JP6570716B2 - Biological substance measuring device - Google Patents

Description

  The present invention relates to a biological material measuring device, and more particularly, to a biological material measuring device that measures biological materials such as sugar existing in a living body using infrared light.

  A conventional invasive sensor collects blood using a needle and analyzes a component of a substance in a living body. In particular, for blood glucose level sensors that are used on a daily basis, a non-invasive method is required in order to alleviate patient pain due to puncture. As a non-invasive blood sugar level sensor, measurement using infrared light that can directly detect the fingerprint spectrum of sugar has been attempted, but infrared light reaches deep from the skin surface due to strong water absorption. I can't. For this reason, there is a need for a technique for stably and highly accurately detecting blood sugar levels even when the absorption of sugar in the living body is small.

  In response to such a request, for example, the apparatus described in Patent Document 1 measures the blood glucose level using an ATR (Attenuated Total Reflection) method.

JP 2003-42952 A

  In Patent Document 1, a tunable laser is used because it is necessary to measure at a plurality of wavelengths in order to improve measurement accuracy. However, since the wavelength tunable laser is composed of an external resonator, the size is large and the cost is high.

  Therefore, an object of the present invention is to provide a biological material measuring apparatus that can measure the amount of biological material at low cost.

  The biological material measuring apparatus according to the first aspect of the present invention is an infrared light source that emits infrared light in the whole or part of the absorption wavelength of a biological material and a red surface in contact with the biological surface. A prism that transmits infrared light emitted from the external light source unit and emits it to the surface of the living body, a light source that emits light having a wavelength in the visible light region or near infrared region to the prism, and a light source emitted from the prism And an optical position detector that detects a path of light from the light source by detecting light from the light source.

  The biological material measuring apparatus according to the second aspect of the present invention provides an ATR prism that can be brought into close contact with the surface of a living body, and infrared light in the whole or part of the absorption wavelength of the biological material to the ATR prism. An infrared light source unit that radiates, and an infrared light detector that detects infrared light of at least one wavelength emitted from the ATR prism.

  A biological material measuring apparatus according to a third aspect of the present invention provides an ATR prism that can be brought into close contact with the surface of a living body, and infrared light in the whole or part of the absorption wavelength of the biological material to the ATR prism. An infrared light source unit that radiates and an infrared light detector that detects infrared light emitted from the ATR prism, and each infrared light source unit has a wavelength range that the infrared light detector can detect. It is the some light source which radiates | emits the infrared light of the single wavelength contained.

  According to the present invention, since it is not necessary to use a wavelength tunable laser, the amount of biological material existing on the surface of the living body can be measured at a low cost.

1 is a diagram illustrating a configuration of a portable non-invasive biological material measurement device 80 according to Embodiment 1. FIG. It is a figure showing the usage example of the portable noninvasive biological material measuring apparatus 80 of Embodiment 1-6. 6 is a diagram illustrating a configuration of a portable non-invasive biological material measuring apparatus 80 according to Embodiment 2. FIG. It is a figure which shows the fingerprint spectrum of sugar. FIG. 6 is a diagram illustrating a structure of a head of a non-invasive biological material measurement device 80 according to a second embodiment. It is a figure which shows the spectrum of the output light of the infrared light source part 32 of Embodiment 2. FIG. 2 is a schematic diagram of a sensor array 1000 included in an infrared light detector 30. FIG. 10 is a flowchart showing an operation procedure of the noninvasive biological material measuring apparatus 80 according to the second embodiment. It is a figure showing the structure of the infrared-light detector 30 of Embodiment 3. FIG. 6 is a top view of a semiconductor optical device 100 according to a third embodiment. FIG. It is a top view of the semiconductor optical element 100 of Embodiment 3 which abbreviate | omitted the absorber 10. FIG. FIG. 13 is a cross-sectional view (including the absorber 10 and the like) when the semiconductor optical device 100 of FIG. 11 is viewed in the III-III direction. 6 is a diagram illustrating an absorber 10 included in a semiconductor optical device 100 according to a third embodiment. FIG. It is a figure showing the structure of the infrared light source part 32 of Embodiment 5. FIG. It is a figure which shows the spectrum of the output light of the infrared light source part 32 of Embodiment 5. FIG. FIG. 10 is a top view of a wavelength selection structure unit 11 according to a sixth embodiment. It is sectional drawing at the time of seeing the wavelength selection structure part 11 of FIG. 16 in a VV direction.

Hereinafter, embodiments will be described with reference to the drawings.
Embodiment 1 FIG.
Hereinafter, although a blood glucose level will be described as an example of a measurement target, the measurement apparatus of the present invention is not limited to the measurement of a blood glucose level, and can be applied to the measurement of other biological substances.

  In the ATR method described in Patent Document 1, since the prism is brought into contact with the skin to be measured, evanescent light does not penetrate deep into the skin to be measured. As a result, there is a problem that the measurement accuracy of the amount of biological material is low. In this embodiment, the amount of biological material is measured without using the ATR method.

  FIG. 1 is a diagram illustrating a configuration of a portable non-invasive biological material measuring apparatus 80 according to the first embodiment.

  The noninvasive biological material measuring device 80 includes a light source 200, a prism 210, an optical position detector 220, and an infrared light source unit 32.

  The infrared light source unit 32 includes at least one infrared light source. The infrared light source unit 32 includes a broadband quantum cascade laser that emits infrared light in the wavelength range of 8.5 μm to 10 μm including the wavelength of the sugar fingerprint spectrum or in a part of the wavelength range. The wavelengths used for measurement are, for example, λ1, λ2, and λ3. Light having wavelengths λ1 and λ2 is absorbed by sugar in the human body. The light of λ3 is not absorbed by sugar in the human body and is used as a reference wavelength. The wavelengths used for the measurement may be four wavelengths including λ4.

  The infrared light emitted from the infrared light source unit 32 passes through the prism 210 as incident infrared light 11a and enters the living body surface 40 that is the skin of the subject.

