Patent Description:
In medical institutions such as hospitals and clinics, nursing facilities, and homes, biosensors are used for measuring biological information, for example, electrocardiograms, pulse waves, electroencephalograms, myoelectricity, or the like. A biosensor includes a bioelectrode that contacts a living body to obtain biological information of a test subject. When measuring biological information, a biosensor is affixed to a skin of a test subject to cause the bioelectrode to contact the skin of the test subject. The biological information is measured by obtaining electrical signals related to biological information through the bioelectrode.

As such a biosensor, a biocompatible polymer substrate is disclosed that includes, for example, a polymer layer having an electrode on one surface, in which as the polymer layer, a layer constituted with dimethylvinyl-terminated dimethylsiloxane (DSDT) polymerized with tetramethyltetravinylcyclotetrasiloxane (TTC) by a predetermined ratio is used (see, e.g., Patent Document <NUM>).

In the biocompatible polymer substrate, the polymer layer is affixed to a skin of a person to cause the electrodes to detect a cardiac voltage signal from the skin of the person, and a module for data obtainment receives and records cardiac voltage signals.

Further related art can be found in <CIT> which describes a laminate for biosensor and method for producing laminate for biosensor, in <CIT> which describes a bioelectrode and biosignal measurement device, in <CIT> which describes a sheet for biological sensor and in <CIT> which describes a bioelectrode.

The present invention is defined by appended independent claim. The dependent claims describe optional features and distinct embodiments.

However, the biocompatible polymer substrate of Patent Document <NUM> is used by having the polymer layer affixed to the skin of the test subject; therefore, in some cases, the biocompatible polymer substrate is folded in the thickness direction, or depending on motion of the skin of the test subject, the biosensor may be pulled in a direction along the surface. Therefore, in the conventional biocompatible polymer substrate, there is a likelihood that the electrode is peeled off from a living body or the polymer layer. Also, due to the electrode being peeled off from the living body or the polymer layer, there is a likelihood that the electrical conductivity is not obtained stably.

One aspect of the present invention has an object to provide a biosensor that can suppress peeling of an adhesive layer formed on one side of an electrode from a biological surface on which the electrode is placed, and simultaneously, can hold the electrical conductivity.

According to one aspect of the present disclosure, a biosensor includes a pressure-sensitive adhesive layer to be affixed to a biological surface; an electrode arranged to be capable of contacting the biological surface on a side of the pressure-sensitive adhesive layer to be affixed to the biological surface; an electronic device configured to process a biological signal obtained via the electrode; and a circuit part connecting the electrode and the electronic device, wherein the electrode has a connecting surface connected to the circuit part on a side affixed to the biological surface.

According to one aspect of the present invention, a biosensor can suppress peeling of an adhesive layer provided on one side of an electrode from a biological surface on which the electrode is placed, and simultaneously, can hold the electrical conductivity.

In the following, embodiments according to the present invention will be described in detail. Note that in order to make the description easier to understand, the same elements throughout the drawings are assigned the same reference codes, and duplicate descriptions are omitted. Also, the scale of a member in the drawings may differ from an actual scale. In the present description, a three-dimensional orthogonal coordinate system having triaxial directions (X axis direction, Y axis direction, and Z axis direction) is used, and it is assumed that coordinates in a principal surface of an electrode are taken in the X axis direction and in the Y axis direction, and the height direction (thickness direction) corresponds to the Z axis direction. A direction from the bottom to the top of an electrode is referred to as the +Z axis direction and the opposite direction is referred to as the -Z axis direction. In the following description, for the sake of convenience of description, the +Z axis direction will be referred to as the upper side or the top, and the -Z axis direction will be referred to as the lower side or the bottom; however, these do not represent a universal vertical relationship. In the present specification, a tilde "~" indicating a numerical range is meant to include a lower limit and an upper limit that are given as numerical values before and after the tilde, unless otherwise noted.

A biosensor according to an embodiment will be described. In the present embodiment, as an example, a case will be described in which a patch-type biosensor is affixed to a living body to measure biometric information. Note that the living body here may include a human body (a person) and animals such as cattle, horses, pigs, chickens, dogs, cats, and the like. The biosensor is affixed to part of the living body (e.g., skin, scalp, forehead, etc.). The biosensor can be suitably used for living bodies, in particular for human bodies.

<FIG> is an exploded view illustrating a patch-type biosensor <NUM> according to an embodiment. <FIG> is a diagram illustrating a cross section in a completed state corresponding to a cross section viewed in the direction of arrows A-A in <FIG>. As illustrated in <FIG> and <FIG>, the patch-type biosensor <NUM> according to an embodiment includes a pressure-sensitive adhesive layer <NUM>, a base material layer <NUM>, circuit parts <NUM>, a substrate <NUM>, probes <NUM>, fixing tapes <NUM>, an electronic device <NUM>, a battery <NUM>, and a cover <NUM>, as major components. In the following, the respective members constituting the patch-type biosensor <NUM> will be described.

The patch-type biosensor <NUM> is a sheet-like member having a generally elliptic shape in plan view. The patch-type biosensor <NUM> is covered with the cover <NUM> on the top surface opposite to the bottom surface (a surface on the -Z direction side) that is to be affixed to a skin <NUM> of a living body. The bottom surface of the patch-type biosensor <NUM> is the affixing surface.

The circuit part <NUM> and the substrate <NUM> are mounted on the top surface of the base material layer <NUM>. Also, the probe <NUM> is provided in a state of being embedded in a pressure-sensitive adhesive layer 110A so as to be exposed from a bottom surface <NUM> of the pressure-sensitive adhesive layer <NUM>. The bottom surface <NUM> is the affixing surface of the patch-type biosensor <NUM>.

The pressure-sensitive adhesive layer <NUM> is a flat plate-shaped adhesive layer. The pressure-sensitive adhesive layer <NUM> is oriented to have its longitudinal direction extend in the X axis direction and its short direction extend in the Y axis direction. The pressure-sensitive adhesive layer <NUM> is supported by the base material layer <NUM>, and is affixed to a bottom surface <NUM> of the base material layer <NUM>.

As illustrated in <FIG>, the pressure-sensitive adhesive layer <NUM> has a top surface <NUM> and a bottom surface <NUM>. The top surface <NUM> and the bottom surface <NUM> are flat surfaces. The pressure-sensitive adhesive layer <NUM> is a layer with which the patch-type biosensor <NUM> contacts the living body. The bottom surface <NUM> has pressure-sensitive adhesiveness, and hence, can be affixed to the skin <NUM> of the living body. The bottom surface <NUM> is the bottom surface of the patch-type biosensor <NUM>, and can be affixed to a biological surface such as the skin <NUM>.

The material of the pressure-sensitive adhesive layer <NUM> is not limited in particular as long as being a material having pressure-sensitive adhesiveness, and a material having biocompatibility or the like may be enumerated. As the material of the pressure-sensitive adhesive layer <NUM>, an acryl-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, or the like may be enumerated. Favorably, an acryl-based pressure-sensitive adhesive may be recommended.

The acryl-based pressure-sensitive adhesive contains an acrylic polymer as the main component.

The acrylic polymer is a pressure-sensitive adhesive component. As the acrylic polymer, a polymer polymerized with a monomer component that contains (meth)acrylic ester such as isononyl acrylate, methoxyethyl acrylate, or the like as the main component, and contains a monomer copolymerizable with (meth)acrylic ester such as acrylic acid or the like as an optional component, can be used. The content of the main component among the monomer components is <NUM> mass% to <NUM> mass%, and the content of the optional component among the monomer components is <NUM> mass% to <NUM> mass%. As the acrylic polymer, for example, a (meth)acrylic ester-based polymer described in <CIT>, or the like can be used.

Favorably, the acryl-based pressure-sensitive adhesive further contains carboxylic acid ester.

The carboxylic acid ester contained in the acryl-based pressure-sensitive adhesive is a pressure-sensitive adhesiveness modifier that reduces the pressure-sensitive adhesiveness of the acrylic polymer, to modify the pressure-sensitive adhesiveness of the pressure-sensitive adhesive layer <NUM>. The carboxylic acid ester is a carboxylic acid ester compatible with an acrylic polymer.

Specifically, the carboxylic acid ester is tri-fatty acid glyceryl, as an example.

The content of carboxylic acid ester is, with respect to <NUM> parts by mass of the acrylic polymer, favorably <NUM> parts by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> parts by mass.

The acryl-based pressure-sensitive adhesive may contain a crosslinking agent as necessary. The crosslinking agent is a crosslinking component that crosslinks the acrylic polymer. As the crosslinking agent, a polyisocyanate compound, epoxy compound, melamine compound, peroxide compound, urea compound, metal alkoxide compound, metal chelate compound, metal salt compound, carbodiimide compound, oxazoline compound, aziridine compound, or amine compound, or the like may be enumerated. Any of these crosslinking agents may be used alone, or two or more may be used in combination. As the crosslinking agent, favorably, a polyisocyanate compound (polyfunctional isocyanate compound) may be recommended.

The content of crosslinking agent is, with respect to <NUM> parts by mass of the acrylic polymer, for example, favorably <NUM> parts by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> part by mass.

