Analysis device

Abstract

To provide an analyzer that can be miniaturized.SOLUTION: The analyzer includes a substrate having a first surface and a second surface located on the opposite side of the first surface, a light source unit provided on the first surface of the substrate and including a quantum cascade laser, a light detection unit provided on the first surface of the substrate, and a wiring unit provided on the first surface of the substrate and electrically connected to the light source unit and the light detection unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an analytical apparatus.

Background Art

[0002] As a method for measuring the concentration of a substance in blood by a non-invasive method, an optical method is used. In the mid-infrared wavelength range targeted by the present invention, when measuring the blood concentration in blood vessels rather than the tissue fluid of somatic cells, a high output is required for the light source, making miniaturization difficult.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide an analytical apparatus that can be miniaturized.

Means for Solving the Problems

[0005] According to an embodiment of the present invention, an analytical apparatus includes a substrate having a first surface and a second surface located on the opposite side of the first surface, a light source unit provided on the first surface of the substrate and including a quantum cascade laser, a photodetection unit provided on the first surface of the substrate, and a wiring unit provided on the first surface of the substrate and electrically connected to the light source unit and the photodetection unit.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

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Figure 7

Mode for Carrying Out the Invention

[0007] Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals.

[0008] [First Embodiment] FIG. 1 is a schematic cross-sectional view of the analyzer 1 of the first embodiment. The analyzer 1 includes a substrate 10, a light source unit 21, and a light detection unit 22.

[0009] The substrate 10 is transparent to the light emitted by the light source unit 21. The substrate 10 is, for example, a silicon substrate containing Si. Alternatively, the substrate 10 may be a compound semiconductor substrate containing InP or GaAs. The substrate 10 has a first surface 11 on which the light source unit 21 and the light detection unit 22 are provided, and a second surface 12 located on the opposite side of the first surface 11. The substrate 10 includes a lens unit 15 on the second surface 12. The lens unit 15 includes a concave portion, a convex portion, or a periodic structure portion obtained by processing the substrate 10.

[0010] The light source unit 21 includes a first quantum cascade laser 21a and a second quantum cascade laser 21b having different oscillation wavelengths from each other. The first quantum cascade laser 21a and the second quantum cascade laser 21b have a light-emitting layer including, for example, a III-V compound semiconductor. The light-emitting layer has a quantum well structure that causes inter-subband transitions of carriers and emits light by inter-subband transitions of electrons.

[0011] The first quantum cascade laser 21a and the second quantum cascade laser 21b are surface-emitting types including a photonic crystal layer 30. The surface of the light-emitting layer is parallel to the first surface 11 of the substrate 10. The photonic crystal layer 30 includes a two-dimensional diffraction grating. The photonic crystal layer 30 has, as the two-dimensional diffraction grating, for example, a plurality of pits periodically arranged in a plane parallel to the first surface 11 of the substrate 10. The light emitted from the light-emitting layer resonates in a direction along the surface of the light-emitting layer by the photonic crystal layer 30 and is emitted in a direction generally perpendicular to the first surface 11 of the substrate 10. The generally perpendicular direction includes a direction inclined within a range of 2° or more and 10° or less with respect to the direction perpendicular to the first surface 11. Since this structure is a surface-emitting type, high output can be easily obtained by increasing the element area. Since the quantum cascade laser is TM polarized, a surface-emitting type can be realized using a photonic crystal. Furthermore, the quantum cascade laser can, in principle, operate at high speed and can generate a very short pulse. This can reduce the total energy, irradiate a pulse with a high peak value without damaging the biological tissue, and enable highly sensitive measurement of the target analyte in the blood vessel.

[0012] The light detection unit 22 includes a first quantum cascade detector 22a and a second quantum cascade detector 22b. The first quantum cascade detector 22a can detect the light emitted by the first quantum cascade laser 21a. The second quantum cascade detector 22b can detect the light emitted by the second quantum cascade laser 21b. The first quantum cascade detector 22a and the second quantum cascade detector 22b are light detection elements that utilize intersubband transitions of electrons. When a conventional quantum cascade detector tried to detect light incident from a direction perpendicular to the substrate, since the thickness of the active region that absorbs light and converts it into electrons was at most about 2 μm, the light absorption was insufficient and the sensitivity was extremely low. On the other hand, the quantum cascade detector using a photonic crystal according to an embodiment of the present invention converts the light incident perpendicular to the substrate into a direction parallel to the active layer by the photonic crystal, so that it is sufficiently absorbed in the active layer and the sensitivity is increased.

