Detection device, detection system and detection method for tiny objects

Abstract

A detection system (100) for detecting micro-objects comprises a focusing kit (10) and a detection device (1). The focusing kit (10) has a thin film (106) that converts light into heat and is configured to be able to hold a sample (SP) on the thin film (106). The detection device (1) uses the focusing kit (10) to focus a plurality of micro-objects dispersed in the sample (SP), thereby detecting a plurality of micro-objects in the sample (SP). The detection device (1) comprises a laser module (4), a light receiver (8) and a controller (9). The laser module (4) emits a laser beam for irradiating the focusing kit (10). The light receiver (8) detects the laser beam from the sample (SP) held in the focusing kit (10) and outputs a detection signal thereof. The controller (9) calculates the amount of aggregation of the plurality of micro-objects in the sample (SP) based on the temporal variation of the detection signal.

Description

Technical Field

[0001] The present invention relates to a detection device, a detection system and a detection method for tiny objects. Background Art

[0002] A technology for gathering multiple tiny objects (particles, cells or microorganisms, etc.) dispersed in a liquid is proposed. For example, in International Publication No. 2017 / 195872 (Patent Document 1) and International Publication No. 2018 / 159706 (Patent Document 2), a technology for gathering multiple tiny objects dispersed in a liquid by light irradiation is disclosed. When light is irradiated to a photothermal conversion area that converts light into heat, the liquid near the light irradiation position is locally heated. As a result, microbubbles are generated, and convection is generated in the liquid. As a result, multiple tiny objects are transported toward the microbubbles as convection and gather near the light irradiation position.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2017 / 195872

[0006] Patent Document 2: International Publication No. 2018 / 159706 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] It is desirable not only to gather a plurality of fine objects dispersed in a liquid by light irradiation but also to detect whether a plurality of fine objects have been gathered. In particular, it is desirable to quantitatively determine to what extent a plurality of fine objects have been gathered.

[0009] The present disclosure is made to solve such a problem, and an object of the present disclosure is to aggregate a plurality of fine objects dispersed in a liquid and to determine the aggregated amount.

[0010] Means used to solve problems

[0011] (1) A detection device for tiny objects according to one aspect of the present disclosure detects a plurality of tiny objects in a liquid sample by using a collection kit to collect a plurality of tiny objects dispersed in a liquid sample. The collection kit has a photothermal conversion area that converts light into heat, and is configured to be able to hold a liquid sample on the photothermal conversion area. The detection device includes a light source unit, a light receiver, and a computing unit. The light source unit emits light for irradiating the collection kit. The light receiver detects light from the liquid sample held in the collection kit and outputs a detection signal thereof. The computing unit calculates the amount of aggregation of the plurality of tiny objects in the liquid sample based on the temporal variation of the detection signal.

[0012] (2) The detection device heats the liquid sample by irradiating light to the photothermal conversion region, thereby generating bubbles at the light irradiation position and generating convection in the liquid sample, thereby gathering a plurality of fine objects near the bubbles.

[0013] (3) The calculation unit calculates the amount of accumulation of the plurality of fine objects in the liquid sample based on the slope of an approximate straight line obtained by regression of the detection signal within a predetermined period after the start of light irradiation to the photothermal conversion region.

[0014] (4) The calculation unit calculates the amount of accumulation of the plurality of fine objects in the liquid sample based on the intensity ratio of two detection signals acquired in association with light irradiation to the photothermal conversion region.

[0015] (5) The plurality of micro-objects are configured to emit fluorescence when excited. The light source unit includes: a laser light source that emits laser light for irradiating the focusing kit; and a fluorescent light source that emits light for exciting the plurality of micro-objects.

[0016] (6) The laser light source and the fluorescent light source are formed integrally.

[0017] (7) The light receiver includes a shielding member that blocks light that is unnecessary to be taken into the light receiver, out of the fluorescent light emitted from the plurality of fine objects.

[0018] (8) The laser light source has a plurality of light-emitting areas, and is configured to emit a plurality of laser beams from the plurality of light-emitting areas. The detection device further comprises: a holder configured to hold a focusing kit; a focusing lens that focuses the plurality of laser beams to the same focusing point; an adjustment mechanism that adjusts the relative positional relationship between the holder and the focusing lens; and a control unit that controls the adjustment mechanism. The control unit is configured to be able to switch between a single irradiation mode and a multi-point irradiation mode, wherein the single irradiation mode and the multi-point irradiation mode are modes of irradiating at least a portion of the plurality of laser beams to the photothermal conversion area. The single irradiation mode is a mode in which the adjustment mechanism is controlled so that the focusing point is consistent with the photothermal conversion area. The multi-point irradiation mode is a mode in which the adjustment mechanism is controlled so that the focusing point is separated from the photothermal conversion area.

[0019] (9) The laser light source includes a vertical cavity surface emitting laser.

[0020] (10) The condenser lens includes a gradient refractive optical fiber and a plano-convex lens. The optical fiber has one end covering a plurality of light emitting regions and the other end joined to a flat surface side of the plano-convex lens.

[0021] (11) The light receiver is a single-pixel type light detector.

[0022] (12) A detection system for tiny objects according to one aspect of the present disclosure includes a gathering kit and a detection device. The gathering kit has a photothermal conversion area that converts light into heat, and is configured to be able to hold a liquid sample on the photothermal conversion area. The detection device gathers a plurality of tiny objects dispersed in the liquid sample by using the gathering kit, thereby detecting a plurality of tiny objects in the liquid sample. The detection device includes a light source unit, a light receiver, and a computing unit. The light source unit emits light for irradiating the gathering kit. The light receiver detects light from the liquid sample held in the gathering kit and outputs a detection signal thereof. The computing unit calculates the amount of aggregation of the plurality of tiny objects in the liquid sample based on the temporal variation of the detection signal.

[0023] (13) The focusing kit further includes: a first surface on which a light-to-heat conversion region is disposed; a second surface on which a liquid sample is sandwiched between the second surface and the first surface; and a spacer for fixing a distance between the first surface and the second surface.

[0024] (14) Another aspect of the detection method disclosed herein is to detect multiple tiny objects in a liquid by using a collection kit to collect multiple tiny objects dispersed in a liquid sample. The collection kit has a photothermal conversion area that converts light into heat, and is configured to be able to drop liquid on the photothermal conversion area. The detection method includes a first step to a third step. The first step is a step of irradiating light to the collection kit. The second step is a step of detecting light from a liquid sample held in the collection kit by a photoreceiver. The third step includes a step of calculating the amount of aggregation of multiple tiny objects in the liquid sample based on the time change of the detection signal from the photoreceiver.

[0025] Effects of the Invention

[0026] According to the present disclosure, a plurality of fine objects dispersed in a liquid can be aggregated and the aggregated amount can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram schematically showing the overall configuration of the micro-object detection system according to the first embodiment.