It is favorable that the pressure-sensitive adhesive layer <NUM> has an excellent biocompatibility. For example, when the pressure-sensitive adhesive layer <NUM> undergoes a keratin peeling test, the ratio of keratin-peeled area is favorably <NUM>% to <NUM>%, and more favorably <NUM>% to <NUM>%. As long as the ratio of keratin-peeled area is within a range of <NUM>% to <NUM>%, the load imposed on the skin <NUM> (see <FIG>) can be suppressed even if the pressure-sensitive adhesive layer <NUM> is affixed to the skin <NUM> (see FIG. Note that the keratin peeling test is measured by a method described in <CIT>.

The moisture permeability of the pressure-sensitive adhesive layer <NUM> is favorably greater than or equal to <NUM>/m<NUM>/day, more favorably greater than or equal to <NUM>/m<NUM>/day, and even more favorably greater than or equal to <NUM>,<NUM>/m<NUM>/day. As long as the moisture permeability of the pressure-sensitive adhesive layer <NUM> is greater than or equal to <NUM>/m<NUM>/day, the load imposed on the skin <NUM> (see <FIG>) can be suppressed even if the pressure-sensitive adhesive layer <NUM> is affixed to the skin <NUM> (see <FIG>) of the living body.

The pressure-sensitive adhesive layer <NUM> comes to have biocompatibility by satisfying at least one of the following requirements: the ratio of keratin-peeled area in the keratin peeling test is less than or equal to <NUM>%; and the moisture permeability is greater than or equal to <NUM>/m<NUM>/day. It is more favorable that the material of the pressure-sensitive adhesive layer <NUM> satisfies both of the requirements described above. This enables the pressure-sensitive adhesive layer <NUM> to have a higher biocompatibility more stably.

The thickness between the top surface <NUM> and bottom surface <NUM> of the pressure-sensitive adhesive layer <NUM> is favorably <NUM> to <NUM>. If the thickness of the pressure-sensitive adhesive layer <NUM> is within a range of <NUM> to <NUM>, the patch-type biosensor <NUM> can be made thinner, especially in a region other than the electronic device <NUM> in the patch-type biosensor <NUM>.

The base material layer <NUM> is a support layer that supports the pressure-sensitive adhesive layer <NUM>, and the pressure-sensitive adhesive layer <NUM> is bonded to the bottom surface <NUM> of the base material layer <NUM>. The circuit part <NUM> and the substrate <NUM> are arranged on the top surface of the base material layer <NUM>.

The base material layer <NUM> is a flat plate-shaped (sheet-like) member made of an insulator. The shape of the base material layer <NUM> in plan view is the same as the shape of the pressure-sensitive adhesive layer <NUM> in plan view, and these are stacked at aligned positions in plan view.

The base material layer <NUM> has the bottom surface <NUM> and a top surface <NUM>. The bottom surface <NUM> and the top surface <NUM> are flat surfaces. The bottom surface <NUM> contacts the top surface <NUM> of the pressure-sensitive adhesive layer <NUM> (by pressure-sensitive bonding). The base material layer <NUM> simply needs to be made of a flexible resin having moderate elasticity, flexibility, and toughness, and may be made of a thermoplastic resin, for example, a polyurethane-based resin, silicone-based resin, acryl-based resin, polystyrene-based resin, vinyl chloride-based resin, polyester-based resin, and the like.

The thickness of the base material layer <NUM> is favorably within a range of <NUM> to <NUM>, more favorably within a range of <NUM> to <NUM>, and even more favorably within a range of <NUM> to <NUM>.

The circuit part <NUM> includes a wire <NUM>, a frame <NUM>, and a substrate <NUM>, to connect the probe <NUM> to the electronic device <NUM>. The patch-type biosensor <NUM> includes two instances of such a circuit part <NUM>. The wire <NUM> and the frame <NUM> are provided on the top surface of the substrate <NUM>, and formed integrally. The wire <NUM> connects the frame <NUM> to the electronic device <NUM> and the battery <NUM>. Also, the circuit part <NUM> is connected to the probe <NUM> on a side (in the +Z axis direction) opposite to the side affixed to the surface of the skin <NUM>. Part of the circuit part <NUM> connected to the probe <NUM> is arranged on a side (in the +Z axis direction) opposite to the side of the probe <NUM> affixed to the surface of the skin <NUM>.

The wire <NUM> and the frame <NUM> can be made of copper, nickel, gold, an alloy of these, or the like. The thickness of the wire <NUM> and the frame <NUM> is favorably within a range of <NUM> to <NUM>, more favorably within a range of <NUM> to <NUM>, and even more favorably within a range of <NUM> to <NUM>.

Each of the two instances of the circuit part <NUM> is provided corresponding to two through holes <NUM> and <NUM> of the pressure-sensitive adhesive layer <NUM> and of the base material layer <NUM>, respectively. The wire <NUM> is connected to the electronic device <NUM> and a terminal 135A for the battery <NUM> via wires of the substrate <NUM>. The frame <NUM> is a rectangular loop-shaped conductive member larger than the opening of the through hole <NUM> of the base material layer <NUM>.

The substrate <NUM> has a shape substantially the same as that of the wire <NUM> and the frame <NUM> in plan view. Part of the substrate <NUM> on which the frame <NUM> is provided has a rectangular loop shape larger than the opening of the through hole <NUM> of the base material layer <NUM>. The frame <NUM> and the rectangular loop-shaped part of the substrate <NUM> on which the frame <NUM> is provided, are provided to surround the through hole <NUM> on the top surface of the base material layer <NUM>. The substrate <NUM> simply needs to be formed of an insulator material, and for example, a substrate or film formed of polyimide or the like can be used. The base material layer <NUM> has tackiness; therefore, the substrate <NUM> is fixed to the top surface of the base material layer <NUM>.

The substrate <NUM> is a substrate formed of an insulator material, to have the electronic device <NUM> and the battery <NUM> mounted, and provided on the top surface <NUM> of the base material layer <NUM>. The substrate <NUM> is fixed by the tackiness of the base material layer. As the substrate <NUM>, a substrate or film formed of polyimide or the like can be used, as an example. On the top surface of the substrate <NUM>, wires and the terminal 135A for the battery <NUM> are provided. The wires of the substrate <NUM> are connected to the electronic device <NUM> and the terminal 135A, and to the wire <NUM> of the circuit part <NUM>.

The probe <NUM> is provided in a state of being pushed into the inner walls of the through holes <NUM> and <NUM> by the pressure-sensitive adhesive layer 110A, from the top surface of the base material layer <NUM> (a surface on the +Z-axis direction side) around the through hole <NUM>, along the inner walls of the through holes <NUM> and <NUM>. As described above, the probe <NUM> is provided in a state of being embedded in the pressure-sensitive adhesive layer 110A so as to be exposed from the bottom surface <NUM> of the pressure-sensitive adhesive layer <NUM>, and arranged on a side of the pressure-sensitive adhesive layer <NUM> (in the -Z axis direction) so as to be capable of contacting the surface of the skin <NUM>. The probe <NUM> has exposed regions from which part of the probe <NUM> is exposed, on the side of the pressure-sensitive adhesive layer <NUM> (in the -Z axis direction) to be affixed to the skin <NUM>. When the pressure-sensitive adhesive layer <NUM> is affixed to the skin <NUM>, the probe <NUM> contacts the skin <NUM> to detect biological signals. The biological signal is, for example, an electrical signal representing an electrocardiographic waveform, electroencephalogram, pulse, or the like.

The probe <NUM> has a connecting surface <NUM> connected to the frame <NUM> of the circuit part <NUM> on the side (in the -Z axis direction) to be affixed to the biological surface, on the top surface (a surface in the +Z axis direction) of the frame <NUM> of the circuit part <NUM> positioned around the through hole <NUM> of the base material layer <NUM>. Note that the connecting surface <NUM> may be connected to both the wire <NUM> and the frame <NUM>.

The probe <NUM> is formed to have a rectangular shape in plan view, and has holes 140A arranged in a matrix that is larger than the respective through holes <NUM> and <NUM> of the pressure-sensitive adhesive layer <NUM> and of the base material layer <NUM>. At the ends (end parts of four sides) in the X direction and the Y direction of the probe <NUM>, the ladder-like sides of the probe <NUM> may protrude.

The probe <NUM> may have the holes 140A over the entirety of its principal surface.

According to the invention the probe <NUM> has the holes 140A in the connecting surface <NUM>. By having the holes 140A provided over the entirety or around the edges of its principal surface, the probe <NUM> can have the holes 140A formed in the connecting surface <NUM>. By having the holes 140A provided in the connecting surface <NUM>, the pressure-sensitive adhesive layer 110A can be exposed from the holes 140A formed in the connecting surface <NUM>; therefore, the pressure-sensitive adhesive layer 110A can be easily come into contact with the top surface (the surface in the +Z axis direction) of the frame <NUM> of the circuit part <NUM>.

The probe <NUM> is formed using an electrode. The electrode will be described with reference to <FIG> and <FIG>. Note that in <FIG> and <FIG>, the electrode corresponds to the probe <NUM> illustrated in <FIG> and <FIG>, and holes in the electrode correspond to the holes 140A illustrated in <FIG> and <FIG>.

<FIG> is a perspective view of the electrode. As illustrated in <FIG>, the electrode <NUM> is a plate-shaped (sheet-like) member having a pair of principal surfaces <NUM> and <NUM> parallel to each other, and has multiple holes <NUM> penetrating through the electrode <NUM> in the thickness direction (the Z axis direction), formed in a lattice pattern.