  The prism 210 is made of a material such as zinc sulfide (ZnS) that has high transparency in the visible light wavelength region to the infrared light wavelength region.

  The light source 200 is a laser that outputs one wavelength of light having a wavelength in the visible wavelength range to the near-infrared wavelength range. The output light from the light source 200 enters the prism 210 as incident light 230a, passes through the prism 210, and then is emitted from the prism 210 as radiated light 230b or refracted light 230c. The difference between the radiated light 230b and the refracted light 230c is caused by a state change in the prism described later. The emitted light 230b or the refracted light 230c is incident on the optical position detector 220.

  The optical position detector 220 detects a light path from the light source 200 by detecting light from the light source 200 emitted from the prism 210. The optical position detector 220 includes a photodetector that can detect the emitted light 230b or the refracted light 230c. The optical position detector 220 detects a position incident on the photodetector. As a material of the optical position detector 220, for example, an inexpensive photodiode or a plasmon having good wavelength selectivity can be used.

Next, the blood glucose level measurement operation in the present embodiment will be described.
The reference state is set when the light output of the infrared light source 32 is zero. Since the internal state of the prism 210 is uniform in the reference state, the light output from the light source 200 is refracted only when it enters the prism 210 and when it exits the prism. In the reference state, the position where the radiated light 230b is incident on the optical position detector 220 is set as the reference position.

  Next, the infrared light source unit 32 outputs infrared light having a fingerprint spectrum wavelength of sugar as incident infrared light 11a. The incident infrared light 11 a enters the subject's biological surface 40 through the prism 210. Infrared light is absorbed by the sugar present on the subject's biological surface 40. Absorption heat generated by absorption is generated on the biological surface 40. The generated absorption heat is conducted to the prism 210, a temperature gradient is generated inside the prism 210, and a refractive index gradient 240 is formed according to the temperature gradient. This is because the refractive index changes as the temperature changes. This state is referred to as state 1.

  In state 1, the incident light 230 a passes through the refractive index gradient 240. The incident light 230 a is refracted according to the refractive index at the transmitting position in the refractive index gradient 240.

  The refracted incident light 230 a is radiated from the prism 210 as radiation refracted light 230 c and enters the optical position detector 220. In the state 1, the position where the radiated light 230b enters the optical position detector 220 is defined as a displacement position.

  In the reference state in which the infrared light source unit does not emit infrared light, the control unit 250 detects the incident position of the radiated light 230b detected by the optical position detector 220 and the infrared light source unit emits infrared light. In state 1, the amount of sugar on the living body surface 40 is measured based on the difference from the incident position of the refracted light 230c detected by the optical position detector 220.

  By performing the above operation at the wavelengths λ1 and λ2 absorbed by the sugar in the human body and the wavelength λ3 that is not absorbed, the influence of noise can be removed, and the blood sugar level can be calculated more accurately.

  Further, when plasmon is used as the optical position detector 220, since there is wavelength selectivity, it is possible to calculate the displacement position at each of the wavelengths λ1, λ2, and λ3, thereby enabling more accurate blood sugar level measurement. become.

  FIG. 2 is a diagram illustrating a usage example of the portable non-invasive biological material measuring apparatus 80 according to the first to sixth embodiments. As shown in FIG. 2, the blood glucose level in the subject's living body is measured by bringing the head of a portable non-invasive biological material measuring device 80 into contact with the thin lips of the subject's horny layer. The site to be measured is preferably a thin horny lip, but is not limited to this, and may be any site other than a thick horny region such as a palm. For example, measurements can be made on the face cheek, earlobe, or back of the hand.

(Appendix)
The biological material measuring apparatus (80) of the first embodiment has the following features.

  (1) The biological material measuring device (80) is in contact with the biological light surface (40) and the infrared light source part (32) that emits infrared light in the whole or part of the absorption wavelength of the biological material. In this state, the infrared light emitted from the infrared light source unit (32) is transmitted, and the prism (210) that emits the infrared light to the surface of the living body and the light having a wavelength in the visible light region or near infrared region are emitted to the prism. And a light position detector (220) for detecting a light path from the light source (200) by detecting light from the light source (200) emitted from the prism (200). .

  By detecting the path of light from the light source (200) with such a configuration, the amount of biological material existing on the surface of the living body can be measured with high accuracy.

  (2) The infrared light emitted to the biological surface (40) is absorbed by the biological material existing on the biological surface (40), and heat of absorption is generated by the absorption, so that the refractive index is generated inside the prism (210). A gradient (240) is generated.

  With such a configuration, it is possible to generate a refractive index gradient (240) corresponding to the biological material existing on the biological surface (40) in the path through which the light emitted from the light source passes.

  (3) The light emitted from the light source (220) is transmitted through the refractive index gradient (240) generated in the prism (210) by the heat of absorption of the biological material.

  With such a configuration, the light emitted from the light source (220) can be refracted at a refractive index corresponding to the amount of the biological material.

  (4) The biological material measuring device (80) is emitted from the light source (200) detected by the optical position detector (220) when the infrared light source unit (32) does not emit infrared light. The incident position of light and the incident position of light emitted from the light source (200) detected by the optical position detector (220) when the infrared light source unit (32) is emitting infrared light. A control unit (250) that measures the amount of the biological material based on the difference is provided.

  With such a configuration, the optical position detector (220) when the infrared light source unit (32) does not emit infrared light and when the infrared light source unit (32) emits infrared light. The amount of the biological substance can be measured based on the difference in the incident position of the light emitted from the light source (200) detected in (1).

Embodiment 2. FIG.
FIG. 3 is a diagram illustrating a configuration of a portable non-invasive biological material measuring apparatus 80 according to the second embodiment.

  The noninvasive biological material measurement device 80 includes an ATR prism 20, an infrared light source unit 32, an infrared light detector 30, a control unit 52, and a user interface 54.