[0028] Figure 2 This is a diagram schematically showing the structure of a laser module.

[0029] Figure 3 It is along Figure 2 Cross-sectional view of a III-III line laser module.

[0030] Figure 4 It is along Figure 2 Cross-sectional view of the IV-IV line laser module.

[0031] Figure 5 It is a perspective view of the gathering kit.

[0032] Figure 6 It is a diagram schematically showing the structure of a honeycomb substrate.

[0033] Figure 7 It is along Figure 6 A cross-sectional view of the honeycomb substrate along line VII-VII.

[0034] Figure 8 This is a diagram for explaining a method of switching between a single irradiation mode and a multi-spot irradiation mode.

[0035] Fig. 9 This is a diagram for explaining the aggregation mechanism of micro objects in a single irradiation mode.

[0036] Fig.10 This is a diagram for explaining the mechanism of focusing tiny objects in the multi-spot irradiation mode.

[0037] Fig.11 This is a flowchart showing the method of clustering fine objects in the first embodiment.

[0038] Fig.12 This is a diagram showing an example of the time change of the detection signal from the light receiver.

[0039] Fig.13 This is a transmission image of the sample when the irradiation of the laser beam is stopped.

[0040] Fig.14 This is a diagram for comparing detection signals from the light receiver 8 when three types of samples are used.

[0041] Fig.15 are images showing the aggregation results of resin beads in three samples.

[0042] Fig.16 It is a graph showing the relationship between the number of resin beads and the attenuation rate of the detection signal.

[0043] Fig.17 This is a flowchart showing a method for clustering fine objects in a modified example of the first embodiment.

[0044] Fig.18 This is a diagram for explaining the structural features of the micro-object detection system according to the second embodiment.

[0045] Fig.19 The diagram shows the fluorescence images of the samples when the irradiation with the laser beam is stopped. DETAILED DESCRIPTION

[0046] Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings. It should be noted that the same or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0047] <Definition of Terms>

[0048] In the present disclosure, "nanoscale" includes a range of 1 nm to 1000 nm (= 1 μm). "Microscale" includes a range of 1 μm to 1000 μm (= 1 mm). Therefore, the "range from nanoscale to microscale" includes a range of 1 nm to 1000 μm. The "range from nanoscale to microscale" can typically show a range of several nm to several hundred μm, preferably a range of 100 nm to 100 μm, and more preferably a range of 1 μm to several tens of μm.

[0049] In the present disclosure, the term "micro-object" refers to an object having a size ranging from nanometers to micrometers. The shape of the micro-object is not particularly limited, and may be, for example, spherical, ellipsoidal, or rod-shaped. In the case where the micro-object is an ellipsoidal sphere, at least one of the length in the long axis direction and the length in the short axis direction of the ellipsoidal sphere may be within the range of nanometers to micrometers. In the case where the micro-object is a rod, at least one of the width and length of the rod may be within the range of nanometers to micrometers.

[0050] As examples of tiny objects, metal nanoparticles, metal nanoparticle aggregates, metal nanoparticle aggregation structures, semiconductor nanoparticles, organic nanoparticles, resin beads, PM (Particulate Matter, particulate matter), etc. are cited. "Metal nanoparticles" refer to metal particles with nanometer-level dimensions. "Metal nanoparticle aggregates" refer to aggregates formed by the aggregation of multiple metal nanoparticles. "Metal nanoparticle aggregation structures" refer to, for example, multiple metal nanoparticles fixed to the surface of a substrate (resin beads, etc.) through interaction sites, and are arranged at intervals below the diameter of the metal nanoparticles with gaps between them. "Semiconductor nanoparticles" refer to semiconductor particles with nanometer-level dimensions. "Organic nanoparticles" refer to particles of organic compounds with nanometer-level dimensions. "Resin beads" refer to particles of resins with sizes ranging from nanometers to micrometers. "PM" is a particulate substance with micrometer-level dimensions. As examples of PM, PM2.5, SPM (Suspended Particulate Matter, suspended particulate matter), etc. are cited.

[0051] Micro-objects may also be substances derived from organisms (biological substances). More specifically, micro-objects may include cells, microorganisms (bacteria, fungi, etc.), biological macromolecules (proteins, nucleic acids, lipids, polysaccharides, etc.), antigens (allergens, etc.), and viruses.

[0052] In the present disclosure, the term "honeycomb" refers to a shape in which a plurality of regular hexagons are arranged in a hexagonal lattice (honeycomb shape) in two dimensions. Pores are formed in each of the plurality of regular hexagons. A structure having a structure in which a plurality of pores are arranged in a honeycomb shape is referred to as a "honeycomb structure". Each pore is a hole having an opening ranging from nanometers to micrometers. The pores may be through holes or non-through holes. In addition, the shape of the pores is not particularly limited and may include any shape such as a cylinder, a prism, a sphere other than a true sphere (e.g., a hemispherical or semi-ellipsoidal sphere).

[0053] In the present disclosure, the term "microbubbles" refers to gas bubbles of micrometer size.

[0054] In the present disclosure, "transmitting light" or "having light transmissivity" refers to the phenomenon or property that the intensity of light that passes through a substance without being absorbed by the substance is greater than zero. The transmission of light includes the scattering of light (forward scattering). The wavelength region of light can also be any one of the ultraviolet region, the visible region and the near-infrared region, a region spanning two of these three regions, or a region spanning all of the three regions. The lower limit of the range of the transmittance of light can be greater than zero, and there is no special limitation. It should be noted that the upper limit of the range of the transmittance is 100%.

[0055] In the following, the x direction and the y direction represent horizontal directions. The x direction and the y direction are orthogonal to each other. The z direction represents the vertical direction. The direction of gravity is downward in the z direction. It should be noted that sometimes the upper side in the z direction is referred to as the upper side, and the lower side in the z direction is referred to as the lower side.

[0056] [Implementation Method 1]

[0057] <Overall structure of the detection system>

[0058] Figure 1 1 is a block diagram schematically showing the overall structure of a micro-object detection system according to Embodiment 1. The detection system 100 includes a detection device 1 and a collection kit 10. The detection device 1 uses the collection kit 10 to collect a plurality of micro-objects dispersed in a liquid, thereby detecting the plurality of micro-objects in the liquid. Figure 1 Although only one aggregation kit 10 is shown in the figure, a plurality of aggregation kits 10 are prepared as needed and are sequentially mounted on the detection device 1 .

[0059] The detection device 1 includes a light source stage 2 , an adjustment mechanism 3 , a laser module 4 , a driver 5 , a sample holder 6 , an optical filter 7 , a light receiver 8 , and a controller 9 .

[0060] The laser module 4 is provided on the light source stage 2. The light source stage 2 is, for example, an XYZ axis stage, and is configured to be movable in the x direction, the y direction, and the z direction.

