Patent Description:
Biological sensors for measuring biological information, such as electrocardiograms, pulses, electroencephalograms, or myoelectric waves, are used at medical institutions, such as hospitals or clinics, nursing homes, or homes. The biological sensor includes a biological electrode that is in contact with a living body and acquires a subject's biological information. When measuring the biological information, the biological sensor is affixed to a subject's skin to bring the biological electrode into contact with the subject's skin. The biological information is measured by acquiring an electrical signal related to the biological information with the biological electrode.

For the above-described biological sensor, a biocompatible polymer substrate is disclosed which includes, for example, a polymer layer having an electrode on one side, the polymer layer being formed by polymerizing dimethylvinyl-terminated dimethyl siloxane (DSDT) and tetramethyl tetravinyl cyclotetrasiloxane (TTC) with a predetermined ratio (see, for example, Patent Document <NUM>).

In the biocompatible polymer substrate disclosed in Patent Document <NUM>, the polymer layer is affixed to human skin, and the electrode detects a myocardial voltage signal from the human skin and receives and records the myocardial voltage signal in a data acquisition module.

Further related art may be found in <CIT> which describes a biological sensor and in <CIT> which describes a multi-part flexible encapsulation housing for electronic devices.

However, because the polymer layer of the biocompatible polymer substrate disclosed in Patent Document <NUM> is affixed to the living body, there is
a problem that the polymer layer tends to peel off from the skin due to movement of the skin, perspiration, or the like. In particular, a biological sensor, such as a biocompatible polymer substrate, is often affixed to the skin for a long period of time, so that once the biological sensor peels away from the skin during use, biological information may not be stably measured.

According to one aspect of the present invention, it is an object to provide a biological sensor capable of being stably affixed to a living body.

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

According to an aspect of the present invention, a biological sensor that is to be affixed to a living body and is for acquiring a biological signal, includes.

According to an aspect of the present invention, a biological sensor can be stably affixed to a living body.

In the following, embodiments of the present disclosure will be described in detail. To facilitate understanding of the description, in each drawing, to the same elements, the same reference numeral will be assigned, and an explanation may be omitted. Moreover, a scale of each member in the drawings may be different from the actual scale, unless otherwise indicated.

A biological sensor according to the present embodiment will be described. The term "living body" includes a human body (human) and an animal, such as a cow, a horse, a pig, a chicken, a dog, and a cat. The biological sensor according to the present embodiment can be suitably used for a living body, especially a human body. In the present embodiment, as an example, a case of a patch-type biological sensor affixed to skin that is a part of a living body to measure biological information will be described.

<FIG> is a perspective view illustrating a configuration of a biological sensor according to the present embodiment. <FIG> is an exploded perspective view of <FIG>. <FIG> is a cross-sectional view of I-I in <FIG>. As shown in <FIG>, the biological sensor <NUM> is a plate-like (sheetlike) member that is approximately elliptically formed in a planar view. As shown in <FIG> and <FIG>, the biological sensor <NUM> includes a cover member <NUM>, a first laminated sheet (first laminated body) <NUM>, an electrode <NUM>, a second laminated sheet (second laminated body) <NUM>, and a sensor unit <NUM>. The biological sensor <NUM> is formed by laminating the cover member <NUM>, the first laminated sheet <NUM>, the electrodes <NUM>, and the second laminated sheet <NUM> from the cover member <NUM> side to the second laminated sheet <NUM> side in this order. The biological sensor <NUM> enables the first laminated sheet <NUM>, the electrodes <NUM>, and the second laminated sheet <NUM> to be affixed to skin <NUM> that is a living body to acquire a biological signal. The cover member <NUM>, the first laminated sheet <NUM>, and the second laminated sheet <NUM> have substantially the same external shape in a planar view. The sensor unit <NUM> is mounted on the second laminated sheet <NUM> and stored in a storage space S formed by the cover member <NUM> and the first laminated sheet <NUM>.

In the specification of the present application, a three-dimensional orthogonal coordinate system in three axes (in an X-axis direction, a Y-axis direction, and a Z-axis direction) is used. A transverse direction of the biological sensor <NUM> is set to be the X-axis direction, the longitudinal direction of the biological sensor <NUM> is set to be the Y-axis direction, and the height direction (in the thickness direction) of the biological sensor <NUM> is set to be the Z-axis direction. A direction opposite to the side (sticking side) on which the biological sensor is affixed to the living body (analyte) is set to be a +Z-axis direction, and the side (sticking side) on which the biological sensor is affixed to the living body (analyte) is set to be a -Z-axis direction. In the following description, for convenience of illustration, the +Z-axis side will be referred to as an upper side or above, and the -Z-axis side will be referred to as a lower side or below. However, they do not represent a universal vertical relationship.

The biological sensor <NUM> exhibits a shear stress of from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM> when the sticking layer <NUM> that is a portion of the first laminated sheet <NUM> is deformed in a direction perpendicular to a thickness direction of the sticking layer <NUM> (X-axis direction and Y-axis direction) by <NUM>% to <NUM>% of a length of the sticking layer <NUM>, and a moisture permeability of the sticking layer <NUM> is within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day. The inventor of the present application has focused on reducing the shear stress when the sticking layer <NUM> is deformed in the longitudinal direction (in the X-axis direction and the Y-axis direction) to make the sticking layer <NUM> reasonably soft, and at the same time, increasing an air-permeability of the sticking layer <NUM>, while making the moisture permeability of the sticking layer <NUM> be within a predetermined range, to make the biological sensor sufficiently flexible. The inventor found that according to the above-described configuration, even when the skin <NUM> is stretched due to contact pressure of the biological sensor <NUM> on the skin of the subject, movement of the living body (body movement), or the like, the stress at the interface between the first laminated sheet <NUM> and the second laminated sheet <NUM> and the skin <NUM> can be reduced, and thereby the biological sensor <NUM> can be prevented from peeling off from the skin <NUM>.

The amount of deformation when the sticking layer <NUM> is deformed in a direction perpendicular to the thickness direction of the sticking layer <NUM> (in the X-axis direction and the Y-axis direction) is preferably <NUM>% to <NUM>% of the length of the sticking layer <NUM>, more preferably <NUM>% to <NUM>%, and most preferably <NUM>%.

The shear stress, when the sticking layer <NUM> is deformed in a direction perpendicular to the thickness direction of the sticking layer <NUM> (X-axis direction and Y-axis direction) by <NUM>% to <NUM>% of a length of the sticking layer <NUM>, is preferably within a range from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM>, and more preferably within a range from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM>. In the case where the shear stress, when the sticking layer <NUM> is deformed by <NUM>% to <NUM>% of the length of the sticking layer <NUM>, is within a range from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM>, the flexibility of the sticking layer <NUM> can be further stably enhanced.

