Fluorescence detection device

Abstract

Provided is a fluorescence detection device with improved fluorescence detection sensitivity. The fluorescence detection device comprises: a light source that irradiates a sample with a circularly polarized excitation light; a cholesteric liquid crystal layer that transmits fluorescence emitted by the sample due to irradiation with the excitation light and reflects the excitation light; and a detection circuit that detects fluorescence transmitted by the cholesteric liquid crystal layer.

Description

[Technical field]

[0001] The present disclosure relates to a fluorescence detection device. [Background technology]

[0002] The fluorescence detection device of Patent Document 1 has an optical system with a dichroic mirror, and detects fluorescence reflected from a sample. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-321753 A Summary of the Invention [Problem to be solved by the invention]

[0004] The fluorescence detection device of Patent Document 1 does not require a dichroic mirror, and there is a demand for further excitation light removal performance.

[0005] An object of the present disclosure is to provide a fluorescence detection device with improved fluorescence detection sensitivity. [Means for solving the problem]

[0006] A fluorescence detection device according to one aspect of the present disclosure includes a light source that irradiates a sample with circularly polarized excitation light, a cholesteric liquid crystal layer that transmits fluorescence emitted by the sample in response to the excitation light and reflects the excitation light, and a detection circuit that detects the fluorescence that has transmitted through the cholesteric liquid crystal layer. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a fluorescence detection device according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view for illustrating a schematic configuration of the cholesteric liquid crystal layer of the first embodiment. [Diagram 3]FIG. 3 is a plan view illustrating a schematic diagram of the first and seventh layers of the cholesteric liquid crystal layer of the first embodiment. [Figure 4] FIG. 4 is a plan view illustrating a schematic diagram of the second layer of the cholesteric liquid crystal layer of the first embodiment. [Diagram 5] FIG. 5 is a plan view illustrating a schematic configuration of the third layer of the cholesteric liquid crystal layer of the first embodiment. [Figure 6] FIG. 6 is a plan view illustrating a schematic diagram of the fourth layer of the cholesteric liquid crystal layer of the first embodiment. [Figure 7] FIG. 7 is a plan view illustrating a schematic diagram of the fifth layer of the cholesteric liquid crystal layer of the first embodiment. [Figure 8] FIG. 8 is a plan view illustrating a schematic diagram of the sixth layer of the cholesteric liquid crystal layer of the first embodiment. [Figure 9] FIG. 9 is an explanatory diagram for explaining the relationship between the excitation light and the reflected light. [Figure 10] FIG. 10 is a schematic diagram showing a fluorescence detection device according to a comparative example. [Figure 11] FIG. 11 is a schematic diagram showing a fluorescence detection device according to the second embodiment. [Figure 12] FIG. 12 is a schematic diagram showing a fluorescence detection device according to the third embodiment. [Figure 13] FIG. 13 is a schematic diagram showing a fluorescence detection device according to the fourth embodiment. [Figure 14] FIG. 14 is an explanatory diagram showing the relationship between the wavelength characteristics of the excitation light reflected by the first liquid crystal layer and the wavelength characteristics of the excitation light reflected by the second liquid crystal layer in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The form (embodiment) for carrying out the present disclosure will be described in detail with reference to the drawings. The present disclosure is not limited by the contents described in the following embodiments. In addition, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the components described below can be appropriately combined. Note that the disclosure is merely an example, and those that a person skilled in the art can easily imagine appropriate modifications while maintaining the gist of the present disclosure are naturally included in the scope of the present disclosure. In addition, in order to make the explanation clearer, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual embodiment, but they are merely examples and do not limit the interpretation of the present disclosure. In addition, in this disclosure and each figure, elements similar to those described above with respect to the previously mentioned figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0009] In the present embodiment and claims, when expressing an aspect of arranging another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is arranged directly on top of a certain structure so as to be in contact with the certain structure, and a case in which another structure is arranged above a certain structure via yet another structure.

