JP2013000158A - Biosensor and biological information detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress influence of stray light on a biosensor including a light emitting part and a light receiving part.SOLUTION: The biosensor includes: substrates 21 and 22 with translucency; the light emitting part 24 disposed on the rear surface of the substrate 22 to irradiate a subject with light sequentially via the substrates 22 and 21; the light receiving part 26 disposed on a surface of the substrate 21 which faces the subject with a light receiving surface turned toward the subject to output a signal according to the light received from the subject; and a shading part 27 formed in such a way as to cover the light receiving part 26 excluding an opening 27a in the inner peripheral edge of the light receiving surface 26a as seen from the top.

Description

  The present invention relates to a technique for detecting biological information such as pulse wave number and oxygen saturation.

  In recent years, there has been known a biological sensor that emits light to a living body by a light emitting unit, receives light reflected by blood of the living body by a light receiving unit, converts the light into an electrical signal, and outputs the signal (for example, Patent Documents 1 and 2) reference). The light reflected by the blood reflects biological information such as the pulse rate and oxygen saturation, so that the biological information can be detected non-invasively by processing the signal output from the biological sensor. .

JP 2009-231577 A JP 2004-173826 A

By the way, since blood is flowing through a fine blood vessel of a living body, it is actually weak against emitted light. For this reason, in a configuration in which the light emitting unit and the light receiving unit are provided on the same surface of the same substrate, the light emitted from the light emitting unit may enter the light receiving unit as leakage light. Since this leaked light does not reflect biological information at all, it acts as a noise component for light reflecting biological information. For this reason, it has been pointed out that the above-described biological sensor cannot accurately detect a weak light component.
The present invention has been made in view of the above-described circumstances, and one of its purposes is to provide a biological sensor and a biological information detection apparatus capable of accurately detecting a weak light component reflecting biological information. There is.

In order to solve the above problems, the biosensor according to the present invention includes a first substrate having light transparency, a light emitting unit that irradiates a subject with light through the first substrate, and the first sensor. A light receiving surface provided on the surface of the substrate facing the subject facing the subject, and a light receiving portion that outputs a signal corresponding to light received from the subject, and the light receiving surface when viewed in plan And a light-shielding portion formed to cover the light-receiving portion.
In the present invention, the light emitting unit irradiates the subject with light through the first substrate, while the light receiving unit with the light receiving surface facing the subject on the opposite surface of the first substrate receives light passing through the opening of the light shielding unit. Receive light. For this reason, light other than the component reflected by the subject, that is, light other than the light component reflecting biological information, is difficult to pass through the opening. Therefore, according to the present invention, it is possible to accurately detect a weak light component reflecting biological information.

  By the way, in the configuration in which the light emitting unit and the light receiving unit are provided on the same substrate, the manufacturing process is likely to be prolonged and the yield may be decreased. Therefore, in the present invention, the light emitting unit is provided on a second substrate having light transmittance, and the subject is irradiated with light through the second substrate and the first substrate in order, and the first substrate is provided. A configuration in which the second substrate is bonded to each other is preferable. According to this configuration, since the light emitting unit is provided on the second substrate different from the first substrate on which the light receiving unit is provided, the manufacturing process can be shortened and the yield can be improved.

In this configuration, the light emitting unit may be a stacked body including at least a first electrode layer, a light emitting layer, and a second electrode layer in order from the second substrate. According to this aspect, the light emitting unit can be formed on the second substrate using the thin film forming technique. For example, an OLED is suitable as the light emitting unit.
In this aspect, when the diameter of the opening in the light-shielding portion is smaller than the depth of the opening, it is possible to suppress the reception of light incident at an angle of 45 degrees or more with respect to the light receiving surface.
In the above aspect, a first light-receiving part protective layer and a second light-receiving part protective layer are formed in order from the light-receiving surface in the opening in the light-shielding part, and the refractive index of the first light-receiving part protective layer is set to the second light receiving part. Even if the refractive index is lower than the refractive index of the partial protective layer, it is possible to suppress the reception of the light component incident at an oblique angle with respect to the light receiving surface.
In addition, it is preferable that a plurality of the light emitting units are provided so as to surround the light receiving unit when seen in a plan view. This is because, according to this configuration, the amount of light applied to the subject increases, and accordingly, the light component reflecting the biological information also increases.
It should be noted that the present invention can also be conceptualized as a biological information detection apparatus having an arithmetic processing circuit that outputs biological information based on a signal output from such a biological sensor.