The moisture permeability of the sticking layer <NUM> is preferably within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, more preferably within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, and further more preferably within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day. When the moisture permeability of the sticking layer <NUM> is within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, the flexibility of the first laminated sheet <NUM> can be more stably maintained.

The moisture permeability can be calculated using a publicly-known method, for example, a moisture permeability test called a cup method, a MOCON method, or the like. In the cup method, water vapor permeated through the material to be measured is absorbed by a hygroscopic agent in the cup, and moisture permeability is measured from a change in the weight of the absorbing agent. In the MOCON method, water vapor transmitted through the material to be measured is measured using an infrared sensor.

Moreover, the biological sensor <NUM> preferably exhibits the shear stress of from <NUM>×<NUM><NUM> N/m<NUM> to 25N×<NUM><NUM> N/m<NUM> when <NUM>% to <NUM>% of the entire length of the biological sensor <NUM> (in the Y-axis direction) with respect to the contact surface with the skin <NUM> is deformed, more preferably from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM>, and even more preferably from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM>. When the shear stress is within the above-described ranges, the stress at an interface between the second laminated sheet <NUM> and the skin <NUM> can be reduced, so that the biological sensor <NUM> can be deformed more flexibly relative to the contact surface with the skin <NUM>, and the biological sensor <NUM> can be prevented from peeling off from the skin <NUM>.

An amount of deformation of the biological sensor <NUM> in the entire length direction (Y-axis direction) is preferably <NUM>% to <NUM>% of the length of the sticking layer <NUM>, more preferably <NUM>% to <NUM>%, and most preferably <NUM>%.

As shown in <FIG>, the cover member <NUM> is positioned outermost (in the +Z-axis direction) of the biological sensor <NUM> and affixed to the upper surface of the first laminated sheet <NUM>. The cover member <NUM> has a projection portion <NUM> that protrudes with substantially a dome shape in the height direction (the +Z-axis direction) of <FIG> in the central portion in the longitudinal direction (the Y-axis direction). A concave portion 11a on the living body side is formed into a recessed shape inside (sticking side) the projection portion <NUM>. The lower surface (on the sticking side) of the cover member <NUM> is formed flat. Inside the projection portion <NUM> (sticking side), a storage space S for storing the sensor unit <NUM> is formed by the concave portion 11a of the inner surface of the projection portion <NUM> and through hole 211a in a porous substrate <NUM>.

The cover member <NUM> may be formed of a flexible material such as silicone rubber, fluorine rubber, urethane rubber, or the like. Moreover, the cover member <NUM> may be formed by laminating the above-described flexible material on a surface of a base resin, such as polyethylene terephthalate (PET), as a support. When the cover member <NUM> is formed using the above-described flexible material and the like, the sensor unit <NUM> disposed in the storage space S of the cover member <NUM> is protected, and an impact applied to the biological sensor <NUM> from the upper side is absorbed, thereby reducing an impact on the sensor unit <NUM>.

Thicknesses of the upper surface and side walls of the projection portion <NUM> of the cover member <NUM> are greater than thicknesses of flat portions 12a and 12b disposed at both end sides of the cover member <NUM> in the longitudinal direction (Y-axis direction). Thus, flexibility of the projection portion <NUM> can be made lower than flexibility of the flat portions 12a and 12b, and thereby the sensor unit <NUM> can be protected from an external force applied to the biological sensor <NUM>.

The thicknesses of the upper surface and the side walls of the projection portion <NUM> are preferably within a range from <NUM> to <NUM>, and the thicknesses of the flat portions 12a and 12b are preferably within a range from <NUM> to <NUM>.

Because the thinner flat portions 12a and 12b are more flexible than the projection portion <NUM>, when the biological sensor <NUM> is affixed to the skin <NUM>, the biological sensor <NUM> can be readily deformed conforming to deformation of a surface of the skin <NUM> caused by body movements such as stretching, bending, and twisting. Accordingly, a stress applied to the flat portions 12a and 12b when the surface of the skin <NUM> is deformed can be reduced, and thereby the biological sensor <NUM> can be made unlikely to peel off from the skin <NUM>.

Outer peripheries of the flat portions 12a and 12b are shaped so that thicknesses gradually decrease toward the ends. Thus, the flexibilities of the outer peripheries of the flat portions 12a and 12b can be made further higher, and the wearing feeling when the biological sensor <NUM> is affixed to the skin <NUM> can be improved compared to a case where the thicknesses of the outer peripheries of the flat portions 12a and 12b are not reduced.

A hardness (strength) of the cover member <NUM> is preferably within a range from <NUM> to <NUM>, and more preferably within a range from <NUM> to <NUM>. When the hardness of the cover member <NUM> is within the above-described range, a third adhesive layer <NUM> provided on the sticking side (in the -Z-axis direction) of a second substrate <NUM> can readily reduce a stress at the interface with the skin <NUM> when the skin <NUM> is stretched by body movement. The hardness refers to Shore A hardness.

As shown in <FIG>, the first laminated sheet <NUM> is affixed to a lower surface of the cover member <NUM>. The first laminated sheet <NUM> has a through hole 20a at a position facing the projection portion <NUM> of the cover member <NUM>. With the through hole 20a, the sensor body <NUM> of the sensor unit <NUM> can be stored in the storage space S formed by the concave portion 11a on the inner surface of the cover member <NUM> and the through hole 20a without being obstructed by the first laminated sheet <NUM>.

The first laminated sheet <NUM> includes a sticking layer <NUM> and a second adhesive layer <NUM> disposed on a surface on the cover member <NUM> side (in the +Z-axis direction) of the first laminated sheet <NUM>.

As shown in <FIG>, the sticking layer <NUM> includes a porous substrate <NUM> and a first adhesive layer <NUM> disposed on the living body side (-Z-axis direction) of the porous substrate <NUM>.

The porous substrate <NUM> has a porous structure and can be formed of a porous body having flexibility, waterproof property, and moisture permeability. For example, a foamed material having an open-cell structure, a closed-cell structure, a semi-closed-cell structure, or the like can be used for the porous body. Therefore, water vapor emitted/generated by perspiration or the like from the skin <NUM>, to which the biological sensor <NUM> is affixed, can be discharged to the outside of the biological sensor <NUM> through the porous substrate <NUM>.

The moisture permeability of the porous substrate <NUM> is preferably within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, more preferably within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, and even more preferably within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day. When the moisture permeability of the sticking layer <NUM> is set to be within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, water vapor entering from one side of the porous substrate <NUM> can be caused to pass through the porous substrate <NUM> and can be stably discharged from the other side of the porous substrate <NUM>.

For the material forming the porous substrate <NUM>, a thermoplastic resin, such as a polyurethane resin, a polystyrene resin, a polyolefin resin, a silicone resin, an acrylic resin, a vinyl chloride resin, or a polyester resin, may be used.

