface opposite the attachment surface is 1 or less, measured using a finger model tactile contactor under conditions of a load of 50 g, a sweep speed of 10 mm / s, and a sweep distance of 10 mm.

4. The sheet according to any one of claims 1 to 3, wherein the average thickness is 10 μm or less.

5. A sheet according to any one of claims 1 to 4, wherein the light scattering material contains a metal oxide.

6. The sheet according to claim 5, wherein the metal oxide is titanium oxide.

7. A sheet according to any one of claims 1 to 6, wherein the light scattering material is particles having a primary particle size of 5 to 500 nm.

8. A wearable device comprising: a sheet according to any one of claims 1 to 7; and a device attached to the sheet.

9. A bioelectrode comprising: a sheet according to any one of claims 1 to 7; and an electrode attached to the sheet.

10. A bioelectrode according to claim 9, wherein the electrode is a shaped object containing metal nanowires, and within the shaped object, the metal nanowires are bonded to each other by metal species produced by a reduction treatment.

11. A laminate for application comprising: a sheet according to any one of claims 1 to 7; and a release film on the opposite side of the sheet to the application surface, the release film being exposed to the outside.

12. The adhesive laminate according to claim 11, wherein the release film contains PVA (polyvinyl alcohol).

13. A method of application comprising the steps of: preparing an application laminate as described in claim 11; applying the sheet with the application surface facing the skin to be applied; and removing the release film.

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