It is a figure showing a living body information detecting device using a living body sensor concerning an embodiment. It is principal part sectional drawing which shows the structure of a biometric information detection apparatus. It is a top view which shows the biosensor which concerns on embodiment. It is sectional drawing etc. which were cut | disconnected by the DD line | wire in FIG. It is a figure which shows the emission / incident of the light in a biosensor. It is a figure which shows an example of the light-shielding part in a biometric sensor. It is a figure which shows the other example of the light-shielding part in a biometric sensor. It is a block diagram which shows the structure of a biometric information detection apparatus.

Hereinafter, biosensors and the like according to embodiments of the present invention will be described with reference to the drawings.
In each of the following drawings, the scales may be varied in order to make each part, particularly each layer, recognizable.

FIG. 1 is a diagram illustrating a biological information detection apparatus to which a biological sensor according to an embodiment is applied. This biological information detection apparatus 1 detects and outputs, for example, a pulse rate as biological information of a subject.
As shown in the figure, the housing 10 of the biological information detection device 1 has a shape imitating a wristwatch. One end and the other end of the wristband 12 wound around the left wrist of the subject (subject) are attached to portions of the outer periphery of the housing 10 that face each other across the center. As a result, the housing 10 is mounted with the back side in contact with the subject.

FIG. 2 is a cross-sectional view illustrating a configuration of a main part of the biological information detection apparatus 1. As shown in the figure, the inside of the housing 10 has a shape having a hollow portion 15. A living body sensor 20 is attached to the hollow portion 15. The biological sensor 20 includes a light emitting unit 24, a light receiving unit 26, and a light shielding unit 27, and is configured such that when the housing 10 is attached to a subject, the light shielding unit 27 that covers the light receiving unit 26 contacts the subject. Yes.
Although not shown in the drawing, the above-described arithmetic processing circuit and the like are actually mounted in the hollow portion 15. For convenience of explanation, the side that contacts the subject in the biosensor 20 is called the wearing side.

3 is a plan view of the configuration of the biosensor 20 before being attached to the biometric information detection apparatus 1 as viewed from the mounting side, and FIG. 4B is a cross-sectional view taken along line D-d in FIG. is there. FIG. 4A is a diagram illustrating a structure before the substrates are bonded to each other with respect to the biological sensor 20.
As shown in these drawings, the biosensor 20 has a configuration in which a substrate 21 as a first substrate and a substrate 22 as a second substrate are bonded to each other, and when viewed from the mounting side, the substrate 21 is located on the near side, and the substrate 22 is located on the far side. As shown in FIG. 3, the substrates 21 and 22 are both light transmissive. As shown in FIG. 3, for example, the substrates 21 and 22 surround the light receiving unit 26 when viewed from the mounting side. A plurality of light emitting units 24 are arranged.

As shown in FIG. 4 (A) or (B), the light emitting unit 24 is formed on the non-facing surface (back surface) of the substrate 22 on the back side as viewed from the mounting side with various thin films. It is formed by laminating. Specifically, when the light emitting unit 24 is an organic light emitting diode, the first electrode layer 241, the organic layer 242, and the second electrode layer 243 are sequentially stacked starting from the substrate 22. ing.
Here, the first electrode layer 241 is an anode of the OLED and is made of a light-transmitting conductive layer such as ITO (Indium Tin Oxide).
The organic layer 242 includes at least a light-emitting layer, and the light-emitting layer is formed by an inkjet method using a light-emitting layer using, for example, an aluminum quinolinol complex (Alq ₃ ) as a host material and rubrene as a dopant. is there. Here, the inkjet method is a method in which a layer material is dissolved or dispersed in a solvent, the ink composition is discharged from an inkjet head, and a pattern is formed through a drying process.
The second electrode layer 243 is a cathode of the OLED, and includes a reflective conductive layer, for example, a reflective metal layer or alloy layer such as aluminum or silver.
The sealing layer 25 is provided so as to cover the back surface of the substrate 22 including the light emitting unit 24 in order to prevent the OLED from being deteriorated due to the intrusion of oxygen or moisture. The sealing layer 25 is made of, for example, a silicon oxynitride film (SiON).

In the light emitting unit 24 configured in this manner, when a forward bias is applied from the anode to the cathode, the light emitted from the organic layer 242 includes holes injected from the anode side and electrons injected from the cathode side. By combining the layers, light having a spectrum corresponding to the material of the light emitting layer is generated. This light passes through the substrates 22 and 21 in order, and is emitted toward the subject. For this reason, the light emitting unit 24 has a so-called bottom emission structure in which light is emitted through the substrate 22 on which the light emitting unit 24 is formed.
Therefore, as described above, the substrate 21 and 22 is made of light-transmitting glass or the like. Here, the light transmissive property means a property of transmitting a light component included in a wavelength band of light emitted from the light emitting unit 24.
Note that the organic layer 242 may be multilayered in order from the first electrode layer 241 such as a hole injection layer, a hole transport layer, a light emitting layer, a potential transport layer, and an electron injection layer. In FIG. 4, the first electrode layer 241 and the second electrode layer 243 are each patterned, but may be so-called solid.

