Patent Description:
Conventionally, there are apparatuses that measures biological information of a subject by a sensor sheet with a sensor incorporated therein applied to the body surface of the subject. For example, in the case of electrocardiographic measurement apparatuses, an electrocardiogram of a subject is obtained via electrodes incorporated in a sensor sheet (see Patent Literatures <NUM> and <NUM>).

In the sensor sheet (biological electric signal recording device) disclosed in Patent Literature <NUM>, electrodes are provided in a sheet-like base material that is flexible enough to follow movements of a living body, and the electrodes are surrounded in a watertight manner by the sheet-like base material, such that measurement of electrocardiograms can be made even during bathing in addition to walking, eating and sleeping. PTL <NUM> discloses "a sensor sheet for biological information measurement, the sensor sheet comprising: a first sheet to be applied to a skin of a subject; a second sheet to be stuck to a front surface side of the first sheet; and a measuring element provided in an area in the second sheet, wherein the second sheet is thicker than the first sheet. "
PTL <NUM> discloses a biomedical sensor system. The system can include a sensor adapted to create a signal based on a physiological characteristic from a subject, and a hub adapted to receive the signal from the sensor. The signal can include at least one of an electromagnetic signal, an electrical signal, an acoustic signal, a mechanical signal, a thermal signal, and a chemical signal. The system can further include a connector adapted to couple the sensor and the hub, the connector having a variable length, such that the sensor and the hub can be positioned a variable distance apart by changing the length of the connector. The connector can be adapted to provide a pathway between the sensor and the hub for the signal. A method of applying a biomedical sensor system to a subject can include changing the length of the variable-length connector to provide an appropriate distance between the sensor and the hub, and coupling the sensor to the subject.

Biological information measurement apparatuses, such as represented by Holter monitors, need a sensor sheet to be continuously applied to a body surface over a long period of time in order to continuously obtain biological information over a long period of time via sensors such as electrodes. For example, in a follow-up after an ablation treatment, continuous data of no less than two weeks is supposed to be obtained, and in this case, it is necessary to continuously apply a sensor sheet to the body surface of a subject over no less than two weeks.

However, when a sensor sheet is continuously applied for many days, the sheet comes off or wrinkles or the surface of the body itches, and thus sensor sheets are generally changed every day or every few days. Therefore, as a result of the sensor sheet changes, the data is temporarily discontinued. Also, there are problems such as inconvenience of changing sensor sheets and wasteful disposal of a sheet equipped with electrodes every time sheets are changed. In addition, the position at which the sensor sheet is applied shifts between before and after a sheet sensor change, and thus the obtained data may be affected by the sheet change and may, for example, fluctuate. Therefore, fewest possible sheet changes are desirable.

Conventionally, sheets that are resistant to coming off for many days have already been provided by giving increased adhesive force of sheets. However, in the conventional sensor sheets, no sufficient consideration has not been given to itching experienced by a subject as a result of such sheets being continuously applied for many days. Here, a main purpose of a sensor sheet is to obtain highly-accurate data, and for that purpose, a sensor sheet needs to be brought into firm and close contact with the body surface, resulting in a dilemma that itching is developed by the firm and close contact.

The present invention has been made in consideration the above points and provides a sensor sheet that can reduce itching experienced by a subject when the sensor sheet is applied to the subject over a long period of time, without decreasing a measurement accuracy.

According to the independent claim a sensor sheet for biological information measurement is provided. The sensor sheet includes: a first sheet of no more than <NUM>, to be applied to a skin of a subject; a second sheet to be stuck to a front surface side of the first sheet; and a measuring element provided in an area in the second sheet between the first sheet and the second sheet, in which the second sheet is thicker than the first sheet. The first sheet and the second sheet comprise polyurethane as a main component. The first sheet is higher in stretchability than the second sheet, and the stretchability of a peripheral edge area of the second sheet is higher than that of a center area of the second sheet.

The present invention enables provision of a sensor sheet that can reduce itching experienced by a subject when the sensor sheet is continuously applied to the subject over a long period of time, without decreasing a measurement accuracy.