The principal surfaces <NUM> and <NUM> are flat surfaces. The principal surface <NUM> is a principal surface on one side (in the +Z axis direction) of the electrode <NUM>, and serves as the top surface of the electrode <NUM>. The principal surface <NUM> is a principal surface positioned in the direction opposite to the principal surface <NUM> (in the -Z axis direction), and serves as the bottom surface of the electrode <NUM>. The principal surfaces <NUM> and <NUM> are formed to have a rectangular shape in plan view. Note that in the present embodiment, a rectangular shape means a rectangle, a square, or a rectangle or square having its corners chamfered.

The electrode <NUM> favorably has a size of <NUM> to <NUM> in plan view.

The electrode <NUM> favorably has a thickness of <NUM> to <NUM>. As long as the thickness of the electrode <NUM> is within a range <NUM> to <NUM>, the electrode <NUM> can have strength and easy handleability.

The multiple holes <NUM> are arranged in a square lattice pattern on the principal surface <NUM>, and are arrayed in the principal surface <NUM> with approximately equal intervals and in parallel with two crossing axial directions (the X axis direction and the Y axis direction). The holes <NUM> are all formed to have substantially the same size and shape. Note that the multiple holes <NUM> may not be equally spaced.

As illustrated in <FIG>, each of the holes <NUM> is formed to have a circular shape in plan view. The diameter L of the hole <NUM> can be designed appropriately depending on the size of the principal surface <NUM> and the like, and is favorably <NUM> to <NUM>, more favorably <NUM> to <NUM>, and even more favorably <NUM> to <NUM>. Note that the shape of the hole <NUM> may be elliptic. In the case where the shape of the hole <NUM> is elliptic, it is favorable that the major axis of the hole <NUM> has a value of L as described above.

Although depending on the shape and size of the holes <NUM>, the distance P between the holes <NUM> is favorably <NUM> to <NUM>, more favorably <NUM> to <NUM>, and even more favorably <NUM> to <NUM>. Note that the distance P between the holes <NUM> means a shortest distance between adjacent holes <NUM>. The hole <NUM> is formed to have a circular shape in plan view; therefore, the distance between the holes <NUM> means the distance between the closest points of the adjacent holes <NUM>.

The opening ratio of the holes <NUM> is <NUM>% to <NUM>%, favorably <NUM>% to <NUM>%, and more favorably <NUM>% to <NUM>%. If the opening ratio of the holes <NUM> is less than <NUM>%, the area of the adhesive layer exposed from the holes <NUM> of the electrode <NUM> is small when the adhesive layer is formed on the electrode <NUM>. Therefore, when the electrode <NUM> together with the adhesive layer is peeled off from the bonding surface, the peeling adhesive strength of the adhesive layer with respect to the bonding surface becomes too small. If the opening ratio of the holes <NUM> exceeds <NUM>%, the area of the adhesive layer exposed from the holes <NUM> in the electrode <NUM> becomes too large. Therefore, when the electrode <NUM> together with the adhesive layer is peeled off from the bonding surface, the adhesive strength becomes too strong.

Note that the opening ratio is a ratio of the sum of the areas of holes <NUM> to the total area of the principal surface (the principal surface <NUM> or the principal surface <NUM>) of the electrode <NUM> including the areas of the holes <NUM>, and is expressed by the following formula (<NUM>): <MAT>.

The number of holes <NUM> is favorably less than or equal to <NUM>,<NUM> holes/cm<NUM>, more favorably less than or equal to <NUM>,<NUM> holes/cm<NUM>, and even more favorably less than or equal to <NUM> holes/cm<NUM>. As long as the number of holes <NUM> is less than or equal to <NUM>,<NUM> holes/cm<NUM>, when the adhesive layer is formed on the electrode <NUM>, a sufficient number of regions of the adhesive layer exposed from the holes <NUM> of the electrode <NUM> can be secured, and it becomes easier to maintain the electrical conductivity. The lower limit of the number of holes <NUM> is two, and may be greater.

The electrode <NUM> can be formed using a conductive composition containing a conductive polymer and a binder resin.

As the conductive polymer, for example, polythiophene, polyacetylene, polypyrrole, polyaniline, polyphenylene vinylene, or the like can be used. Any of these may be used alone, or two or more may be used in combination. Among these, it is favorable to use a polythiophene compound. From the viewpoints of having a lower contact impedance with a living body and high electrical conductivity, it is more favorable to use PEDOT/PSS doped with polystyrenesulfonic acid (poly4-styrenesulfonate; PSS) in poly3,<NUM>-ethylenedioxythiophene (PEDOT).

The content of the conductive polymer is, with respect to <NUM> parts by mass of the conductive composition, favorably <NUM> to <NUM> parts by mass, more favorably <NUM> to <NUM> parts by mass, and even more favorably <NUM> to <NUM> parts by mass. As long as the content is, with respect to the conductive composition, within a range of <NUM> parts by mass to <NUM> parts by mass, excellent electrical conductivity, toughness, and flexibility can be imparted to the conductive composition.

The conductive polymer may be used as an aqueous solution dissolved in a solvent. In this case, as the solvent, an organic solvent or an aqueous solvent can be used. As the organic solvent, for example, ketones such as acetone, methyl ethyl ketone (MEK), or the like; ester such as ethyl acetate; ethers such as propylene glycol monomethyl ether or the like; amides such as N, N-dimethylformamide, or the like, may be enumerated. As the aqueous solvent, for example, water; alcohol such as methanol, ethanol, propanol, isopropanol, or the like, may be enumerated. Among these, it is favorable to use an aqueous solvent.

As the binder resin, a water-soluble polymer, a water-insoluble polymer, or the like can be used. As the binder resin, it is favorable to use a water-soluble polymer from the viewpoint of compatibility with other components contained in the conductive composition. Note that the water-soluble polymer includes a hydrophilic polymer that is hydrophilic though not completely soluble in water.

As the water-soluble polymer, a hydroxyl group-containing polymer or the like can be used. As the hydroxyl group-containing polymer, sugars such as agarose or the like, polyvinyl alcohol (PVA), modified polyvinyl alcohol, a copolymer of acrylic acid and sodium acrylate, or the like can be used. Any of these may be used alone, or two or more may be used in combination. Among these, polyvinyl alcohol or modified polyvinyl alcohol is favorable, and modified polyvinyl alcohol is more favorable.

As the modified polyvinyl alcohol, acetoacetyl group-containing polyvinyl alcohol, diacetone acrylamide modified polyvinyl alcohol, or the like may be enumerated. Note that as the diacetone acrylamide modified polyvinyl alcohol, for example, a diacetone acrylamide modified polyvinyl alcohol-based resin (DA modified PVA-based resin) described in <CIT> can be used.

The content of the binder resin is, with respect to <NUM> parts by mass of the conductive composition, favorably <NUM> to <NUM> parts by mass, more favorably <NUM> to <NUM> parts by mass, and even more favorably <NUM> to <NUM> parts by mass. As long as the content is within a range of <NUM> parts by mass to <NUM> parts by mass with respect to the conductive composition, excellent electrical conductivity, toughness, and flexibility can be imparted to the conductive composition.

The binder resin may be used as an aqueous solution dissolved in a solvent. As the solvent, a similar solvent can be used as in the case of the conductive polymer described above.

It is favorable that the conductive composition further contain at least one of a crosslinking agent and a plasticizing agent. The crosslinking agent and the plasticizing agent have a function of giving toughness and flexibility to the conductive composition.

Note that the toughness is a property that makes excellent strength and elongation compatible with each other. The toughness does not include a property in which either one of the strength or elongation is remarkably excellent whereas the other is remarkably inferior, but includes a property in which both are balanced.

The flexibility is a property in that after having bent the electrode <NUM> obtained as a cured material of the conductive composition, occurrence of damage such as fracture in the bent part can be suppressed.

The crosslinking agent crosslinks the binder resin. By having the crosslinking agent contained in the binder resin, the toughness of the conductive composition can be improved. It is favorable that the crosslinking agent has reactivity with a hydroxyl group. If the crosslinking agent has reactivity with a hydroxyl group, in the case where the binder resin is a hydroxyl group-containing polymer, the crosslinking agent can react with hydroxyl groups of a hydroxyl group-containing polymer.

As the crosslinking agent, a zirconium compound such as zirconium salt; a titanium compound such as titanium salt; a borate such as boric acid; an isocyanate compound such as blocked isocyanate; an aldehyde compound such as dialdehyde such as glyoxal; an alkoxyl group-containing compound, a methylol group-containing compound, or the like may be enumerated. Any of these may be used alone, or two or more may be used in combination. Among these, a zirconium compound, isocyanate compound, or aldehyde compound is favorable from the viewpoint of the reactivity and the safety.

The content of the crosslinking agent is, with respect to <NUM> parts by mass of the conductive composition, favorably <NUM> to <NUM> parts by mass, more favorably <NUM> to <NUM> parts by mass, and even more favorably <NUM> to <NUM> parts by mass. As long as the content is, with respect to <NUM> parts by mass of the conductive composition, within a range of <NUM> parts by mass to <NUM> parts by mass, excellent toughness and flexibility can be imparted to the conductive composition.

The crosslinking agent may be used as an aqueous solution dissolved in a solvent. As the solvent, a similar solvent can be used as in the case of the conductive polymer described above.

