阅读说明：本技术 生物体传感器 (Biosensor and method for measuring the same ) 是由 植屋夕辉 于 2019-08-06 设计创作，主要内容包括：本发明的课题在于提供灵敏度高、抗干扰性强的生物体传感器。本发明的一个方式的生物体传感器(1)具备：片状的压电元件(2)；俯视时在压电元件(2)的周围隔开空隙(3)配设的间隔件(4)；覆盖压电元件(2)以及间隔件(4)的表侧的覆盖部件(5)；间隔件(4)从背侧支承覆盖部件(5),压电元件(2)固定于覆盖部件(5)。(The present invention addresses the problem of providing a biosensor having high sensitivity and high interference immunity. A biosensor (1) according to one embodiment of the present invention comprises: a sheet-like piezoelectric element (2); a spacer (4) disposed around the piezoelectric element (2) with a gap (3) therebetween in a plan view; a covering member (5) that covers the piezoelectric element (2) and the front side of the spacer (4); the spacer (4) supports the covering member (5) from the back side, and the piezoelectric element (2) is fixed to the covering member (5).)

1. A biosensor, comprising:

a sheet-like piezoelectric element;

a spacer disposed around the piezoelectric element with a gap in a plan view;

a covering member covering a front side of the piezoelectric element and the spacer;

the spacer supports the covering member from the back side,

the piezoelectric element is fixed to the covering member.

2. The biosensor of claim 1,

the back side is a side facing a biological surface of a vibration detection target, and the front side is a side opposite to the back side.

3. The biosensor in accordance with claim 1 or 2,

the surface of the back side of the spacer is a plane parallel to the surface of the back side of the piezoelectric element.

4. The biosensor of any one of claims 1 to 3,

a plate is provided on the back side of the piezoelectric element so as to face the covering member.

5. The biosensor of claim 4,

the surface of the back side of the plate protrudes more to the back side than the surface of the back side of the spacer.

6. The biosensor of any one of claims 1 to 5,

the piezoelectric element is provided with a plurality of piezoelectric elements which are arranged not to overlap in a plan view.

7. The biosensor of any one of claims 1 to 6,

the average thickness of the spacer is 300 [ mu ] m or more and 800 [ mu ] m or less.

Technical Field

The present invention relates to a biosensor.

Background

For example, diagnosis, health management, and the like can be performed by measuring or observing vibrations (not limited to acoustic vibrations in the audible region, but also low-frequency vibrations in the non-audible region or ultrasonic vibrations) generated inside a living body such as heart rate, pulse, bloodstream sound, respiratory sound, and the like.

As a biosensor for detecting vibration of a living body, for example, a vibration waveform sensor using a piezoelectric element is known (see international publication No. 2017/187710). The known vibration waveform sensor includes a piezoelectric element mounted on a substrate, a spacer arranged around the piezoelectric element, and a covering portion covering the piezoelectric element, and a region surrounded by the spacer or the like is filled with, for example, silicone resin. In this conventional biosensor (vibration waveform sensor), the cover portion side is brought into contact with the living body to detect the vibration of the living body.

However, in the above-described conventional biosensor, the propagation path is long because the vibration transmitted from the spacer to the piezoelectric element via the substrate is mainly detected. Therefore, the sensitivity is easily lowered, and interference is easily mixed. Further, since the covering portion or the silicone resin is present between the piezoelectric sensor and the living body as the object to be measured, the vibration is easily attenuated by the elasticity thereof, and the piezoelectric element is tightly surrounded by the spacer, the covering portion, and the like, so that the deformation of the piezoelectric element can be suppressed. From this point of view, the sensitivity of the conventional biosensor is also liable to be lowered. Therefore, a biosensor having high sensitivity and high interference resistance is required.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2017/187710

Disclosure of Invention

Problems to be solved by the invention

In view of the above circumstances, an object of the present invention is to provide a biosensor having high sensitivity and high interference resistance.

Means for solving the problems

A biosensor according to an embodiment of the present invention to solve the above problems includes: a sheet-like piezoelectric element; a spacer disposed around the piezoelectric element with a gap in a plan view; a covering member covering a front side of the piezoelectric element and the spacer; the spacer supports the covering member from a back side, and the piezoelectric element is fixed to the covering member.