Prior to description of embodiments of the present invention, the manner how the inventors arrived at the present invention will be described. The inventors of the present invention conducted a detailed study on causes of itching when a sensor sheet is applied to the skin. In addition, the inventors conducted a diligent and comprehensive study on a material, a thickness and a placement of a sensor sheet that enable suppressing itching while suppressing a decrease in measurement accuracy.

The study revealed that causes of itching lie largely in the thickness and the moisture vapor permeability in the peripheral edge portion of a sensor sheet.

A reason that intense itching is developed at the edge portion of a sensor sheet when the sheet is applied to the skin can be thought as follows: while the skin can freely expand and contract in a region to which the sheet is not applied, expansion and contraction of the skin are restricted by the sheet in the region to which the sheet is applied, and accordingly, a large difference occurs in expansion and contraction of the skin around the edge portion of the sheet, causing, e.g., a feeling of discomfort and leading to itching. In consideration of this point, in the present invention, in particular, the thickness of the edge portion of a sheet is reduced. As a result of the thickness of the edge portion of a sheet being reduced in this manner, it is possible that itching is less likely to occur even if the sheet is applied for a long time. Also, as a result of the thickness of the edge portion of a sheet being reduced, even if the sheet is tensioned by a movement of the body, the edge portion of the sheet can flexibly follow the movement, the edge portion of the sheet is less likely to wrinkle, and thus the edge portion of the sheet is prevented from coming off. As a result, the prevention of the edge portion of the sheet from coming off leads to suppression of the entire sheet coming off. In other words, the sheet generally starts coming off at the edge portion, but employment of the configuration provided by the present invention enables effectively prevents the edge portion of the sheet from coming off.

Also, for a material of the sheet, polyurethane, which has an excellent moisture vapor permeability, is used. Consequently, a rash caused by sweating is suppressed, enabling further suppression of itching.

Furthermore, in a part other than the edge portion of the sheet, the thickness in the part to which electrodes, wires, gels and a terminal are attached of the sheet is made to be thicker than that of the edge portion. Consequently, the sheet can be prevented from being torn and such components can stably be held.

A sensor sheet according to the present invention is a sensor sheet ensuring all of itching prevention, prevention of the sheet coming off and stable holding of mounted components.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<FIG> is an exploded perspective view illustrating an overall configuration of a sensor sheet according to Embodiment <NUM> of the present invention. <FIG> is a top view of the sensor sheet with a terminal attached thereto. The sensor sheet is attached to the chest region of a subject and used to obtain an electrocardiogram.

The present embodiment will be described in terms of a case where a terminal to be attached to a sensor sheet is a recording terminal including a memory and a coin cell housed inside a case thereof; however, the terminal to be attached to the sensor sheet is not limited to this type of terminal. For example, the terminal may be a terminal that includes a wireless transmission section inside a case and wirelessly transmits biological information measured by the sensor sheet. Also, the terminal may be, for example, a telemeter.

As illustrated in <FIG>, before use, sensor sheet <NUM> is held between liner <NUM> and top separator <NUM>. Then, in use, liner <NUM> and top separator <NUM> are removed and sensor sheet <NUM> is applied to the chest region, and as illustrated in <FIG>, terminal <NUM> is attached to the front surface side.

Sensor sheet <NUM> includes lower sheet (first sheet) <NUM> and upper sheet (second sheet) <NUM>. Electric circuit section <NUM>, which serves as a measuring element, is disposed between lower sheet <NUM> and upper sheet <NUM>. An adhesion layer is provided on a surface on the skin side of each of lower sheet <NUM> and upper sheet <NUM>, and consequently, lower sheet <NUM> is to be applied to the skin of a subject and upper sheet <NUM> is stuck to the front surface side of lower sheet <NUM>. Electric circuit section <NUM> is held between lower sheet <NUM> and upper sheet <NUM> as a result of upper sheet <NUM> being stuck to the front surface side of lower sheet <NUM>.

Upper sheet <NUM> is smaller in area than lower sheet <NUM>. The area of upper sheet <NUM> is large enough to cover electric circuit section <NUM>. More specifically, as can be seen from <FIG>, which illustrates upper sheet <NUM> stuck to lower sheet <NUM>, peripheral edge portion 110a, which is formed of lower sheet <NUM> alone, is formed over an entire circumference of sensor sheet <NUM> while electric circuit section <NUM> is fully covered by upper sheet <NUM>.