  The infrared light source unit 32 includes at least one infrared light source. The infrared light source unit 32 emits infrared light in the entire absorption wavelength or a partial wavelength range of the biological material.

The infrared light detector 30 detects the infrared light emitted from the ATR prism 20.
The control unit 52 controls the infrared light source unit 32 and the infrared light detector 30. The controller 52 calculates the concentration of the blood glucose level in the living body based on the intensity of the infrared light detected by the infrared light detector 30.

  The user interface 54 includes a display 501, a keyboard 503, and a speaker 504.

  The ATR prism 20 is mounted on the head of the noninvasive biological material measuring apparatus 80. The ATR prism 20 can be in close contact with the biological surface 40 of the subject.

FIG. 4 is a diagram showing a fingerprint spectrum of sugar.
As shown in FIG. 3, when the biological material measuring device 80 is activated with the ATR prism 20 in close contact with the biological surface 40 of the subject, the wavelength including the fingerprint spectrum of sugar as shown in FIG. Infrared light in the entire wavelength range of a range of 8.5 μm to 10 μm or a part of the wavelength range is emitted.

  Incident infrared light 11a emitted from the infrared light source unit 32 is reflected by the end face 20c of the ATR prism 20, and becomes propagation infrared light 11b. The propagating infrared light 11b passes through the inside of the ATR prism 20 in contact with the living body surface 40 while repeating total reflection at the end surfaces 20a and 20b of the ATR prism 20. The propagating infrared light 11b that has passed through the ATR prism 20 is reflected by the end face 20d of the ATR prism 20 and becomes radiant infrared light 11c. The intensity of the radiant infrared light 11 c is detected by the infrared light detector 30.

  Evanescent light is generated at the end face 20a which is the interface between the ATR prism 20 and the living body surface 40. This evanescent light enters the living body surface 40 and is absorbed by the sugar.

  If the refractive index difference between the biological surface 40 and the ATR prism 20 is small, the evanescent light becomes large. When the propagating infrared light 11b is totally reflected by the end surface 20a, the evanescent light that has oozed out from the ATR prism 20 to the living body surface 40 side is absorbed by the biological material in the living body surface 40, and thus totally reflected by the end surface 20a. The intensity of infrared light is attenuated. Therefore, if the amount of biological material is large, the evanescent light is more absorbed, and the attenuation of the intensity of the totally reflected infrared light also increases.

  The skin is composed of the epidermis near the surface and the dermis below the epidermis. The epidermis includes a stratum corneum, a granular layer, a spiny layer, and a basal layer in order from the vicinity of the surface. Each thickness is about 10 μm, several μm, 100 μm, and several μm. Cells are generated in the basal layer and stacked in the spiny layer. In the granular layer, moisture (tissue interstitial fluid) does not reach and the cells die. In the stratum corneum, dead cells are hardened. Sugars and other biological materials are present in tissue interstitial fluid in the epidermis. Tissue interstitial fluid increases from the stratum corneum to the spinous layer. Therefore, the intensity of the totally reflected infrared light changes according to the penetration length of the evanescent light. Here, the penetration length is also called penetration depth.

  The evanescent light attenuates exponentially from the interface toward the biological surface 40, and the penetration length is about the wavelength. Therefore, in the spectroscopy using the ATR prism 20, the amount of the biological material in the region up to the penetration length can be measured. For example, since the sugar fingerprint spectrum has a wavelength of 8.5 μm to 10 μm, the amount of sugar in this region can be detected from the prism surface of the ATR prism 20.

  FIG. 5 is a diagram showing the structure of the head of the noninvasive biological material measuring apparatus 80 according to the second embodiment. The head includes a substrate 50, an ATR prism 20, an infrared light source unit 32, and an infrared light detector 30.

  The ATR prism 20 has a shape in which a part of a rectangular parallelepiped is cut off. The cross section of the ATR prism 20 has a shape obtained by shaving two rectangular apex angles at a constant angle. As shown in FIG. 5, the shorter surface whose apex angle is cut is brought into contact with the living body surface 40 as a measurement surface. The angle of the end surface 20c of the ATR prism 20 is set so that the propagating infrared light 11b in the ATR prism 20 is totally reflected on the end surface 20a and the end surface 20b of the ATR prism 20. Further, the angle of the end surface 20 d of the ATR prism 20 is set so that the radiated infrared light 11 c enters the infrared light detector 30 perpendicularly.

  The end face 20c where the incident infrared light 11a from the infrared light source 32 is incident and the end face 20d where the radiated infrared light 11c is emitted to the infrared light detector 30 are provided with a non-reflective coating. Alternatively, the incident infrared light 11a from the infrared light source unit 32 is changed to p-polarized light (polarized light is parallel to the substrate 50), and the end face 20c and the exit surface, which are incident surfaces, so that the incident / exit angle becomes the Brewster angle. The end face 20d, which is a surface, may be cut off.

  As a material of the ATR prism 20, a single crystal of zinc sulfide (ZnS) that is transparent in the mid-infrared region and has a relatively low refractive index can be used. The material of the ATR prism 20 is not limited to a single crystal of zinc sulfide (ZnS), and may be a known material such as zinc selenide (ZnSe). A thin film such as SiO2 or SiN is coated on the end surface 20a, which is a contact surface with the skin, of the ATR prism 20 so as not to harm the human body.

  In the second embodiment, for example, a quantum cascade laser module is used as the infrared light source unit 32. The quantum cascade laser is a single light source, has a large output, and has a high signal-to-noise ratio (SNR), so that highly accurate measurement is possible. The quantum cascade laser module is equipped with a lens for collimating the beam. The quantum cascade laser emits infrared light in all or part of the wavelength range of 8.5 μm to 10 μm where the sugar fingerprint spectrum exists.

  In order to improve measurement accuracy, a wavelength tunable laser can be used so that measurement can be performed at a plurality of wavelengths. However, since the wavelength tunable laser is composed of an external resonator, there is a problem that the size is large and the cost is high due to a complicated structure.

