WO2021070607A1

WO2021070607A1 - Biological sensor and method for using biological sensor

Info

Publication number: WO2021070607A1
Application number: PCT/JP2020/035707
Authority: WO
Inventors: 夕輝植屋
Original assignee: ヤマハ株式会社
Priority date: 2019-10-11
Filing date: 2020-09-23
Publication date: 2021-04-15
Also published as: JP2021061971A

Abstract

A biological sensor (1) according to an aspect of the present invention is provided with: a piezoelectric sheet (10) having a band shape; and a cover member (30) covering the piezoelectric sheet (10), wherein the cover member (30) is curved along the longitudinal direction of the piezoelectric sheet (10), and the piezoelectric sheet (10) is located at a curved section of the cover member (30).

Description

How to use biosensors and biosensors

The present invention relates to a biosensor and a method of using the biosensor.

For example, measurement or observation of vibrations generated inside the living body such as heartbeat, pulse wave, blood flow sound, and breathing sound (not limited to sonic vibration in the audible range, including low frequency vibration and ultrasonic vibration in the non-audible range). By doing so, for example, diagnosis, health management, and the like can be performed.

Examples of the biological sensor for detecting the vibration of the living body include a piezoelectric sensor, a foam sheet laminated and integrated on one surface of the piezoelectric sensor, and a shape-retaining plate laminated and integrated on the other surface of the piezoelectric sensor. Is known (see JP-A-2014-147571). In this known biosensor, a weak biovibration such as a pulse wave can be detected by locating the subject's arm or the like on the foam sheet.

In the conventional biosensor, the piezoelectric sensor is held by the shape-retaining plate so as not to bend, so that when the biosensor is applied to a curved surface such as the surface of the arm to measure the biovibration, the movement of the arm during measurement is used. If the position of the biosensor is displaced, it may be difficult to stably measure the biovibration such as a pulse wave.

Japanese Unexamined Patent Publication No. 2014-147571

In view of the above circumstances, the present invention is a biosensor and a biosensor capable of easily and stably measuring biovibration even when the biovibration such as a pulse wave is measured by applying it to a curved surface of the skin. The subject is to provide a method of using.

The biosensor according to one aspect of the present invention includes a strip-shaped piezoelectric sheet and a cover member that covers the piezoelectric sheet, and the cover member is curved along the longitudinal direction of the piezoelectric sheet. It is located at the curved portion of the cover member.

A method of using the biosensor according to another aspect of the present invention includes a step of fixing the biosensor of the present invention on the surface of the forearm so that the longitudinal direction of the band-shaped piezoelectric sheet is orthogonal to the fingertip direction of the forearm. A step of measuring the biological vibration after the fixing step is provided.

FIG. 1 is a schematic exploded perspective view showing a biosensor according to an embodiment of the present invention. FIG. 2 is a schematic side view of the biosensor of FIG. FIG. 3 is a schematic cross-sectional view when the biosensor of FIG. 2 is cut along the line AA. FIG. 4 is a schematic exploded perspective view showing a biosensor different from that of FIG.

In the biosensor according to one aspect of the present invention, the cover member is curved along the longitudinal direction of the piezoelectric sheet, and the piezoelectric sheet is located at the curved portion of the cover member. Therefore, it is easy to apply the longitudinal direction of the piezoelectric sheet to the curved surface of the skin. Further, since the piezoelectric sheet has a band shape, the biological sensor can detect the biological vibration if any position in the longitudinal direction of the piezoelectric sheet is in contact with a portion capable of detecting the biological vibration. Therefore, the biosensor can easily and stably measure the biovibration even when the biosensor is applied to the curved surface of the skin to measure the biovibration.

It is preferable that the curved portion of the cover member has flexibility along the longitudinal direction.

It is preferable that the flexibility of the curved portion of the cover member increases toward one end side in the longitudinal direction.

It is preferable that the thickness of the cover member gradually decreases toward one end side in the longitudinal direction.

The radius of curvature of the curved portion of the cover member is preferably 20 cm or more and 50 cm or less.

It is preferable that the cover member has a recess capable of accommodating a detection circuit for detecting the potential difference of the piezoelectric sheet.

A spacer that surrounds the periphery of the piezoelectric sheet is further provided, and the front side surface of the piezoelectric sheet facing the living body to be measured and the front side surface of the spacer are flush with each other, or the front side surface of the piezoelectric sheet is the front surface of the spacer. It is good that it protrudes from the side surface.