[0010] (Embodiment 1) FIG. 1 is a schematic diagram showing a fluorescence detection device according to the first embodiment. FIG. 2 is a cross-sectional view for typically explaining the cholesteric liquid crystal layer of the first embodiment. FIG. 3 is a plan view for typically explaining the first and seventh layers of the cholesteric liquid crystal layer of the first embodiment. FIG. 4 is a plan view for typically explaining the second layer of the cholesteric liquid crystal layer of the first embodiment. FIG. 5 is a plan view for typically explaining the third layer of the cholesteric liquid crystal layer of the first embodiment. FIG. 6 is a plan view for typically explaining the fourth layer of the cholesteric liquid crystal layer of the first embodiment. FIG. 7 is a plan view for typically explaining the fifth layer of the cholesteric liquid crystal layer of the first embodiment. FIG. 8 is a plan view for typically explaining the sixth layer of the cholesteric liquid crystal layer of the first embodiment. As shown in FIG. 1, the fluorescence detection device 1 has a light source 60, a cholesteric liquid crystal layer 10, a light-transmitting substrate 20, a sample holder 30, and a detection circuit 50 in a light-shielded space.

[0011] When the fluorescence detection device 1 irradiates the sample 31 with excitation light L11 of a predetermined wavelength, the substance in the sample 31 is excited to emit fluorescence L13 having spectral characteristics whose peak wavelength is slightly shifted from the wavelength of the excitation light. The fluorescence detection device 1 makes it possible to observe the intensity of this fluorescence L13 and the emission intensity distribution of the fluorescence L13.

[0012] The light-transmitting substrate 20 is an insulating base material, and is made of, for example, glass or a resin material.

[0013] The cholesteric liquid crystal layer 10 includes a liquid crystal layer 16 formed on a light-transmitting substrate 20 via an alignment film 15. The alignment film 15 is made of polyimide or the like, and is subjected to rubbing or photo-alignment treatment. In the cholesteric liquid crystal, elongated liquid crystal molecules are aligned in one plane with the long axis direction aligned, and the liquid crystal molecules LC spirally as they move in a direction perpendicular to the plane of the light-transmitting substrate 20. Specifically, the first layer LC1, the second layer LC2, the third layer LC3, the fourth layer LC4, the fifth layer LC5, the sixth layer LC6, and the seventh layer LC7 shown in FIG. 2 have the liquid crystal molecules LC spirally as shown in FIG. 3 to FIG. 8. The long axis direction of the liquid crystal molecules LC is aligned every 1 / 2 of the pitch p of the spiral, so that the long axis direction of the liquid crystal molecules LC in the first layer LC1 and the long axis direction of the liquid crystal molecules LC in the seventh layer LC7 are the same as each other, as shown in FIG. 3.

[0014] Fig. 9 is an explanatory diagram for explaining the relationship between excitation light and reflected light. The cholesteric liquid crystal layer 10 reflects light of a specific wavelength that has circular polarization in the same direction as the rotation direction of the helix. As shown in Fig. 9, the excitation light L11 incident on the cholesteric liquid crystal layer 10 is reflected according to the same conditions as Bragg's law shown in formula (1).

[0015] 2×(p / 2)×n×sinθ=m×λ (1) Here, m is the reflection order, λ is the reflection wavelength, p is the helical pitch, n is the refractive index, and θ is the angle that the incident direction of the excitation light makes with respect to the reflecting surface BL.

[0016] The sample holder 30 has light transmitting properties and holds a sample 31. The sample holder 30 is preferably made of a transparent material that does not emit fluorescence, such as silicon nitride (SiN). However, in this embodiment, the sample holder 30 may be omitted.

[0017] The light source 60 includes a light emitter 61, a polarizing plate 62, and a quarter-wave plate 63. The light emitter 61 is a light-emitting element that oscillates and emits a predetermined excitation light. The polarizing plate 62 linearly polarizes the light from the light emitter 61. The quarter-wave plate 63 converts the light from the polarizing plate 62 into circularly polarized excitation light L11.

[0018] The detection circuit 50 is a charge coupled device and an imaging circuit, and is capable of detecting the intensity of the fluorescent light and the distribution of the fluorescent light emission intensity.