Drawings

Fig. 1 is a schematic bottom view showing a back surface of a biosensor according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of the biosensor of fig. 1 taken along line a-a.

Fig. 3 is a schematic bottom view showing a back surface of a biosensor according to an embodiment different from that shown in fig. 1.

Fig. 4 is a schematic cross-sectional view showing a biosensor of an embodiment different from that of fig. 1 and 3.

Detailed Description

A biosensor according to one embodiment of the present invention includes a sheet-like piezoelectric element, spacers arranged around the piezoelectric element with a gap therebetween in a plan view, and a cover member covering the piezoelectric element and the spacers on the front side, wherein the spacers support the cover member from the back side, and the piezoelectric element is fixed to the cover member.

In the biosensor, the back side is a side facing a surface of a living body to be vibration-detected, and the front side is a side opposite to the back side.

In the biosensor, a surface on the back side of the spacer is preferably a plane parallel to a surface on the back side of the piezoelectric element.

Preferably, the biosensor further includes a plate disposed on a back side of the piezoelectric element so as to face the covering member.

In the biosensor, the back surface of the plate preferably protrudes to the back side of the spacer.

Preferably, the biosensor includes a plurality of the piezoelectric elements arranged so as not to overlap in a plan view.

Preferably, in the biosensor, the spacer has an average thickness of 300 μm or more and 800 μm or less.

In the present invention, the "back side" refers to a side facing the living body surface, and the "front side" refers to a side opposite to the "back side", that is, a side opposite to the living body surface. "average thickness" means the average of the thickness at any ten points.

In this biosensor, the cover member to which the piezoelectric element is fixed is supported by the spacer. Therefore, in the biosensor, the piezoelectric element can be brought into contact with the living body to detect the vibration of the living body, and thus the propagation path can be shortened. In addition, the biosensor has a gap between the piezoelectric element and the spacer. Therefore, the deformation of the piezoelectric element is hardly suppressed by the spacer or the like, and thus the sensitivity of the piezoelectric element is easily ensured. Therefore, the biosensor has high sensitivity and high anti-interference performance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings as appropriate.

Fig. 1 and 2 show a biosensor 1 according to an embodiment of the present invention. The biosensor 1 is disposed in close contact with the surface of a living body such as a human being or an animal, and detects vibrations, for example, a pulse, inside the living body.

The biosensor 1 includes a sheet-shaped piezoelectric element 2, spacers 4 disposed around the piezoelectric element 2 with gaps 3 therebetween in a plan view, a cover member 5 covering the front sides of the piezoelectric element 2 and the spacers 4, a plate 6 disposed on the back side of the piezoelectric element 2 so as to face the cover member 5, and a shield layer 7 disposed so as to surround the entire part at the outermost portion.

< piezoelectric element >

The piezoelectric element 2 is formed of a piezoelectric material that converts pressure into voltage, and converts deformation caused by the force applied by the pressure wave of the biological vibration into voltage. The piezoelectric element 2 includes a sheet-like or film-like piezoelectric body 21 and a pair of electrodes 22 laminated on the front and back surfaces of the piezoelectric body 21.

(piezoelectric body)

As the piezoelectric material forming the piezoelectric body 21, for example, an inorganic material such as lead zirconate titanate may be used, but a polymer piezoelectric material having flexibility that can adhere to a living body surface is preferable. Further, by using a porous film in which a plurality of pores are formed in a polymer piezoelectric material as the piezoelectric body 21, the flexibility and piezoelectric constant can be made relatively large.

Examples of the polymer piezoelectric material include polyvinylidene fluoride (PVDF), a vinylidene fluoride-trifluoroethylene copolymer (P (VDF/TrFE), a vinylidene cyanide-vinyl acetate copolymer (P (VDCN/VAc)), and the like. By forming these polymer piezoelectric materials into porous films, the piezoelectric element 2 having a large flexibility and a large piezoelectric constant can be formed.

As the piezoelectric body 21, for example, a piezoelectric body having piezoelectric properties, which is obtained by forming a plurality of flat air holes in Polytetrafluoroethylene (PTFE), polypropylene (PP), Polyethylene (PE), polyethylene terephthalate (PET), or the like, for example, and polarizing and charging the opposed surfaces of the flat air holes by corona discharge or the like, for example, may be used.