On the other hand, as shown in FIG. 4, the light receiving unit 26 and the light shielding unit 27 are formed on the surface on the mounting side (the surface facing the subject) of the substrate 21 positioned on the near side as viewed from the mounting side.
Specifically, as shown in FIG. 3 and FIG. 4, the light-shielding unit 27 is configured to remove the light-receiving unit 26 from the light-receiving unit 26 except for the opening 27 a of the light-receiving surface 26 a facing the subject. It is formed so as to cover the whole. The opening 27a is provided so as to open the inner peripheral edge of the light receiving surface 26a.

The light shielding portion 27 is formed, for example, divided into a plurality of processes as follows. That is, first, a light shielding layer (first layer) is formed on the mounting side surface of the substrate 21 and patterned into a circle. Secondly, the light-receiving part 26 is formed by using a light shielding layer patterned in a circle as a cushion. Third, a light shielding layer (second layer) is formed again so as to cover the surface on the mounting side of the substrate 21 and the light receiving unit 26. Fourth, in the second light shielding layer, the region for transmitting the light of the light emitting portion 24 in the substrate 21 and the region corresponding to the opening 27a are removed by photolithography.
As a result, the second light-shielding layer is combined with the first light-shielding layer, so that the light-shielding part 27 is formed so as to cover the light-receiving part 26 as shown in FIGS.
In addition, as a material of the light shielding part 27, a light shielding material such as aluminum or chromium can be used.

  The light receiving unit 26 is formed by laminating various thin films on the mounting surface side of the substrate 21. Specifically, when the light receiving unit 26 is, for example, a light absorption organic photodiode, a protective layer serving as an insulating base for the first light shielding layer is formed on the mounting surface of the substrate 21. Thus, a structure in which a cathode layer, a light receiving layer, and an anode layer having optical transparency are stacked in this order may be employed. In such a configuration, when light enters the light receiving layer through the opening 27a, a pair of electrons and holes is generated. Here, when a bias is applied in the opposite direction between the cathode and the anode, electrons and holes are separated and moved, so that a current corresponding to the amount of incident light flows through the light receiving unit 26.

In the present embodiment, finally, as shown in FIG. 4B, the substrate 21 and the substrate 22 are bonded together with an adhesive so that the light emitting unit 24 and the light receiving unit 26 are back to back. The biosensor 20 is configured. Here, as the adhesive, an ultraviolet curable type or an epoxy type is used.
In this embodiment, since the non-defective products of the substrates 21 and 22 may be bonded together, the manufacturing process is compared with a configuration in which the light emitting unit 24 is provided on one surface of one substrate and the light receiving unit 26 is provided on the other surface. Can be shortened and the yield in manufacturing can be improved.

FIG. 5 is a diagram showing light emission / incidence paths in the biological sensor 20.
As described above, the light shielding part 27 is formed so as to cover the entire light receiving part 26 except for the opening 27a of the light receiving surface 26a. Here, reference numerals 27b, 27c, and 27d denote an upper surface, a bottom surface, and a side surface of the light shielding unit 27, respectively. Since the light shielding portion 27 is formed from the substrate 21 side, the light shielding portion 27 is grasped with reference to the substrate 21. For this reason, in the drawing, the upper side is the bottom surface 27c (the lower side is the upper surface 27b).
In the configuration of FIG. 5, the upper surface 27b, the bottom surface 27c, and the side surface 27d are shielded except for the light receiving surface 26a of the light receiving unit 26. However, it is not always necessary to shield all the surfaces. A light-shielding portion may be provided so as to cover a necessary surface of the light-receiving portion 26 according to the incident direction of light that becomes noise for the light-emitting device 26.
When the housing 10 (see FIG. 1) is attached to the subject, the light shielding unit 27 contacts the subject. For this reason, as shown in FIG. 5, the skin 40 of the subject comes into contact with the upper surface 27 b provided with the opening 27 a in the light shielding portion 27.