The thickness of the porous substrate <NUM> is within a range from <NUM> to <NUM>.

The porous substrate <NUM> has a through hole 211a at a position facing the projection portion <NUM> of the cover member <NUM>. Because the first adhesive layer <NUM> and the second adhesive layer <NUM> are formed on the surface of the porous substrate <NUM> other than the through hole 211a, the through hole 20a can be formed.

As shown in <FIG>, the first adhesive layer <NUM> is affixed to the lower surface of the porous substrate <NUM>, and has a function of sticking the second substrate <NUM> onto the porous substrate <NUM> and sticking the electrodes <NUM> onto the porous substrate <NUM>.

The first adhesive layer <NUM> preferably has a moisture permeability. The water vapor or the like generated from the skin <NUM>, to which the biological sensor <NUM> is affixed, can be discharged to the porous substrate <NUM> through the first adhesive layer <NUM>. Furthermore, since the porous substrate <NUM> has a cell structure as described above, water vapor can be discharged to the outside of the biological sensor <NUM> via the second adhesive layer <NUM>. Thus, it is possible to prevent perspiration or water vapor from accumulating at the interface between the skin <NUM>, to which the biological sensor <NUM> is affixed, and the third adhesive layer <NUM>. As a result, it is possible to prevent the biological sensor <NUM> from peeling off from the skin <NUM> due to the moisture accumulated at the interface between the skin <NUM> and the first adhesive layer <NUM> that reduces the adhesion force of the first adhesive layer <NUM>.

The moisture permeability of the first adhesive layer <NUM> is preferably <NUM>/m<NUM>·day or more, and more preferably <NUM>/m<NUM>·day or more. Moreover, the moisture permeability of the first adhesive layer <NUM> is <NUM>/m<NUM>·day or less. If the moisture permeability of the first adhesive layer <NUM> is <NUM>/m<NUM>·day or more, when the third adhesive layer <NUM> is affixed to the skin <NUM>, perspiration or the like transmitted from the second laminated sheet <NUM> can be discharged to the outside, so that a load of the skin <NUM> can be reduced.

A material forming the first adhesive layer <NUM> preferably has a pressure-sensitive adhesiveness. The same material for the third adhesive layer <NUM> can be used. Specifically, an acrylic-based pressure-sensitive adhesive is preferably used.

The first adhesive layer <NUM> may be a double-sided adhesive tape formed of the above-described material. When the cover member <NUM> is laminated on the first adhesive layer <NUM> to form the biological sensor <NUM>, the waterproof property of the biological sensor <NUM> can be enhanced and a bonding strength with the cover member <NUM> can be increased.

The first adhesive layer <NUM> may have a corrugated pattern (web pattern) formed on the surface in which an adhesive forming portion with the adhesive and an adherend portion without the adhesive are alternately formed. For the first adhesive layer <NUM>, for example, a double-sided adhesive tape having a web pattern formed on the surface may be used. Since the first adhesive layer <NUM> has a web pattern on the surface, the adhesive can be attached to a convex portion of the surface and its periphery without the adhesive attaching to a concave portion of the surface and its periphery. Thus, since there are both a portion in which the adhesive is present on the surface of the first adhesive layer <NUM> and a portion in which the adhesive is not present, the adhesive can be dispersed on the surface of the first adhesive layer <NUM>. The moisture permeability of the first adhesive layer <NUM> is likely to be higher, as the adhesive becomes thinner. Therefore, since the first adhesive layer <NUM> has a web pattern formed on the surface and a portion in which the adhesive is a partially thin, the moisture permeability can be enhanced while maintaining the adhesive strength, compared to the case where the web pattern is not formed.

Widths of the adhesive forming portion and the adherend portion can be suitably designed. The width of the adhesive forming portion is preferably, for example, within a range from <NUM> to <NUM>, and the width of the adherend portion is preferably within a range from <NUM> to <NUM>. If the widths of the adhesive forming portion and the adherend portion are within the above-described corresponding preferred ranges, the first adhesive layer <NUM> exhibits an excellent moisture permeability while maintaining the adhesive strength.

The thickness of the first adhesive layer <NUM> is appropriately set. The thickness is within a range from <NUM> to <NUM>, more preferably within a range from <NUM> to <NUM>, and even more preferably within a range from <NUM> to <NUM>. If the thickness of the first adhesive layer <NUM> is within a range from <NUM> to <NUM>, the biological sensor <NUM> can be made thinner.

As shown in <FIG>, the second adhesive layer <NUM> is disposed in a state of being affixed to the upper surface of the porous substrate <NUM>. The second adhesive layer <NUM> is affixed to the upper surface of the porous substrate <NUM> at a position corresponding to the flat surface on the sticking side (-Y-axial direction) of the cover member <NUM>, and has a function of sticking the cover member <NUM> onto the porous substrate <NUM>.

For the material forming the second adhesive layer <NUM>, a silicon-based adhesive, silicone-tape, or the like may be used.

The thickness of the second adhesive layer <NUM> may be appropriately set. The thickness is, for example, within a range from <NUM> to <NUM>.

As shown in <FIG>, the electrode <NUM> is affixed to the lower surface that is the sticking side of the first adhesive layer <NUM> (in the -Z-axis direction) with a portion on the sensor body <NUM> side of the electrode <NUM> being connected to wirings 53a and 53b and the portion being held between the first adhesive layer <NUM> and the fourth adhesive layer <NUM>. A portion of the electrode <NUM> that is not held between the first adhesive layer <NUM> and the fourth adhesive layer <NUM> is brought into contact with the living body. When the biological sensor <NUM> is affixed to the skin <NUM>, the electrode <NUM> is brought into contact with the skin <NUM>, so that the biological signal is detected. A biological signal is, for example, an electrical signal representing an electrocardiogram, an electroencephalogram, a pulse, or the like. The electrode <NUM> may be embedded in the second substrate <NUM> in a state of being exposed contactably with the skin <NUM>.

The electrode <NUM> can be formed using an electrode sheet which is obtained by forming a cured product of a conductive composition including a conductive polymer and a binder resin, metals, alloys, or the like into a shape of sheet.

For the conductive polymer, for example, a polythiophene-based conductive polymer, a polyaniline-based conductive polymer, a polypyrrolebased conductive polymer, a polyacetylene-based conductive polymer, a polyphenylene-based conductive polymer and derivatives thereof, and a complex thereof may be used. The above-described conductive polymers may be used singly, or a combination of two or more conductive polymers may be used. Among them, a complex obtained by doping polyaniline as a dopant to polythiophene is preferably used. Among the complexes of polythiophene and polyaniline, PEDOT/PSS obtained by doping polystyrene sulfonic acid (poly4-styrene sulfonate; PSS) to poly3,<NUM>-ethylene dioxythiophene (PEDOT), is more preferably used because of a lower contact impedance with the living body and the high electrical conductivity.