The plasticizing agent improves the tensile elongation and the flexibility of the conductive composition. As the plasticizing agent, glycerin, ethylene glycol, propylene glycol, sorbitol, a polyol compound of these polymers or the like, N-methylpyrrolidone (NMP), an aprotonic compound such as dimethyl formaldehyde (DMF), N-N'-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), or the like may be enumerated. Any of these may be used alone, or two or more may be used in combination. Among these, glycerin is favorable from the viewpoint of compatibility with the other components.

The content of the plasticizing agent is, with respect to <NUM> parts by mass of the conductive composition, favorably <NUM> parts by mass to <NUM> parts by mass, more favorably <NUM> parts by mass to <NUM> parts by mass, and even more favorably <NUM> parts by mass to <NUM> parts by mass. As long as the content is, with respect to <NUM> parts by mass of the conductive composition, within a range of <NUM> parts by mass to <NUM> parts by mass, excellent toughness and flexibility can be imparted to the conductive composition.

As for the crosslinking agent and the plasticizing agent, at least one of these may be contained in the conductive composition. By having at least one of the crosslinking agent and the plasticizing agent contained in the conductive composition, the electrode <NUM> can be improved in terms of the toughness and the flexibility.

In the case where the crosslinking agent is contained in the conductive composition, but the plasticizing agent is not contained, the electrode <NUM> can be improved in terms of both the tensile strength and the tensile elongation, and improved in terms of the flexibility.

In the case where the plasticizing agent is contained in the conductive composition, but the crosslinking agent is not contained, the electrode <NUM> can be improved in terms of the tensile elongation; therefore, as a whole, the electrode <NUM> can be improved in terms of the toughness. Also, the flexibility of the electrode <NUM> can be improved.

It is favorable that both the crosslinking agent and the plasticizing agent are contained in the conductive composition. By having both the crosslinking agent and the plasticizing agent contained in the conductive composition, more outstanding toughness can be imparted to the electrode <NUM>.

In addition to the above components, the conductive composition may optionally contain a variety of publicly known additives such as a surfactant, a softening agent, a stabilizer, a leveling agent, an antioxidant, an anti-hydrolysis agent, a swelling agent, a thickener, a colorant, a bulking agent, and the like, by appropriate ratios, as necessary. As the surfactant, a silicone-based surfactant and the like may be enumerated.

The conductive composition is prepared by mixing the components described above by the ratios as described above.

The conductive composition may optionally contain a solvent by an appropriate ratio, as necessary. In this way, an aqueous solution of the conductive composition (the aqueous solution of the conductive composition) is prepared.

As the solvent, an organic solvent or an aqueous solvent can be used. As the organic solvent, for example, ketones such as acetone, methyl ethyl ketone (MEK), or the like; esters such as ethyl acetate; ethers such as propylene glycol monomethyl ether or the like; amides such as N, N-dimethylformamide, or the like may be enumerated. As the aqueous solvent, for example, water; alcohol such as methanol, ethanol, propanol, isopropanol, or the like may be enumerated. Among these, it is favorable to use an aqueous solvent.

An example of the production method of an electrode <NUM> will be described. After having the conductive composition applies onto a surface of a peeling substrate, by heating the conductive composition, a crosslinking reaction of the binder resin is advanced by the crosslinking agent contained in the conductive composition, to cure the binder resin. In this way, a cured material of the conductive composition is obtained. Thereafter, the surface of the cured material is pressed to have a predetermined shape by using a press machine or the like. In this way, as illustrated in <FIG>, an electrode <NUM> is obtained, in which holes <NUM> having a size and a shape both being substantially uniform are formed to be arranged in a square lattice pattern on the principal surface <NUM>.

As the peeling substrate, a separator, a core material, or the like can be used. As the separator, a resin film such as a polyethylene terephthalate (PET) film, polyethylene (PE) film, polypropylene (PP) film, polyamide (PA) film, polyimide (PI) film, fluororesin film, or the like can be used. As the core material, a resin film such as a PET film or PI film; a ceramic sheet; a metal film such as aluminum foil; a resin substrate reinforced with fiberglass or plastic nonwoven fiber; a silicone substrate or a glass substrate, or the like can be used.

As the method of applying the conductive composition onto the peeling substrate, a method of roll coating, screen coating, gravure coating, spin coating, reverse coating, bar coating, blade coating, air knife coating, dipping, dispensing, or the like; a method of dripping a small amount of the conductive composition onto the substrate, that is then stretched with a doctor blade; or the like can be used. By these application methods, the conductive composition is uniformly applied onto the peeling substrate.

As the method of heating the conductive composition, a publicly known dryer such as a drying oven, a vacuum oven, an air circulation oven, a hot-air dryer, a far-infrared dryer, a microwave decompression dryer, a high-frequency dryer, or the like can be used.

As the heating condition, any condition can be adopted as long as the crosslinking agent contained in the aqueous solution of the conductive composition can react.

The heating temperature of the aqueous solution of the conductive composition is set to a temperature at which the reaction of crosslinking agent contained in the aqueous solution of the conductive composition can be advanced. The heating temperature is favorably <NUM> to <NUM>, and more favorably <NUM> to <NUM>. As long as the heating temperature is within a range of <NUM> to <NUM>, the reaction of the crosslinking agent can be advanced readily, and curing of the binder resin can be advanced.

The heating time of the aqueous solution of the conductive composition is favorably <NUM> minutes to <NUM> minutes, and more favorably <NUM> minutes to <NUM> minutes. As long as the heating time is within a range of <NUM> to <NUM> minutes, the binder resin can be sufficiently cured.

As described above, the electrode <NUM> is a sheet-like electrode having the principal surfaces <NUM> and <NUM>, has multiple holes <NUM>, and has an opening ratio of the holes <NUM> on the principal surfaces <NUM> and <NUM> set to <NUM>% to <NUM>%. This configuration enables, when the pressure-sensitive adhesive layer <NUM> is formed as the adhesive layer on the principal surface <NUM> side, the electrode <NUM> to suppress reduction of the adhesive strength required for being connected with the skin <NUM> as a biological surface to which the pressure-sensitive adhesive layer <NUM> contacts as an affixed part through the holes <NUM> in the electrode <NUM>. Therefore, when the pressure-sensitive adhesive layer <NUM> is formed on the principal surface <NUM> side, the electrode <NUM> can suppress occurrence of peeling of the pressure-sensitive adhesive layer <NUM> from the skin <NUM>. The electrode <NUM> can have a peeling adhesive strength of, for example, greater than or equal to <NUM>. 010N/<NUM>.

The peeling adhesive strength is determined, for example, by a method compliant with JIS Z <NUM>:<NUM>, or a modified method of JIS Z <NUM>:<NUM> in which the specified test plate is changed to another object to be affixed. As the peeling adhesive strength, for example, a peeling strength obtained in the case of conducting a peeling test in which the electrode <NUM> is adhered to a test plate or an object to be affixed, and then, peeled off at a peeling angle of <NUM> degrees and at a tensile speed of <NUM>/min can be used. The peeling adhesive strength is favorably within a range of <NUM> N/<NUM> to <NUM> N/<NUM>, and more favorably within a range of <NUM> N/<NUM> to <NUM> N/<NUM>. If the peeling adhesive strength is less than <NUM> N/<NUM>, in the case of using the electrode <NUM> affixed to the pressure-sensitive adhesive layer <NUM>, the adhesive strength of the pressure-sensitive adhesive layer <NUM> to the skin <NUM> is low, and there is a likelihood that the affixation is not sufficient. If the peeling adhesive strength exceeds <NUM> N/<NUM>, the adhesive strength of the pressure-sensitive adhesive layer <NUM> is high; therefore, there is a likelihood that re-adhesion or the like of the pressure-sensitive adhesive layer <NUM> is hindered.

Also, by setting the opening ratio of the holes <NUM> on the principal surfaces <NUM> and <NUM> to <NUM>% to <NUM>%, a sufficient area can be secured for the electrode <NUM> to have the principal surface <NUM> or the principal surface <NUM> contact the skin <NUM>. Therefore, the electrode <NUM> can stably maintain the electrical conductivity with the skin <NUM>.

Therefore, when the pressure-sensitive adhesive layer <NUM> is formed on the principal surface <NUM> side, the electrode <NUM> can suppress peeling of the pressure-sensitive adhesive layer <NUM> from the skin <NUM>, and simultaneously, can hold the electrical conductivity. Therefore, when the electrode <NUM> is used in a biosensor, measurement can be executed while suppressing peeling of the electrode <NUM> from the skin for a long period of time.

In the electrode <NUM>, the number of holes <NUM> can be less than or equal to <NUM>,<NUM> holes/cm<NUM>. With a number as such, when the adhesive layer is formed on the electrode <NUM>, a sufficient number of regions of the adhesive layer exposed from the holes <NUM> of the electrode <NUM> can be secured, and the contact area of the electrode <NUM> to the skin <NUM> can be maintained. Therefore, when the pressure-sensitive adhesive layer <NUM> is formed on the principal surface <NUM> side, the electrode <NUM> can further suppress occurrence of peeling of the pressure-sensitive adhesive layer <NUM> from the skin <NUM>, and simultaneously, can secure the electrical conductivity.