The light emitted from the light emitting layer of the organic layer 242 is emitted in all directions, but the light traveling upward is reflected by the second electrode layer 243. For this reason, since the light from the light emitting part 24 is emitted substantially downward in the drawing, it passes through the substrates 22 and 21 in this order.
Of the emitted light, the component that has reached the back surface of the light receiving unit 26 is blocked by the bottom surface 27c of the light blocking unit 27, and thus does not affect the light reception of the light receiving unit 26. Similarly, since the component that has reached the side surface of the light receiving unit 26 is shielded by the side surface 27d of the light shielding unit 27, the light reception of the light receiving unit 26 is not affected.

On the other hand, of the light emitted from the light emitting unit 24 and sequentially passing through the substrates 22 and 21, the light that is not shielded by the light shielding unit 27 enters the skin 40 of the subject. The light that has entered the skin 40 reaches the blood vessel 42 and is reflected, absorbed, or transmitted by the blood flowing through the blood vessel 42. Of the light reflected by the blood flowing in the blood vessel 42, only the light passing through the opening 27a is incident on the light receiving unit 26.
Here, the blood vessel 42 repeats expansion and contraction in the same cycle as the heartbeat. Therefore, since the amount of reflected light increases or decreases in the same cycle as the expansion / contraction cycle of the blood vessel 42, a change in the current output from the light receiving unit 26 indicates a change in the volume of the blood vessel 42.

  According to the biological sensor 20 according to the present embodiment, it is possible to suppress the light component that is noise that does not reflect the biological information from being received by the light receiving unit 26 with respect to the optical component that reflects the biological information. Therefore, it is possible to accurately detect a weak light component reflecting biological information.

  Further, when the housing 10 is attached to the subject, for some reason, for example, when the subject exercises, the housing 10 may be shaken and the upper surface 27b may be separated from the skin 40 to create a gap. The light generated through the gap at this time enters at a deep angle, that is, from the direction along the surface of the skin 40, but cannot pass through the opening 27a. For this reason, according to the biological sensor 20 according to the present embodiment, it is possible to make it difficult for the detection accuracy of biological information to decrease even when there is a body movement.

Specifically, as shown in FIG. 6A, when the diameter of the opening 27a is R and the depth of the opening 27a (thickness of the light shielding portion 27) is d,
R <d
The light shielding part 27 is formed so as to be In this light shielding portion 27, even if the upper surface 27b is separated from the skin 40 and a gap is formed, the light having the incident angle θ shown in FIG. 6B of 45 degrees or more cannot pass through the opening 27a. The incident on the light receiving unit 26 is blocked. Even if the upper surface 27b is not separated from the skin 40, the light having an incident angle θ of 45 degrees or more may be a light component that does not reflect biological information.
According to the present embodiment, since such light components do not enter the light receiving unit 26, biological information can be detected with high accuracy in this sense.

  As shown in FIG. 7A, a protective layer 261 (first light receiving portion protective layer) is provided on the light receiving surface 26a side in the opening 27a, and then a protective layer 262 (second light receiving portion protection) is provided. A refractive index n1 of the protective layer 261 may be smaller than a refractive index n2 of the protective layer 262. In this way, light incident on the interface between the protective layers 261 and 262 at an angle θa shown in FIG. 7B is emitted at an angle θb larger than the angle θa. It becomes easy to stop. For this reason, biological information can be detected with high accuracy.

FIG. 8 is a block diagram showing an electrical configuration of the biological information detection apparatus 1 using the biological sensor 20 according to the embodiment. Note that this configuration is only briefly described.
In this figure, the drive circuit 50 drives the light emitting unit 24 by supplying current constantly or intermittently according to an instruction from the arithmetic processing circuit 60. Here, it is preferable to drive the current intermittently in order to reduce power consumption. On the other hand, the conversion circuit 55 converts the current flowing through the light receiving unit 26 into a voltage and converts the voltage into digital data at a predetermined sampling interval.

  The arithmetic processing circuit 60 processes a signal received by the light receiving unit 26 when light is emitted from the light emitting unit 24, that is, a signal of light reflecting biological information. For example, the arithmetic processing circuit 60 calculates the pulse rate from the digital data or records the pulse rate in association with the time measured by the internal timer. The information and data may be transferred to an external computer, displayed on a display unit (not shown), or output by speech synthesis.

The present invention can be variously applied and modified in addition to the above-described embodiments.
The light emitting unit 24 and the light receiving unit 26 are formed on different surfaces, the light emitting unit 24 emits light toward the subject, and the light receiving unit 26 receives light that has passed through the opening 27a. For example, the arrangement / number and the shapes of the light emitting surface and the light receiving surface are arbitrary.
For example, in the embodiment, the plurality of light emitting units 24 are disposed so as to surround the light receiving unit 26, but one light emitting unit 24 and one light receiving unit 26 may be provided. However, as compared with the embodiment, the light irradiated to the subject is weakened, and the received light amount is reduced accordingly. Further, the planar shape of the opening 27a is not limited to a circle.