The length of the piezoelectric sheet in the longitudinal direction is preferably 10 mm or more and 25 mm or less, and the length of the piezoelectric sheet in the width direction is preferably 2 mm or more and 4 mm or less.

The biosensor includes a plurality of the piezoelectric sheets, and it is preferable that the plurality of piezoelectric sheets are arranged in parallel so that their longitudinal directions are parallel to each other.

[First Embodiment]
Hereinafter, the biosensor and the method of using the biosensor according to the first embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

The biosensor 1 shown in FIGS. 1 to 3 includes a sensor unit 20 having a strip-shaped piezoelectric sheet 10, a cover member 30 covering the sensor unit 20, and a detection circuit 40 connected to the sensor unit 20.

As shown in FIG. 2, the biosensor 1 includes a curved portion. Specifically, the cover member 30 included in the biosensor 1 is curved from the base end α to the tip end β in FIG. 2 along the longitudinal direction of the piezoelectric sheet 10 included in the sensor unit 20. Further, the cover member 30 has a curved portion 31 and a flat portion 32 continuous with the base end α of the curved portion 31 (the end portion opposite to the tip end β on one end side in the longitudinal direction). In the biosensor 1, the sensor unit 20 is located on the inner surface side of the curved portion 31 of the cover member 30, and the sensor unit 20 is curved along the cover member 30. That is, in the biosensor 1, the piezoelectric sheet 10 is located at the curved portion 31 of the cover member 30. In the present invention, the "inner surface side" refers to the surface side where the inner circumference of the curved portion of the cover member is located.

The biological sensor 1 is brought into contact with a living body to acquire biological vibration. In order to measure the pulse wave of the human body, which is one of the biological vibrations, with the biological sensor 1, it is preferable to bring the biological sensor 1 into contact with the forearm W, which easily acquires the pulse wave from the artery. As shown in FIG. 2, the biosensor 1 can measure a pulse wave by applying a curved portion 31 of the biosensor 1 to a curved surface portion of the surface of the forearm W. At this time, the biosensor 1 is placed so that the curved portion 31 thereof is along the curved surface portion of the surface of the forearm W.

<Cover member>
As shown in FIG. 1, the cover member 30 is made of a rectangular plate having a curved portion. The width and length of the cover member 30 are appropriately determined so as to cover the piezoelectric sheet 10.

Examples of the material of the cover member 30 include resin, metal, glass, and rubber. Among them, as the material of the cover member 30, a resin whose flexibility is easily controlled is preferable.

Examples of the resin include acrylic resin, polycarbonate, polypropylene, polyamide, acrylonitrile-butadiene-styrene copolymer (ABS) and the like. Further, examples of the metal include aluminum, copper and the like.

The curved portion 31 of the cover member 30 has flexibility along the longitudinal direction of the piezoelectric sheet 10 (hereinafter, also simply referred to as “longitudinal direction”) of the sensor unit 20. That is, the curved portion 31 bends. Since the curved portion 31 of the cover member 30 has flexibility along the longitudinal direction in this way, the curved portion 31 can be brought into contact with the curved surface portion of the surface of the forearm W while bending. That is, the sensor unit 20 can be brought into contact with the forearm W without excessively deforming the curved surface shape. In addition, "the curved portion 31 of the cover member 30 has flexibility" means that the curvature indicating the degree of curvature of the curved portion 31 can be changed.

The flexibility of the curved portion 31 of the cover member 30 can be adjusted by selecting the material of the cover member 30 and controlling the thickness thereof.

It is preferable that the flexibility of the curved portion 31 of the cover member 30 increases toward one end side in the longitudinal direction. In the biosensor 1 shown in FIG. 2, the flexibility of the curved portion 31 of the cover member 30 is on the side opposite to the flat portion 32 from the boundary (base end α) between the flat portion 32 and the curved portion 31 of the cover member 30. It increases toward one end side (tip β) of. By increasing the flexibility of the curved portion 31 of the cover member 30 toward one end side in the longitudinal direction in this way, the curved portion 31 comes into contact with the curved surface portion of the forearm W while being deformed from the easily flexible portion on the tip end side thereof. Can be made to. That is, the sensor unit 20 is brought into contact with the forearm W while maintaining the curved shape of the forearm W (without strongly pressing the forearm W) and naturally bending the curved portion 31 with respect to the curved surface portion of the forearm W. Can be done.