[0019] 9, in accordance with Bragg's law, excitation light L11 incident from a light source 60 is selectively reflected as reflected light L12. For example, when a plurality of liquid crystal molecules rotate clockwise, the cholesteric liquid crystal layer 10 reflects right-handed circularly polarized light having a wavelength corresponding to the pitch p of the excitation light L11 as reflected light L12. On the other hand, when a plurality of liquid crystal molecules rotate counterclockwise, the cholesteric liquid crystal layer 10 reflects left-handed circularly polarized light having a wavelength corresponding to the pitch p of the excitation light L11 as reflected light L12.

[0020] The cholesteric liquid crystal layer 10 is manufactured by selecting a liquid crystal material and a chiral agent according to the wavelength of the excitation light.

[0021] Fig. 10 is a schematic diagram showing a fluorescence detection device according to a comparative example. Fluorescence detection device 1a of the comparative example shown in Fig. 10 does not have a cholesteric liquid crystal layer 10, as compared to fluorescence detection device 1 shown in Fig. 1. In the fluorescence detection device 1a of the comparative example shown in Fig. 10, a sample holder 30 is laminated on a light-transmitting substrate 20.

[0022] In the fluorescence detection device 1a of the comparative example, when excitation light L21 of a predetermined wavelength is irradiated onto a sample 31, substances in the sample are excited to emit fluorescence having spectral characteristics whose peak wavelength is slightly shifted from the wavelength of the excitation light. In the fluorescence detection device 1a, fluorescence L22 containing noise from the excitation light reaches the detection circuit 50.

[0023] In contrast, in the fluorescence detection device 1 of the first embodiment, the cholesteric liquid crystal layer 10 selectively reflects the excitation light L11 as reflected light L12.

[0024] As described above, the fluorescence detection device 1 of the first embodiment includes the light source 60 that irradiates the sample 31 with excitation light L11 in a circularly polarized state, the cholesteric liquid crystal layer 10 that transmits fluorescence L13 emitted by the sample 31 in response to the excitation light L11 and reflects the excitation light L11, and a detection circuit that detects the fluorescence L13 that has transmitted through the cholesteric liquid crystal layer 10. This allows the excitation light L11 to be selectively reflected as reflected light L12, and the excitation light L11 that reaches the detection circuit 50 is suppressed. As a result, the detection sensitivity of the fluorescence L13 detected by the detection circuit 50 is improved.

[0025] (Embodiment 2) 11 is a schematic diagram showing a fluorescence detection device according to embodiment 2. In the following description, the same components as those described in the above-mentioned embodiments are given the same reference numerals, and duplicated description will be omitted.

[0026] The fluorescence detection device 1A has a light source 60, a cholesteric liquid crystal layer 10, a light-transmitting substrate 20, a sample holder 30, and a detection circuit 50 in a light-shielded space.

[0027] 11, in the fluorescence detection device 1A according to the second embodiment, the light source 60 includes a light emitter 64 and a quarter-wave plate 63. The light emitter 64 emits linearly polarized laser light. The quarter-wave plate 63 converts the light from the light emitter 64 into circularly polarized excitation light L11.

[0028] (Embodiment 3) 12 is a schematic diagram showing a fluorescence detection device according to embodiment 3. In the following description, the same components as those described in the above embodiments are given the same reference numerals, and duplicated description will be omitted.

[0029] The fluorescence detection apparatus 1B has, in a light-shielded space, a light source 60, a cholesteric liquid crystal layer 10, a light-transmitting substrate 20, a sample holder 30, a detection circuit 50, and a lens 70. As shown in Fig. 12, the fluorescence detection apparatus 1B according to the third embodiment further has a lens 70 between the cholesteric liquid crystal layer 10 and the detection circuit 50, which collects fluorescence from the sample 31.

[0030] This improves the efficiency with which the lens 70 collects the fluorescent light L13.

[0031] (Embodiment 4) Fig. 13 is a schematic diagram showing a fluorescence detection device according to embodiment 4. Fig. 14 is an explanatory diagram showing the relationship between the wavelength characteristics of excitation light reflected at the first liquid crystal layer and the wavelength characteristics of excitation light reflected at the second liquid crystal layer in embodiment 4. In the following description, the same components as those described in the above embodiments are denoted by the same reference numerals, and duplicated description will be omitted.