4A, the light emitting unit 24 may be formed on the back surface of the substrate 21 opposite to the surface on which the light receiving unit 26 and the light shielding unit 27 are formed. However, in this configuration, it is necessary to form the light receiving part 26 and the light shielding part 27 on the front surface and the light emitting part 24 on the back surface as viewed from the mounting side in the substrate 21, so that the manufacturing process tends to be prolonged. Also, if a defect occurs in the formation process on either side, it will be a defective product at that time, so the yield during manufacturing will be reduced compared to the embodiment, and the cost will be increased accordingly. Easy to invite.
In the embodiment, the light shielding unit 27 is in contact with the light receiving unit 26, but another layer or the like may be interposed between the light receiving unit 26 and the light shielding unit 27. However, the light-shielding property with respect to the light receiving part is higher in the structure in contact.

In the biosensor 20 according to the present embodiment, the OLED is used as the light emitting unit 24. However, the present invention is not limited thereto, and various elements such as an LED can be applied.
Further, the light receiving unit 26 is not limited to an organic photodiode. For example, the light receiving unit 26 may be a CCD (Charge Coupled Device) or the like, or a nano (micro) crystal thin film or a CGIS (Copper: Copper, Gallium: Gallium, Indium: Indium, Selenium: Selenium) compound. A solar cell using a thin film made of for the light receiving layer may be used. In any case, the light receiving unit 26 may be a photoelectric conversion element that outputs a signal corresponding to light reception.

  In the embodiment, the measurement site of the subject is the left wrist, but the fingertip may be set as the measurement site by incorporating a biosensor in the cuff body, for example. In other words, the finger plethysmogram may be detected.

Although the biological sensor 20 has exemplified the configuration for detecting the pulse wave, it can also be applied to a sensor for detecting the oxygen saturation of arterial blood. The hemoglobin in blood has different absorbances for red light and infrared light depending on the presence or absence of binding to oxygen. Therefore, while preparing multiple pairs of light emitting / receiving parts with different emission wavelengths and light receiving wavelengths such as red light emitting / receiving parts, infrared light emitting / receiving parts, etc., measure the reflected light.・ Oxygen saturation can be detected by analysis.
The blood vessel may be an artery or a vein.
The biological information may be a blood vessel pattern of the living body, and can also be applied to an authentication device that authenticates the living body from this blood vessel pattern.
Of course, the measurement target is not limited to a human but may be an animal.

DESCRIPTION OF SYMBOLS 1 ... Biological information detection apparatus, 20 ... Biological sensor, 21, 22 ... Board | substrate, 24 ... Light-emitting part, 26 ... Light-receiving part, 26a ... Light-receiving surface, 27 ... Light-shielding part, 42 ... Blood vessel, 50 ... Arithmetic processing circuit, 261, 262 ... Protective layer.

Claims (7)

A first substrate having optical transparency;
A light emitting unit that irradiates the subject with light through the first substrate;
A light receiving portion provided on the opposite surface side of the first substrate to the subject with a light receiving surface facing the subject, and outputting a signal in response to light received from the subject;
A light-shielding portion having an opening provided to expose the light-receiving surface when viewed in plan, and covering the light-receiving portion;
A biological sensor comprising: The light emitting unit is provided on a second substrate having light transparency,
The subject is irradiated with light through the second substrate and the first substrate in order,
The biosensor according to claim 1, wherein the first substrate and the second substrate are bonded to each other. The light emitting unit
The biosensor according to claim 2, wherein the biosensor is a laminate including at least a first electrode layer, a light emitting layer, and a second electrode layer in order from the second substrate. The biosensor according to claim 3, wherein a diameter of the opening in the light shielding portion is smaller than a depth of the opening. In the opening in the light shielding part, a first light receiving part protective layer and a second light receiving part protective layer are formed in order from the light receiving surface,
The biosensor according to claim 3, wherein a refractive index of the first light receiving part protective layer is lower than a refractive index of the second light receiving part protective layer. The biosensor according to any one of claims 2 to 5, wherein when viewed in a plan view, a plurality of the light emitting units are provided so as to surround the light receiving unit. The biological sensor according to any one of claims 1 to 6,
An arithmetic processing circuit that outputs biological information based on a signal output from the light receiving unit;
A biological information detection device comprising:

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