The electrode <NUM> can be configured to have the holes <NUM> arranged in a square lattice pattern on the principal surfaces <NUM> and <NUM>. With this arrangement, when the adhesive layer is formed on the electrode <NUM>, the adhesive layer can contact the skin <NUM> substantially equally around the entire perimeter of the electrode <NUM> through the holes <NUM> in the electrode <NUM>, and the contact area of the electrode <NUM> to the skin <NUM> can be secured substantially evenly. Therefore, when the adhesive layer is formed on the principal surface <NUM> side, even if stretching or contraction occurs in any direction of the skin <NUM>, the adhesive layer can stably maintain the adhesive strength to the skin <NUM>, and the electrode <NUM> can stably maintain the electrical conduction with the skin <NUM>.

In the electrode <NUM>, the holes <NUM> can be formed to penetrate through the principal surfaces <NUM> and <NUM> perpendicularly. This enables, when the pressure-sensitive adhesive layer <NUM> is formed on the electrode <NUM>, the pressure-sensitive adhesive layer <NUM> to easily pass through the holes <NUM>. Therefore, the pressure-sensitive adhesive layer <NUM> can easily contact the skin <NUM> from the holes <NUM>; therefore, the electrode <NUM> can stably maintain the connection between the pressure-sensitive adhesive layer <NUM> and the skin <NUM>. Also, the effect of the viscosity and the like of the pressure-sensitive adhesive layer <NUM> can be reduced; therefore, an optimum adhesive layer can be used depending on the type of the skin <NUM>.

As illustrated in <FIG> and <FIG>, the probe <NUM> is fixed to the frame <NUM> by a fixing tape <NUM> that covers edge parts along the four sides, in a state of the edge parts along the four sides being arranged on the frame <NUM>. The fixing tape <NUM> is adhered to the frame <NUM> through gaps such as the holes 140A in the probe <NUM>.

The fixing tape <NUM> is, as an example, a copper tape, and has a rectangular loop shape in plan view. The fixing tape <NUM> has its bottom surface coated with an adhesive. The fixing tape <NUM> is provided on the frame <NUM> so as to surround the four sides of the probe <NUM> on the outside of the opening of the through holes <NUM> and <NUM> in plan view, to fix the probe <NUM> to the frame <NUM>. The fixing tape <NUM> may be a tape of metal other than copper.

In a state of the probe <NUM> having its edge parts along the four sides fixed on the frame <NUM> by the fixing tape <NUM> in this way, the pressure-sensitive adhesive layer 110A and the base material layer 120A are overlaid on the fixing tape <NUM> and the probe <NUM>. When the pressure-sensitive adhesive layer 110A and the base material layer 120A are pressed downward, the probe <NUM> is pushed along the inner walls of the through holes <NUM> and <NUM>, and the pressure-sensitive adhesive layer 110A is pushed into the interior of the holes 140A in the probe <NUM>.

The probe <NUM> is pushed down to a position at which its center part becomes substantially flush with the bottom surface <NUM> of the pressure-sensitive adhesive layer <NUM>, in a state of its edge parts along the four sides being fixed on the frame <NUM> by the fixing tape <NUM>. Therefore, if having the probe <NUM> come in contact with the skin <NUM> of the living body (see <FIG>), the pressure-sensitive adhesive layer 110A can be adhered to the skin <NUM>, and the probe <NUM> can be firmly adhered to the skin <NUM>.

It is favorable that the thickness of the probe <NUM> is thinner than the thickness of the pressure-sensitive adhesive layer <NUM>. The thickness of the probe <NUM> is favorably within a range of <NUM> to <NUM>, and more favorably within a range of <NUM> to <NUM>, similar to the thickness of the electrode <NUM> described above.

Also, the surrounding part (rectangular loop-shaped part) surrounding the central part of the pressure-sensitive adhesive layer 110A in plan view is positioned above the fixing tape <NUM>. In <FIG>, although the top surface of the pressure-sensitive adhesive layer 110A is generally flat, the center part may be recessed downward compared to the surrounding part. The base material layer 120A is overlaid on the generally flat top surface of the pressure-sensitive adhesive layer 110A.

The pressure-sensitive adhesive layer 110A and the base material layer 120A as such may be made of the same materials as the pressure-sensitive adhesive layer <NUM> and the base material layer <NUM>, respectively. Also, the pressure-sensitive adhesive layer 110A may be made of a material different from that of the pressure-sensitive adhesive layer <NUM>. Also, the base material layer 120A may be made of a material different from that of the base material layer <NUM>.

Note that in <FIG>, although the thicknesses of the respective parts are exaggerated, in practice, the thicknesses of the pressure-sensitive adhesive layer <NUM> and 110A is within a range of <NUM> to <NUM>, and the thicknesses of the base material layer <NUM> and 120A is within a range of <NUM> to <NUM>. Also, the thicknesses of the wire <NUM> is within a range of <NUM> to <NUM>, the thicknesses of the substrate <NUM> is around several <NUM>, and the thicknesses of the fixing tape <NUM> is within a range of <NUM> to <NUM>.

Also, as illustrated in <FIG>, in the case where the probe <NUM> directly contacts the frame <NUM>, and the electrical connection is secured, the fixing tape <NUM> may be a tape made of resin or the like that does not have electrical conductivity.

Also, in <FIG>, the fixing tape <NUM> covers the side surfaces of the frame <NUM> and the substrate <NUM> in addition to the probe <NUM>, and reaches the top surface of the base material layer <NUM>. However, the fixing tape <NUM> simply needs to have the probe <NUM> and the frame <NUM> joined, and hence, does not need to reach the top surface of the base material layer <NUM>; does not need cover the side surfaces of the substrate <NUM>; and does not need cover the side surfaces of the frame <NUM>.

Also, the substrate <NUM> and the two substrates <NUM> may be one integrated substrate. In this case, the wires <NUM>, the two frames <NUM>, and the terminal 135A are provided on a surface of the one substrate, to have the electronic device <NUM> and the battery <NUM> mounted.

The electronic device <NUM> is formed on the top surface <NUM> of the base material layer <NUM>, and electrically connected to the wires <NUM>. The electronic device <NUM> has a rectangular shape in cross sectional view. The bottom surface (in the -Z direction) of the electronic device <NUM> is provided with terminals. As the material of the terminals of the electronic device <NUM>, solder, conductive paste, or the like may be enumerated.

As illustrated in <FIG>, the electronic device <NUM> includes, as an example, an application specific integrated circuit (ASIC) 150A, a micro processing unit (MPU) 150B, a memory 150C, and a wireless communication unit 150D; and is connected to the probes <NUM> via the circuit parts <NUM> and the battery <NUM>. The electronic device <NUM> processes biological signals obtained through the probes <NUM>.

The ASIC 150A includes an A/D (Analog to Digital) converter. The electronic device <NUM> is driven by electric power supplied from the battery <NUM>, to obtain biological signals measured by the probes <NUM>. The electronic device <NUM> executes processing such as filtering and digital conversion on the biological signals, and the MPU 150B calculates an arithmetic mean of values of the biological signals obtained multiple times, to store the mean in the memory 150C. The electronic device <NUM> can obtain biological signals continuously, as an example, for <NUM> hours or longer. In some cases, the electronic device <NUM> measures biological signals for a long period of time; therefore, various ideas are incorporated to reduce the electric power consumption.

The wireless communication unit 150D is a transceiver used when a test device of an evaluation test reads biological signals stored in the memory 150C during the evaluation test via the wireless communication, and executes communication, as an example, at <NUM>. The evaluation test is a test, as an example, compliant with the standard of JIS <NUM>-<NUM>-<NUM>. The evaluation test is a test executed after completion of a biosensor, to verify operations of the biosensor to detect biological signals as a medical device. The evaluation test requires an attenuation factor of a biological signal extracted from the biosensor being less than <NUM>% with respect to a biological signal input into the biosensor. This evaluation test is to be executed for all completed products.

As illustrated in <FIG>, the battery <NUM> is provided on the top surface <NUM> of the base material layer <NUM>. As the battery <NUM>, a lead battery, a lithium ion secondary battery, or the like can be used. The battery <NUM> may be a button battery. The battery <NUM> is an example of a battery. The battery <NUM> has terminals provided on its bottom surface. The terminals of the battery <NUM> are connected to the probes <NUM> via the circuit parts <NUM>, and the electronic device <NUM>. The capacity of the battery <NUM> is set so that the electronic device <NUM> can measure biological signals, as an example, for <NUM> hours or longer.

The cover <NUM> covers the base material layer <NUM>, the circuit parts <NUM>, the substrate <NUM>, the probes <NUM>, the fixing tapes <NUM>, the electronic device <NUM>, and the battery <NUM>. The cover <NUM> has a base part 170A and a protruding part 170B protruding in the +Z direction from the center of the base part 170A. The base part 170A is a part positioned at the periphery of the cover <NUM> in plan view, and is a part positioned lower than protruding part 170B. A recessed part 170C is provided below the protruding part 170B. In the cover <NUM>, the bottom surface of the base part 170A is adhered to the top surface <NUM> of the base material layer <NUM>. In the recessed part 170C, the substrate <NUM>, the electronic device <NUM>, and the battery <NUM> are housed. The cover <NUM> is bonded to the top surface <NUM> of the base material layer <NUM> in a state of having the electronic device <NUM>, the battery <NUM>, and the like housed in the recessed part 170C.