[0061] The adjustment mechanism 3 is configured to be able to adjust the position of the light source stage 2 in the x-direction, y-direction, and z-direction according to the command from the controller 9. In the example described below, the relative positional relationship between the laser module 4 and the focusing kit 10 provided on the light source stage 2 is adjusted by adjusting the height (position in the z-direction) of the light source stage 2. However, the structure of the adjustment mechanism 3 is not particularly limited as long as it is able to adjust the relative positional relationship between the laser module 4 and the focusing kit 10. The adjustment mechanism 3 can adjust the position of the focusing kit 10 relative to the fixed laser module 4, or can adjust the positions of both the focusing kit 10 and the laser module 4.

[0062] The laser module 4 is, for example, a semiconductor laser module. In the present embodiment, the wavelength of the laser light L emitted from the laser module 4 is included in the near-infrared region, for example, 850 nm. Figure 2 to Figure 4 The structure of the laser module 4 will be described in detail. Although not shown in the figure, a cooling device (Peltier element, etc.) for cooling the laser module 4 may be provided in the laser module 4. It should be noted that the laser module 4 is an example of the "laser light source" of the present disclosure.

[0063] The driver 5 supplies a current for driving the laser module 4 in accordance with a command from the controller 9 .

[0064] The sample holder 6 holds the collection kit 10. As described above, the sample holder 6 may be an XYZ axis stage similar to the light source stage 2. The collection kit 10 contains the sample SP. Figure 5 to Figure 7 The structure of the aggregation kit 10 will be described.

[0065] The filter 7 is, for example, a ND (Neutral Density) filter. The filter 7 reduces the intensity of the laser light L irradiated from the laser module 4 to the sample SP and transmitted through the sample SP. The filter 7 is appropriately set according to the output (laser output) of the laser light L. The filter 7 may be omitted depending on the laser output.

[0066] The light receiver 8 detects the laser light L whose intensity is reduced by the filter 7, and outputs its detection signal to the controller 9. In the present embodiment, the light receiver 8 is a single-pixel photodetector (single-channel detector). Specifically, the light receiver 8 is a photodiode such as a PIN photodiode or an APD (Avalanche photodiode). However, a photodiode, for example, a phototube or a photomultiplier tube may be used instead of a photodiode.

[0067] In addition, the photoreceiver 8 is not necessarily a single-pixel type. The photoreceiver 8 may also be a multi-pixel photodetector (multi-channel detector). Specifically, the photoreceiver 8 may also be a CCD (Charged-Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor.

[0068] The controller 9 is, for example, a microcomputer. The controller 9 includes a processor such as a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output port (none of which are shown in the figure). The controller 9 controls each device (adjustment mechanism 3 and driver 5) constituting the detection system 100. In addition, the controller 9 calculates the amount of micro-objects accumulated in the sample SP based on the detection signal from the light receiver 8. The calculation method will be described later.

[0069] <Laser module structure>

[0070] Figure 2 1 is a diagram schematically showing the structure of the laser module 4. The laser module 4 is provided on the light source stage 2 and is arranged below the sample holder 6. The sample holder 6 is provided with a focusing kit 10. The laser light L emitted upward from the laser module 4 is irradiated to the focusing kit 10 on the sample holder 6.

[0071] Figure 3 It is along Figure 2 FIG. 4 is a cross-sectional view of the laser module 4 along line III-III. Figure 4 It is along Figure 2 A cross-sectional view of the laser module 4 along line IV-IV. Figure 3 and Figure 4 The laser module 4 includes a substrate 41 , a surface light emitting element 42 , a bonding member 43 , an optical waveguide 44 , and a lens 45 .

[0072] The substrate 41 is a flat plate made of insulating material, such as a printed wiring substrate or a ceramic substrate. A surface light emitting element 42 is mounted on the surface of the substrate 41. A portion of an electrode 411 is formed on the back of the substrate 41. The electrode 411 is electrically connected to the surface light emitting element 42 by wire bonding, for example. Figure 1 ) supplies driving current to the surface light-emitting element 42 via the electrode 411.

[0073] The surface light emitting element 42 is an array type vertical cavity surface emitting laser (VCSEL: Vertical Cavity Surface Emitting LASER). Figure 4 As shown, the surface light-emitting element 42 has a plurality of (30 in this example) light-emitting regions 421 and electrode pads 422. The plurality of light-emitting regions 421 are arranged in an array. All the light-emitting regions 421 emit light at the same time, and emit laser beams L respectively. The emitted plurality of laser beams L are emitted in a direction (z direction) perpendicular to the surface of the surface light-emitting element 42. It should be noted that Figure 4 The numerical values ​​in denoted by represent the size of each component (unit: μm).

[0074] The bonding member 43 is, for example, an adhesive, and bonds the optical waveguide 44 to the surface light-emitting element 42. The bonding member 43 is made of a material that is transparent to the light (near infrared light in this example) emitted from the surface light-emitting element 42.

[0075] The optical waveguide 44 collects the plurality of laser beams L emitted from the surface light emitting element 42 . The optical waveguide 44 is made of a material transparent to the light emitted from the surface light emitting element 42 , such as resin or glass. The optical waveguide 44 includes a core 441 and a cladding 442 .

[0076] The core 441 has a cylindrical shape. The incident end of the core 441 (equivalent to "one end" in the present disclosure) is formed to cover all of the light-emitting region 421 so that all of the laser light L emitted from the surface light-emitting element 42 is incident. The cladding 442 has a cylindrical shape. The cladding 442 is formed to cover the side surface of the core 441.

[0077] The lens 45 is a plano-convex lens having a flat surface and a convex surface. The flat surface of the lens 45 is bonded to the emission end (equivalent to the "other end" of the present disclosure) of the optical waveguide 44. The convex surface of the lens 45 protrudes in the emission direction of the light emitted from the laser emission portion of the laser module 4.

[0078] The propagation path of the laser light L in the laser module 4 constructed as described above is described. The optical waveguide 44 is a graded index (GI) type optical fiber. Therefore, the refractive index of the core 441 of the optical waveguide 44 is the highest at the radial center of the core 441, and gradually decreases toward the radial outside. There are multiple modes with different propagation distances in the laser light L propagating inside the core 441. Light in a low-order mode travels in the center of the core, and light in a high-order mode travels away from the center of the core. Although the propagation distance of light in a low-order mode is short, the propagation speed of light in a low-order mode is relatively slow due to the height of the refractive index at the center of the core. In contrast, in light in a high-order mode, the propagation distance is long, but the propagation speed is relatively fast. The refractive index distribution of the core 441 is designed so that the difference in propagation time between modes is sufficiently short.