The electrode <NUM> has a plurality of through holes <NUM> on the contact surface with the skin <NUM>. Because the first adhesive layer <NUM> can be exposed to the sticking side through the through holes <NUM> in the state where the electrode <NUM> is affixed to the first adhesive layer <NUM>, adhesiveness of the electrode <NUM> with the skin <NUM> can be enhanced.

As shown in <FIG>, the second laminated sheet <NUM> includes a second substrate <NUM>, a third adhesive layer <NUM>, and a fourth adhesive layer <NUM>.

As shown in <FIG>, an outer shape of the second substrate <NUM> on both sides, in the width direction (the X-axis direction) of the third adhesive layer <NUM>, is substantially the same as an outer shape of the first laminated sheet <NUM> and the cover member <NUM> on both sides in the width direction (the X-axis direction). The length (Y-axis direction) of the second substrate <NUM> is shorter than the length (Y-axis direction) of the cover member <NUM> and the first laminated sheet <NUM>. Both ends in the longitudinal direction of the second laminated sheet <NUM> are at positions where the wirings 53a and 53b of the sensor unit <NUM> are held between the second laminated sheet <NUM> and the first laminated sheet <NUM> and where the second laminated sheet <NUM> overlaps with the portion of the electrode <NUM>. The fourth adhesive layer <NUM> is disposed on an upper surface of the second substrate <NUM>, and the first adhesive layer <NUM> is disposed on the sticking surface of the first laminated sheet <NUM>. The fourth adhesive layer <NUM> of the second laminated sheet <NUM> and the first adhesive layer <NUM> of the first laminated sheet <NUM> extending from both ends in the longitudinal direction of the second laminated sheet <NUM> form a sticking surface to the skin <NUM>. Thus, water resistance/moisture permeability differs depending on the position on the sticking surface, and likewise adhesiveness differs. However, as a whole of the biological sensor <NUM>, the adhesiveness on the sticking surface corresponding to the first laminated sheet <NUM> significantly affects a sticking performance to the skin <NUM>.

The second substrate <NUM> can be formed of a flexible resin with appropriate elasticity, flexibility, and toughness. For materials forming the second substrate <NUM>, for example, thermoplastic resins including a polyester-based resin, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; an acrylic-based resin, such as polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethyl methacrylate (PMMA), polyethyl methacrylate, and polybutyl acrylate; a polyolefinbased resin, such as polyethylene and polypropylene; a polystyrene-based resin, such as polystyrene, imide-modified polystyrene, acrylonitrile-butadiene styrene (ABS) resin, imide-modified ABS resin, styrene-acrylonitrile copolymerization (SAN) resin, and acrylonitrile-ethylene-propylene-diene styrene (AES) resin; a polyimide-based resin; a polyurethane-based resin; a silicone-based resin; and a polyvinyl chloride-based resin, such as polyvinyl chloride resin, and vinyl chloride-vinyl acetate copolymer resin, may be used. Among them, a polyolefin resin and PET are preferably used. The above-described thermoplastic resins are waterproof (with low moisture permeability). Thus, when the second substrate <NUM> is formed of the above-described thermoplastic resins, it is possible to prevent water vapor emitted/generated by perspiration from the skin <NUM> from entering the flexible substrate <NUM> side of the sensor unit <NUM> through the second substrate <NUM> in the state where the biological sensor <NUM> is affixed to the skin <NUM> of the living body.

Preferably, the second substrate <NUM> is formed in a flat plate shape, since the sensor unit <NUM> is disposed on the upper surface of the second substrate <NUM>.

The thickness of the second substrate <NUM> may be appropriately selected. For example, the thickness is preferably within a range from <NUM> to <NUM>, more preferably within a range from <NUM> to <NUM>, and even more preferably within a range from <NUM> to <NUM>.

As shown in <FIG>, the third adhesive layer <NUM> is disposed on the surface of the sticking side (in the -Z-axis direction) of the second substrate <NUM>. The third adhesive layer <NUM> is brought into contact with the living body.

The third adhesive layer <NUM> preferably has pressure-sensitive adhesiveness. Since the third adhesive layer <NUM> has the pressure-sensitive adhesiveness, the biological sensor <NUM> can be readily affixed to the skin <NUM> by pressing the biological sensor <NUM> against the skin <NUM> of the living body.

The material of the third adhesive layer <NUM> is not particularly limited, as long as the material has a pressure-sensitive adhesiveness. The material includes a biocompatible material, and the like. Suitable materials forming the third adhesive layer <NUM> include, for example, an acrylic pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive. The material preferably includes an acrylic pressure-sensitive adhesive.

The acrylic pressure-sensitive adhesive preferably includes an acrylic polymer as a main ingredient. The acrylic polymer can function as a pressure sensitive adhesive component. For the acrylic polymer, a polymer containing (meth)acrylic ester, such as isononyl acrylate or methoxyethyl acrylate, as a main ingredient, and obtained by being polymerized with a monomer component containing, as an optional component, a monomer that can be copolymerized with (meth)acrylic ester, such as acrylic acid, may be used.

Preferably, the acrylic pressure-sensitive adhesive further includes a carboxylic acid ester. The carboxylic acid ester functions as a pressure-sensitive adhesive force regulator to reduce a pressure-sensitive adhesive force of the acrylic polymer to adjust the pressure-sensitive adhesive force of the third adhesive layer <NUM>. For the carboxylic ester, carboxylic acid ester compatible with acrylic polymers may be used. For the carboxylic acid ester, trifatty acid glyceryl or the like may be used.

The acrylic pressure-sensitive adhesive may contain a crosslinking agent, as necessary. The crosslinking agents are cross-linking components that cross-link acrylic polymers. Suitable crosslinking agents include, for example, a polyisocyanate compound (a polyfunctional isocyanate compound), an epoxy compound, a melamine compound, a peroxide compound, a urea compound, a metal alkoxide compound, a metal chelate compound, a metal salt compound, a carbodiimide compound, an oxazoline compound, an aziridine compound, and an amine compound. Among the above-described compounds, the polyisocyanate compound is preferable. The above-described crosslinking agents may be used singly, or a combination of two or more crosslinking agents may be used.

The third adhesive layer <NUM> preferably has excellent biocompatibility. For example, when the third adhesive layer <NUM> is subjected to a keratin peeling test, a keratin peeling area ratio is preferably within a range from <NUM>% to <NUM>%, and more preferably within a range from <NUM>% to <NUM>%. When the keratin peeling area ratio is within the range of <NUM>% to <NUM>%, the load on the skin <NUM> can be suppressed even when the third adhesive layer <NUM> is affixed to the skin <NUM>.