In the curved portion 31 of the cover member 30, the region where the flexibility increases toward one end side (tip β) (hereinafter, also referred to as “flexibility increasing region”) is the entire curved portion 31. It may be a part of the curved portion 31. When the flexibility increasing region is a part of the curved portion 31, the flexibility increasing region preferably includes a region in which the piezoelectric sheet 10 included in the sensor unit 20 is arranged.

Further, it is preferable that the thickness of the cover member 30 gradually decreases toward the one end side (tip β) in the longitudinal direction. By gradually reducing the thickness of the cover member 30 toward the tip β in this way, the flexibility of the cover member 30 can be easily increased toward the tip β.

Notches extending in the direction perpendicular to the longitudinal direction may be made on the inner surface side, the outer surface side, or both sides of the cover member 30. By gradually increasing the density of the cuts toward one end side in the longitudinal direction, the flexibility of the cover member 30 can be increased toward one end side in the longitudinal direction.

The lower limit of the radius of curvature of the curved portion 31 of the cover member 30 is preferably 20 cm, more preferably 25 cm. On the other hand, the upper limit of the radius of curvature of the curved portion 31 is preferably 50 cm, more preferably 40 cm. If the radius of curvature of the curved portion 31 is less than the lower limit, it may be too small compared to the curvature of the curved surface of the forearm W, and may hit the skin strongly and press the living body. On the contrary, if the radius of curvature of the curved portion 31 exceeds the upper limit, it may be difficult to bring the piezoelectric sheet 10 into contact with the curved surface of the skin.

As shown in FIG. 2, the flat portion 32 of the cover member 30 is connected to one end side (tip β) and the opposite end (base end α) of the curved portion 31. The inner surface side of the flat portion 32 is a flat surface. The forearm W has a portion having a large curvature and a portion having a relatively flat portion. Therefore, by providing the curved portion 31 and the flat portion 32 on the cover member 30, the region where the biosensor 1 contacts the forearm W can be made substantially the same as the surface shape of the forearm W. Further, by bringing the flat portion 32 into contact with the relatively flat portion of the forearm W, it is possible to stabilize the fixation of the biosensor 1 to the forearm W.

As shown in FIG. 2, in the cover member 30 of the biosensor 1, the flat portion 32 is configured to be thicker than the curved portion 31, and the thick portion has a recess 33. The recess 33 is open on the inner surface side (forearm W side) of the flat portion 32.

As shown in FIG. 1, the recess 33 can store the circuit body 41 of the detection circuit 40 that detects the potential difference of the piezoelectric sheet 10. By storing the circuit body 41 in the recess 33, the biosensor 1 can be compactly configured. Further, by providing the recess 33 in the flat portion 32, the circuit main body 41 can be easily stored. In this case, the recess 33 is sized to accommodate the circuit body 41. Note that what is stored in the recess 33 is not limited to the detection circuit, and other types of circuits and the like may be stored.

Further, the recess 33 may have an outlet 33a capable of drawing out a wiring (not shown) for transmitting a signal detected by the circuit body 41 to the outside. The circuit body 41 and the piezoelectric sheet 10 are also connected by wiring 42 as shown in FIG. 1, but the width and thickness of the wiring 42 are arbitrary as long as they do not affect the measurement of biological vibration. It's fine.

<Sensor unit>
The sensor unit 20 is configured to be bendable and has a piezoelectric sheet 10, a covering member 17, and a spacer 18.

[Piezoelectric sheet]
The piezoelectric sheet 10 is formed of a piezoelectric material that converts pressure into voltage, and converts deformation due to a force applied by a pressure wave of biological vibration into voltage. As shown in FIG. 3, the piezoelectric sheet 10 has a piezoelectric body 11, a first electrode 12, and a second electrode 13.

(Piezoelectric material)
The piezoelectric material forming the piezoelectric body 11 may be, for example, an inorganic material such as lead zirconate titanate, but a polymer piezoelectric material having flexibility so as to be in close contact with the surface of a living body is preferable. Further, by using a porous film in which a large number of pores are formed in the polymer piezoelectric material as the piezoelectric body 11, the flexibility and the piezoelectric constant can be relatively increased.