Electric circuit section <NUM> includes tongue piece <NUM>, a plurality of wires <NUM> extending from tongue piece <NUM>, and a plurality of electrodes <NUM> formed at terminal ends of respective wires <NUM>.

Holes <NUM> are formed at positions in lower sheet <NUM> that correspond to respective electrodes <NUM>, and gels <NUM> are disposed at positions corresponding to respective holes <NUM>. Consequently, electrodes <NUM> are electrically connected to the skin via gels <NUM>, and electric conductivity between the skin and electrodes <NUM> is enhanced by gels <NUM>.

Connector <NUM> to be connected to terminal <NUM> is provided on the front surface side of tongue piece <NUM>. Hole <NUM> is formed at a position in upper sheet <NUM>, the position corresponding to tongue piece <NUM>. Consequently, in a state in which upper sheet <NUM> is stuck to lower sheet <NUM>, tongue piece <NUM> is exposed on the front surface side of upper sheet <NUM> via hole <NUM>.

Furthermore, hole <NUM> is formed at a position in top separator <NUM>, the position corresponding to connector <NUM>. Consequently, connector <NUM> is exposed on the front surface side of top separator <NUM> via hole <NUM>.

Here, lower sheet <NUM> includes a base material formed of polyurethane and the adhesion layer formed on the surface on the skin side of the base material. Likewise, upper sheet <NUM> includes a base material formed of polyurethane and the adhesion layer formed on the surface on the skin side of the base material. As described above, sheets <NUM>, <NUM> are each formed of polyurethane having a high moisture vapor permeability, enabling suppression of a skin rash caused by sweating and thus enabling suppression of itching caused by a rash.

For further information, polyurethane has the characteristic of transmitting water vapor and not transmitting collected water (that is, transmitting small particles such as water vapor, but not transmitting a large mass of water such as collected water or a water droplet), and thus, when the subject takes a bath, there is almost no permeation of water from the front surface side to the skin side of upper sheet <NUM>. Therefore, entry of water from the front surface side of upper sheet <NUM> to wires <NUM> and electrodes <NUM> can be suppressed, enabling prevention of a short in the electric circuit even when the subject takes a bath with sensor sheet <NUM> applied.

Although in the present embodiment, lower sheet <NUM> and upper sheet <NUM> are both formed of polyurethane, itching is likely to occur particularly at a peripheral edge portion of a sheet, and thus, it is possible that, in configurations useful to understand the claimed invention, only lower sheet <NUM> including peripheral edge portion 110a is formed of polyurethane; and upper sheet <NUM> is formed of a material other than polyurethane. Furthermore, in configurations useful to understand the claimed invention, for materials of lower sheet <NUM> and upper sheet <NUM>, any of various materials other than polyurethane can be used as long as such materials are ones that can prevent entry of water that causes a short in wires <NUM> and electrodes <NUM> while transmitting moisture resulting from sweating. For example, foamed polyethylene or a non-woven material may be used. Also, lower sheet <NUM> and upper sheet <NUM> are not necessarily formed of polyurethane alone, and may be formed of a material containing polyurethane as a main component.

However, the inventors found out that polyurethane is most excellent for materials of lower sheet <NUM> and upper sheet <NUM>. Here, for lower sheet <NUM> and upper sheet <NUM>, for example, almost no permeation of water from the front surface side to the skin side of upper sheet <NUM> when the subject takes a bath (that is, waterproof property), the capability of being used for a long period of time without being torn (that is, durability), a flexibly enabling following movements of the skin (that is, stretchability), and the capability of being thinned are required. Polyurethane is desirable in all of waterproof property, durability, stretchability and the capable of being thinned. On the other hand, foamed polyethylene is poor in durability and the capability of being thinned. Non-woven fabric is poor in waterproof property.