The third adhesive layer <NUM> is preferably moisture permeable. With the moisture permeability, it is possible to discharge water vapor or the like generated from the skin <NUM>, to which the biological sensor <NUM> is affixed, to the first laminated sheet <NUM> side, through the third adhesive layer <NUM>. Furthermore, since the first laminated sheet <NUM> has a cell structure which will be described later, water vapor can be discharged to the outside of the biological sensor <NUM> through the third adhesive layer <NUM>. Therefore, it is possible to prevent perspiration or water vapor from accumulating at the interface between the skin <NUM>, to which the biological sensor <NUM> is affixed, and the third adhesive layer <NUM>. As a result, it is possible to prevent the biological sensor <NUM> from peeling off from the skin due to a decrease in the adhesion force of the third adhesive layer <NUM> by moisture accumulated at the interface between the skin <NUM> and the third adhesive layer <NUM>.

The moisture permeability of the third adhesive layer <NUM> is preferably <NUM>/m<NUM>·day or more, more preferably <NUM>/m<NUM>·day or more, and even more preferably <NUM>/m<NUM>·day or more. Moreover, the moisture permeability of the third adhesive layer <NUM> is <NUM>/m<NUM>·day or less. If the moisture permeability of the third adhesive layer <NUM> is <NUM>/m<NUM>·day or more, perspiration or the like generated from the skin <NUM> can be transmitted appropriately from the second substrate <NUM> to the outside even when the third adhesive layer <NUM> is affixed to the skin <NUM>, thereby the load to the skin <NUM> can be reduced.

The thickness of the third adhesive layer <NUM> can be appropriately selected. The thickness is preferably within a range from <NUM> to <NUM>. When the thickness of the third adhesive layer <NUM> is within a range from <NUM> to <NUM>, the biological sensor <NUM> can be made thinner.

As shown in <FIG>, the fourth adhesive layer <NUM> is disposed on the upper surface of the second substrate <NUM> on the cover member <NUM> side (in the +Z-axis direction), and is a layer to which the sensor unit <NUM> is affixed. Since for the fourth adhesive layer <NUM>, a material the same as or similar to the third adhesive layer <NUM> can be used, details thereof will be omitted. The fourth adhesive layer <NUM> need not necessarily be provided, but may not be provided.

<FIG> is a plan view illustrating a configuration of the sensor unit <NUM>, and <FIG> is an exploded perspective view of a part of the sensor unit <NUM>. The dashed line in <FIG> represents the outer shape of the cover member <NUM>. As shown in <FIG> and <FIG>, the sensor unit <NUM> includes a flexible substrate <NUM> on which various components for acquiring biological information are mounted, a sensor body <NUM>, wirings 53a and 53b connected to the sensor body <NUM> in the longitudinal direction, a battery <NUM>, a positive electrode pattern <NUM>, a negative electrode pattern <NUM>, and a conductive adhesive tape <NUM>. Between a pad portion 522a and a pad portion 522b of the sensor unit <NUM>, the positive electrode pattern <NUM>, the conductive adhesive tape <NUM>, the battery <NUM>, the conductive adhesive tape <NUM>, and the negative electrode pattern <NUM> are laminated in this order from the pad portion 522a side to the pad portion 522b side. In the present embodiment, the positive terminal of the battery <NUM> is set to be in the -Z-axis direction and the negative terminal is set to be in the +Z-axis direction. However, the positive terminal and the negative terminal may be reversed, i.e. the positive terminal may be in the +Z-axis direction and the negative terminal may be in the -Z-axis direction.

The flexible substrate <NUM> is made of a resin, and the flexible substrate <NUM> is integrally formed with the sensor body <NUM> and the wirings 53a and 53b.

An end of each of the wirings 53a and 53b is connected to electrode <NUM>, as shown in <FIG>. As shown in <FIG>, the other end of the wiring 53a is connected to a switch or the like mounted to the component mounting unit <NUM> along the outer periphery of the sensor body <NUM>. The other end of the wiring 53b is connected to a switch or the like mounted on the component mounting unit <NUM> in the same manner as the wiring 53a. The wirings 53a and 53b may be formed on any of wiring layers on the front surface side and the rear surface side of the flexible substrate <NUM>.

As shown in <FIG>, the sensor body <NUM> includes a component mounting unit <NUM> that is a controller and includes a battery mounting unit <NUM>.

The component mounting unit <NUM> includes various components mounted on the flexible substrate <NUM>, such as a CPU and an integrated circuit for processing biological signals acquired from a living body to generate biological signal data; a switch for activating the biological sensor <NUM>; a flash memory for storing the biological signals; or a light emitting element. Examples of circuits using various components will be omitted. The component mounting unit <NUM> is operated by power supplied from the battery <NUM> mounted on the battery mounting unit <NUM>.

The component mounting unit <NUM> wiredly or wirelessly communicates with an external device such as an operation checking device for checking an initial operation, or a readout device for reading biological information from the biological sensor <NUM>.

The battery mounting unit <NUM> supplies power to the integrated circuit mounted on the component mounting unit <NUM>. The battery <NUM> is mounted on the battery mounting unit <NUM>, as shown in <FIG>.

As shown in <FIG>, the battery mounting unit <NUM> is disposed between the wiring 53a and the component mounting unit <NUM>, and includes the pad portions 522a and 522b and a constriction portion 522c.

As shown in <FIG>, the pad portion 522a is provided between the wiring 53a and the component mounting unit <NUM>, located on the positive terminal side of the battery <NUM>, and has the positive electrode pattern <NUM> to which the positive terminal is connected.

As shown in <FIG>, the pad portion 522b is provided separated from the pad portion 522a by a predetermined distance along a direction orthogonal to the longitudinal direction (in the vertical direction in <FIG>) with respect to the pad portion 522a. The pad 522b is located on the negative terminal (second terminal) side of the battery <NUM> and has the negative electrode pattern <NUM> to which the negative terminal is connected.

As shown in <FIG>, the constriction portion 522c is disposed between the pad portions 522a and 522b to connect the pad portions 522a and 522b to each other.

As shown in <FIG>, the battery <NUM> is arranged between the positive and negative electrode patterns <NUM> and <NUM>. The battery <NUM> has positive and negative terminals. For the battery <NUM>, a publicly-known battery may be used. The battery <NUM> may be a coin-type battery, such as CR2025.

As shown in <FIG>, the positive electrode pattern <NUM> is located on the positive terminal side of the battery <NUM> and is connected to the positive terminal. The positive electrode pattern <NUM> has a rectangular shape with chamfered corners.

As shown in <FIG>, the negative electrode pattern <NUM> is located on the negative terminal side of the battery <NUM> and is connected to the negative terminal. The negative electrode pattern <NUM> has a shape substantially corresponding to the size of the circular shape of the negative terminal of the battery <NUM>. The diameter of the negative electrode pattern <NUM> is, for example, equal to the diameter of the battery <NUM> and approximately equal to the diagonal length of the positive electrode pattern <NUM>.