Examples of the polymer piezoelectric material include polyvinylidene fluoride (PVDF), vinylidene fluoride-3 ethylene fluoride copolymer (P (VDF / TrFE)), and vinylidene cyanide-vinyl acetate copolymer (P (VDCN /)). VAc)) and the like can be mentioned. Further, by using these polymer piezoelectric materials as a porous film, it is possible to form a piezoelectric sheet 10 having a larger flexibility and a larger piezoelectric constant.

Further, as the piezoelectric body 11, a large number of flat pores are formed in, for example, polytetrafluoroethylene (PTFE), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), etc., which do not have piezoelectric characteristics, and corona discharge or the like is formed. It is also possible to use a product in which the facing surface of the flat pores is polarized and charged to impart piezoelectric characteristics.

As the lower limit of the average thickness of the

piezoelectric body

11, 10 μm is preferable, and 50 μm is more preferable. On the other hand, the upper limit of the average thickness of the piezoelectric body 11 is preferably 500 μm, more preferably 200 μm. If the average thickness of the piezoelectric body 11 is less than the lower limit, the strength of the piezoelectric sheet 10 may be insufficient. On the contrary, if the average thickness of the piezoelectric body 11 exceeds the upper limit, the deformability of the piezoelectric sheet 10 becomes small, and the detection sensitivity may become insufficient. The "average thickness" refers to the average value of the thickness measured at any 10 points of the piezoelectric body 11. Hereinafter, the "average" regarding the length such as the thickness shall be based on the same measurement.

(First electrode)
The first electrode 12 is an electrode laminated on the first surface of the piezoelectric body 11. The first electrode 12 is used together with the second electrode 13 described later to detect the potential difference between the first surface and the second surface of the piezoelectric body 11.

The material of the first electrode 12 may be any material having conductivity, and examples thereof include metals such as aluminum, copper and nickel, carbon and the like.

The average thickness of the first electrode 12 is not particularly limited, and may be 0.1 μm or more and 30 μm or less, although it depends on the laminating method and the material of the first electrode 12. If the average thickness of the first electrode 12 is less than the lower limit, the strength of the first electrode 12 may be insufficient and the resistivity may increase. On the contrary, if the average thickness of the first electrode 12 exceeds the upper limit, the transmission of vibration to the piezoelectric body 11 may be hindered.

In the piezoelectric sheet 10, the first electrode 12 is laminated on the entire surface of the first surface of the piezoelectric body 11, but may be laminated on a part of the first surface of the piezoelectric body 11 as long as the potential difference can be detected. ..

The method of laminating the first electrode 12 on the piezoelectric body 11 is not particularly limited, and examples thereof include metal deposition, printing of carbon conductive ink, application and drying of silver paste, and the like.

Further, as shown in FIG. 3, the piezoelectric body 11 is electrically connected by laminating the first electrode 12 on the signal terminal 14.

(Second electrode)
The second electrode 13 is an electrode laminated on the second surface of the piezoelectric body 11 so that at least a part thereof faces the first electrode 12. That is, the second electrode 13 is arranged at a position where at least a part thereof overlaps with the first electrode 12 in a plan view. In the piezoelectric sheet 10 shown in FIG. 3, the second electrode 13 has substantially the same shape as the first electrode 12, and the entire surface thereof faces the entire surface of the first electrode 12.

The material, average thickness, and laminating method of the second electrode 13 can be the same as those of the first electrode 12.

Further, as shown in FIG. 3, the ground terminal 15 arranged so as to surround the signal terminal 14 is electrically connected to the second electrode 13 via the metal foil 16.

(Signal terminal and ground terminal)
The signal terminal 14 and the ground terminal 15 described above are used to transmit the potential difference detected by the first electrode 12 and the second electrode 13 of the piezoelectric sheet 10 to the detection circuit 40. Therefore, the signal terminal 14 and the ground terminal 15 are connected to the circuit main body 41 of the detection circuit 40 via the wiring 42.

The signal terminal 14, the ground terminal 15, and the metal foil 16 may be any as long as they have conductivity. For example, a film made of a metal such as aluminum, copper, or nickel, or a film containing a conductive material such as carbon. Examples thereof include textiles and non-woven fabrics made of conductive fibers.

(Size of piezoelectric sheet)
The piezoelectric sheet 10 has a strip shape as described above. The piezoelectric sheet 10 may have both ends rounded.