The lower limit of the average thickness of piezoelectric body 21 is preferably 10 μm, and more preferably 50 μm. On the other hand, the upper limit of the average thickness of piezoelectric body 21 is preferably 500 μm, and more preferably 200 μm. When the average thickness of the piezoelectric body 21 is less than the lower limit, the strength of the piezoelectric element 2 may become insufficient. Conversely, when the average thickness of the piezoelectric body 21 exceeds the upper limit, the deformability of the piezoelectric element 2 decreases, and the detection sensitivity may become insufficient.

(electrode)

Electrodes 22 are laminated on both surfaces of piezoelectric body 21, and detect a potential difference between the front and back surfaces of piezoelectric body 21.

The material of the electrode 22 may be any material having conductivity, and examples thereof include metals such as aluminum, copper, and nickel, and carbon.

The average thickness of the electrode 22 is not particularly limited, and may be, for example, 0.1 μm or more and 30 μm or less depending on the lamination method. In the case where the average thickness of the electrode 22 is less than the lower limit, there is a risk that the strength of the electrodes 6, 7 becomes insufficient. Conversely, if the average thickness of electrode 22 exceeds the upper limit, transmission of vibration to piezoelectric body 21 may be inhibited.

The method of laminating electrode 22 on piezoelectric body 21 is not particularly limited, and examples thereof include vapor deposition of a metal, printing of a carbon conductive ink, and coating and drying of a silver paste.

The electrode 22 may be formed by being divided into a plurality of regions in a plan view, and the piezoelectric element 2 may effectively function as a plurality of piezoelectric elements.

In the piezoelectric element 2 shown in fig. 2, the electrode 22 is formed to the outer edge thereof, but the formation region of the electrode 22 may not reach the outer edge of the piezoelectric element 2. That is, electrode 22 may be laminated on the entire surface of the front side and the entire surface of the back side of piezoelectric body 21, but may be laminated on a part of the front side and the back side of piezoelectric body 21 as long as the potential difference can be detected.

The piezoelectric element 2 may have a circular shape with a diameter of 2mm to 10mm, for example, in a plan view. If the diameter is smaller than the lower limit, for example, in the case of measuring a pulse, it may be difficult to align the biosensor 1 so that the piezoelectric element 2 covers the blood vessel. On the contrary, if the diameter exceeds the upper limit, the biosensor 1 becomes unnecessarily large, and there is a risk that the process becomes inconvenient.

The signal wiring 8 is disposed on the front surface of the piezoelectric element 2, that is, between the front electrode 22 of the piezoelectric element 2 and the cover member 5. Further, a ground wiring 9 is disposed on the surface on the back side of the piezoelectric element 2, that is, between the electrode 22 on the back side of the piezoelectric element 2 and the plate 6.

The signal wiring 8 and the ground wiring 9 are used for transmitting the potential difference detected by the pair of electrodes 22 of the piezoelectric element 2 to the detection circuit. Therefore, the signal wiring 8 and the ground wiring 9 are connected to a detection circuit not shown.

The signal wiring 8 and the ground wiring 9 may be conductive, and examples thereof include a thin film made of a metal such as aluminum, copper, or nickel, a thin film containing a conductive material such as carbon, and a woven fabric or a nonwoven fabric made of conductive fibers.

The average thickness of the signal wiring 8 and the ground wiring 9 is not particularly limited, and may be, for example, 15 μm or more and 50 μm or less. If the average thickness of the signal wiring 8 and the ground wiring 9 is less than the lower limit, there is a risk that the conductivity of the signal wiring 8 and the ground wiring 9 is insufficient. On the contrary, if the average thickness of the signal wiring 8 and the ground wiring 9 exceeds the upper limit, there is a risk of inhibiting the transmission of the vibration to the piezoelectric element 2.