The conductive adhesive tape <NUM> is a conductive adhesive that is disposed between the battery <NUM> and the positive electrode pattern <NUM> and also is disposed between the battery <NUM> and the negative electrode pattern <NUM>. The conductive adhesive tape may also generally be referred to as a conductive adhesive sheet, a conductive adhesive film, or the like.

A conductive adhesive tape 57A and a conductive adhesive tape 57B are affixed to the entire positive electrode pattern <NUM> and the negative electrode pattern <NUM>, respectively, when a battery <NUM> is mounted to the biological sensor <NUM>. Then, the positive terminal and the negative terminal of the battery <NUM> are affixed to the positive electrode pattern <NUM> and the negative electrode pattern <NUM> via the conductive adhesive tape 57A and the conductive adhesive tape 57B, respectively, so that the battery <NUM> is mounted to the battery mounting unit <NUM>. <FIG> shows the sensor body <NUM> in which the battery <NUM> is mounted to the battery mounting unit <NUM> in the state where the battery <NUM> is held between the positive electrode pattern <NUM> and the negative electrode pattern <NUM> by deflecting the constriction portion 522c.

As shown in <FIG>, a peelable sheet <NUM> is preferably affixed to the surface of the biological sensor <NUM> on the sticking side (-Z-axis direction) until the biological sensor <NUM> is affixed to the skin <NUM>, in order to protect the second substrate <NUM> and the electrode <NUM>. By peeling the peelable sheet <NUM> off the second substrate <NUM> and the electrodes <NUM> when the biological sensor <NUM> is used, the adhesion force of the second substrate <NUM> can be maintained.

<FIG> is an explanatory diagram illustrating a state where the biological sensor <NUM> shown in <FIG> is affixed to a chest of the living body P. For example, the longitudinal direction (Y-axis direction) of the biological sensor <NUM> is aligned with the sternum of the living body P, and the biological sensor <NUM> is affixed to the skin of the living body P with one electrode <NUM> being on the upper side and another electrode <NUM> being on the lower side of the living body P. The biological sensor <NUM> acquires a biological signal, such as an electrocardiogram signal, through the electrodes <NUM> from the living body P in the state where the electrodes <NUM> are pressed into contact with the skin of the living body P by sticking the third adhesive layer <NUM> shown in <FIG> onto the skin of the living body P. The biological sensor <NUM> stores the acquired biological signal data in a non-volatile memory such as a flash memory mounted in the component mounting unit <NUM>.

As described above, the biological sensor <NUM> includes the cover member <NUM>, the porous substrate <NUM>, and exhibits a shear stress of from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM> when the sticking layer <NUM>, having the porous substrate <NUM> and the first adhesive layer <NUM>, is deformed in a direction perpendicular to the thickness direction of the sticking layer <NUM> (X-axis direction or Y-axis direction) by <NUM>% to <NUM>% of a length of the sticking layer <NUM>, and a moisture permeability of the sticking layer <NUM> is within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day. With the above-described properties, it is possible to soften the sticking layer <NUM> by increasing the shear stress when the sticking layer <NUM> is deformed, while increasing an air-permeability by controlling the moisture permeability to be within a predetermined range, and thereby the entire sticking layer <NUM> has adequate flexibility. As a result, upon attaching the biological sensor <NUM> to the skin <NUM>, even when the skin <NUM> is stretched due to attaching the biological sensor <NUM> on the skin <NUM> with pressure, a body movement, or the like, it is possible to reduce the stress generated at the interface between the third adhesive layer <NUM>, which is provided on the surface of the second substrate <NUM> on the sticking side (-Z-axis direction), and the skin <NUM>. Thus, it is possible to prevent the biological sensor <NUM> from peeling off the skin <NUM>. Therefore, the biological sensor <NUM> can be stably affixed to the skin <NUM>.

In particular, in the biological sensor <NUM> having the above-described configuration, since the electrode <NUM> is disposed on a part of the sticking surface of the first adhesive layer <NUM>, and the porous substrate <NUM> has a through hole 211a at a substantially central portion thereof, it is important that the first adhesive layer <NUM> readily follows the movement of the skin <NUM>, and that the biological sensor <NUM> is flexible. In the biological sensor <NUM>, when a shear force applied to the sticking layer <NUM> is within a predetermined range, the sticking layer <NUM> is softened by increasing a shear stress when the sticking layer <NUM> is deformed, while increasing an air-permeability of the sticking layer <NUM> by controlling the moisture permeability to be within a predetermined range, and thereby the entire sticking layer <NUM> has adequate flexibility. Thus, it is possible to prevent the sticking surface of the first adhesive layer <NUM>, onto which the electrodes <NUM> are affixed, from peeling off from the skin <NUM>. Furthermore, in the planar view of the biological sensor <NUM>, it is possible to prevent the sticking surface located in the region of the porous substrate <NUM>, including the through hole 211a and the connecting portions of the wirings 53a and 53b to the electrode <NUM>, from peeling off from the skin <NUM>.

Accordingly, the biological sensor <NUM> can stably measure biological information from the skin <NUM>, since at least a part of the biological sensor <NUM> can be prevented from peeling off the subject's skin <NUM> even if the subject moves during using the biological sensor <NUM>.

The biological sensor <NUM> may include a second adhesive layer <NUM> on a surface of the sticking layer <NUM> on the cover member <NUM> side that is an upper surface of the sticking layer <NUM>. According to the above-described configuration, the first laminated sheet <NUM> can be made softer. Thus, when the skin <NUM> is stretched due to the body movement, the first adhesive layer <NUM> and the third adhesive layer <NUM> are more readily deformed along the interface with the skin <NUM>, and the stress generated at the interface between the first adhesive layer <NUM> and the third adhesive layer <NUM> and the skin <NUM> can be reduced more. Accordingly, since the biological sensor <NUM> is further prevented from peeling off from the skin <NUM>, it is possible to maintain the stable state of sticking to the skin <NUM>.

Additionally, a hardness of the cover member <NUM> of the biological sensor <NUM> can be within a range from <NUM> to <NUM>. When the hardness of the cover member <NUM> is within a range from <NUM> to <NUM>, the cover member <NUM> can have an appropriate softness, and it is possible to reduce the obstructing the deformation of the second laminated sheet <NUM> by the cover member <NUM>. Thus, because when the skin <NUM> is stretched by the body movement the third adhesive layer <NUM> can be more readily deformed along the interface with the skin <NUM>, the stress at the interface between the third adhesive layer <NUM> and the skin <NUM> can be further reduced. Accordingly, since the biological sensor <NUM> can be more stably prevented from being peeled from the skin <NUM>, it is possible to more stably maintain the state of sticking to the skin <NUM>.