[0079] The plurality of laser beams L propagating inside the core 441 having such a refractive index distribution form nodes P and antinodes Q. It should be noted that the positions of the nodes P and antinodes Q can be changed according to the wavelength of the laser beam L. In the direction of travel of the laser beam L, the length of the optical waveguide 44 is determined so that the emission end of the optical waveguide 44 is not located halfway between the node P and the antinode Q (in other words, Figure 3 As shown in FIG. 1 , the emission end of the optical waveguide 44 is located midway from the antinode Q to the node P, or the emission end of the optical waveguide 44 coincides with the antinode Q). As a result, the plurality of laser beams L propagating in the optical waveguide 44 are emitted from the emission end of the optical waveguide 44 in a converging trend. The emitted plurality of laser beams L are further converged by the lens 45 to form the same focal point F.

[0080] <Structure of the Aggregation Kit>

[0081] Figure 5 1 is a perspective view of the aggregation kit 10 . The aggregation kit 10 includes a honeycomb substrate 101 , a cover substrate 102 , and a spacer 103 .

[0082] The honeycomb substrate 101 is configured to generate heat by irradiation with the laser beam L. In addition, the honeycomb substrate 101 is formed of a light-transmitting material. Figure 6 and Figure 7 The structure of the honeycomb substrate 101 will be described.

[0083] A sample SP is held (dropped) on the upper surface of the honeycomb substrate 101. The sample SP is a liquid in which fine objects are dispersed. The type of the liquid (dispersion medium) is not particularly limited, but in this example, it is ultrapure water.

[0084] The cover substrate 102 is arranged above the sample SP. That is, the honeycomb substrate 101 and the cover substrate 102 are arranged to sandwich the sample SP from the top and the bottom. The cover substrate 102 is formed of a light-transmitting material (e.g., glass, transparent resin) in the same manner as the honeycomb substrate 101. In the present embodiment, cover glass is used as the cover substrate 102. It should be noted that (the upper surface of) the honeycomb substrate is equivalent to the "first surface" of the present disclosure. (The lower surface) of the cover substrate 102 is equivalent to the "second surface" of the present disclosure.

[0085] The spacer 103 is provided on the honeycomb substrate 101 to support the cover substrate 102. The spacer 103 is provided to fix the distance between the honeycomb substrate 101 and the cover substrate 102 to a specified value. Therefore, it is desirable to use a material with a controlled thickness (such as a double-sided tape) for the spacer 103. When a plurality of aggregation kits 10 are prepared, the distance (optical path length) that the laser light L passes through in the sample SP becomes a common value by providing the spacer 103. Thus, it is possible to reduce the intensity deviation of the laser light L that has passed through the sample SP (in other words, to make the measurement conditions of all the aggregation kits 10 consistent).

[0086] It should be noted that the spacer 103 may be formed integrally with one of the honeycomb substrate 101 and the cover substrate 102. In addition, the shape of the honeycomb substrate 101 and the cover substrate 102 is not limited to a flat plate shape. The honeycomb substrate 101 and the cover substrate 102 may also be a part of a container having an internal space for holding the sample SP.

[0087] Figure 6 1 is a diagram schematically showing the structure of the honeycomb substrate 101 . Figure 7 It is along Figure 6 A cross-sectional view of the honeycomb substrate 101 along line VII-VII. Figure 6 and Figure 7 The sample SP is omitted in the figure. Figure 6 The honeycomb substrate 101 includes a substrate 104 , a honeycomb polymer film 105 , and a film 106 .

[0088] The substrate 104 is formed of a material that does not affect light-to-heat conversion (described later) of the laser light L by the thin film 106 . Examples of such a material include transparent resin and glass. In this embodiment, a transparent resin is used as the substrate 104 .

[0089] The honeycomb polymer film 105 is a polymer film obtained by configuring a honeycomb structure on a substrate 104. A polymer that can be dissolved in an organic solvent (hydrophobic solvent) is used as the material of the honeycomb polymer film 105. In this embodiment, polystyrene is used as a matrix of the honeycomb polymer film 105. A trace amount of an amphiphilic polymer having both a hydrophilic group and a hydrophobic group is added to the matrix.

[0090] The thin film 106 is formed on the honeycomb polymer film 105. The thin film 106 absorbs the laser light L from the laser module 4 and converts the light energy into heat energy. The material of the thin film 106 is preferably a material with high photothermal conversion efficiency in the wavelength region of the laser light L (near infrared region in this example). In the present embodiment, a gold thin film with a film thickness of nanometer level (specifically, for example, 40nm to 50nmm) is formed as the thin film 106. The gold thin film can be formed using a known method such as sputtering or electroless plating. It should be noted that the thin film 106 may not be formed on the entire surface of the substrate 104, but may be formed on at least a portion of the substrate 104.

[0091] When the thin film 106 is a gold thin film, the free electrons on the surface of the gold thin film form surface plasma, which is vibrated by the laser light L. Polarization is thereby generated. The energy of the polarization is converted into the energy of lattice vibration by the Coulomb interaction between the free electrons and the atomic nuclei. As a result, the gold thin film generates heat. Hereinafter, this effect is also referred to as "photothermal effect".

[0092] The material of the thin film 106 is not limited to gold, and may also be a metal element other than gold that can produce a photothermal effect (such as silver) or a metal nanoparticle aggregation structure (such as a structure using gold nanoparticles or silver nanoparticles). Alternatively, the material of the thin film 106 may also be a material other than a metal that has a high light absorption rate in the wavelength region of the laser light L. As such a material, a material close to a black body (such as a carbon nanotube black body) is cited. Considering the laser output and the absorption wavelength region and photothermal conversion efficiency of the material of the thin film 106, the thickness of the thin film 106 is determined by design or experiment. The area where the thin film 106 is formed is equivalent to the "photothermal conversion area" of the present disclosure.

[0093] The film 106 reflects the structure of the honeycomb polymer film 105 and has a honeycomb structure. Figure 7 As shown, a plurality of pores 107 for capturing a plurality of micro-objects and a plurality of partition walls 108 for separating adjacent pores in the plurality of pores 107 from each other are formed in the film 106 (for the detailed structure of the honeycomb substrate 101, refer to Patent Document 2). The film 106 is provided to cover at least a portion of the upper portions of the plurality of pores 107 and the plurality of partition walls 108.

[0094] <Single irradiation mode and multi-point irradiation mode>

[0095] Refer again Figure 2 and Figure 3 Hereinafter, the distance from the front end of the laser module 4 (the convex surface of the lens 45) to the upper surface of the focusing kit 10 along the emission direction (z direction) of the laser light L is referred to as the "irradiation distance D". Figure 1As described in , the adjustment mechanism 3 is configured to be able to adjust the position of the light source stage 2 in the z direction according to a command from the controller 9. Therefore, the controller 9 can set the irradiation distance D to an arbitrary value by controlling the adjustment mechanism 3.

[0096] The detection system 100 of the first embodiment is configured to be able to switch between a "single irradiation mode" and a "multi-point irradiation mode" by setting the irradiation distance D. The single irradiation mode is a control mode in which a single laser beam L is irradiated toward the sample SP. The multi-point irradiation mode is a control mode in which a plurality of (two or more) laser beams L are irradiated toward the sample SP.