In addition to the role of serving as a cover for protecting the circuit parts <NUM>, the electronic device <NUM>, and the battery <NUM> on the base material layer <NUM>, the cover <NUM> has a role of serving as a shock absorbing layer to protect the interior components from shocks applied to the patch-type biosensor <NUM> from the top surface side. As the cover <NUM>, for example, silicone rubber, soft resin, urethane, or the like can be used.

<FIG> is a diagram illustrating a circuit configuration of the patch-type biosensor <NUM>. Each of the probes <NUM> is connected to the electronic device <NUM> and the battery <NUM> via the wire <NUM> and the wire 135B of the substrate <NUM>. The two probes <NUM> are connected in parallel to the electronic device <NUM> and the battery <NUM>.

In this way, the patch-type biosensor <NUM> is provided with the probes <NUM> each having the connecting surface <NUM> connected to the frame <NUM> of the circuit part <NUM>, on the side (in the -Z axis direction) to be affixed to the surface of the skin <NUM>. By connecting the probe <NUM> to the frame <NUM> through the connection surface <NUM>, the probe <NUM> can be less likely to be peeled off from the frame <NUM>. This enables the patch-type biosensor <NUM> to make the connection between the probe <NUM> and the frame <NUM> stable; therefore, the conduction between the probe <NUM> and the frame <NUM> can be secured stably. Also, the patch-type biosensor <NUM> has the probe <NUM> arranged on the side of the pressure-sensitive adhesive layer <NUM> (in the -Z axis direction) to be affixed to the surface of the skin <NUM>, to be capable of contacting the surface of the skin <NUM>; therefore, the conduction with the skin <NUM> can be held stably. Therefore, the patch-type biosensor <NUM> can suppress peeling of the pressure-sensitive adhesive layer <NUM> formed on one side of the probe <NUM> from the skin <NUM> on which the probe <NUM> is placed, and simultaneously, can hold the electrical conductivity. Therefore, the patch-type biosensor <NUM> can stably measure biological information even when the patch-type biosensor <NUM> is affixed to a skin and used for a long period of time.

The patch-type biosensor <NUM> has one or more holes 140A in the connecting surface <NUM> of the probe <NUM>, and can have the circuit part <NUM> connected to the probe <NUM> on a side (in the +Z axis direction) opposite to the side (in the -Z axis direction) to be affixed to the surface of the skin <NUM>. By having the holes 140A in the connecting surface <NUM>, the probe <NUM> can have the pressure-sensitive adhesive layer 110A, that is exposed from the holes 140A formed in the connecting surface <NUM>, contact the top surface of the frame <NUM> of the circuit part <NUM> (a surface in the +Z axis direction). This enables the probe <NUM> to be held in a state of being connected to the frame <NUM> by the pressure-sensitive adhesive layer 110A. Therefore, the patch-type biosensor <NUM> can have the probe <NUM> and the frame <NUM> to be more stably connected by the pressure-sensitive adhesive layer 110A exposed through the holes 140A formed in the connecting surface <NUM>.

The patch-type biosensor <NUM> is provided with the probe <NUM> formed using the electrode <NUM> described above (see <FIG>), and the probe <NUM> can have an opening ratio of <NUM>% to <NUM>%. This enables the patch-type biosensor <NUM> to suppress reduction in the adhesive strength to the skin <NUM> contacted by the pressure-sensitive adhesive layer <NUM> through the holes 140A in the probe <NUM>, and hence, to suppress the probe <NUM> from being peeled off from the skin <NUM>. Also, the patch-type biosensor <NUM> can secure the electrical conductivity in the probe <NUM>; therefore, the conduction with the skin <NUM> can be held stably. Therefore, the patch-type biosensor <NUM> can more stably suppress peeling of the pressure-sensitive adhesive layer <NUM> formed on one side of the probe <NUM> from the skin <NUM> on which the probe <NUM> is placed, and simultaneously, can hold the electrical conductivity. Therefore, as for the patch-type biosensor <NUM>, even when the patch-type biosensor <NUM> affixed to a skin and used for a long period of time, the patch-type biosensor <NUM> can stably measure biological information.

In the patch-type biosensor <NUM>, the number of holes 140A in the probe <NUM> can be less than or equal to <NUM> holes/cm<NUM>. This can further suppress occurrence of peeling of the pressure-sensitive adhesive layer <NUM> passing through the holes 140A in the probe <NUM> from the skin <NUM>, and can secure the electrical conductivity. Therefore, the patch-type biosensor <NUM> can be used stably in a state of being affixed to the skin <NUM> for a long period of time.

The patch-type biosensor <NUM> can be configured to have the holes 140A in the probe <NUM> arranged in a square lattice pattern on the principal surface. This enables the pressure-sensitive adhesive layer <NUM> to contact the skin <NUM> substantially equally around the entire perimeter of the probe <NUM> through the holes 140A, and the contact area of the probe <NUM> to the skin <NUM> can be secured substantially evenly. Therefore, even if the surface of the skin <NUM> moves, and the skin <NUM> contacting the probe <NUM> stretches or contracts in any direction, the patch-type biosensor <NUM> can have the pressure-sensitive adhesive layer <NUM> stably maintain a state of being affixed to the skin <NUM> through the holes 140A of the probe <NUM>.

The patch-type biosensor <NUM> can have the holes 140A in the probe <NUM> penetrate through the principal surfaces of the probe <NUM> perpendicularly. This enables the patch-type biosensor <NUM> to have the pressure-sensitive adhesive layer <NUM> easily contact the skin <NUM> through the holes 140A in the probe <NUM>; therefore, a connection between the pressure-sensitive adhesive layer <NUM> and the skin <NUM> can be easily formed.

After being used for measuring biometric information, the patch-type biosensor <NUM> can be recovered as necessary to remove the electronic device <NUM> and the battery <NUM>, and by replacing these components, can be reused.

The patch-type biosensor <NUM> is a measurement device that senses electrical signals from a living body to measure biological information, and can be used as a patch-type electrocardiogram, patch-type electroencephalograph, patch-type blood pressure manometer, patch-type pulse meter, patch-type myometer, patch-type thermometer, patch-type accelerometer, or the like.

Among these applications, the patch-type biosensor <NUM> is favorably used as a patch-type electrocardiogram. In electrocardiography, by having the patch-type biosensor <NUM> obtain as biological information minute action potentials (electromotive forces) of the myocardium that occur with the heartbeat of a test subject, abnormal electrocardiograms such as arrhythmias and ischemic heart disease can be investigated. In electrocardiography, the patch-type biosensor <NUM> being affixed to the chest, both wrists, both ankles, or the like of a test subject can stably detect, as electrical signals, myocardial active potentials generated by the heartbeat of the test subject by the probes <NUM>. By using the electrical signals detected by the probes <NUM>, the patch-type biosensor <NUM> can obtain electrocardiogram waveforms more precisely.

As illustrated in <FIG>, the patch-type biosensor <NUM> may include a moisture barrier layer <NUM> in the through holes <NUM> and <NUM> instead of the pressure-sensitive adhesive layer 110A.

The moisture barrier layer <NUM> has a function of suppressing moisture present around the probe <NUM> from penetrating through the patch-type biosensor <NUM> in the thickness direction. The moisture barrier layer <NUM> forms the bottom surface of the patch-type biosensor <NUM>, together with the pressure-sensitive adhesive layer <NUM>. By having the moisture barrier layer <NUM> provided around the bottom surface of the probe <NUM>, moisture around the probe <NUM> can be suppressed from penetrating through the patch-type biosensor <NUM> in the thickness direction; therefore, when having the probe <NUM> come in contact with the skin <NUM> of a living body, the moisture between the bottom surface of the probe <NUM> and the skin <NUM> can be maintained at the interface. Also, by having the moisture between the bottom surface of the probe <NUM> and the skin <NUM> maintained at the interface, drying of the probe <NUM> can be suppressed; therefore, the increase and variation in impedance of the probe <NUM> due to drying of the surface of the probe <NUM>, can be suppressed.

The moisture permeability of the moisture barrier layer <NUM> is lower than that of the pressure-sensitive adhesive layer <NUM> and the base material layer <NUM>. Specifically, the moisture permeability of the moisture barrier layer <NUM> is, for example, less than <NUM>,<NUM>/m<NUM> per day, favorably less than or equal to <NUM>/m<NUM> per day, more favorably less than or equal to <NUM>/m<NUM> per day, even more favorably less than or equal to <NUM>/m<NUM> per day, and, for example, greater than or equal to <NUM>/m<NUM> per day.

As the material of the moisture barrier layer <NUM>, for example, a rubber-based resin (polyisobutylene-based resin, butyl rubber-based resin, SBR-based resin, natural rubber/SBR-based resin, or the like), polystyrene-based resin, polyolefin-based resin (polypropylene-based resin, polyethylene-based resin layer), acryl-based resin, polyvinyl alcohol-based resin, or the like may be enumerated. Any of these resins may be used alone, or two or more may be used in combination.

The moisture barrier layer <NUM> may include air bubbles. As the moisture barrier layer <NUM>, foam of a polypropylene-based resin, acryl-based resin, or the like can be used.

It is favorable that the moisture barrier layer <NUM> has pressure-sensitive adhesiveness. As the moisture barrier layer having such pressure-sensitive adhesiveness, favorably, a rubber-based resin layer (rubber-based pressure-sensitive adhesive layer), and more favorably, a polyisobutylene-based resin layer (polyisobutylene-based pressure-sensitive adhesive layer) may be enumerated.