The piezoelectric element 2 of the biosensor 1 is fixed to a cover member 5 described later. That is, there is no elastic member such as a spring or rubber for biasing the piezoelectric element 2 to the front side or the back side between the piezoelectric element 2 and the cover member 5. By fixing the piezoelectric element 2 to the cover member 5 in this manner, absorption of biological vibration by the elastic member can be suppressed, and thus the sensitivity of the piezoelectric element 2 can be improved. As shown in fig. 2, the piezoelectric element 2 is fixed to the cover member 5 with the signal wiring 8 interposed therebetween. The piezoelectric element 2 and the covering member 5 may be fixed via a fixing member having no elasticity such as a spring or rubber in the middle. The fixing member interposed between the piezoelectric element 2 and the cover member 5 may be a conductive wire using a conductive thin film or the like, or may be a member for adjusting the thickness of the biosensor.

< spacer >

The spacer 4 is formed by stacking a wall 41 and a ground wiring 42 as shown in fig. 2, for example. The spacer 4 is not limited to the structure shown in fig. 2, and may be formed only by the wall 41, for example, and the structure shown in fig. 2 will be described as an example below.

Examples of the material of the wall 41 of the spacer 4 include polyethylene terephthalate (PET), polypropylene (PP), Polyethylene (PE), polyethylene naphthalate (PEN), Polyarylate (PAR), Polyimide (PI), and the like, and among them, PET having appropriate rigidity is preferable.

The ground wiring 42 may be made of the same material as the ground wiring 9 of the piezoelectric element 2. Further, it is preferable that the ground wiring 42 is disposed so that the height position (position in the front-back direction of the biosensor 1) coincides with the height positions of the signal wiring 8 disposed on the front surface of the piezoelectric element 2 and the ground wiring 9 disposed on the back surface of the piezoelectric element 2. Specifically, it is preferable that the thickness of the ground wiring 42 of the spacer 4 is the same as the thickness of the signal wiring 8 and the ground wiring 9 corresponding to the height position, and the thickness of the wall 41 sandwiched by the ground wirings 42 is equal to the thickness of the piezoelectric element 2. By such arrangement, the ground wiring 42 of the spacer 4 functions as a shield, and interference can be suppressed from being mixed into the signal detected by the piezoelectric element 2. In addition, in manufacturing the biosensor 1, the signal wiring 8 and the ground wiring 9 of the piezoelectric element 2 and the ground wiring 42 of the spacer 4 can be manufactured by being laminated at once on the same layer, and therefore, manufacturing efficiency can be improved.

The spacer 4 supports a covering member 5 described later from the back side. That is, the position of the covering member 5 is fixed by the spacer 4, and vibration thereof is suppressed. Therefore, the sensitivity of the piezoelectric element 2 fixed to the cover member 5 can be improved.

The spacers 4 may be intermittently arranged around the piezoelectric element 2 as long as they can support the covering member 5, but are preferably arranged so as to surround the entire circumference of the piezoelectric element 2 in plan view. By disposing the spacers 4 so as to surround the entire circumference of the piezoelectric element 2 in plan view in this manner, the covering member 5 can be stably supported, and therefore, the sensitivity of the piezoelectric element 2 can be further improved.

Further, the surface on the back side of the spacer 4 is preferably a plane parallel to the surface on the back side of the piezoelectric element 2. By forming the surface on the back side of the spacer 4 as a flat surface parallel to the surface on the back side of the piezoelectric element 2 in this way, the contact area between the spacer 4 and the living body increases when the biosensor 1 is brought into contact with the living body, and therefore the cover member 5 can be stably supported. Therefore, the sensitivity of the piezoelectric element 2 can be further improved.

The thickness of the spacer 4 is such that the covering member 5 can be fixed by the surface on the back side of the spacer 4 coming into contact with the living body when the biosensor 1 is used. The thickness of the spacer 4 is adjusted so that the piezoelectric element 2 can detect vibration from the back side when the biosensor 1 is used, that is, the piezoelectric element 2, the plate 6, the shield layer 7, and the living body are continuous in a direction from the front side to the back side (hereinafter, also referred to as "back side direction") regardless of the state of the biological vibration. The phrase "continuous in the back surface direction regardless of the state of the biological vibration" means that, for example, even when the piezoelectric element 2 receives a force compressed by the biological vibration, for example, no gap is generated between the plate 6 and the piezoelectric element 2.