[0097] Figure 8 This is a diagram for explaining the method of switching between the single irradiation mode and the multi-spot irradiation mode. Figure 2 and Figure 8 The plurality of laser beams L emitted upward from the front end of the laser module 4 are separated near the lens 45 , but intersect each other above to form a focal point F. Then, the plurality of laser beams L are separated again at a position above the focal point F.

[0098] When the controller 9 sets the irradiation distance D so that the position of the focal point F coincides with the upper surface of the focusing kit 10, the focusing kit 10 is irradiated with a single laser beam L. That is, single irradiation (single irradiation mode) to the focusing kit 10 is realized.

[0099] On the other hand, when the controller 9 sets the irradiation distance D so that the position of the light-converging point F is located below the upper surface of the focusing kit 10, the focusing kit 10 is irradiated with a plurality of laser beams L. That is, multi-point irradiation (multi-point irradiation mode) to the focusing kit 10 is achieved. It should be noted that, although not shown in the figure in this example, multi-point irradiation can also be achieved by setting the irradiation distance D by the controller 9 so that the position of the light-converging point F is located above the upper surface of the focusing kit 10.

[0100] In the multi-spot irradiation mode, the interval between the plurality of laser beams L at the position of the upper surface of the focusing kit 10 is referred to as a "spot interval". The spot interval becomes wider as the position of the upper surface of the focusing kit 10 is directed upward from the focusing point F. Therefore, the controller 9 adjusts the irradiation distance D through the control of the adjustment mechanism 3, thereby also being able to set the spot interval to a desired value.

[0101] <Gathering Mechanism>

[0102] Fig. 9This is a diagram for explaining the aggregation mechanism of micro-objects in a single irradiation mode. When the irradiation of the laser light L starts, the vicinity of the laser spot is locally heated by the photothermal effect of the thin film 106 at the laser spot. As a result, the dispersion medium of the sample SP near the laser spot boils, and microbubbles MB are generated at the laser spot. The microbubbles MB grow over time.

[0103] The closer to the laser spot, the higher the temperature of the dispersion medium. That is, a temperature gradient is generated in the dispersion medium by light irradiation. Due to the temperature gradient, regular thermal convection (buoyancy convection) is stably generated in the dispersion medium. The direction of the thermal convection generated during a single irradiation is temporarily toward the microbubble MB and then away from the microbubble MB as shown by the reference mark HC.

[0104] The reason for the generation of thermal convection can be explained as follows. The dispersion medium above the region where the microbubbles MB are generated becomes relatively rarefied by heating and rises due to buoyancy. Along with this, the dispersion medium with a relatively low temperature in the horizontal direction of the microbubbles MB flows toward the microbubbles MB.

[0105] The micro-objects X are transported toward the micro-bubbles MB by thermal convection and gather near the laser spot. More specifically, when a region (stagnation region) where the flow rate of convection is substantially zero is generated between the micro-bubbles MB and the film 106, the micro-objects X transported by thermal convection are retained and gathered in the stagnation region. Afterwards, when the irradiation of the laser beam L is stopped, the thermal convection weakens and eventually stops.

[0106] Fig.10 is a diagram for explaining the mechanism of aggregation of micro-objects X in multi-point irradiation mode. Fig.10 In order to avoid cumbersome paper space, only two laser beams L are shown.

[0107] In the multi-point irradiation mode, microbubbles MB are generated near each of the many laser points. However, depending on the point interval, adjacent microbubbles MB may merge with each other during the growth process. Therefore, in the multi-point irradiation mode, the maximum number of microbubbles MB remaining is the same as the number of laser points. In the multi-point irradiation mode, as in the single irradiation mode, the micro-objects X are transported by thermal convection, and are retained and gathered in the stagnation area of ​​each microbubble MB.

[0108] According to the findings obtained by the present inventors, in the multi-point irradiation mode, faster convection is generated toward the gaps between adjacent microbubbles MB. Due to the influence of this convection, many micro-objects X are gathered in the stagnant areas generated between adjacent microbubbles MB. As a result, when the light irradiation conditions such as laser output are made consistent between the single irradiation mode and the multi-point irradiation mode, the amount of micro-objects X gathered in the multi-point irradiation mode may increase.

[0109] <Gathering process>

[0110] Fig.11 1 is a flowchart showing a method for gathering tiny objects in Embodiment 1. Each step after step S104 in the flowchart is basically implemented by software processing based on the controller 9, but part or all of it can also be implemented by hardware (electronic circuit) made in the controller 9. It should be noted that the controller 9 is equivalent to both the "calculation unit" and the "control unit" of the present disclosure. However, the "calculation unit" and the "control unit" of the present disclosure can also be different devices.

[0111] In step S101, a liquid in which micro-objects are dispersed, i.e., a sample SP, is prepared. The prepared sample SP is introduced into the aggregation kit 10 (step S102). More specifically, a predetermined amount of the sample SP is dripped onto the honeycomb substrate 101. Then, the cover substrate 102 is set from above the sample SP. The aggregation kit 10 prepared for measurement is set on the sample holder 6 (step S103).

[0112] In step S104, the controller 9 selects one of the single irradiation mode and the multi-spot irradiation mode based on the user operation. When the multi-spot irradiation mode is selected, the user can also set the spot interval.

[0113] The appropriate position and height (irradiation distance D) of the light source stage 2 are predetermined according to the control mode (single irradiation mode or multi-point irradiation mode). The controller 9 controls the adjustment mechanism 3 according to the selected control mode, thereby adjusting the position of the light source stage 2 (step S105). It should be noted that, according to the specifications of the laser module 4 (the wavelength of the laser light L, and the shape of the optical waveguide 44 and the lens 45, etc.), the vertical position of the focal point F where all the laser light L is focused is known. Therefore, the controller 9 can set the irradiation distance D to the desired value by appropriately adjusting the height of the light source stage 2 from the initial height.

[0114] In step S106, the controller 9 controls the driver 5 to start irradiation of the laser beam L. The controller 9 continues irradiation of the laser beam L to the collection kit 10 for a predetermined time (step S107). The predetermined time is typically several tens of seconds to several minutes and can be set by the user. Micro-objects are collected with the light irradiation. After the light irradiation for the predetermined time, the controller 9 controls the driver 5 to stop irradiation of the laser beam L to the collection kit 10 (step S108).

[0115] During the execution of steps S106 to S108, the controller 9 continuously or intermittently obtains the detection signal of the laser beam L from the light receiver 8. In step S109, the controller 9 calculates the amount of micro-objects (collection amount) collected by the irradiation of the laser beam L based on the time change of the detection signal. The calculation method will be described later. Thus, a series of processing ends.

[0116] <Agglomeration calculation>

[0117] Next, based on the actual measurement results, the results obtained by aggregating tiny objects and calculating the amount of aggregation are described. Here, resin beads are used as an example of tiny objects. The material of the resin beads is polystyrene. However, the material of the resin beads is not limited to this, and can also be acrylic acid, polyolefin, polyethylene, polypropylene, etc.