Lower sheet <NUM> in the present embodiment has a thickness of <NUM>. This thickness is much smaller than a thickness of around <NUM>, which is a thickness of a conventional sheet of this type. On the other hand, upper sheet <NUM> has a thickness that is larger than that of lower sheet <NUM>. In the case of the present embodiment, upper sheet <NUM> has a thickness of <NUM><NUM>. In other words, in the case of the present embodiment, while peripheral edge portion 110a formed of lower sheet <NUM> alone has a thickness of <NUM> [µm] and thus, is very thin, a center area in which electric circuit section <NUM> is held has a thickness of <NUM> including the thicknesses of lower sheet <NUM> and upper sheet <NUM>. Consequently, even if peripheral edge portion 110a is very thin, the center area in which electric circuit section <NUM> is held is thick, enabling a measurement accuracy decrease to be prevented without a decrease in reliability of electric circuit section <NUM>.

In particular, it is desirable that upper sheet <NUM> be made to be thicker than lower sheet <NUM>. In other words, in configurations useful to understand the claimed invention, it is only necessary to form upper sheet <NUM> so as to be higher in strength than lower sheet <NUM>. For example, upper sheet <NUM> may be formed of a material having a strength that is higher than that of lower sheet <NUM>.

The reason why a conventional sheet has a large thickness including a peripheral edge portion thereof is that a priority is placed on suppression of damage of the sheet and highly reliable holding of electric circuit section <NUM>, which serves as a measuring element, and no sufficient consideration is given to itching caused when the sheet is continuously applied for a long period of time.

In the present invention, as described above, paying attention to the point that itching can substantially be reduced if peripheral edge portion 110a follows the skin, lower sheet <NUM> was studied in terms of material and thickness. As a result, it has been found that if lower sheet <NUM> is formed of polyurethane in consideration of moisture vapor permeability, itching is less likely to occur even if lower sheet <NUM> is continuously applied for around two weeks as long as lower sheet <NUM> has a thickness of no more than <NUM>.

In other words, in the claimed invention, forming lower sheet <NUM> from polyurethane and making lower sheet <NUM> have a thickness of no more than <NUM> are proposed.

Also, as described above, lower sheet <NUM> is made to have a very small thickness of no more than <NUM> and is thus superior in following the skin, which provides the advantage of enabling provision of a sheet that is less likely to come off in addition to suppression of itching. In other words, a sheet almost always starts coming off at a peripheral edge portion and thus, can be prevented from coming off by the configuration provided by the present embodiment.

Wires <NUM> and electrodes <NUM> are configured by forming a metal layer on a base material formed of, e.g., PET (polyethylene terephthalate) or PEN (polyethylene naphthalate). The base material has a thickness of, for example, around <NUM> to <NUM>.

It is also possible that wires <NUM> and electrodes <NUM> are formed directly on upper sheet <NUM> or lower sheet <NUM>; however, in the case of the present embodiment, wires <NUM> and electrodes <NUM> are formed on, e.g., the base material formed of, e.g., PET (polyethylene terephthalate) or PEN (polyethylene naphthalate), enabling prevention of occurrence of, e.g., disconnection.

Here, the base material formed of, e.g., PET (polyethylene terephthalate) or PEN (polyethylene naphthalate) is less flexible than polyurethane, which is the material of lower sheet <NUM> and upper sheet <NUM>. Therefore, in the case of the present embodiment, wires <NUM> have a pattern including a meandering pattern. Consequently, wires <NUM> follows movements of the body surface (skin) well. As a result, the capability of following the skin can be enhanced also in the area of electric circuit section <NUM>, as well as peripheral edge portion 110a, enabling further suppression of occurrence of itching. However, wires <NUM> do not necessarily need to be made to meander, and wires <NUM> may be formed in a shallow curve or a linear fashion.

Tongue piece <NUM> is thicker than the base material of wires <NUM> and electrodes <NUM>. Terminal <NUM> is detachably attached to connector <NUM> provided on tongue piece <NUM>. A structure of the attachment of connector <NUM> to terminal <NUM> will be described later.

Next, a procedure for applying sensor sheet <NUM> to the chest region of a subject will be described.

When sensor sheet <NUM> is applied to a predetermined position in the chest region, first, liner <NUM> is removed and sensor sheet <NUM> is pressed against the predetermined position in the chest region together with top separator <NUM> to apply lower sheet <NUM> to the predetermined position in the chest region.

Top separator <NUM> is rubbed from above in this state, whereby lower sheet <NUM> is firmly applied to the skin of the subject. For further information, an adhesion layer having a small adhesive force enough to hold sensor sheet <NUM> is formed on a lower surface of top separator <NUM>.