As the lower limit of the length of the piezoelectric sheet 10 in the longitudinal direction, 10 mm is preferable, and 12 mm is more preferable. On the other hand, the upper limit of the length of the piezoelectric sheet 10 in the longitudinal direction is preferably 25 mm, more preferably 20 mm. If the length of the piezoelectric sheet 10 in the longitudinal direction is less than the lower limit, the biosensor 1 may not be able to sufficiently detect biovibration when the biosensor 1 is displaced. On the contrary, when the length of the piezoelectric sheet 10 in the longitudinal direction exceeds the upper limit, the area of the piezoelectric body 11 which is not involved in the detection of biological vibration becomes large, and the sensitivity of the biological sensor 1 may be relatively lowered. .. For example, when both ends of the piezoelectric sheet 10 are rounded and are not constant depending on the position, the "length" refers to the average thereof.

The lower limit of the length of the piezoelectric sheet 10 in the width direction is preferably 2 mm, more preferably 2.5 mm. On the other hand, as the upper limit of the length of the piezoelectric sheet 10 in the width direction, 4 mm is preferable, and 3.5 mm is more preferable. If the length of the piezoelectric sheet 10 in the width direction is less than the lower limit, the sensitivity of the biosensor 1 may be insufficient. On the contrary, if the length of the piezoelectric sheet 10 in the width direction exceeds the upper limit, the biosensor 1 may become unnecessarily large and the handleability may be deteriorated.

[Coating member]
As shown in FIG. 3, the signal terminal 14, the ground terminal 15, and the spacer 18 described later may be laminated on the surface of a covering member 17 such as a flexible substrate. By using the covering member 17 in this way, the sensor unit 20 can be made flexible.

〔Spacer〕
As shown in FIG. 3, the spacer 18 is arranged on the surface of the covering member 17, and is arranged so as to surround the ground terminal 15 to which the piezoelectric body 11 is connected. As a result, the spacer 18 surrounds the piezoelectric sheet 10. The spacer 18 may continuously surround the ground terminal 15, but as shown in FIG. 3, the spacer 18 is intermittently surrounded so as to have a gap in a part thereof, and the wiring 42 is arranged using the gap. You may.

It is preferable that the front side surface of the piezoelectric sheet 10 facing the forearm W to be measured and the front side surface of the spacer 18 are flush with each other, or the front side surface of the piezoelectric sheet 10 protrudes from the front side surface of the spacer 18. .. That is, the height of the spacer 18 is set so that the second electrode 13 side of the piezoelectric sheet 10 described later is in contact with the living body when the biological sensor 1 is used, and the piezoelectric sheet 10 can be fixed by the spacer 18. Specifically, as shown in FIG. 3, the height of the spacer 18 is set to be slightly lower than the surface of the piezoelectric sheet 10 on the second electrode 13 side. By setting the height of the spacer 18 in this way, the piezoelectric sheet 10 can more reliably receive the biological vibration from the forearm W in a state where the front side surface of the spacer 18 is in contact with the forearm W.

The spacer 18 is preferably configured by using a flexible substrate or the like in order to secure flexibility.

[Shield layer]
The sensor unit 20 may have a shield layer. In this case, the shield layer is arranged so as to wrap the entire sensor unit 20 on the outermost side.

The shield layer has an insulating layer and a conductive layer laminated on the surface of the insulating layer. As the insulating layer, for example, an acrylic resin can be used. Further, the conductive layer can be a coating layer of a conductive paint of silver or copper. By making the back surface of the shield layer an insulating layer and making the front surface conductive in this way, noise can be shielded while suppressing a short circuit with the piezoelectric sheet 10.

<How to use the biosensor>
The biosensor 1 is used by being fixed to the living body so that the inner surface side of the cover member 30 comes into contact with the living body. As a specific example, as shown in FIG. 2, the case where the pulse wave is measured by applying it to the surface of the forearm W will be described, but the application of the biosensor 1 is not limited to the pulse wave measurement with the forearm W. .. When the sensor unit 20 has a shield layer, the biosensor 1 comes into contact with the living body via the shield layer.

When using the biosensor 1, first, the longitudinal direction of the strip-shaped piezoelectric sheet 10 is fixed to the surface of the forearm W so as to be orthogonal to the fingertip direction of the forearm W. Since the pulse wave is measured by a blood vessel flowing in the forearm W in the fingertip direction, the biosensor 1 is fixed so that the piezoelectric sheet 10 straddles the blood vessel. At this time, as shown in FIG. 2, the biosensor 1 is arranged so that the inner surface side of the curved portion 31 of the cover member 30 is along the curved surface portion of the forearm W.