[0118] Fig.12 is a diagram showing an example of the time variation of the detection signal from the light receiver 8. Fig.12 and the following Fig.14 In FIG. 8 , the horizontal axis represents the elapsed time, and the vertical axis represents the intensity of the detection signal from the light receiver 8 .

[0119] exist Fig.12 In the measurement example shown, the concentration of the resin beads in the sample SP is 1.01×10 8 [particles / mL] The diameter of the resin beads is 1.0 μm. It should be noted that the resin beads do not contain fluorescent dyes. The liquid volume of the sample SP is 20 μL. The output (laser output) of the laser light L irradiated to the sample SP is 180 mW. The irradiation time of the laser light L is set to 180 seconds.

[0120] Reference Fig.12 It takes about 30 seconds from the start of irradiation of the laser beam L to the stabilization of the laser output. After the laser output is stabilized, the intensity of the detection signal gradually decreases over time. At the 180-second irradiation time point, the intensity of the detection signal is roughly constant.

[0121] Fig.13 is a transmission image of the sample SP when the irradiation of the laser beam L stops. This image is obtained by photographing the sample SP from below using a photographing device (image sensor) not shown. Fig.13 As shown, a collection of fine objects X (resin beads) is confirmed around the irradiation site (laser spot) of the laser beam L.

[0122] Fig.14 1 is a diagram for comparing detection signals from the light receiver 8 when three types of samples SP are used. In this example, a sample containing only ultrapure water without resin beads and a resin bead concentration of 1.01×10 8[particles / mL] of the sample and the concentration of the resin beads was 1.01×10 9 [particles / mL] samples. These samples are called "ultrapure water sample", "low concentration sample" and "high concentration sample" in turn. In all samples, the liquid volume is 20μL. The output of laser light L (laser output) is 180mW. The irradiation time of laser light L is set to 180 seconds.

[0123] Reference Fig.14 In ultrapure water samples, the intensity of the detection signal is roughly constant. In low-concentration samples, the intensity of the detection signal decreases slightly over time. In high-concentration samples, the intensity of the detection signal decreases more significantly over time than in low-concentration samples.

[0124] For the period from 50 seconds to 150 seconds based on the start time of irradiation of the laser light L, the time function of the detection signal of each sample (the rate of decrease of the detection signal) was linearly regressed by the least squares method, and the slope of the approximate straight line was calculated. As a result, the slope of the approximate straight line in the ultrapure water sample was -1.68. The slope of the approximate straight line in the low-concentration sample was -2.18. The slope of the approximate straight line in the high-concentration sample was -11.04. It should be noted that these values ​​are the average values ​​of the measurement results obtained by implementing each sample three times.

[0125] In this way, by tracking the attenuation of the detection signal obtained from the light receiver 8, the concentration of the resin beads contained in the sample SP can be quantitatively calculated. Specifically, the correlation between the concentration of the resin beads and the slope of the approximate straight line is obtained in advance through experiments. Then, the correlation is summarized in a table or a map, etc., and stored in advance in the memory of the controller 9. In this way, the slope of the approximate straight line can be calculated based on the detection signal from the light receiver 8, and the concentration of the resin beads can be calculated based on the slope of the approximate straight line.

[0126] Fig.15 are images showing the aggregation results of resin beads in three samples SP. Fig.15 In the low concentration sample, it can be confirmed that the resin beads (micro-objects X) are gathered in the stagnant area generated in the central part of the microbubble MB. In the high concentration sample, it can be confirmed that many resin beads are gathered in the stagnant area and around the microbubble MB. The aggregation of resin beads around the microbubble MB is considered to be the reason for the significant attenuation of the detection signal.

[0127] As described above, in Embodiment 1, the micro-objects are gathered by irradiating the sample SP in which the micro-objects are dispersed with the laser light L. In this gathering, the shift of the detection signal (transmission amount) of the laser light L that has passed through the sample SP is obtained using the light receiver 8. In Embodiment 1, the correlation between the reduction rate (slope of the approximate straight line) of the detection signal of the laser light L and the amount of micro-objects gathered is obtained in advance. Therefore, according to Embodiment 1, by using the laser light L to gather the micro-objects in the liquid and calculating the reduction rate of the detection signal of the laser light L, the amount of micro-objects gathered can be obtained.

[0128] The absolute value of the detection signal of the laser beam L does not necessarily indicate the amount of micro-objects gathered. Fig.14 The measurement results shown are understood, for example, based on the fact that the intensity of the laser light L in the low-concentration sample is greater than the intensity of the laser light L in the ultrapure water sample. This is considered to be because the absolute value of the intensity of the laser light L may be affected by various factors such as the difference in the size of the microbubbles MB generated by light irradiation. According to Embodiment 1, by using the reduction rate of the detection signal (i.e., the time change of the detection signal) instead of the absolute value of the detection signal, the aggregation amount of micro-objects can be quantitatively evaluated.

[0129] [Variation of Embodiment 1]

[0130] exist Fig.15 In the example described in , the reduction rate of the detection signal of the laser beam L is used, but the parameters that can be used in calculating the amount of accumulation of small objects are not limited to this. The following is an example of using the intensity ratio (more specifically, the attenuation rate) of the detection signal before and after irradiation with the laser beam L.

[0131] Fig.16 is a graph showing the relationship between the number of resin beads and the attenuation rate of the detection signal. Fig.16 In FIG. 8 , the horizontal axis represents the number of resin beads in a logarithmic scale, and the vertical axis represents the attenuation rate of the detection signal from the light receiver 8 .

[0132] The attenuation rate of the detection signal can be calculated according to the following formula (1). In formula (1), the intensity of the detection signal at the start of the irradiation of the laser light L (at time 0 seconds) is recorded as RX1, and the intensity of the detection signal at the end of the irradiation of the laser light L (at time 180 seconds) is recorded as RX2. According to formula (1), it can be understood that the attenuation rate of the detection signal is an example of the ratio of the intensity of two detection signals obtained after the start of the irradiation of the laser (more generally, an example of the time change of the detection signal).

[0133] Attenuation rate = 100 × (1-RX2 / RX1) (1)

[0134] according to Fig.16 It can be seen that when the correlation between the number of resin beads (or concentration) and the attenuation rate of the detection signal is plotted on a semi-logarithmic graph, a high linearity is shown. Such a linear correlation is obtained in advance and stored in advance in the memory of the controller 9. Thus, the number of resin beads can be calculated based on the attenuation rate of the detection signal.

[0135] Fig.17 1 is a flowchart showing a method for clustering fine objects in a modified example of the first embodiment. The processing of steps S201 to S205 in the flowchart is the same as the corresponding processing in the first embodiment (see Fig.11 ) are the same, so they will not be repeated.