The provision of top separator <NUM> enables prevention of twisting of peripheral edge portion 110a of very thin lower sheet <NUM>. Hole <NUM> for avoiding connector <NUM> is formed at a center of top separator <NUM>. A user holds areas in the periphery of hole <NUM> between his/her fingers and separate and peel back top separator <NUM> so as to be separated and removed outward like opening a double door, whereby top separator <NUM> is removed from sensor sheet <NUM>. As described above, as a result of top separator <NUM> being removed from sensor sheet <NUM> from the center to the edge side of sensor sheet <NUM>, rather than from the edge side, lower sheet <NUM> is strained by top separator <NUM>, enabling reduction in possibility of the edge of lower sheet <NUM> peeling off and wrinkling.

After sensor sheet <NUM> is applied to the chest region to the subject in this way, the user attaches terminal <NUM> to connector <NUM> of sensor sheet <NUM>.

<FIG> are diagrams illustrating a configuration of terminal <NUM>; <FIG> is a perspective view, <FIG> is a side view and <FIG> is a bottom view.

Terminal <NUM> includes, e.g., a coin cell and a memory incorporated therein. Upon power supply button <NUM> being pressed, terminal <NUM> starts an electrocardiographic measurement and recording operation, and records an electrocardiogram based on an electrocardiographic signal from the sensor sheet. This measurement and recording operation is a known technique and thus, description thereof will be omitted.

As illustrated in <FIG>, attachment section <NUM> to be detachably attached to connector <NUM> provided in sensor sheet <NUM> is provided in a back surface of terminal <NUM>.

<FIG> are cross-sectional views for description of a structure of attachment of terminal <NUM> to sensor sheet <NUM>. <FIG> is a cross-sectional view before attachment, and <FIG> is a cross-sectional view after attachment.

<FIG> are perspective views for description of a structure of attachment of terminal <NUM> to sensor sheet <NUM>; <FIG> is a perspective view before attachment, and <FIG> is a perspective view after attachment.

Here, connector <NUM> provided on the sensor sheet <NUM> side includes packing <NUM> having an oval shape in plan view. Terminal ends of wires <NUM>, other ends of which are connected to respective electrodes <NUM>, are disposed on an area in tongue piece <NUM>, the area being surrounded by packing <NUM>.

Also, insertion opening <NUM> having a size that allows packing <NUM> to be just fitted therein is formed in the back surface of terminal <NUM>. Inside insertion opening <NUM>, spring probes <NUM> and USB port <NUM> are disposed.

Consequently, as illustrated in <FIG>, upon insertion of packing <NUM> to insertion opening <NUM> in the back surface of terminal <NUM>, spring probes <NUM> are brought into abutment with the terminal ends of wires <NUM>, the terminal ends being exposed on tongue piece <NUM>, at a predetermined pressure, whereby the spring probes <NUM> and the wires <NUM> are electrically interconnected, respectively. Also, in this state, the inner side surrounded by packing <NUM> is prevented from entry of water from the outside. In other words, the plurality of spring probes <NUM> and the plurality of wires <NUM> are electrically connected without short-circuiting caused by water.

Furthermore, inside insertion opening <NUM>, USB port <NUM> is disposed in addition to spring probes <NUM>, and thus, when electrocardiographic measurement is being performed with terminal <NUM> attached to sensor sheet <NUM>, USB port <NUM> cannot be used. Consequently, the risk of electrical shock caused by connection of an external electronic device to USB port <NUM> during electrocardiograph measurement can reliably be eliminated. In other words, in the present embodiment, the contacts for electrocardiographic measurement (spring probes <NUM>) and USB port <NUM> are prevented from being connected simultaneously to ensure safety. Furthermore, the contacts for electrocardiographic measurement (spring probes <NUM>) and USB port <NUM> are housed inside packing <NUM> and are thus waterproofed at the same time. In other words, both waterproofing and safety can be ensured by the simple configuration.

Furthermore, as illustrated in <FIG>, wide portion <NUM> is formed at a distal end of tongue piece <NUM>. Also, locking cut <NUM> is formed in the back surface of terminal <NUM>. Upon insertion of packing <NUM> of connector <NUM> to insertion opening <NUM>, wide portion <NUM> of tongue piece <NUM> engages with locking cut <NUM>, whereby terminal <NUM> is locked by tongue piece <NUM> so as not to move in the arrow Z direction (direction around the ground where terminal <NUM> is attached).