The lower limit of the average thickness of the spacer 4 is preferably 300 μm, and more preferably 400 μm. On the other hand, the upper limit of the average thickness of the spacer 4 is preferably 800 μm, and more preferably 700 μm. If the average thickness of the spacer 4 is less than the lower limit, when the biosensor 1 is brought into contact with a living body, the plate 6 protrudes too far from the back surface of the spacer 4, and the spacer 4 does not come into contact with the living body, and the covering member 5 may not be supported. In contrast, if the average thickness of the spacer 4 exceeds the upper limit, for example, the wobbling on the back side of the spacer 4 is enlarged on the front side with the thickness of the spacer 4 as a radius, and therefore the covering member 5 is at risk of being easily vibrated.

The average width of the back surface of the spacer 4 (average width in the radial direction) is not particularly limited, and may be, for example, 1mm to 5 mm. If the average width of the spacer 4 is smaller than the lower limit, the contact area of the spacer 4 is reduced when the biosensor 1 is brought into contact with a living body, and therefore the cover member 5 may not be stably supported. On the other hand, if the average width of the spacer 4 exceeds the upper limit, the biosensor 1 becomes unnecessarily large in a plan view, which may make handling inconvenient.

A gap 3 exists between the spacer 4 and the piezoelectric element 2. The void 3 may have a size that does not contact the spacer 4 even when the piezoelectric element 2 is deformed, and the lower limit of the width of the void 3 may be, for example, 10 μm. On the other hand, the upper limit of the width of the gap 3 is not particularly limited, but may be, for example, 3mm from the viewpoint of the operability of the biosensor 1, that is, the size reduction.

The gap 3 is not filled with a filler such as gel. By not filling the gap 3 with the filler in this way, the deformation of the piezoelectric element 2 is not suppressed, and therefore, the sensitivity of the piezoelectric sensor is easily ensured.

< covering Member >

The covering member 5 is plate-shaped, and covers the piezoelectric element 2 and the front side of the spacer 4 as described above. The covering member 5 may cover the front sides of the piezoelectric elements 2 and the spacers 4 so as to include the outer edges of the spacers 4 in plan view, or may cover the outer edges of the covering member 5 so as to coincide with the outer edges of the spacers 4. By covering in this way, the size of the covering member 5 can be reduced in a plan view, and thus the operability of the biosensor 1 is improved.

The material of the covering member 5 may be the same as the wall 41 of the spacer 4. In addition, the covering member 5 preferably has flexibility. By providing the cover member 5 with a certain flexibility in this manner, the biosensor 1 can be brought into contact with the surface of the living body to be measured even if the surface is curved.

The lower limit of the average thickness of the covering member 5 is preferably 50 μm, and more preferably 100 μm. On the other hand, the upper limit of the average thickness of the covering member 5 is preferably 400 μm, and more preferably 250 μm. If the average thickness of the cover member 5 is less than the lower limit, the cover member 5 becomes too easily bent, and thus it is difficult to fix the position of the piezoelectric element 2. Therefore, the sensitivity of the biosensor 1 is at risk of being lowered. In addition, if the average thickness of the covering member 5 is smaller than the lower limit, the parasitic capacitance becomes large, and there is a risk that interference is easily generated. Conversely, if the average thickness of the cover member 5 exceeds the upper limit, the flexibility of the cover member 5 is insufficient, and when the surface of the living body to be measured is a curved surface, there is a risk that it is difficult to bring the biosensor 1 into contact with the curved surface.

< plate >

The plate 6 transmits the vibration generated and transmitted by a part of the living body to the piezoelectric element 2 as the vibration of the entire surface of the plate 6. In this way, by transmitting vibration to the piezoelectric element 2 as vibration having a large area, the sensitivity of the piezoelectric element 2 can be improved.

In the biosensor 1, the plate 6 is smaller than the piezoelectric element 2 in a plan view. That is, the piezoelectric element 2 protrudes outward from the plate 6 in a plan view. On the other hand, the plate 6 may be larger than the piezoelectric element 2 in a plan view. That is, the plate 6 may be configured to protrude outward of the piezoelectric element 2 in a plan view.