[0013] For example, the first quantum cascade detector 22a and the second quantum cascade detector 22b include semiconductor layers of the same type as the first quantum cascade laser 21a and the second quantum cascade laser 21b. For example, the first quantum cascade laser 21a, the second quantum cascade laser 21b, the first quantum cascade detector 22a, and the second quantum cascade detector 22b are integrally formed on a growth substrate different from the substrate 10, and then bonded to the first surface 11 of the substrate 10 via a silicon oxide film or directly. Alternatively, the first quantum cascade laser 21a, the second quantum cascade laser 21b, the first quantum cascade detector 22a, and the second quantum cascade detector 22b may be grown on the first surface 11 of the substrate 10.

[0014] The first quantum cascade detector 22a and the second quantum cascade detector 22b are, for example, surface light receiving types including a photonic crystal layer 30 similar to the first quantum cascade laser 21a and the second quantum cascade laser 21b.

[0015] Each of the first quantum cascade laser 21a, the second quantum cascade laser 21b, the first quantum cascade detector 22a, and the second quantum cascade detector 22b has a first electrode 41 and a second electrode 42.

[0016] The first electrode 41 is provided above the photonic crystal layer 30. As shown in Fig. 2(a), in a top view, the second electrode 42 is provided around the first electrode 41.

[0017] The analyzer 1 is provided on the first surface 11 of the substrate 10 and further has a wiring part electrically connected to the light source part 21 and the light detection part 22. As the material of the wiring part, for example, Ti / Au, Ni / Au, AuGe / Au, etc. can be used. As shown in Fig. 2(a), the wiring part includes a first wiring 45 connected to the first electrode 41, a first pad 46 connected to the first wiring 45, a second wiring 43 connected to the second electrode 42, and a second pad 44 connected to the second wiring 43. The light source part 21 and the light detection part 22 are electrically connected to an external circuit through wires joined to the first pad 46 and the second pad 44.

[0018] As shown in Fig. 2(b), the first electrode 41 may be circular in a top view. The second electrode 42 annularly surrounds the first electrode 41 in a top view. A wire may be directly joined to the first electrode 41 without connecting the first electrode 41 to a pad.

[0019] The first quantum cascade laser 21a and the second quantum cascade laser 21b output laser light in the mid-infrared region. The first quantum cascade laser 21a outputs laser light with a wavelength λ1, and the second quantum cascade laser 21b outputs laser light with a wavelength λ2 different from λ1. λ1 and λ2 are, for example, 7.8 μm or more and 8.8 μm or less.

[0020] The laser light from the first quantum cascade laser 21a and the second quantum cascade laser 21b travels through the substrate 10 towards the second surface 12 and is emitted from the second surface 12 to the outside of the substrate 10. The laser light is focused or redirected by the lens portion 15 of the second surface 12 and, for example, enters the human skin and reaches and is reflected by the blood vessel 100.

[0021] The laser light reflected by the blood vessel 100 is focused or redirected by the lens portion 15 and enters the substrate 10 from the second surface 12. The reflected light entering the substrate 10 enters the first quantum cascade detector 22a and the second quantum cascade detector 22b from the first surface 11. The light entering the first quantum cascade detector 22a and the second quantum cascade detector 22b is photoelectrically converted. From the photoelectrically converted electrical signal, the intensity of the reflected light corresponding to the glucose absorption rate in the blood vessel 100 is measured. Here, the blood glucose level is the concentration of glucose contained in the blood. Therefore, the blood glucose level can be obtained from the intensity of the reflected light corresponding to the glucose absorption rate in the blood vessel 100.

[0022] According to this embodiment, the light source unit 21, the light detection unit 22, and the wiring unit are integrated on the first surface 11 of the substrate 10 by a semiconductor process. Also, the lens portion 15 is provided on the second surface 12 of the substrate 10 by processing the substrate 10. For this reason, a small non-invasive analyzer can be provided. For example, an analyzer with a chip size of about 1 mm can be provided and can be mounted on a mobile terminal or the like.

[0023] The light source unit 21 may be constituted by one quantum cascade laser, and the light detection unit 22 may be constituted by one quantum cascade detector. In this case, the analyzer 1 can be made smaller. When two quantum cascade lasers 21a, 21b and two quantum cascade detectors 22a, 22b are used, the blood glucose level can be obtained with high precision from the ratio of the absorbance of glucose for two different wavelengths of light.

[0024] [Second Embodiment] FIG. 3 is a schematic cross-sectional view of the analyzer 2 according to the second embodiment.

[0025] The analyzer 2 of the second embodiment has a photodetector 60 that utilizes plasmons. The photodetector 60 includes a metal antenna 61 provided on the first surface 11 of the substrate 10. As shown in Fig. 4(a), the metal antenna 61 includes a plurality of metal pillars (or uneven structures) 61a that are, for example, nanostructures. A wiring portion electrically connected to the metal antenna 61 is provided on the first surface 11. The wiring portion includes a wiring 63 connected to the metal antenna 61 and a pad 64 connected to the wiring 63.