[0032] As described above, in the fluorescence detection device 1 of embodiment 1, in accordance with Bragg's law, the excitation light L11 incident from the light source 60 selectively becomes reflected light L12 and is reflected by the cholesteric liquid crystal layer 10. For this reason, if the angle of incidence from the light source 60 is shifted, the excitation light L11 is more likely to enter the detection circuit 50. In contrast, the fluorescence detection device 1C of embodiment 4 has multiple liquid crystal layers with different reflection bands, so that it can reflect the excitation light L11 even if the incident angle of the excitation light L11 is slightly tilted, and the guaranteed range of the incident angle of the excitation light L11 can be expanded.

[0033] The fluorescence detection device 1C has, in a light-shielded space, a light source 60, a cholesteric liquid crystal layer 10, a light-transmitting substrate 20, a sample holder 30, and a detection circuit 50. Specifically, the cholesteric liquid crystal layer 10 of the fourth embodiment includes a first liquid crystal layer 11 having a first helical pitch, and a second liquid crystal layer 12 having a second helical pitch different from the first pitch. Second liquid crystal layer 12 is formed on the alignment film 15. First liquid crystal layer 11 teeth, Second liquid crystal layer 12 A film is formed on the first liquid crystal layer 11. The first pitch of the helix of the first liquid crystal layer 11 and the second pitch of the helix of the second liquid crystal layer 12 are made different by changing the chiral agent or the like. As shown in Fig. 14, the wavelength characteristic C11 of the excitation light reflected by the first liquid crystal layer 11 is shifted in wavelength from the wavelength characteristic C12 of the excitation light reflected by the second liquid crystal layer 12. The cholesteric liquid crystal layer 10 may include three or more liquid crystal layers having different helical pitches.

[0034] For example, as shown in FIG. 13, when the position of the light source 60 is shifted to the position of the light source 60A rotated in the direction R from the position of the light source 60, Second liquid crystal layer 12 cannot reflect the excitation light L11 from the light source 60A, First liquid crystal layer 11 can reflect the excitation light L11 from the light source 60A.

[0035] Although the preferred embodiment of the present disclosure has been described above, the present disclosure is not limited to such an embodiment. The contents disclosed in the embodiment are merely examples, and various modifications are possible within the scope of the present disclosure. Appropriate modifications made within the scope of the present disclosure naturally belong to the technical scope of the present disclosure. At least one of various omissions, substitutions, and modifications of components can be made within the scope of the gist of each of the above-mentioned embodiments and each modified example. [Explanation of symbols]

[0036] 1, 1A, 1B, 1C, 1a Fluorescence detection device 10 Cholesteric Liquid Crystal Layer 11 First liquid crystal layer 12 Second liquid crystal layer 15 Alignment film 16 Liquid crystal layer 20 Translucent substrate 30 Sample holder 31 Sample 50 Detection circuit 60, 60A light source 61, 64 Illuminant 62 Polarizing Plate 63 1 / 4 wave plate 70 Lens L11, L21 excitation light L12 reflected light L13, L22 Fluorescence

Claims

1. A fluorescence detection device comprising: a light source that irradiates a sample with circularly polarized excitation light; a cholesteric liquid crystal layer that transmits fluorescence emitted by the sample in response to the excitation light and reflects the excitation light; and a detection circuit that detects the fluorescence that has transmitted through the cholesteric liquid crystal layer.

2. The fluorescence detection device according to claim 1, wherein the light source includes a light emitter, a polarizing plate that linearly polarizes the light emitted from the light emitter, and a quarter-wave plate that converts the linearly polarized light emitted from the polarizing plate into the circularly polarized excitation light.

3. The fluorescence detection device according to claim 1, further comprising a light-transmitting substrate on which the cholesteric liquid crystal layer is formed.

4. The fluorescence detection device according to claim 1, wherein the cholesteric liquid crystal layer includes a first liquid crystal layer having a first helical pitch and a second liquid crystal layer having a second helical pitch different from the first pitch.

5. A fluorescence detection device according to any one of claims 1 to 4, further comprising a lens for focusing the fluorescence between the cholesteric liquid crystal layer and the detection circuit.