The polyisobutylene-based resin layer is formed of a polyisobutylene-based composition. The polyisobutylene-based composition contains polyisobutylene as a rubber component. The content of polyisobutylene in the polyisobutylene-based composition is, for example, favorably <NUM> mass% to <NUM> mass%, and more favorably <NUM> mass% to <NUM> mass%.

It is favorable that the polyisobutylene-based composition contains a high water absorption resin and a tackifier. This enables a rubber-based composition such as the polyisobutylene-based composition to have an excellent moisture barrier property and pressure-sensitive adhesiveness.

As the high water absorption resin, for example, a maleic anhydride-based resin (e.g., crosslinked sodium salt of a copolymer of isobutylene and maleic anhydride), polyacrylate-based resin, polysulfonate-based resin, polyacrylamide-based resin, polyvinyl alcohol-based resin, or the like may be enumerated, and favorably, a maleic anhydride-based resin or the like may be recommended. The content of the high water absorption resin is, with respect to <NUM> parts by mass of polyisobutylene, for example, favorably <NUM> part by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> part by mass.

As the tackifier, for example, a rosin-based resin, terpene-based resin (e.g., terpene-aromatic-based liquid resin), coumarone-indene-based resin, phenol-based resin, phenolic-formalin-based resin, xylene-formalin-based resin, petroleum-based resin (e.g., C5-based petroleum resin, C9-based petroleum resin, C5/C9-based petroleum resin, etc.), or the like may be enumerated, and favorably, a petroleum-based resin may be recommended. The content of the tackifier is, with respect to <NUM> parts by mass of polyisobutylene, for example, favorably <NUM> parts by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> parts by mass.

The polyisobutylene-based composition can further contain a softening agent, a bulking agent, a crosslinking agent, and the like, as necessary.

As the softening agent, for example, liquid rubber such as polybutene, liquid isoprene rubber, or liquid butadiene rubber; oils such as paraffin-based oil, naphthene-based oil, and the like; esters such as phthalate ester and phosphateester may be enumerated, and favorably, liquid rubber may be recommended. The content of the softening agent is, with respect to <NUM> parts by mass of polyisobutylene, favorably <NUM> parts by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> parts by mass.

As the bulking agent, for example, calcium carbonate such as heavy calcium carbonate, light calcium carbonate, white luster, or the like; carbon black, talc, mica, clay, mica flour, bentonite, silica, alumina, aluminum silicate, titanium oxide, glass flour, boron nitride flour; metal powders such as aluminum powder and iron powder; resin powders such as acrylic powder and styrenic powder; metal hydroxides such as aluminum hydroxide and magnesium hydroxide may be enumerated, and favorably, calcium carbonate may be recommended. The content of the bulking agent is, with respect to <NUM> parts by mass of polyisobutylene, favorably <NUM> parts by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> parts by mass.

As the crosslinking agent, for example, an isocyanate-based compound such as hexamethylene diisocyanate, or the like may be enumerated. For example, the content of the crosslinking agent is, with respect to <NUM> parts by mass of polyisobutylene, favorably <NUM> part by mass to <NUM> parts by mass, and more favorably <NUM> parts by mass to <NUM> parts by mass.

The polyisobutylene-based composition can contain publicly known additives such as a plasticizing agent, a foaming agent, and the like at any suitable ratios.

As the rubber-based resin layer, from the viewpoint of stability in terms of fixture on a skin, favorably, a styrene-butadiene rubber (SBR)-based resin layer and a natural rubber/SBR-based resin layer may be enumerated, and more favorably, a SBR-based resin layer may be recommended.

The SBR-based resin layer is formed of an SBR-based composition. The SBR-based composition contains SBR as a rubber component. The content of SBR in the SBR-based composition is favorably <NUM> mass% to <NUM> mass%, and more favorably <NUM> mass% to <NUM> mass%.

The SBR-based composition may also contain a high water absorption resin, a tackifier, a softening agent, a bulking agent, a crosslinking agent, and the like, as contained in the polyisobutylene-based composition.

A natural rubber/SBR-based resin layer is formed of a natural rubber/SBR-based composition. The natural rubber/SBR-based composition contains natural rubber and SBR as the rubber components. The total content of natural rubber and SBR in the natural rubber/SBR-based composition is favorably <NUM> mass% to <NUM> mass%, and more favorably <NUM> mass% to <NUM> mass%.

The natural rubber/SBR-based composition may also contain a high water absorption resin, a tackifier, a softening agent, a bulking agent, a crosslinking agent, and the like, as contained in the polyisobutylene-based composition.

The thickness of the moisture barrier layer <NUM> is substantially the same as the thickness of the pressure-sensitive adhesive layer <NUM>. Specifically, the thickness of the moisture barrier layer <NUM> is favorably within a range of <NUM> to <NUM>, more favorably within a range of <NUM> to <NUM>, and even more favorably within a range of <NUM> to <NUM>.

Note that in the present embodiment, the electrode <NUM> does not need to be provided with holes <NUM> in its principal surface <NUM>.

In the present embodiment, the holes <NUM> may be provided with an optimum number depending on the size of the electrode <NUM> and the like, and the number simply needs to be one or more.

In the present embodiment, as illustrated in <FIG>, the electrode <NUM> may have multiple recessed parts <NUM> recessed from the principal surface <NUM> toward the principal surface <NUM>, in addition to the holes <NUM>. This configuration can enlarge the area of the principal surface <NUM> of the electrode <NUM> that contacts the skin <NUM>; therefore, the electrode <NUM> can more stably secure the electrical conductivity with the skin <NUM>.

In the present embodiment, the arrangement of the holes <NUM> is not limited to be a square lattice pattern, and may be an oblique lattice pattern or a hexagonal (staggered) lattice pattern. Also, the multiple holes <NUM> may be arranged regularly or irregularly.

In the present embodiment, the shape of the hole <NUM> may be a polygon such as a rectangle in plan view. For example, as illustrated in <FIG>, the hole <NUM> may be formed to have a rectangular shape in plan view. The rectangle may be square or oblong. In this case, the length L of each side of the hole <NUM> is favorably <NUM> to <NUM>, more favorably <NUM> to <NUM>, and even more favorably <NUM> to <NUM>. In the case where the shape of the hole <NUM> is rectangular, it is favorable that the long side has a dimension of a numerical value as described above.

In the present embodiment, the shapes and dimensions of the respective holes <NUM> may not be uniform necessarily.

In the present embodiment, although the through holes <NUM> and <NUM> of the patch-type biosensor <NUM> are formed to have a rectangular shape in plan view, these may be formed to have another shape such as a circle.

In the present embodiment, the patch-type biosensor <NUM> does not need to be provided with the electronic device <NUM>, the battery <NUM>, or the cover <NUM>.

In the present embodiment, the patch-type biosensor <NUM> may be provided with a peeling sheet formed of a resin such as polyethylene terephthalate, on the bottom surfaces of the pressure-sensitive adhesive layer <NUM>, the pressure-sensitive adhesive layer 110A, and the probes <NUM>.

In the following, the embodiment will be described in further detail with reference to Examples and Comparative examples; note that the embodiment is not limited by these Examples and Comparative examples.

As a conductive polymer, <NUM> parts by mass of an aqueous solution containing PEDOT/PSS (PEDOT/PSS by a concentration of <NUM>%, "Clevious PH <NUM>", manufactured by Heleus); as a binder resin, <NUM> parts by mass of an aqueous solution containing modified polyvinyl alcohol (modified polyvinyl alcohol by a concentration of <NUM>%, "GOSENX Z-<NUM>", manufactured by Nippon Synthetic Chemical Co. ); as a crosslinking agent, <NUM> parts by mass of an aqueous solution containing a zirconium-based compound (a zirconium-based compound by a concentration of <NUM>%, "Safelink SPM-<NUM>", manufactured by Nippon Synthetic Chemical Co. ); as a plasticizing agent, <NUM> parts by mass of glycerin (Wako Pure Chemical Corp. ); and as a surfactant, <NUM> parts by mass of a silicone-based surfactant (Silface SAG002, manufactured by Nissin Chemical Co. ) are added to an ultrasonic bath. Then, the aqueous solution containing these components was mixed in the ultrasonic bath for <NUM> minutes, to prepare a uniform aqueous solution of the conductive composition.

The concentration of PEDOT/PSS in the aqueous solution containing PEDOT/PSS was approximately <NUM>%; therefore, the content of PEDOT/PSS in the aqueous solution of the conductive composition became <NUM> parts by mass. The concentration of modified polyvinyl alcohol in the aqueous solution containing modified polyvinyl alcohol was approximately <NUM>%; therefore, the content of modified polyvinyl alcohol in the aqueous solution of the conductive composition became <NUM> parts by mass. The concentration of the zirconium-based compound in the aqueous solution containing the zirconium-based compound was approximately <NUM>%; therefore, the content of the zirconium-based compound in the aqueous solution of the conductive composition became <NUM> parts by mass. Note that the remaining parts were the solvent in the aqueous solution of the conductive composition.

The contents of the conductive polymer, the binder resin, the crosslinking agent, the plasticizing agent, and the surfactant with respect to <NUM> parts by mass of the conductive composition were <NUM> parts by mass, <NUM> parts by mass, <NUM> parts by mass, <NUM> parts by mass, and <NUM> parts by mass, respectively.