FIG. 6 is a diagram illustrating a spectrum of output light from the infrared light source unit 32 of the second embodiment.
The infrared light source unit 32 emits infrared light in all or part of the wavelength range 8.5 μm to 10 μm including the wavelength of the sugar fingerprint spectrum as shown in FIG. Specifically, as already described, a broadband quantum cascade laser that is not a wavelength tunable laser is used as the infrared light source unit 32.

  In addition to the broadband quantum cascade laser, a thermal light source of the type that heats the filament by passing a current may be used as the infrared light source unit 32. In this case, since the temperature can be controlled by the amount of applied current, broadband infrared light according to blackbody radiation is emitted.

  Alternatively, as the infrared light source unit 32, a plasmon or metamaterial light source provided with a periodic pattern in the heating unit may be used instead of the filament. In this case, since the radiation wavelength region is defined by the surface structure, unnecessary radiation is suppressed, so that the infrared light source unit 32 is a highly efficient light source.

  In FIG. 6, the fingerprint spectrum of the sugar shown in FIG. 4 is indicated by a dotted line for comparison. Spontaneous radiation amplified light is used as light over a wide wavelength range as shown in FIG. Therefore, since it is not necessary to use an expensive wavelength tunable laser as the infrared light source unit 32, the infrared light source unit 32 can be a small and low-cost light source.

  At least one wavelength of the radiated infrared light 11 c emitted from the ATR prism 20 is detected by the infrared light detector 30. Thereby, the amount of at least one biological substance corresponding to at least one absorption wavelength can be measured. When plasmon resonance occurs on the surface of the light receiving portion of the infrared light detector 30, infrared light having at least one wavelength is absorbed. At least one of the absorbed wavelengths corresponds to the absorption wavelength of the biological material.

  FIG. 7 is a schematic diagram of a sensor array 1000 included in the infrared light detector 30. The sensor array 1000 includes uncooled infrared sensors (hereinafter also referred to as sensor pixels) 110, 120, 130, and 140 that detect light of different wavelengths.

  The sensor pixels 110, 120, 130, and 140 include, for example, wavelength selective absorbers that use plasmon resonance on the surface of the light receiving unit. With such a structure, infrared light having a selected wavelength can be detected. By using the infrared light detector 30 including an array of uncooled infrared sensors that detect only infrared light of a selected wavelength, a plurality of wavelengths can be measured at the same time, thus enabling measurement in a short time. .

  Further, as will be described later, the use of plasmon resonance eliminates the need for a spectral filter, thereby simplifying the configuration of the infrared light detector 30 and reducing the cost. Also, in the infrared wavelength range, the wavelength selectivity is lowered due to the thermal radiation of the spectral filter itself, but the wavelength selectivity is improved by using a plasmon structure in the light receiving part without using the spectral filter. . As a result, it is possible to achieve high sensitivity for detecting extremely small amounts of components such as analysis of blood glucose levels.

  When the quantum cascade laser and the plasmon are used at the same time, the selectivity of the measurement wavelength is ensured, so that black body radiation components other than the absorption peak wavelength of glucose can be removed. As a result, the SN ratio is improved. In addition, since it is not always necessary to use a quantum cascade laser as a reference wavelength, wavelength selection is possible with a broad light source and plasmon. As a result, cost reduction can be realized.

  Furthermore, when installing a diffraction grating, it is necessary to increase the wavelength resolution, so it is necessary to place the infrared light detector and the diffraction grating apart, but by using plasmons in the light receiving section, the diffraction grating And optical components of the mirror are not necessary. As a result, downsizing of the biological material measuring device can be realized.

  Of the wavelength range 8.5 μm to 10 μm where the sugar fingerprint spectrum exists, the wavelengths used for measurement are, for example, λ1, λ2, λ3, and λ4. As described above, the radiated infrared light 11 c radiated from the infrared light source unit 32 passes through the ATR prism 20 while repeating total reflection. At this time, light of wavelengths λ1, λ2, and λ3 is absorbed by sugar in the human body, and the intensity thereof is attenuated before reaching the infrared light detector 30. Therefore, if the light with wavelengths λ1, λ2, and λ3 can be measured by the infrared light detector 30, the blood glucose level in the human body can be measured. Further, infrared light having a wavelength λ4 that is not absorbed by sugar is used as a reference wavelength.

  The sensor pixels 110, 120, 130, and 140 of the infrared light detector 30 detect infrared light having wavelengths λ1, λ2, λ3, and λ4.

  Infrared light having wavelengths λ1, λ2, and λ3 is absorbed not only by sugar but also by water and other biological materials. On the other hand, infrared light having a wavelength λ4 is not absorbed by sugar but is absorbed by water and other biological substances. Therefore, the intensity of the detected infrared light having the wavelengths λ1, λ2, and λ3 is corrected by using the intensity of the infrared light having the wavelength λ4, respectively, thereby improving the measurement accuracy.

  Infrared radiation emitted from the external background and human body may also enter the infrared photodetector 30. By setting the wavelengths λ1, λ2, and λ3 to values that are very close to each other, the influence of the infrared rays emitted from the background and the human body becomes substantially equal, so that the influence of noise can be minimized.

  In order to exclude this noise, the radiant infrared light 11c may be chopped at a specific frequency using a chopper. Further, the detection sensitivity can be increased by pulsing the infrared light source unit 32 itself and chopping using the frequency. Furthermore, the output signal from the sensor pixels 110, 120, 130, and 140 may be Fourier transformed at the chopping frequency to obtain an output with reduced noise.

  Furthermore, when increasing the wavelength to be detected, a sensor pixel may be added. When the detection wavelength can be adjusted by controlling only the surface periodic structure of the sensor pixel, it is possible to detect as many wavelengths as the number of the arrayed pixels.