When the plate 6 is smaller than the piezoelectric element 2 in a plan view, the plate 6 may be smaller than the electrodes 22 of the piezoelectric element 2 in a plan view, and may be in contact with the piezoelectric element 2 in a region narrower than the electrodes 22. On the other hand, the plate 6 may be configured to be larger than the electrodes 22 of the piezoelectric element 2 in a plan view, that is, to be in contact with the piezoelectric element 2 in a region wider than the electrodes 22.

The surface on the back side of the plate 6 may be the same as the surface on the back side of the spacer 4, or the surface on the back side of the plate 6 may protrude further to the back side than the surface on the back side of the spacer 4. By configuring the plate 6 in this way, the piezoelectric element 2 can receive vibration from the living body more reliably in a state where the back surface of the spacer 4 is in contact with the living body.

The material of the plate 6 may be the same as that of the wall 41 of the spacer 4. The shape of the plate 6 in plan view is preferably the same as the shape of the piezoelectric element 2 in plan view. The average thickness of the plate 6 may be the same as that of the covering member 5.

< Shielding layer >

As described above, the shield layer 7 is disposed so as to entirely surround the outermost portion of the biosensor 1. That is, the shield layer 7 is disposed so as to enclose the piezoelectric element 2, the spacer 4, the covering member 5, and the board 6.

The shield layer 7 has an insulating layer and a conductive layer laminated on the outer surface side of the insulating layer. As the insulating layer, for example, acrylic resin can be used. Additionally, the conductive layer may be a coating layer of a conductive paint of silver or copper. In this way, by forming the inner surface side of the shield layer 7 as an insulating layer and forming the outer surface side as a conductive layer, it is possible to suppress a short circuit with the piezoelectric element 2 and shield interference.

In addition, the shielding layer 7 preferably has flexibility. Since the shield layer 7 is flexible in this manner, vibrations generated by the living body can be transmitted to the plate 6 more reliably.

The average thickness of the shield layer 7 is not particularly limited, and may be, for example, 10 μm or more and 100 μm or less. If the average thickness of the shield layer 7 is less than the lower limit, the shield layer 7 is at risk of being easily broken in use. On the contrary, if the average thickness of the shielding layer 7 exceeds the upper limit, the flexibility of the shielding layer 7 is insufficient, and there is a risk of lowering the sensitivity of the biosensor 1.

< method for producing the biosensor >

The biosensor 1 can be manufactured by a manufacturing method including, for example, a signal wiring lamination step, a piezoelectric element lamination step, a ground wiring lamination step, a plate lamination step, and a shield layer covering step.

(Signal Wiring lamination Process)

In the signal wiring laminating step, the signal wiring 8 is laminated on the surface on the back side of the cover member 5. Specifically, a metal film on which the signal wiring 8 is formed is bonded to the back surface of the cover member 5 with an adhesive. At this time, the ground wiring 42 on the front side of the spacer 4 is simultaneously laminated.

(piezoelectric element laminating step)

In the piezoelectric element laminating step, the piezoelectric element 2 is laminated on the surface on the back side of the signal wiring 8 laminated in the signal wiring laminating step. Specifically, the piezoelectric element 2 is bonded to the surface on the back side of the signal wiring 8 with an adhesive. At this time, the walls 41 of the spacers 4 located at the same height position as the piezoelectric elements 2 are simultaneously laminated on the ground wiring 42.

(grounding Wiring laminating Process)

In the grounding wiring stacking step, the grounding wiring 9 is stacked on the surface on the back side of the piezoelectric element 2 stacked in the piezoelectric element stacking step. Specifically, a metal thin film on which the ground wiring 9 is formed is attached to the surface on the back side of the piezoelectric element 2 with an adhesive. At this time, the grounding line 42 on the back side of the spacer 4 is simultaneously laminated on the wall 41. It is preferable that the ground wiring 9 laminated on the surface on the back side of the piezoelectric element 2 and the ground wiring 42 of the spacer 4 are connected to each other because they have the same potential.

(sheet lamination Process)

In the plate laminating step, the plate 6 is laminated on the surface on the back side of the ground wiring 9 laminated in the ground wiring laminating step. Specifically, the plate 6 is bonded to the surface on the back side of the ground wiring 9 with an adhesive. At this time, the walls 41 of the spacer 4 located at the same height position as the plate 6 are stacked at the same time.