After having applied the prepared aqueous solution of the conductive composition onto the PET film (<NUM> x <NUM>), the conductive composition aqueous solution was heated and dried at <NUM> for <NUM> minutes, to produce a cured material of the conductive composition (<NUM> long by <NUM> wide, and <NUM> thick). Thereafter, the cured material in a state of closely adhering to a peeling sheet (a PET film) was pressed by a pressing machine. In this way, on the peeling sheet, a probe sheet having an electrode in which multiple holes were formed to be circular and arranged in a square lattice pattern on the principal surface (a hole diameter of <NUM>, and an opening ratio of <NUM>%), was produced.

A moisture barrier layer to be attached to the electrode and an object to be affixed when evaluating the peeling resistance of the electrode, were prepared.

An SBR-based resin (product name "SLY-<NUM>", manufactured by Nitto Denko Corporation) was diluted with a toluene solvent so as to have a ratio of the SBR-based resin to the toluene solvent become <NUM>:<NUM>, to prepare a mixed solution. The mixed solution was applied onto the surface of a second peeling sheet (a PET film), and then, heated and dried. In this way, a moisture barrier layer sheet having pressure-sensitive adhesiveness was obtained. The shape of the moisture barrier layer was generally rectangular (<NUM> by <NUM>, and <NUM> thick) in plan view.

A pig skin (skin set of Yucatan micropig (YMP), manufactured by CHARLES RIVER LABORATORIES JAPAN, INC. ) frozen and stored at -<NUM> was thawed at room temperature, and preprocessed to remove subcutaneous fat. Thereafter, the preprocessed pig skin was cut to <NUM> x <NUM> x <NUM>. The cut pig skin was used as the object to be affixed.

The moisture barrier layer prepared as described above was formed on one of the principal surfaces of the produced electrode, to produce a test specimen. Thereafter, the principal surface on which the electrode as the test specimen was exposed was affixed to the object to be affixed, to which pressure joining was applied by one reciprocation motion of a <NUM>-kg roller. Thereafter, the test specimen was held at <NUM> for <NUM> minutes under reference atmosphere of <NUM>% RH. Thereafter, under the reference atmosphere, by using a table-top precision universal test machine ("Autograph AGS-50NX", manufactured by Shimadzu Corporation), under conditions of a peeling angle of <NUM> degrees, and a tensile speed of <NUM>/min, a <NUM>-degree peeling test was conducted for the specimen, and the <NUM>-degree peeling adhesive strength (in unit of N/<NUM>) of the specimen was measured with respect to the object to be affixed. Measurements were made three times (N=<NUM>), and a mean of these measurements was taken as the peeling adhesive strength (initial peeling strength). The measurement results are shown in <FIG>. Also, in the case where the peeling adhesive strength at room temperature obtained in the above test was greater than or equal to <NUM> mN/<NUM>, the result was evaluated as good (in Table <NUM>, denoted as A). In the case where the peeling adhesive strength was less than <NUM> N/<NUM> or exceeding <NUM> N/<NUM>, the result was evaluated as poor (in Table <NUM>, denoted as B). The measurement results of peeling adhesive strength and the evaluation results are shown in Table <NUM>.

In contrast to Example <NUM>-<NUM>, the interval between the holes of the electrode was changed to <NUM>, and the opening ratio was changed to <NUM>%; other than these, the production and measurements were performed in substantially the same way as in Example <NUM>-<NUM>.

In contrast to Example <NUM>-<NUM>, the hole diameter of the electrode was changed to <NUM>, and the opening ratio was changed to <NUM>%; other than these, the production and measurements were performed in substantially the same way as in Example <NUM>-<NUM>.

In contrast to Example <NUM>-<NUM>, the interval between the holes of the electrode was changed to <NUM>,<NUM>, and the opening ratio was changed to <NUM>%; other than these, the production and measurements were performed in substantially the same way as in Example <NUM>-<NUM>.

Table <NUM> shows the shape of the holes, the hole diameter, the interval between the holes, the opening ratio, and the peeling adhesive strength in each of Examples and Comparative example.

As shown in <FIG> and Table <NUM>, in Examples <NUM>-<NUM> to <NUM>-<NUM>, the opening ratio was greater than or equal to <NUM>%, and the peeling adhesive strength was greater than or equal to0. <NUM> N/<NUM>. In contrast , in Comparative exampel <NUM>-<NUM>, the opening ratio was <NUM>%, and the peeling adhesive strength was <NUM> N/<NUM>.

Therefore, when the opening ratio of the electrode is within a range of <NUM>% to <NUM>%, it was confirmed that the peeling adhesive strength of the electrode could be greater than or equal to <NUM> N/<NUM>, and the electrode had high adhesiveness. Therefore, in the biosensor according to an embodiment, the electrode has an opening ratio within a predetermined range; therefore, when used as the electrode of the biosensor, the electrode can have stable adhesive strength, and can have electrical conductivity. Therefore, it can be stated that the biosensor can be effectively used for measuring electrocardiograms continuously for a long period of time (e.g., <NUM> hours) while being closely adhered to a skin of a test subject.

The electrode produced in Example <NUM>-<NUM> was used. The number of holes per unit area of the electrode was <NUM> holes/cm<NUM>.

The peeling adhesive strength was measured and evaluated in substantially the same way as in Example <NUM>-<NUM>. The measurement results are shown in <FIG>. Also, as in Example <NUM>-<NUM>, the peeling adhesive strength at room temperature obtained by the test described above was evaluated. The measurement results of peeling adhesive strength and the evaluation results are shown in Table <NUM>.

The stretching rate upon breaking was measured while the <NUM>-degree peeling test of the test specimen was performed. The results of the measurement of the stretching rate upon breaking are illustrated in <FIG>. Table <NUM> shows the results of measurements of the stretching rate upon breaking.

In Example <NUM>-<NUM>, the hole diameter and the interval between holes of the electrode were changed to <NUM>, and the number of holes per unit area of the electrode was changed to <NUM> holes/cm<NUM>; other than these, the production and measurements were performed in substantially the same way as in Example <NUM>-<NUM>.

In Example <NUM>-<NUM>, the hole diameter and the interval between holes of the electrode were changed to <NUM>,<NUM>, and the number of holes per unit area of the electrode was changed to <NUM> holes/cm<NUM>; other than these, the production and measurements were performed in substantially the same way as in.

In Example <NUM>-<NUM>, the hole diameter and the interval between holes of the electrode were changed to <NUM>, and the number of holes per unit area of the electrode was changed to <NUM>,<NUM> holes/cm<NUM>; other than these, the production and measurements were performed in substantially the same way as in Example <NUM>-<NUM>.

Table <NUM> shows the shape of the holes, the hole diameter, the interval between the holes, the number of holes per unit area, the peeling adhesive strength, and the stretching rate upon breaking in each of Examples and Comparative example.

As shown in <FIG> and Table <NUM>, in Examples <NUM>-<NUM> to <NUM>-<NUM>, the number of holes per unit area was greater than or equal to <NUM> holes, and the peeling adhesive strength was greater than or equal to <NUM>. 082N/<NUM>. In contrast, as shown in Table <NUM>, in Comparative example <NUM>-<NUM>, the number of holes per unit area was <NUM>,<NUM> holes/cm<NUM>, and the peeling adhesive strength was <NUM> N/<NUM>.

Also, as shown in <FIG> and Table <NUM>, in Examples <NUM>-<NUM> to <NUM>-<NUM>, even if the peeling adhesive strength was greater than or equal to <NUM> N/<NUM>, the stretching rate upon breaking was greater than or equal to <NUM>%.

Therefore, as long as the number of holes per unit area of the electrode is less than or equal to <NUM>, it was confirmed that the peeling adhesive strength of the electrode could be greater than or equal to <NUM> N/<NUM>, and the electrode had high adhesiveness. Also, it was confirmed that the electrode can have a stretch rate upon breaking of greater than or equal to <NUM>%.

Therefore, the electrode has the number of holes per unit area being less than the predetermined value, and the stretching rate upon breaking of greater than or equal to the predetermined value; therefore, when the electrode is used as a probe of a biosensor, peeling of the adhesive layer formed on one surface of the probe from a biological surface on which the probe is mounted can be suppressed, and simultaneously, the electrical conductivity can be held. Therefore, the biosensor can have a stable adhesive strength, and can have electrical conductivity; therefore, it can be stated that the biosensor can be effectively used for measuring electrocardiograms continuously for a long period of time (e.g., <NUM> hours) while being closely adhered to a skin of a test subject.

Claim 1:
A biosensor (<NUM>) comprising:
a pressure-sensitive adhesive layer (<NUM>) to be affixed to a biological surface;
an electrode (<NUM>) arranged to be capable of contacting the biological surface on a side of the pressure-sensitive adhesive layer to be affixed to the biological surface;
an electronic device (<NUM>) configured to process a biological signal obtained via the electrode; and
a circuit part (<NUM>) connecting the electrode and the electronic device,
wherein the electrode has a connecting surface (<NUM>) connected to the circuit part on its bottom side, wherein
the electrode is formed to have a plate shape having a pair of principal surfaces (<NUM>, <NUM>) parallel to each other, and to have one or more holes (<NUM>, 140A) penetrating through the electrode in a thickness direction on the connecting surface (<NUM>).