Hereinafter, a specific example of the infrared light detector 30 will be described.
As a method of an uncooled infrared sensor which is a thermal infrared sensor used for a sensor pixel of the infrared light detector 30, there are a pyroelectric type, a bolometer, a thermopile, or an SOI (silicon on insulator) type diode. . Even if the method is different, the wavelength can be selected by using the plasmon resonance in the light receiving portion of the sensor, that is, the absorber. Therefore, this embodiment can be used as the detection method of the infrared light detector 30 regardless of the method of the uncooled infrared sensor.

  FIG. 8 is a flowchart showing an operation procedure of the noninvasive biological material measuring apparatus 80 according to the second embodiment.

  In step S <b> 101, the control unit 52 determines whether or not the measurement start is instructed through the keyboard 503. If the user instructs to start measurement, the process proceeds to step S102.

  In step S <b> 102, the control unit 52 outputs a message voice such as “Start measurement” from the speaker 504 to notify the user of the start of blood glucose measurement.

In step S107, the control unit 52 starts measuring the blood sugar level.
In step S108, the control unit 52 determines whether the measurement of the blood sugar level is completed. If completed, the process proceeds to step S109.

  In step S <b> 109, the control unit 52 outputs a message sound such as “Measurement is completed” from the speaker 504.

  In step S110, the control unit 52 calculates a blood glucose level based on the measured intensity of infrared light.

  In step S111, the control unit 52 displays the calculated blood glucose level on the display 501.

(Appendix)
The biological material measurement device (80) of the second embodiment includes the following features.

  (5) The biological material measuring device (80) includes an ATR prism (20) that can be brought into close contact with the biological surface (40), and an ATR prism (20) to the whole or a part of the absorption wavelength of the biological material. An infrared light source unit (32) that emits infrared light in a wavelength range and an infrared light detector (30) that detects infrared light of at least one wavelength emitted from the ATR prism (20).

  With such a configuration, the amount of at least one biological material corresponding to at least one absorption wavelength can be measured.

  (6) The infrared light source unit (32) is a single light source that emits infrared light in a wavelength region that can be detected by the infrared light detector (30).

  With such a configuration, the size of the infrared light can be increased and the SN ratio can be increased, so that highly accurate measurement is possible.

  (7) When plasmon resonance occurs on the surface of the light receiving portion of the infrared light detector (30), infrared light of at least one wavelength is absorbed, and at least one of the absorbed wavelengths is absorbed by the biological material. Corresponds to wavelength.

  With such a configuration, infrared light having a selected wavelength can be detected, and thus the amount of biological material that absorbs the selected wavelength can be measured.

Embodiment 3 FIG.
Differences from the second embodiment will be described.

FIG. 9 is a diagram illustrating the configuration of the infrared light detector 30 according to the third embodiment.
The infrared light detector 30 is an integrated wavelength selective infrared sensor. The infrared light detector 30 includes a sensor array 1000 and a detection circuit 1010.

  The sensor array 1000 includes 9 × 6 pixels (semiconductor optical elements) 100 arranged in a matrix. On the substrate 1, 9 × 6 semiconductor optical devices 100 are arranged in a matrix (array) in the X-axis and Y-axis directions. Light enters from a direction parallel to the Z axis. That is, the infrared light detector 30 receives the infrared light emitted from the ATR prism 20 vertically.

  The detection circuit 1010 is provided around the sensor array 1000. The detection circuit 1010 detects an image by processing a signal detected by the semiconductor optical device 100. The detection circuit 1010 does not need to detect an image when the detection wavelength is small, and may detect the output from each element.

Hereinafter, a thermal infrared sensor will be used as an example of the semiconductor optical device 100.
FIG. 10 is a top view of the semiconductor optical device 100 according to the third embodiment. As shown in FIG. 10, the semiconductor optical device 100 includes an absorber 10 which is a light receiving unit.

  FIG. 11 is a top view of the semiconductor optical device 100 according to the third embodiment in which the absorber 10 is omitted. In FIG. 11, the protective film and the reflective film on the wiring are omitted for clarity. 12 is a cross-sectional view (including the absorber 10) when the semiconductor optical device 100 of FIG. 11 is viewed in the III-III direction. FIG. 13 is a diagram illustrating the absorber 10 included in the semiconductor optical device 100 according to the third embodiment.

  As shown in FIG. 12, the semiconductor optical device 100 includes a substrate 1 made of, for example, silicon. The substrate 1 is provided with a hollow portion 2. A temperature detector 4 for detecting temperature is disposed on the hollow portion 2. The temperature detector 4 is supported by two support legs 3. As shown in FIG. 11, the support leg 3 has a bridge shape bent in an L shape when viewed from above. The support leg 3 includes a thin film metal wiring 6 and a dielectric film 16 that supports the thin film metal wiring 6.

  The temperature detection unit 4 includes a detection film 5 and a thin film metal wiring 6. The detection film 5 is made of a diode using crystalline silicon, for example. The thin film metal wiring 6 is also provided on the support leg 3 and electrically connects the aluminum wiring 7 covered with the insulating film 12 and the detection film 5. The thin film metal wiring 6 is made of, for example, a titanium alloy having a thickness of 100 nm. The electrical signal output from the detection film 5 is transmitted to the aluminum wiring 7 through the thin film metal wiring 6 formed on the support leg 3 and is extracted by the detection circuit 1010 in FIG. The electrical connection between the thin-film metal wiring 6 and the detection film 5 and the electrical connection between the thin-film metal wiring 6 and the aluminum wiring 7 are made of a conductor (not shown) extending in the vertical direction as necessary. ).

  The reflective film 8 that reflects infrared rays is disposed so as to cover the hollow portion 2. However, the reflective film 8 and the temperature detector 4 are arranged so as to cover at least a part of the support leg 3 in a state where they are not thermally connected.