Since the piezoelectric sheet 10 of the biosensor 1 has a band shape, it is not necessary to perform alignment with high accuracy, and the blood vessel can be relatively easily fixed at a position where the piezoelectric sheet 10 straddles. Further, even if the biosensor 1 is displaced in a direction orthogonal to the fingertip direction of the forearm W, since the piezoelectric sheet 10 is strip-shaped, it is difficult to be removed from the state in which the piezoelectric sheet 10 straddles the blood vessel. That is, the biosensor 1 is resistant to misalignment.

The method of fixing to the living body is not particularly limited, but for example, the living body sensor 1 may be sandwiched between the forearm W by a bracelet or a band, or may be attached with a tape or the like.

After fixing the biosensor 1, measure the biovibration. According to the biosensor 1 fixed as described above, the potential displacement from the piezoelectric sheet 10 can be observed according to the pulse wave. By measuring this potential displacement with a known measuring device, the pulse wave can be known.

<Advantage>
In the biosensor 1, the cover member 30 is curved along the longitudinal direction of the piezoelectric sheet 10, and the piezoelectric sheet 10 is located at the curved portion 31 of the cover member 30. Therefore, it is easy to apply the longitudinal direction of the piezoelectric sheet 10 to the curved surface of the skin such as the surface of the forearm W. Further, since the piezoelectric sheet 10 has a band shape, the biosensor 1 can detect the biovibration if any position in the longitudinal direction of the piezoelectric sheet 10 is in contact with a portion capable of detecting the biovibration. Therefore, the biosensor 1 can easily and stably measure the biovibration even when the pulse wave is measured by applying it to the curved surface of the skin such as the surface of the forearm W.

[Second Embodiment]
The biosensor 2 shown in FIG. 4 includes a sensor unit 21 having two strip-shaped piezoelectric sheets 10, a cover member 30 covering the sensor unit 21, and a detection circuit 40 connected to the sensor unit 21.

These two piezoelectric sheets 10 are arranged side by side so that their longitudinal directions are parallel to each other. Further, the cover member 30 is curved along the longitudinal direction of the two piezoelectric sheets 10, and the piezoelectric sheet 10 is located at the curved portion of the cover member 30.

The biosensor 2 has the same components as the biosensor 1 of the first embodiment except that the sensor unit 21 has two piezoelectric sheets 10. Therefore, the same reference numerals are given and detailed description thereof will be omitted. To do.

The two piezoelectric sheets 10 may be connected in series or in parallel, but preferably they are independently connected to the detection circuit 40. The position where the pulse wave is detected is limited, and even if two piezoelectric sheets 10 are similarly parallel to each other perpendicular to the fingertip direction of the forearm, it is not possible to obtain the same signal on both of the two piezoelectric sheets 10. Not exclusively. Therefore, by selecting and measuring one of them with higher sensitivity, it is possible to perform measurement with increased sensitivity while reducing parasitic capacitance.

<Advantage>
The pulse wave detected from the artery may or may not be detected depending on the position and time even in the fingertip direction of the forearm (longitudinal direction of the artery). In the biosensor 2, the two piezoelectric sheets 10 can be measured side by side in the fingertip direction of the forearm, so that the probability of detecting the pulse wave can be increased.

[Other Embodiments]
The embodiments do not limit the configuration of the present invention. Therefore, it is possible to omit, replace or add components of each part of the embodiment based on the description of the present specification and common general technical knowledge, and all of them are construed as belonging to the scope of the present invention. Should be.

In the above-described embodiment, the case where the entire piezoelectric sheet is located at the curved portion of the cover member has been described, but it is not an indispensable constituent requirement that the entire piezoelectric sheet is located at the curved portion of the cover member. That is, the piezoelectric sheet may be partially detached from the curved portion of the cover member. The same effect can be obtained as long as at least a part of the piezoelectric sheet is located at the curved portion of the cover member.

In the above embodiment, the case where the piezoelectric sheet is located on the inner surface side of the cover member has been described, but the position of the piezoelectric sheet is not limited to the inner surface side, and can be incorporated in the cover member, for example. However, from the viewpoint of sensitivity, the position of the piezoelectric sheet is preferably the inner surface side of the cover member.