[0136] The controller 9 controls the adjustment mechanism 3 according to the control mode selected in S204 so as to adjust the position of the light source stage 2 (step S205). Then, in S206, the controller 9 controls the driver 5 so as to irradiate the sample SP with a weak laser light L for measuring the intensity of the transmitted light before the tiny objects are gathered. That is, the controller 9 obtains the intensity RX1 of the detection signal. The laser output at this time can be set to a value that is, for example, 1 to 2 digits smaller (or greater than this value) than the laser output for gathering tiny objects. As an example, the laser output for measuring the intensity of the transmitted light can be set to 3 mW relative to the laser output for gathering tiny objects of 180 mW.

[0137] In the next steps S207 to S209, the controller 9 controls the driver 5 so that the laser beam L for collecting the fine objects is irradiated onto the sample SP. These processes are the same as the processes of S106 to S108 in the first embodiment.

[0138] In S210, the controller 9 controls the driver 5 so that the weak laser light L for measuring the intensity of the transmitted light after the micro-objects are gathered is irradiated to the sample SP. That is, the controller 9 obtains the intensity RX2 of the detection signal. The laser output for measuring the intensity of the transmitted light after the micro-objects are gathered is preferably set to a value equal to the laser output for measuring the intensity of the transmitted light before the micro-objects are gathered. Thus, a series of processing ends.

[0139] In this flowchart, an example is described in which the laser light L for collecting tiny objects is separated from the laser light L for measuring the intensity of transmitted light. However, the irradiation of the laser light L for measuring the intensity of transmitted light may be omitted, and the intensity of the transmitted light of the laser light L for collecting tiny objects may be measured before and after the collection of tiny objects.

[0140] As described above, in this modification, for the detection signal of the laser light L that has passed through the sample SP, the intensity ratio (attenuation rate) of the intensity RX1 before the micro-objects start to gather and the intensity RX2 after the gathering is finished is obtained. In this modification, the correlation between the attenuation rate of the detection signal of the laser light L (refer to formula (1)) and the amount of micro-objects gathered is obtained in advance. Therefore, according to this modification, by using the laser light L to gather micro-objects in the liquid and calculating the attenuation rate of the detection signal of the laser light L, the amount of micro-objects gathered can be obtained.

[0141] It should be noted that the timing of obtaining the two detection signals (the timing of measuring the intensity of the transmitted light) is not limited to before and after the aggregation of tiny objects, but can also be during the aggregation of tiny objects. For example, the first measurement can be made before the aggregation of tiny objects, and the second measurement can be made during the aggregation of tiny objects (for example, just before the end). In addition, both the first and second measurements can be made during the aggregation of tiny objects (for example, just after the beginning and just before the end). Alternatively, the first measurement can be made during the aggregation of tiny objects (for example, just after the beginning), and the second measurement can be made after the aggregation of tiny objects. In this way, the intensity ratio of the two detection signals obtained at any time accompanied by light irradiation can be calculated.

[0142] [Implementation Method 2]

[0143] Generally, the fluorescence imaging method is widely used when observing biological samples such as microorganisms. In Embodiment 2, an example of combining the quantitative evaluation method of the aggregation amount of tiny objects described in Embodiment 1 (or its variant) with the fluorescence imaging method is described. In this measurement example, fluorescent beads are used as tiny objects. The fluorescent beads include YG (Yellow Green) fluorescent pigment. The material of the fluorescent beads is polystyrene. The diameter of the resin beads is 1.0μm. It should be noted that the tiny objects can also be microorganisms (bacteria, etc.) stained with fluorescent pigments.

[0144] Fig.18 1 is a diagram for explaining the structural features of the micro-object detection system of Embodiment 2. The micro-object detection device of Embodiment 2 has a structure similar to that of the micro-object detection device 1 of Embodiment 1 (see FIG. 1 ). Figure 1 to Figure 4 ) is that, in addition to the laser module 4, a fluorescent light source 49 is also provided, and a masking member 81 is also provided. In this case, the laser module 4 and the fluorescent light source 49 are equivalent to the "light source unit" of the present disclosure. The other structures of the micro-object detection device of embodiment 2 are the same as the corresponding structures of the detection device 1, and thus will not be described again.

[0145] The fluorescent light source 49 is provided on the light source stage 2 together with the laser module 4. The fluorescent light source 49 emits excitation light L0 (e.g., light of a blue wavelength) for exciting the fluorescent pigment in the fluorescent beads. Fluorescence (e.g., light of a green wavelength) is emitted from the fluorescent beads by irradiation with the excitation light L0. Regarding the fluorescent beads used in this measurement, the maximum wavelength of the excitation light L0 is 441 nm, and the maximum wavelength of the fluorescence is 486 nm. In this example, the fluorescent light source 49 is an LED (Light Emitting Diode), but it may also be another type of light source such as a mercury lamp.

[0146] It should be noted that the laser module 4 and the fluorescent light source 49 can also be formed integrally. More specifically, the laser module 4 can also serve as a light source for gathering fluorescent beads and a light source for exciting fluorescent pigments. That is, the laser module 4 can also emit excitation light L0 of the fluorescent pigment (for example, blue light instead of near-infrared light), and generate a photothermal effect of the film 106 by the excitation light L0. In this way, the light from the laser module 4 can be used together for the aggregation of tiny objects in the liquid, the calculation of the amount of tiny objects gathered based on the time change of the detection signal, and the photography of the fluorescent image.

[0147] The masking member 81 is provided on the lower surface of the photoreceiver 8. The masking member 81 blocks light (stray light) that is not necessary to be taken into the photoreceiver 8 among the fluorescence emitted from the fluorescent beads. Thus, the sensitivity of the photoreceiver 8 to the fluorescence is improved.

[0148] It should be noted that in this example, in order to capture the fluorescent image, the light receiver 8 is a multi-pixel type photodetector (CCD or CMOS image sensor, etc.). However, the fluorescent image is used to confirm the aggregation of fluorescent beads, rather than to calculate the aggregation amount of fluorescent beads. Therefore, in Embodiment 2, a single-pixel type light receiver 8 (photodiode, etc.) can also be used.

[0149] In this measurement example, three types of samples SP were also prepared. The first sample was a sample with 2.02×10 4 The second sample is a sample with 2.02×10 fluorescent beads. 5 The third sample is a sample with 2.02×10 fluorescent beads. 6 Samples. Hereinafter, the first to third samples are referred to as "reference sample", "10 times concentration sample" and "100 times concentration sample" respectively. In any sample, the liquid volume is 20 μL. The output of the laser light L (laser output) is 180 mW. The irradiation time of the laser light L is set to 180 seconds.

[0150] Fig.191 is a diagram showing the fluorescence image of each sample when the irradiation of the laser beam L is stopped. In the figure, the square area indicated by the dotted line is the photometric area of ​​the photoreceiver 8 (the area where the masking member 81 is not provided). The circular area indicated by the solid line in the center is the irradiation area of ​​the laser beam L (laser spot).