(Shielding layer covering Process)

In the shield layer covering step, the piezoelectric element 2, the spacer 4, the covering member 5, and the plate 6 after the plate laminating step are covered with the shield layer 7 so as to be enclosed therein.

Through the above steps, the biosensor 1 can be manufactured. In the above-described manufacturing method, the bonding between the cover member 5 and the signal wiring 8 and between the ground wiring 9 and the board 6 is described, but the signal wiring 8, the piezoelectric element 2, and the ground wiring 9 may be sandwiched between the cover member 5 and the board 6 without bonding therebetween. With such a configuration, it is difficult to suppress deformation of the piezoelectric element 2 compared to the case of bonding, and therefore, it is easy to ensure sensitivity of the piezoelectric element 2.

< method of Using the biosensor >

The biosensor 1 is used by being fixed to a living body such that the back surface of the spacer 4 is in contact with the living body.

The fixed position of the biosensor 1 to the living body is a position where the living body vibrates, and is a position overlapping with the piezoelectric element 2 in a plan view. In practice, since the piezoelectric element 2 has a certain size, for example, a method of arranging the biosensor 1 at a site where it is estimated that the biological vibration occurs and confirming that the biological vibration can be detected can be used as the alignment of the biosensor 1. When the biological vibration cannot be detected, it is preferable to change the arrangement position and perform the checking operation again.

In addition, in a case where the living body is curved at a fixed position to the living body, it is preferable to follow the curved surface of the living body by bending the covering member 5.

The method of fixing the biosensor 1 to the living body is not particularly limited, and for example, a method of attaching the biosensor to a living body with a tape or the like can be used. In the biosensor 1, the covering member 5 may be fixed to the spacer 4 to such an extent that the biosensor 1 is pressed against the living body. Therefore, it is not necessary to fix the biosensor 1 to a living body with a large suppression pressure.

According to the biosensor 1 fixed as described above, a sudden change in potential from the piezoelectric element 2 can be observed from the biological vibration. By measuring the potential displacement with a known measuring device, the magnitude, cycle, and the like of the vibration of the living body can be observed.

< advantages >

In the biosensor 1, the cover member 5 to which the piezoelectric element 2 is fixed is supported by the spacer 4. Therefore, in the biosensor 1, the piezoelectric element 2 can be brought into contact with the living body to detect the vibration of the living body, and thus the propagation path can be shortened. In addition, the biosensor 1 has a gap 3 between the piezoelectric element 2 and the spacer 4. Therefore, the deformation of the piezoelectric element 2 is hardly suppressed by the spacer 4 and the like, and therefore, the sensitivity of the piezoelectric element 2 is easily ensured. Therefore, the biosensor 1 has high sensitivity and high interference resistance.

[ second embodiment ]

Fig. 3 shows a biosensor 10 according to an embodiment of the present invention. The biosensor 10 is disposed in close contact with the surface of a living body such as a human being or an animal, and detects vibrations, for example, a pulse, inside the living body.

The biosensor 10 includes three sheet-shaped piezoelectric elements, spacers arranged around the piezoelectric elements with a gap therebetween in a plan view, a cover member covering the front sides of the piezoelectric elements and the spacers, a plate arranged on the back side of the piezoelectric elements so as to face the cover member, and a shield layer arranged so as to surround the entire part at the outermost portion.

< piezoelectric element >

The piezoelectric element may have a circular shape with a diameter of 2mm to 10mm, for example, in a plan view.

The three piezoelectric elements are arranged so as not to overlap in a plan view. The positions at which the three piezoelectric elements are arranged are not particularly limited, and for example, as shown in fig. 3, the three piezoelectric elements are arranged so that their centers form a regular triangle, and one side thereof is 5mm to 15 mm.

Further, it is preferable that the three piezoelectric elements are connected in parallel. By connecting the three piezoelectric elements in parallel in this way, the biosensor 10 can detect vibration if any one of the piezoelectric elements detects vibration of a living body. Therefore, the biosensor 10 can be easily aligned.