The moisture permeability of the porous substrate <NUM> of the biological sensor <NUM> can be within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day. Accordingly, the porous substrate <NUM> can stably discharge water vapor generated from the skin <NUM> to the outside of the biological sensor <NUM> via the first adhesive layer <NUM> and the second adhesive layer <NUM>, and thus it is possible to further suppress the peeling from the skin <NUM>.

Moreover, the biological sensor <NUM> can exhibit the shear stress of from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM> when <NUM>% to <NUM>% of the entire length of the biological sensor <NUM> (in the Y-axis direction) with respect to the contact surface with the skin <NUM> is deformed. Typically, when a biological sensor is affixed to skin, an amount of deformation of the biological sensor with respect to a contact surface with the skin <NUM> is <NUM>% or less of the entire length of the biological sensor. Even when the biological sensor <NUM> is deformed by <NUM>% to <NUM>% of the entire length of the biological sensor <NUM>, the shear stress of the biological sensor <NUM> can be made within a range from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM>. Thus, in the state where the biological sensor <NUM> is affixed to the skin <NUM>, even when the skin <NUM> is stretched by the body movement, it is possible to more stably prevent the biological sensor <NUM> from peeling off from the skin <NUM>. It is possible to maintain more stably the state of being affixed to the skin <NUM>.

The biological sensor <NUM> includes the electrode <NUM>, the second substrate <NUM>, and a sensor body <NUM>. The cover member <NUM> has the concave portion 11a on the skin <NUM> side. The porous substrate <NUM> has the through hole 211a in a position corresponding to the concave portion 11a, and the storage space S can be formed by the concave portion 11a and the through hole 211a. Even if the biological sensor <NUM> is provided with the sensor body <NUM> inside the biological sensor <NUM>, the first adhesive layer <NUM> can further suppress the peeling from the skin <NUM>, and the biological sensor <NUM> can maintain the state of stably sticking to the skin <NUM>.

The biological sensor <NUM> includes the third adhesive layer <NUM>, and can form a sticking surface to the living body by the first adhesive layer <NUM> and the third adhesive layer <NUM>. In the biological sensor <NUM>, Even when the third adhesive layer <NUM> is in contact with the skin <NUM>, the third adhesive layer <NUM> can further suppress the peeling from the skin <NUM>, and the biological sensor <NUM> can maintain the state where the third adhesive layer <NUM> is stably affixed to the skin <NUM>.

In addition, the biological sensor <NUM> may provide a through hole <NUM> in the electrode <NUM>. By exposing the first adhesive layer <NUM> through the through hole <NUM> to the sticking side, the adhesion between the electrode <NUM> and the skin <NUM> can be enhanced. Therefore, even when the electrode <NUM> is affixed to the first adhesive layer <NUM>, the biological sensor <NUM> can prevent the first adhesive layer <NUM> from peeling off from the skin <NUM>, and can maintain the state of stably sticking to the skin <NUM>.

As described above, because the biological sensor <NUM> can make it unlikely to peel off from the skin <NUM>, the biological sensor <NUM> may be suitably used for a wearable device for healthcare, such as a biological sensor.

In the following, the embodiments will be more specifically described presenting practical examples and comparative examples. However, the embodiments are not limited by the practical examples and comparative examples.

A first adhesive layer (long-term adhesive tape <NUM> (by Nitto Denko Corporation, thickness: <NUM>)) was formed on a lower surface of a porous substrate <NUM> (polyolefin foam sheet (Folec(TM)), by INOAC Corporation, thickness: <NUM>), formed in a rectangular shape. The long-term adhesive tape <NUM> was a double-sided adhesive tape having a corrugated pattern (web pattern) formed on the surface thereof such that a width of an adhesive agent forming portion without an adhesive agent was about <NUM> and a width of an adherend portion without an adhesive agent was about <NUM>. Thereafter, a second adhesive layer (a silicone tape <NUM> (ST503(HC)<NUM>, by Nitto Denko Corporation, thickness: <NUM>) was formed on an upper surface of a sticking layer. Thus, the first laminated sheet was prepared.

A second laminated sheet, which was a skin tape obtained by sticking adhesive films <NUM> (Permerol, by Nitto Denko Corporation, moisture permeability: <NUM>/m<NUM>·day), as a third adhesive layer, onto both surfaces of a substrate <NUM> (PET (PET-<NUM>-SCA1 (white), by Mitsui & Co. Plastics, Ltd. ), thickness: <NUM>), formed in a rectangular shape, was prepared.

A cover member was prepared by forming a coating layer with a Shore hardness A40 formed of a silicone rubber on a support formed using PET as a base resin, and forming the product in a predetermined shape.

A sensor unit provided with a battery and a controller was deposited in the center of an upper surface of the second laminated sheet. Then, a pair of electrodes were affixed to a sticking surface side of the first adhesive layer in the state of being held by the first adhesive layer of the first laminated sheet and the second laminated sheet, thereby the electrodes were connected to a wiring of the sensor unit. Thereafter, a cover member was laminated on the first laminated sheet so that the sensor unit was arranged within a storage space formed by the first laminated sheet and the cover member. Thus, the biological sensor was prepared.

The moisture permeability of the porous substrate <NUM> was measured according to the conditions of JIS Z <NUM> (Moisture permeability test method of moisture-proof packaging material (cup method)). A test article was prepared from the porous substrate having a width of <NUM> × a length of <NUM> × a thickness of <NUM>, and a mass of the test article was measured. Then, the test article was left under a constant temperature and humidity environment with a temperature of <NUM> and a relative humidity of <NUM>% for <NUM> hours, and the mass of the test article was measured. The moisture permeability of the porous substrate <NUM> at a thickness of <NUM> was calculated by using the following equation (<NUM>).

A shear stress when the sticking layer was deformed by <NUM>%, moisture permeability, and water retention rate were evaluated as characteristics of the sticking layer.

As shown in <FIG>, a double-sided adhesive tape (No. <NUM>, by Nitto Denko Corporation) was affixed to one surface of the sticking layer (<NUM> × <NUM>) and then the sticking layer was held by a pair of stainless steel plates (SUS plates). Then, one stainless steel plate was pulled at a rate of <NUM>/min parallel to the other stainless steel plate, until the length of the sticking layer was deformed by <NUM>% (i.e. <NUM>), and the shear stress when the adhesive layer was deformed by <NUM>% in the length direction was measured.

The moisture permeability of the sticking layer was measured by the same method as the above-described method of the porous substrate <NUM>. The water retention rate of the sticking layer was calculated by using the following equation (<NUM>).

The moisture permeability of the second laminated sheet was measured by the same method as the above-described method for measuring moisture permeability of the porous substrate <NUM>.

As characteristics of the biological sensor obtained as above, a shear stress when the biological sensor is deformed by <NUM>% in the length direction (at <NUM>% deformation of the biological sensor), stability of sticking, and a peel position were evaluated.