In the above embodiment, the case where the cover member has a recess in the flat portion has been described, but it is also possible to provide the recess in the curved portion.

Further, in the above-described embodiment, the case where the recess is open to the inner surface side has been described, but the recess may be open to the outer surface side or the side surface side.

In the above embodiment, the case where the flat portion of the cover member has a recess is described, but the recess is not an essential component and can be omitted. In this case, other installation means such as attaching the detection circuit or the like to the surface of the cover member or arranging the detection circuit or the like outside the biosensor can be appropriately used.

In the above embodiment, the case where the cover member has a flat portion has been described, but the flat portion is not an essential component, and the cover member may be composed of only a curved portion.

In the second embodiment, the case where the two piezoelectric sheets are arranged in parallel so that their longitudinal directions are parallel has been described, but the number of the piezoelectric sheets to be arranged in parallel is not limited to two, and may be three or more. There may be. However, from the viewpoint of handleability of the biosensor, the number of piezoelectric sheets to be paralleled is preferably 3 or less.

In the above embodiment, the case where the sensor unit has a spacer has been described, but for example, the piezoelectric sheet may be directly embedded in the cover member. In such a configuration, the cover member around the embedded piezoelectric sheet acts as a spacer.

In the above embodiment, the case where the covering member on which the piezoelectric sheet is laminated is directly laminated on the cover member has been described, but an individual difference absorption mechanism which is arranged between the covering member and the cover member and whose shape changes is provided. You may prepare.

As the individual difference absorption mechanism, for example, rubber can be mentioned. Of these, soft rubber that is soft, highly flexible, and elastic is preferable.

The biosensor is applied to the curved surface of the skin, and the shape of the curved surface varies depending on the individual human body. The individual difference absorption mechanism can absorb the individual difference by changing its shape, and the piezoelectric sheet can be suitably applied along the curved surface of the skin.

The biosensor according to the present invention can easily and stably measure biovibration even when it is applied to a curved surface of the skin to measure biovibration.

1, 2 Biosensor 10 Piezoelectric sheet 11 Piezoelectric body 12 First electrode 13 Second electrode 14 Signal terminal 15 Ground terminal 16 Metal leaf 17 Coating member 18

Spacer

20, 21 Sensor unit 30 Cover member 31 Curved part 32 Flat part 33 Recess 33a Outlet 40 Detection circuit 41 Circuit body 42 Wiring W Forearm α Base end β Tip

Claims

With a strip-shaped piezoelectric sheet,
A cover member for covering the piezoelectric sheet is provided.
The cover member is curved along the longitudinal direction of the piezoelectric sheet.
A biosensor in which the piezoelectric sheet is located at a curved portion of the cover member.
The biosensor according to claim 1, wherein the curved portion of the cover member has flexibility along the longitudinal direction.
The biosensor according to claim 2, wherein the flexibility of the curved portion of the cover member increases toward one end side in the longitudinal direction.
The biosensor according to claim 1, claim 2 or claim 3, wherein the thickness of the cover member gradually decreases toward one end side in the longitudinal direction.
The biosensor according to any one of claims 1 to 4, wherein the radius of curvature of the curved portion of the cover member is 20 cm or more and 50 cm or less.
The biosensor according to any one of claims 1 to 5, wherein the cover member has a recess capable of accommodating a detection circuit for detecting a potential difference of the piezoelectric sheet.
Further provided with a spacer surrounding the piezoelectric sheet,
Claims 1 to 6 wherein the front side surface of the piezoelectric sheet facing the living body to be measured and the front side surface of the spacer are flush with each other, or the front side surface of the piezoelectric sheet protrudes from the front side surface of the spacer. The biosensor according to any one of the above.
The length of the piezoelectric sheet in the longitudinal direction is 10 mm or more and 25 mm or less.
The biosensor according to any one of claims 1 to 7, wherein the length of the piezoelectric sheet in the width direction is 2 mm or more and 4 mm or less.
With a plurality of the piezoelectric sheets,
The biosensor according to any one of claims 1 to 8, wherein the plurality of piezoelectric sheets are arranged in parallel so that their longitudinal directions are parallel to each other.
A step of fixing the biosensor according to any one of claims 1 to 9 to the surface of the forearm so that the longitudinal direction of the strip-shaped piezoelectric sheet is orthogonal to the fingertip direction of the forearm.
A method of using a biological sensor including a step of measuring biological vibration after the fixing step.