[0026] A back surface electrode 62 is provided on the second surface 12 of the substrate 10. As shown in Fig. 4(b), the back surface electrode 62 surrounds the light incident region 12a on the second surface 12. A lens unit 15 is disposed in the light incident region 12a.

[0027] Also in the second embodiment, since the light source unit 21, the metal antenna 61, and the wiring portion are integrated on the first surface 11 of the substrate 10 by a semiconductor process, a small non-invasive analyzer can be provided.

[0028] [Third Embodiment] Fig. 5 is a schematic cross-sectional view of the analyzer 3 of the third embodiment.

[0029] The analyzer 3 of the third embodiment has an end-face-emitting quantum cascade laser 24 and a diffraction grating 25 as the light source unit 23.

[0030] Fig. 6(a) is a schematic top view of the quantum cascade laser 24, and Fig. 6(b) is a schematic bottom view of the bottom surface electrode 28 of the quantum cascade laser 24.

[0031] The quantum cascade laser 24 has, for example, a semiconductor layer 26 including a III-V group compound semiconductor, a top surface electrode 27 provided on the semiconductor layer 26, and a bottom surface electrode 28 provided in a region below the semiconductor layer 26 on the second surface 12 of the substrate 10.

[0032] The diffraction grating 25 is provided on the first surface 11 of the substrate 10 and is located on the side of the end face (light emitting face) of the quantum cascade laser 24. The lens portion 15 is located in the lower region of the diffraction grating 25 on the second surface 12. The laser light emitted from the end face of the quantum cascade laser 24 is redirected by the diffraction grating 25 in the direction from the first surface 11 toward the second surface 12.

[0033] A surface emitting type quantum cascade laser having a photonic crystal layer has better diffraction efficiency than a combination of an edge emitting type quantum cascade laser and a diffraction grating.

[0034] [Fourth Embodiment] FIG. 7 is a schematic cross-sectional view of the analyzer 4 according to the fourth embodiment.

[0035] The analyzer 4 according to the fourth embodiment includes a quantum cascade element 51 that also serves as a light source unit and a light detection unit. The quantum cascade element 51 is a surface emitting / receiving type including a photonic crystal layer 30.

[0036] The quantum cascade element 51 has a surface emission mode in which laser light is emitted in the direction from the first surface 11 to the second surface 12 of the substrate 10, and a surface light reception mode in which reflected light incident from the second surface 12 is received from the first surface 11 side. By rapidly switching between the surface emission mode and the surface light reception mode, one quantum cascade element 51 can also serve as a light source unit and a light detection unit. According to such a fourth embodiment, the analyzer 4 can be made smaller.

[0037] It is also possible to non-invasively acquire biological information other than blood glucose level using the analyzers of the embodiments described above. Although the quantum cascade laser and the quantum cascade detector serving as light sources have been described in detail above, a drive circuit for the quantum cascade laser and an electric circuit for processing an electric signal from the quantum cascade detector may be formed on the substrate. In the case of this configuration, a more compact device can be configured. In addition, regarding the structures of the quantum cascade laser and the quantum cascade detector, a general structure and configuration capable of oscillating in this wavelength range may be used.

[0038] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Description of Reference Numerals

[0039] 1 to 4... analyzer, 10... substrate, 11... first surface, 12... second surface, 15... lens unit, 21, 23... light source unit, 21a... first quantum cascade laser, 21b... second quantum cascade laser, 22, 60... photodetector, 22a... first quantum cascade detector, 22b... second quantum cascade detector, 24... quantum cascade laser, 30... photonic crystal layer, 51... quantum cascade element, 61... metal antenna, 100... blood vessel

Claims

1. A substrate having a first surface and a second surface located on the opposite side of the first surface, a light source unit provided on the first surface of the substrate and including a first quantum cascade laser and a second quantum cascade laser having different oscillation wavelengths from each other, a light detection unit provided on the first surface of the substrate, a wiring unit provided on the first surface of the substrate and electrically connected to the light source unit and the light detection unit, comprising: The substrate is an analyzer including a lens unit on the second surface.

2. The analyzer according to claim 1, wherein the first quantum cascade laser and the second quantum cascade laser are surface emission types including a photonic crystal layer.

3. The analyzer according to claim 1 or 2, wherein the light detection unit includes a quantum cascade detector.

4. The analyzer according to claim 1 or 2, wherein the light detection unit includes a metal antenna.

5. A substrate having a first surface and a second surface located on the opposite side of the first surface, a quantum cascade element provided on the first surface of the substrate and serving as both a light source unit and a light detection unit, a wiring unit provided on the first surface of the substrate and electrically connected to the quantum cascade element, comprising: The quantum cascade element is a surface emission / reception type including a photonic crystal layer.

6. The analyzer according to any one of claims 1 to 5, wherein the substrate includes Si, InP, or GaAs.

7. The analyzer according to claim 5 or 6, wherein the substrate includes a lens unit on the second surface.

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