  A support column 9 is provided above the temperature detection unit 4 as shown in FIG. The absorber 10 is supported on the support column 9. That is, the absorber 10 is connected by the temperature detection unit 4 and the support column 9. Since the absorber 10 is thermally connected to the temperature detector 4, the temperature change generated in the absorber 10 is transmitted to the temperature detector 4.

  On the other hand, the absorber 10 is disposed above the reflective film 8 in a state where it is not thermally connected to the reflective film 8. The absorber 10 spreads in a plate shape on the side so as to cover at least part of the reflective film 8. Therefore, when the semiconductor optical device 100 is viewed from above, only the absorber 10 can be seen as shown in FIG. As another aspect, the absorber 10 may be formed directly on the temperature detection unit 4.

  In the present embodiment, as shown in FIG. 12, a wavelength selection structure portion 11 that selectively absorbs light of a certain wavelength is provided on the surface of the absorber 10. On the back surface of the absorber 10, that is, on the support pillar 9 side, an absorption preventing film 13 that prevents light absorption from the back surface is provided. With this configuration, the absorber 10 can selectively absorb light having a certain wavelength. In the present embodiment, it is assumed that the absorber 10 includes the wavelength selection structure 11 because light absorption may occur also in the wavelength selection structure 11.

  Next, a structure in the case where the wavelength selection structure unit 11 uses surface plasmons will be described. When a metal periodic structure is provided on the light incident surface, surface plasmons are generated at a wavelength corresponding to the surface periodic structure, and light is absorbed. Therefore, the surface of the absorber 10 is formed of metal, and the wavelength selectivity of the absorber 10 can be controlled by the wavelength of incident light, the incident angle, and the periodic structure of the metal surface.

  In the present embodiment, the phenomenon contributed by free electrons inside the metal film and the generation of the surface mode by the periodic structure are considered to be synonymous from the viewpoint of absorption, and without distinguishing both, surface plasmon, Called surface plasmon resonance, resonance, pseudo-surface plasmon, or metamaterial. The configuration of the present embodiment is also effective for light in a wavelength region other than infrared light, for example, in the visible, near infrared, and THz wavelength.

  As shown in FIG. 13, the wavelength selection structure portion 11 that selectively increases the absorption of light having a certain wavelength provided on the surface of the absorber 10 includes a metal film 42, a main body 43, and a recess 45. .

  The type of the metal film 42 provided on the outermost surface of the absorber 10 that is a light receiving portion is selected from metals that easily cause surface plasmon resonance such as Au, Ag, Cu, Al, Ni, or Mo. Alternatively, the type of the metal film 42 may be a material that causes plasmon resonance, such as a metal nitride such as TiN, a metal boride, or a metal carbide. The thickness of the metal film 42 on the outermost surface of the absorber 10 may be a thickness that does not transmit incident infrared light. With such a film thickness, only surface plasmon resonance on the outermost surface of the absorber 10 affects the absorption and emission of electromagnetic waves, and the material under the metal film 42 does not optically affect the absorption or the like. is there.

  When μ is the magnetic permeability of the metal film 42, σ is the electric conductivity of the metal film 42, and ω is the angular frequency of the incident light, the skin effect thickness δ1 is expressed by the following equation.

δ1 = (2 / μσω) ^1/2 (1)
For example, if the film thickness δ of the metal film 42 on the surface of the absorber 10 is at least twice as thick as δ1, that is, about several tens nm to several hundreds nm, the leakage of incident light to the lower part of the absorber 10 is Can be small enough.

  For example, comparing the heat capacities of gold and silicon oxide (SiO2), silicon oxide has a smaller heat capacity. Therefore, the absorber made of the surface of the silicon oxide main body 43 and the gold metal film 42 can have a smaller heat capacity than the absorber made of only gold, so that the response can be made faster.

Next, the manufacturing method of the absorber 10 is demonstrated.
After a periodic structure is formed on the surface side of the main body 43 made of a dielectric or semiconductor using photolithography and dry etching, a metal film 42 is formed by sputtering or the like. Next, similarly, the metal film 42 is formed on the back surface after forming the periodic structure.

  Since the diameter of the recess 45 is as small as several μm, the manufacturing process is more effective in forming the metal film 42 after etching the main body 43 and forming the recess than directly etching the metal film 42 to form the recess. It becomes easy. Since an expensive material such as Au or Ag is used for the metal film 42, the amount of metal used can be reduced by using the dielectric or semiconductor body 43, thereby reducing the cost.

  Next, the characteristics of the absorber 10 will be described with reference to FIG. It is assumed that cylindrical recesses 45 having a diameter d = 4 μm and a depth h = 1.5 μm are arranged in a square lattice pattern with a period p = 8 μm. In this case, the absorption wavelength is about 8 μm. Alternatively, it is assumed that cylindrical concave portions 45 having a diameter d = 4 μm and a depth h = 1.5 μm are arranged in a square lattice pattern with a period p = 8.5 μm. In this case, the absorption wavelength is approximately 8.5 μm.

  If the absorber 10 has a two-dimensional periodic structure, the absorption wavelength and emission wavelength of incident light, the period of the recess 45, and the recess 45 are arranged in a square lattice shape or a triangular lattice shape. The relationship is almost the same. That is, the absorption wavelength and the emission wavelength are determined by the period of the recess 45. Considering the reciprocal lattice vector of the periodic structure, theoretically, in the square lattice arrangement, the absorption and emission wavelengths are almost equal to the period, whereas in the triangular lattice arrangement, the absorption and emission wavelengths are the period × √ 3/2. However, in actuality, the absorption and emission wavelengths slightly change depending on the diameter d of the concave portion 45. Therefore, it is considered that a wavelength substantially equal to the period is absorbed or emitted in either periodic structure.