Furthermore, hook-and-loop fastener <NUM> is firmly fixed to the front surface side of upper sheet <NUM>. Hook-and-loop fastener <NUM> can be joined to hook-and-loop fastener <NUM> provided on the back side of terminal <NUM>.

Consequently, upon insertion of packing <NUM> to insertion opening <NUM>, terminal <NUM> is held on sensor sheet <NUM> by engagement between tongue piece <NUM> and locking cut <NUM> and joining between hook-and-loop fasteners <NUM>, <NUM>. Here, hook-and-loop fasteners <NUM>, <NUM> have only a small holding force in a direction perpendicular to the surface, but have a large force in the surface direction. Therefore, tongue piece <NUM> and hook-and-loop fasteners <NUM>, <NUM> reliably prevent terminal <NUM> from dropping in the surface direction.

Here, terminal <NUM> engages with tongue piece <NUM> at an upper portion and thereby hang down with tongue piece <NUM> as an axis. Upon terminal <NUM> being lightly pushed to the sensor sheet <NUM> side (that is, the subject side) in this state, hook-and-loop fasteners <NUM>, <NUM> are joined to each other and terminal <NUM> are thereby prevented from wobbling. In fact, terminal <NUM> is held by tongue piece <NUM> so as to be at least partly floated from sensor sheet <NUM>.

The subject perceives terminal <NUM> via the skin at the part of the joining between tongue piece <NUM> and the packing <NUM> and the part of the joining between hook-and-loop fasteners <NUM>, <NUM>, and as a result, for example, a feeling of discomfort the subject have due to the presence of terminal <NUM> can be reduced compared to a case where the entire back surface of terminal <NUM> is firmly fixed to sensor sheet <NUM>. A further decrease in area of hook-and-loop fasteners <NUM>, <NUM> enables further reduction of a feeling of discomfort the subject has.

Furthermore, hook-and-loop fastener <NUM> is disposed at a position corresponding to gel <NUM>. Consequently, the gel serves as a buffer, which makes the subject be less likely to feel the presence of terminal <NUM>.

Instead of hook-and-loop fasteners <NUM>, <NUM>, for example, a snap fastener or magnets may be used. In brief, any various rejoinable joining devices can be used.

As described above, according to the present embodiment, lower sheet (first sheet) <NUM> to be applied to the skin of a subject, upper sheet (second sheet) <NUM> stuck to the front surface side of lower sheet <NUM>, and electric circuit section (measuring element) <NUM> provided in an area corresponding to upper sheet <NUM> are provided, peripheral edge portion 110a has a single-layer structure including lower sheet <NUM> alone, and the center area has a multi-layer structure including lower sheet <NUM> and upper sheet <NUM>, whereby while the capability of following the skin is enhanced in sheet peripheral edge portion 110a, which is likely to cause itching, electric circuit section (measuring element) <NUM> can firmly be held in the center area, and thus, sensor sheet <NUM> that can reduce itching experienced by the subject when sensor sheet <NUM> is continuously applied to the subject over a long period of time can be provided without decreasing measurement accuracy. In particular, sensor sheet <NUM> can significantly reduce itching experienced by a subject when sensor sheet <NUM> is applied to the subject for no less than two weeks, compared to conventional sensor sheets.

Also, as a result of upper sheet (second sheet) <NUM> being made to be thicker than lower sheet (first sheet) <NUM>, electric circuit section (measuring element) <NUM> can more firmly held while the capability of following the skin is further be enhanced in sheet peripheral edge portion 110a.

Also, as a result of lower sheet <NUM> being formed of a material containing polyurethane as a main component and being made to have a thickness of no more than <NUM>, itching can further be reduced.

Although Embodiment <NUM> above has been described in terms of a sensor sheet according to the present invention in which all of electrodes <NUM> are held inside single sheets <NUM>, <NUM>, the present invention is applicable to a sheet in which in electrodes <NUM> are disposed on individual sheets and electrodes <NUM> are interconnected via lead wires to be not applied to a subject. However, in Embodiment <NUM> above, electrodes <NUM>, wires <NUM> and tongue piece <NUM> are integrally formed, and thus, a signal with small noise can be obtained in comparison to a configuration in which electrodes <NUM>, wires <NUM> and tongue piece <NUM> are formed separately and interconnected via cables or connection sections.