[0151] according to Fig.19 It can be seen that as the concentration of fluorescent beads increases, the number of bright spots representing the aggregation of fluorescent beads (the area of ​​aggregated fluorescent beads) increases. Therefore, as the concentration of fluorescent beads increases, the intensity of the detection signal increases. Therefore, in Embodiment 2, as in Embodiment 1, the slope of the approximate straight line can be calculated based on the change in the detection signal (the rate of increase of the detection signal), and the concentration of the fluorescent beads can be calculated based on the slope of the approximate straight line. In addition, as in the modified example of Embodiment 1, the concentration of the fluorescent beads can also be calculated based on the intensity ratio (attenuation rate, etc.) of the detection signal accompanying the change in the detection signal.

[0152] The embodiments disclosed this time are illustrative in all aspects and should not be construed as restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the embodiments above, and includes all modifications within the meaning and scope equivalent to the claims.

[0153] Description of Reference Numerals

[0154] 1 detection device, 2 light source stage, 3 adjustment mechanism, 4 laser module, 5 driver, 6 sample holder, 7 filter, 8 light receiver, 81 masking component, 9 controller, 10 focusing kit, 100 detection system, 101 honeycomb substrate, 102 cover substrate, 103 spacer, 104 substrate, 105 honeycomb polymer film, 106 film, 107 pore, 108 partition wall, 41 substrate, 411 electrode, 42 surface light emitting element, 421 light emitting region, 422 electrode pad, 441 core, 442 cladding, 43 bonding member, 44 optical waveguide, 45 lens, 49 fluorescent light source, X tiny object, SP sample.

Claims

1. A device for detecting micro-objects, which detects a plurality of micro-objects dispersed in a liquid sample by using a collection kit, wherein: The focusing kit has a photothermal conversion region for converting light into heat, and is configured to be able to hold the liquid sample on the photothermal conversion region. The detection device comprises: a light source unit that emits light for irradiating the focusing kit; a light receiver that detects light from the liquid sample held in the focusing kit and outputs a detection signal thereof; and a calculation unit for calculating the concentration of the plurality of micro-objects in the liquid sample; The detection device heats the liquid sample by irradiating light to the photothermal conversion region, thereby generating bubbles at the light irradiation position and generating convection in the liquid sample, thereby gathering the plurality of tiny objects near the bubbles. The calculation unit calculates the concentration of the plurality of fine objects based on a temporal change in the detection signal during the aggregation of the plurality of fine objects.

2. The device for detecting small objects according to claim 1, wherein: The calculation unit calculates the concentration of the plurality of fine objects in the liquid sample based on a slope of an approximate straight line obtained by regression of the detection signal within a predetermined period after the start of light irradiation to the photothermal conversion region.

3. The device for detecting small objects according to claim 1, wherein: The calculation unit calculates the concentration of the plurality of fine objects in the liquid sample based on an intensity ratio of two detection signals acquired in association with light irradiation to the photothermal conversion region.

4. The device for detecting small objects according to any one of claims 1 to 3, wherein: The plurality of micro-objects are configured to emit fluorescence when excited, The light source unit comprises: a laser light source that emits laser light for irradiating the focusing kit; and A fluorescent light source emits light for exciting the plurality of micro-objects.

5. The device for detecting small objects according to claim 4, wherein: The laser light source and the fluorescent light source are formed integrally.

6. The device for detecting small objects according to claim 4, wherein: The light receiver includes a shielding member that blocks light that is unnecessary to be taken into the light receiver, among the fluorescent light emitted from the plurality of fine objects.

7. The device for detecting small objects according to any one of claims 1 to 3, wherein: The light source unit has a plurality of light emitting regions, and is configured to emit a plurality of laser beams from each of the plurality of light emitting regions. The detection device also has: a retainer configured to retain the aggregation kit; A focusing lens, which focuses the multiple laser beams to a same focusing point; an adjustment mechanism for adjusting the relative positional relationship between the holder and the focusing lens; and a control unit that controls the adjustment mechanism, The control unit is configured to be able to switch between a single irradiation mode and a multi-point irradiation mode, wherein the single irradiation mode and the multi-point irradiation mode are modes in which at least a part of the plurality of laser beams is irradiated to the photothermal conversion region. The single irradiation mode is a mode in which the adjustment mechanism is controlled so that the focal point coincides with the photothermal conversion area. The multi-point irradiation mode is a mode in which the adjustment mechanism is controlled so that the focal point is separated from the photothermal conversion region.

8. The device for detecting small objects according to claim 7, wherein: The light source portion includes a vertical cavity surface emitting laser.

9. The device for detecting small objects according to claim 8, wherein: The focusing lens includes a gradient refraction optical fiber and a plano-convex lens. The optical fiber has one end covering the plurality of light emitting regions and the other end joined to the plane side of the plano-convex lens.

10. The device for detecting small objects according to any one of claims 1 to 3, wherein: The light receiver is a single-pixel type light detector.

11. A system for detecting small objects, wherein: The micro-object detection system has: A focusing kit having a light-to-heat conversion region for converting light into heat, and configured to be able to hold a liquid sample on the light-to-heat conversion region; and A detection device that detects a plurality of microscopic objects dispersed in the liquid sample by using the aggregation kit, The detection device comprises: a light source unit that emits light for irradiating the focusing kit; a light receiver that detects light from the liquid sample held in the focusing kit and outputs a detection signal thereof; and a calculation unit for calculating the concentration of the plurality of micro-objects in the liquid sample; The detection device heats the liquid sample by irradiating light to the photothermal conversion region, thereby generating bubbles at the light irradiation position and generating convection in the liquid sample, thereby gathering the plurality of tiny objects near the bubbles. The calculation unit calculates the concentration of the plurality of fine objects based on a temporal change in the detection signal during the aggregation of the plurality of fine objects.

12. The micro-object detection system according to claim 11, wherein: The aggregation kit also includes: A first surface, which is provided with the light-to-heat conversion area; a second surface, the liquid sample being sandwiched between the second surface and the first surface; and A spacer is used to fix the distance between the first surface and the second surface.

13. A method for detecting micro-objects, comprising: using a collection kit to collect a plurality of micro-objects dispersed in a liquid sample, thereby detecting the plurality of micro-objects in the liquid sample, wherein: The focusing kit has a photothermal conversion region for converting light into heat, and is configured to be able to hold the liquid sample on the photothermal conversion region. The detection method comprises: The step of heating the liquid sample by irradiating light to the photothermal conversion region, thereby generating bubbles at the light irradiation position and generating convection in the liquid sample, thereby gathering the plurality of micro-objects near the bubbles; a step of detecting light from the liquid sample held in the focusing kit by a light receiver; and A step of calculating the concentration of the plurality of fine objects in the liquid sample based on a time change in a detection signal from the light receiver during aggregation of the plurality of fine objects.

Images