  Therefore, the wavelength of the absorbed infrared light can be controlled by the period of the recess 45. In general, the diameter d of the recess 45 is desirably 1/2 or more of the period p. When the diameter d of the recess 45 is smaller than ½ of the period p, the resonance effect is reduced, and the absorption rate tends to decrease. However, since the resonance is a three-dimensional resonance in the recess 45, sufficient absorption may be obtained even if the diameter d is smaller than ½ of the period p. Therefore, the value of the diameter d with respect to the period p is Designed individually as appropriate. What is important is that the absorption wavelength is mainly controlled by the period p. If the diameter d is equal to or greater than a certain value with respect to the period p, the absorber 10 has sufficient absorption characteristics, so that the design can be widened. On the other hand, referring to the general formula of the surface plasmon dispersion relationship, the absorbed light is independent of the depth h of the recess 45 and depends only on the period p. Therefore, the absorption wavelength and the emission wavelength do not depend on the depth h of the recess 45 shown in FIG.

  In the above description, the absorbent body in which the concave portions 45 are periodically arranged has been described. However, the same effect can be obtained as a structure in which the convex portions 45a are periodically arranged.

  The absorption of the absorber 10 having such a concavo-convex structure is maximized in the case of normal incidence. When the angle of incidence on the absorber 10 deviates from normal incidence, the absorption wavelength also changes. Therefore, the infrared light detector 30 is arranged so that the infrared light emitted from the ATR prism 20 is irradiated perpendicularly to the surface of the absorber 10 as a light receiving unit.

(Appendix)
The biological material measurement apparatus (80) of Embodiment 3 has the following features.

  (8) Concave portions (45) or convex portions (45b) are periodically formed on the surface of the light receiving portion of the infrared light detector (30), and the outermost surface of the light receiving portion is a material that causes surface plasmon resonance.

With such a configuration, the infrared light detector (30) has wavelength selectivity.
(9) The period of the concave portion (45) or the convex portion (45b) on the surface of the light receiving portion of the infrared light detector (30) corresponds to the absorption wavelength of the biological material.

  With such a configuration, the biological material to be measured can be changed by changing the period of the concave portion (45) or the convex portion (45b).

  (10) The infrared light emitted from the ATR prism (20) is perpendicularly incident on the surface of the light receiving portion of the infrared light detector (30).

  With such a configuration, absorption of infrared light in the infrared light detector (30) can be maximized.

Embodiment 4 FIG.
Differences from the third embodiment will be described.

  In the fourth embodiment, the wavelength of one or a plurality of signals in the wavelength range of 8.5 μm to 10 μm where the sugar fingerprint spectrum exists as the infrared light source unit 32 and the reference wavelength slightly deviated from the wavelength range. A quantum cascade laser that oscillates with a wavelength is used.

  The quantum laser module of the present embodiment is equipped with a Peltier element for stabilizing the wavelength and a lens for collimating the beam. Other configurations are the same as those in the third embodiment, and thus will not be repeated.

  Since the radiation from the living body surface 40 is detected as noise when measuring the blood glucose level, the measurement accuracy is lowered.

  In this embodiment, the wavelength used in the quantum cascade laser is set to an appropriate one, and the infrared light detector 30 is used to remove the radiation spectrum from the living body. Thereby, highly accurate measurement excluding radiation from a living body becomes possible.

Embodiment 5 FIG.
Differences from the second embodiment will be described.

  FIG. 14 is a diagram illustrating the configuration of the infrared light source unit 32 according to the fifth embodiment. FIG. 15 is a diagram illustrating a spectrum of output light from the infrared light source unit 32 of the fifth embodiment.

  The infrared light source unit 32 includes single wavelength light sources 71a, 71b, 71c, and 71d. The single wavelength light sources 71a, 71b, 71c, 71d output infrared light of single wavelengths A, B, C, D, respectively, as shown in FIG. The single wavelengths A, B, C, and D are included in a wavelength region that can be detected by the infrared light detector 30.

  In the present embodiment, the infrared light detector 30 does not detect a radiation spectrum from a living body, but can detect infrared light having a wide range of wavelengths (that is, has no wavelength selectivity). be able to.

  For example, the single wavelength light sources 71a, 71b, 71c, 71d output infrared light at different timings, and the infrared light detector 30 having no wavelength selectivity receives each infrared light. can do.

(Appendix)
The biological material measurement device (80) of the fifth embodiment has the following features.

  (11) The biological material measuring device (80) includes an ATR prism (20) that can be brought into close contact with the biological surface (40), and an ATR prism that has an entire absorption wavelength or a partial wavelength region of the biological material. An infrared light source unit (32) that emits infrared light and an infrared light detector (30) that detects infrared light emitted from the ATR prism (20) are provided. The infrared light source unit (32) includes a plurality of light sources (71a, 71b, 71c, 71d) each emitting infrared light having a single wavelength included in a wavelength range detectable by the infrared light detector (32). ).

  With such a configuration, when the plurality of light sources output infrared light at different timings, the infrared light detector (30) having no wavelength selectivity may receive the infrared light of the plurality of light sources. it can.

Embodiment 6 FIG.
Differences from the second embodiment will be described.

  FIG. 16 is a top view of the wavelength selection structure unit 11 according to the sixth embodiment. FIG. 17 is a cross-sectional view of the wavelength selection structure 11 of FIG. 16 when viewed in the VV direction.

  The wavelength selection structure unit 11 includes a metal layer 14, an intermediate layer 18 on the metal layer 14, and a metal patch 17 on the intermediate layer 18.

The metal layer 14 is made of, for example, aluminum or gold.
The intermediate layer 18 is made of an insulator such as silicon oxide, a dielectric, or a semiconductor such as silicon or germanium. By selecting the material of the intermediate layer 18, the detection wavelength, the number of detection wavelengths, and the detection wavelength band can be controlled.

  The metal patch 17 is made of, for example, a metal such as gold, silver, or aluminum, or graphene other than metal. When the metal patch 17 is formed of graphene, the film thickness can be reduced to one atomic layer, so that the thermal time constant can be reduced and high-speed operation is possible. Alternatively, the material of the metal patch 17 may be a material that causes surface plasmon resonance as described above.