As shown in <FIG>, the biological sensor was regarded to be a laminated body including a cover member, a first laminated sheet, and a second laminated sheet, and a test piece was prepared from the laminated body having a width of <NUM> × a length of <NUM>. A test article was prepared by sticking an adhesion surface of the test piece onto a collagen membrane (Nippicasing #<NUM>, by Nippi Collagen Cosmetics, Ltd. ) fixed to a stainless steel plate (SUS plate). Then, the test article was pulled at a range of <NUM>/min parallel to the stainless steel plate, until the length of the test article was deformed by <NUM>%, and the shear stress when the test article was deformed by <NUM>% in the length direction was measured.

The stability of sticking of the biological sensor was evaluated by sticking the biological sensors onto skins of a plurality of men and women for <NUM> hours, respectively, and observing an occurrence of peeling and a position of the peeling. When the biological sensor was not peeled off from the skins of the plurality of men or women, the stability of sticking was evaluated to be excellent (symbol "A" in TABLE <NUM>). When the biological sensor was peeled off from the skin of the plurality of men or women a few times, the stability was evaluated to be good (symbol "B" in TABLE <NUM>). When the biological sensor was peeled off from the skins of all men or women, the stability of sticking of the biological sensor was evaluated to be poor (symbol "C" in TABLE <NUM>). In addition, it was investigated whether a peeling position is within a region between the central portion of the adhesive layer and the electrode in a plan view of the biological sensor (region A in <FIG>) or within a region in which the electrode is disposed in the plan view of the biological sensor (region B in <FIG>).

In Example <NUM>, evaluation was performed in the same manner as Example <NUM>, except that the thickness of the porous substrate <NUM> was changed, and a shear force at <NUM>% deformation of the porous substrate <NUM> was changed in Example <NUM>.

In Examples <NUM> to <NUM>, evaluation was performed in the same manner as Example <NUM>, except that the thickness of the porous substrate <NUM> was changed, a shear force at <NUM>% deformation of the porous substrate <NUM> was changed, and a type of the cover member was changed in Example <NUM>.

In Example <NUM>, evaluation was performed in the same manner as Example <NUM>, except that the thickness of the porous substrate <NUM> was changed, a type of the second adhesive layer of the first laminated sheet was changed to a long-term adhesive tape <NUM>, which will be described below, a shear force at deformation of the sticking layer was changed, and a type of the cover member was changed in Example <NUM>. In addition, the long-term adhesive tape <NUM> was a double-sided adhesive tape, formed of the same adhesive agent as that of the long-term adhesive tape <NUM>. However, a corrugated pattern was not formed on the surface of the long-term adhesive tape <NUM>.

The second adhesive layer: a long-term adhesive tape <NUM> (by Nitto Denko Corporation) with thickness of <NUM>.

In Example <NUM>, evaluation was performed in the same manner as Example <NUM>, except that the thickness of the porous substrate <NUM> was changed, and a type of a second adhesive agent of a sheet layer was changed to a long-term adhesive tape <NUM>, which will be described below, a shear force at deformation of the sticking layer was changed in Example <NUM>.

The second adhesive agent: a long-term adhesive tape <NUM> (SLY-<NUM> by Nitto Denko Corporation) with thickness of <NUM>.

In Comparative example <NUM>, evaluation was performed in the same manner as Example <NUM>, except that the porous substrate <NUM> was not used.

In Comparative example <NUM>, evaluation was performed in the same manner as Example <NUM>, except that the porous substrate <NUM> was changed to a porous substrate <NUM>, and a type of the first adhesive layer on the lower surface of the second laminated sheet was changed to a long-term adhesive tape <NUM>, which will be described below, and a shear force at deformation of the sticking layer was changed in Example <NUM>.

Second adhesive agent: a long-term adhesive tape <NUM> (SLY-<NUM> by Nitto Denko Corporation) with thickness of <NUM>.

TABLE <NUM> shows types of cover members, configuration of the first laminated sheet, configuration of the second laminated sheet, and results of evaluation of the characteristics of the biological sensor in each of the Examples and Comparative examples.

As shown in TABLE <NUM>, in Examples <NUM> to <NUM>, the shear stress was <NUM>×<NUM><NUM> N/m<NUM> or less when the sticking layer was deformed by <NUM>%, and the moisture permeability of the sticking layer was within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day. On the other hand, in Comparative examples <NUM> and <NUM>, the moisture permeability of the sticking layer was <NUM>/m<NUM>·day or less.

Accordingly, different from the biological sensors in Comparative examples <NUM> and <NUM>, the biological sensors in Examples <NUM> to <NUM> can flexibly respond to variations of the skin by setting the shear stress when the sticking layer is deformed by <NUM>% to be <NUM>×<NUM><NUM> N/m<NUM> or less, and setting the moisture permeability of the sticking layer to be within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, thereby enabling water vapor generated from the skin to be discharged to the outside. Thus, peeling from the skin can be suppressed. Accordingly, since the biological sensor according to the embodiment of the present application can be stably affixed to the skin, it is possible to stably detect electrical signals obtained from the living body with high sensitivity. Therefore, the biological sensor can be effectively used for stably measuring the electrocardiogram for a long period of time (e.g. <NUM> hours) in close contact with the subject's skin.

As described above, the embodiments of the present application have been described. However, the embodiments have been illustrated as examples, and the present invention is not limited to the embodiments.

Claim 1:
A biological sensor (<NUM>) that is to be affixed to a living body and is for acquiring a biological signal, the biological sensor comprising:
a cover member (<NUM>); and
a porous substrate (<NUM>) having a porous structure, the porous substrate being disposed on the cover member on a side of the living body,
wherein a sticking layer (<NUM>), including the porous substrate and a first adhesive layer (<NUM>) that is disposed on the porous substrate on a side of the living body, exhibits a shear stress of from <NUM>×<NUM><NUM> N/m<NUM> to <NUM>×<NUM><NUM> N/m<NUM> when the sticking layer is deformed in a direction perpendicular to a thickness direction of the sticking layer by <NUM>% to <NUM>% of a length of the sticking layer, wherein the thickness of the porous substrate is within a range from <NUM> to <NUM> and the thickness of the first adhesive layer is within a range from <NUM> to <NUM>,
wherein a moisture permeability of the sticking layer is within a range from <NUM>/m<NUM>·day to <NUM>/m<NUM>·day, and wherein the biological sensor further comprises:
an electrode (<NUM>) affixed to the first adhesive layer;
a sensor body (<NUM>) that is connected to the electrode and acquires biological information; and
a second substrate (<NUM>) on which the sensor body is mounted,
wherein the cover member includes a concave portion (11a) formed in a recessed shape on a side of the living body,
wherein the porous substrate has a through hole (211a) at a position facing the concave portion, and
wherein the concave portion and the through hole form a storage space (S) for storing the sensor body.