Also, although Embodiment <NUM> above has been described in terms of the case where electric circuit section <NUM> including, e.g., wires <NUM> and electrodes <NUM> is mounted in sensor sheet <NUM>, a measuring element mounted in a sensor sheet according to the present invention is not limited to electric circuit section <NUM>. For example, an optical component for measuring SpO<NUM> may be mounted. A sensor sheet according to the present invention may be employed as a sensor sheet for measuring any of various types of biological information if a measuring element mounted in the sensor sheet is selected according to the object to be measured.

Also, although Embodiment <NUM> above has been described in terms of the case where electric circuit section <NUM>, which serves as a measuring element, is disposed between lower sheet <NUM> and upper sheet <NUM>, a measuring element may be disposed on upper sheet <NUM>.

Also, although Embodiment <NUM> above has been described in terms of the case where the center area of sensor sheet <NUM> has a multi-layer structure including lower sheet <NUM> and upper sheet <NUM>, the center area may have a single-layer structure including upper sheet <NUM> alone with no lower sheet <NUM> provided. Even in such case, upper sheet <NUM> is made to be higher in strength than lower sheet <NUM>, enabling provision of both a force for holding the measuring element in the center area and the capability of following the skin in peripheral edge portion 110a.

Also, although Embodiment <NUM> above has been described in terms of the case where tongue piece <NUM> is formed separately from upper sheet <NUM>, tongue piece <NUM> may be formed integrally with upper sheet <NUM>. In other words, tongue piece <NUM> may be provided so as to extend from upper sheet <NUM>.

Furthermore, although Embodiment <NUM> above has been described in terms of a case where a sensor sheet according to the present invention is applied to the chest region of a subject in use, a sensor sheet according to the present invention may be applied not only to the chest region, but also regions other than the chest region, such as the abdominal region or the back, of a subject in use. In brief, a sensor sheet according to the present invention can arbitrarily be applied to a region suitable for obtainment of biological information.

These points are applicable also to Embodiment <NUM> described below.

<FIG>, which illustrates parts corresponding to parts in <FIG> with reference numerals that are the same as those in <FIG> provided thereto, is an exploded perspective view illustrating an overall configuration of a sensor sheet according to Embodiment <NUM>. <FIG> is a top view of the sensor sheet according to Embodiment <NUM> with a terminal attached thereto.

In sensor sheet <NUM> according to the present embodiment, lower sheet <NUM> is higher in stretchability than upper sheet <NUM>, and consequently, even if the sheet is tensioned by a movement of the body, peripheral edge portion 410a having a high stretchability flexibly follows the movement, enabling suppression of itching, wrinkling, and coming-off of the sheet at an edge portion thereof.

In addition to such configuration, a plurality of slits <NUM> are formed in an edge portion of upper sheet <NUM>. Slits <NUM> are formed over an entire circumference of the edge portion. Slits <NUM> are formed so as to extend in a direction toward a center of upper sheet <NUM>, which is perpendicular to a direction of a tangent to the edge portion. An interval and a length of slits <NUM> may arbitrarily be determined according to, e.g., a difference in stretchability between lower sheet <NUM> and upper sheet <NUM>. For example, it is possible that as the difference in stretchability is larger, slits <NUM> are longer or the interval of slits <NUM> is shorter. Also, the length and the interval of slits <NUM> do not need to be constant over the entire circumference. In the case of the present embodiment, the interval of slits <NUM> is <NUM>, and the length of slits <NUM> is <NUM>.