  The wavelength at which plasmon resonance occurs can be controlled by the size of the metal patch 17 (dimensions in the x and y directions in FIG. 16). For this reason, the absorption wavelength can be selected by changing the size of the metal patch 17. Therefore, the size of the metal patch 17 is determined so that the wavelength absorbed by the absorber 10 matches the absorption wavelength of the biological material to be measured. For example, as shown in FIG. 16, when the metal patch 17 is square, if the length of one side is 3 μm, the absorption wavelength is about 7.5 μm, and if the length of one side is 3.5 μm, the absorption wavelength Is about 8.8 μm. In this case, the period of the metal patch 17 is determined to be larger than the absorption wavelength and larger than one side of the metal patch 17. As a result, the period of the metal patch 17 can be made substantially unaffected by the absorption wavelength.

  By using the absorber according to the present embodiment, it is possible to reduce the size of the pixel, so that the area of the infrared light detector 30 can be reduced when the array is formed.

  Further, the absorption structure of the wavelength selection structure portion 11 of the present embodiment has no incident angle dependency, and the absorption wavelength does not change even when the incident angle is changed. Similarly, when the metal patch 17 has a symmetrical shape and a two-dimensional periodic structure, there is no polarization dependency. Therefore, the allowable range for the installation angle of the infrared light detector 30 is widened. In the case of a portable biological material measuring device, there is a concern about the shift of the infrared light detector 30, and therefore, by using the absorption structure of this embodiment, there is a remarkable effect that the portability is excellent.

  In FIG. 16, the metal patches 17 are arranged in a matrix (two-dimensional) with a predetermined period, but may be arranged one-dimensionally. In this case, although polarization dependency occurs, stray light can be removed by aligning the arrangement direction with the polarization of the infrared light source unit 32. Therefore, the S / N ratio is improved, and the blood sugar level can be measured with higher accuracy.

(Appendix)
The biological material measurement device (80) of the sixth embodiment has the following features.

  (12) The surface of the light receiving portion of the infrared light detector (30) is formed by laminating a metal thin film (14), an insulating film (18), and a metal patch (17) in this order from the inside. The absorption wavelength of the biological material can be controlled according to the size of 17).

  With such a configuration, the biological material to be measured can be changed by changing the size of the metal patch (17).

  (13) The period in which the metal patch (17) is arranged is longer than the absorption wavelength of the biological material and larger than one side of the metal patch (17).

  With such a configuration, the period of the metal patch (17) can be made substantially unaffected by the absorption wavelength.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,50 substrate, 2 hollow part, 3 support leg, 4 temperature detection part, 5 detection film, 6 thin film metal wiring, 7 aluminum wiring, 8 reflective film, 9 support film, 10 absorber, 11 wavelength selection structure part, 11a Incident infrared light, 11b Propagating infrared light, 11c Radiant infrared light, 12 Insulating film, 13 Absorption prevention film, 14 Metal layer, 16 Dielectric film, 17 Metal patch, 18 Intermediate layer, 20 ATR prism, 20a, 20b 20c, 20d ATR prism end face, 30 infrared light detector, 32 infrared light source part, 40 biological surface, 42 metal film, 43 body, 45 recess, 52,250 control part, 54 user interface, 71a, 71b, 71c , 71d single wavelength light source, 80 biological material measuring device, 100 semiconductor optical device, 110, 120, 130, 140 uncooled infrared sensor, 100 Sensor array 1010 detection circuit, 200 a light source, 210 a prism, 220 light position detector, 230 prism, 230a incident light, 230b emitted light, 230c radiation refracted light, 240 refractive index gradient.

Claims (8)

An ATR prism that can be brought into close contact with the surface of a living body;
An infrared light source unit that emits infrared light in the whole or part of the absorption wavelength of the biological material to the ATR prism;
An infrared light detector for detecting infrared light of at least one wavelength emitted from the ATR prism;
At least one wavelength of infrared light is absorbed by generating plasmon resonance on the light receiving surface of the infrared light detector, and at least one of the absorbed wavelengths corresponds to an absorption wavelength of the biological material. A biological material measuring device.   The biological material measuring apparatus according to claim 1, wherein the infrared light source unit is a single light source that emits infrared light in a wavelength region that can be detected by the infrared light detector.   The biological material measuring device according to claim 2, wherein a concave portion or a convex portion is periodically formed on the surface of the light receiving portion of the infrared light detector, and the outermost surface of the light receiving portion is a material that causes surface plasmon resonance.   The biological material measuring apparatus according to claim 3, wherein a period of a concave portion or a convex portion on a surface of the light receiving portion of the infrared light detector corresponds to an absorption wavelength of the biological material.   The biological material measuring device according to claim 4, wherein infrared light emitted from the ATR prism is perpendicularly incident on a surface of a light receiving unit of the infrared light detector. The surface of the light receiving portion of the infrared light detector is formed by laminating a metal thin film, an insulating film, and a metal patch sequentially from the inside,
The biological material measuring device according to claim 4 or 5, wherein an absorption wavelength of the biological material can be controlled according to a size of the metal patch.   The biological material measurement device according to claim 6, wherein a period in which the metal patches are arranged is longer than an absorption wavelength of the biological material and larger than one side of the metal patch. An ATR prism that can be brought into close contact with the surface of a living body;
An infrared light source unit that emits infrared light in the whole or part of the absorption wavelength of the biological material to the ATR prism;
An infrared light detector for detecting infrared light emitted from the ATR prism;
Each of the infrared light source units is a plurality of light sources that emit infrared light having a single wavelength included in a wavelength range that can be detected by the infrared light detector,
At least one wavelength of infrared light is absorbed by generating plasmon resonance on the light receiving surface of the infrared light detector, and at least one of the absorbed wavelengths corresponds to an absorption wavelength of the biological material. A biological material measuring device.

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