The piezoelectric element can be configured in the same manner as the piezoelectric element 2 of the first embodiment except for the planar shape described above, and therefore, detailed description thereof is omitted.

< spacers and plates >

The spacer and the plate can be configured as in the spacer 4 and the plate 6 of the first embodiment with respect to the three piezoelectric elements, respectively, and therefore detailed description thereof is omitted.

< covering Member >

The covering member is in the form of a single plate and covers the three piezoelectric elements and the front side of the spacer. The covering member can be configured similarly to the covering member 5 of the first embodiment, and therefore, a detailed description thereof is omitted.

< Shielding layer >

The shield layer can be configured in the same manner as the shield layer 7 of the first embodiment, and therefore, detailed description thereof is omitted.

The biosensor 10 can be manufactured and used in the same manner as the biosensor 1 according to the first embodiment. And thus detailed description is omitted.

< advantages >

Since the biosensor 10 includes the plurality of piezoelectric elements arranged so as not to overlap in plan view, the area of each piezoelectric element in plan view can be reduced as compared with the case where one piezoelectric element is provided. Since the vibration of the living body is generated at one location, the area of the piezoelectric element in contact with the vibration of the living body is small, and therefore the surface pressure generated in the piezoelectric element by the vibration of the living body can be increased. Therefore, the biosensor 10 can have improved sensitivity to the vibration of the living body. In addition, since the area of each piezoelectric element in plan view is small, the biosensor 10 can be easily fixed so as to follow a curved surface even when the measurement position of the living body is the curved surface.

[ other embodiments ]

The above embodiment is not limited to the configuration of the present invention. Therefore, in the embodiments, the constituent elements of the respective portions of the embodiments may be omitted, replaced, or added based on the description of the present specification and the common technical knowledge, and all of them should be construed as belonging to the scope of the present invention.

In the above-described embodiment, the case where the biosensor includes the shield layer has been described, but the shield layer is not an essential constituent element and may be omitted.

In the above-described embodiment, the case where the biosensor includes the plate is described, but the plate is not an essential component and may be omitted. In a biosensor without a plate, vibration is directly detected by a piezoelectric element.

In the above embodiment, the wall of the spacer and the ground wiring have the same area in a plan view, but the area in the plan view may be different depending on the position in the height direction.

In the above-described embodiment, the case where the signal wiring is disposed on the front surface of the piezoelectric element and the ground wiring is disposed on the back surface of the piezoelectric element has been described, but the signal wiring and the ground wiring may be disposed in opposite directions, that is, the signal wiring is disposed on the back surface of the piezoelectric element and the ground wiring is disposed on the front surface of the piezoelectric element.

In the second embodiment, the case where three piezoelectric elements are arranged so as not to overlap in a plan view has been described, but the number of piezoelectric elements arranged so as not to overlap in a plan view is not limited to three, and may be two or four or more.

As shown in fig. 4, the biosensor 11 may include a plurality of piezoelectric elements 2 (two piezoelectric elements 2 in fig. 4) stacked on the back surface of the cover member 5. In the biosensor 11 shown in fig. 4, two piezoelectric elements 2 are connected in series via a connection wire 12. By stacking a plurality of piezoelectric elements 2 in series in this way, the sensitivity of the piezoelectric elements 2 can be improved.

In the above-described embodiment, the case where the planar shape of the piezoelectric element is circular has been described, but the planar shape of the piezoelectric element is not limited to circular. The planar shape of the piezoelectric element may be a polygonal shape such as an elliptical shape, a triangular shape, a rectangular shape, a pentagonal shape, or a hexagonal shape. The planar shape of the piezoelectric element is determined appropriately for efficient arrangement of the piezoelectric element. When the biosensor includes a plurality of piezoelectric elements, the shapes of the piezoelectric elements may be the same in a plan view, but some or all of the piezoelectric elements may have different shapes.

Industrial applicability

The biosensor of the present invention can be used to measure various vibrations generated in the body of a human or an animal.

Description of the reference numerals

1. 10, 11 biosensor

2 piezoelectric element

21 piezoelectric body

22 electrode

3 gap

4 spacer

41 wall

42 ground wiring

5 covering parts

6 board

7 Shielding layer

8 Signal wiring

9 ground wiring

12 connecting wire