As described above, as a result of slits <NUM> being formed in upper sheet <NUM>, upper sheet <NUM> coming off from lower sheet <NUM> can be suppressed. In other words, in the present embodiment, the stretchability of lower sheet <NUM> is made to be higher than that of upper sheet <NUM>, and thus, a difference in stretch occurs between lower sheet <NUM> and upper sheet <NUM>, and as a result, when sensor sheet <NUM> is continuously applied to the body surface over a long period of time, upper sheet <NUM> may come off from lower sheet <NUM>. Such coming-off is highly likely to start at the edge portion of upper sheet <NUM> at which the stretchability sharply changes. Therefore, in the present embodiment, slits <NUM> are formed in the edge portion of upper sheet <NUM> to moderate such sharp stretchability change and thereby suppress upper sheet <NUM> coming off from lower sheet <NUM>. In the present embodiment, slits <NUM> make a peripheral edge area of upper sheet <NUM> be a buffer area having a stretchability that is lower than that of lower sheet <NUM> and higher than that of a center area of upper sheet <NUM>.

As a result of provision of slits <NUM>, a shear stress caused by the stretchability difference, the shear stress causing two types of sheets to come off from each other, is reduced by slits <NUM>. For further information, the slit parts partially come off, but the degree of the coming-off is such that sensor sheet <NUM> can sufficiently function as an electrocardiographic electrode. If no slits <NUM> are provided, the coming-off may become large and develop to the degree that the sensor sheet <NUM> cannot sufficiently function as an electrocardiographic electrode, for example, lower sheet <NUM> and upper sheet <NUM> may be separated from each other.

Although in the present embodiment, slits <NUM> are formed in the edge portion of upper sheet <NUM>, the present invention is not limited to this case, and in brief, the stretchability of peripheral edge area of upper sheet <NUM> just needs to be higher than that of the center area of upper sheet <NUM>. Therefore, for example, the peripheral edge area of upper sheet <NUM> may be formed of a material having a stretchability that is higher than that of the center area of upper sheet <NUM> or a thickness of the peripheral edge area of upper sheet <NUM> may be made to be smaller than that of the center area of upper sheet <NUM>.

As described above, according to the present embodiment, in addition to the configuration of Embodiment <NUM>, in consideration of lower sheet (first sheet) <NUM> having a high stretchability than that of an area in upper sheet (second sheet) <NUM>, the stretchability of the peripheral edge area of upper sheet (second sheet) <NUM> is made to be higher than that of the center area of upper sheet (second sheet) <NUM>, enabling suppression of upper sheet (second sheet) <NUM> coming off from lower sheet (first sheet) <NUM>. As a result, more reliable measurement can be performed.

Sensor sheet <NUM> according to the present embodiment is a sensor sheet for biological information measurement, the sensor sheet including:.

In sensor sheet <NUM> according to the present embodiment, the peripheral edge area of the second sheet is a buffer area having a stretchability that is lower than that of the first sheet and higher than that of the center area of the second sheet.

Sensor sheet <NUM> according to the present embodiment includes slits formed in the peripheral edge area of the second sheet.

In sensor sheet <NUM> according to the present embodiment, the peripheral edge area of the second sheet is formed of a material having a stretchability that is higher than that of the center area of the second sheet.

Also, although Embodiments <NUM> and <NUM> above have been described in terms of a case where an upper sheet (second sheet) is smaller in area than a lower sheet (first sheet), the present invention is not necessarily limited to this case. For example, where a second sheet is attached to a first sheet in such a manner that the second sheet is folded, the second sheet may be larger in area than the first sheet, and the prevent invention is also effective in such case. In other words, the present invention is widely effective for cases where a second sheet is attached to a center area on the front surface side of a first sheet except a peripheral edge area of the first sheet.

Claim 1:
A sensor sheet (<NUM>) for biological information measurement, the sensor sheet (<NUM>) comprising:
a first sheet (<NUM>) to be applied to a skin of a subject
a second sheet (<NUM>) to be stuck to a front surface side of the first sheet (<NUM>); and
a measuring element (<NUM>) provided in an area in the second sheet (<NUM>) between the first sheet (<NUM>) and the second sheet (<NUM>),
characterized in that:
the first sheet (<NUM>) is no more than <NUM> thick,
the first sheet (<NUM>) and the second sheet (<NUM>) comprise polyurethane as a main component,
the second sheet (<NUM>) is thicker than the first sheet (<NUM>),
the first sheet (<NUM>) is higher in stretchability than the second sheet (<NUM>), and
the stretchability of a peripheral edge area of the second sheet (<NUM>) is higher than that of a center area of the second sheet (<NUM>).