Collection device of micro objects

Abstract

To provide a collection device of micro objects which can avoid a situation where collection efficiency of micro objects reduces due to movement of microbubbles.SOLUTION: A micro object collection device 1 comprises: a collection container 11 capable of holding liquid; a collection substrate 12 which is arranged in liquid held in the collection container 11, and collects a plurality of micro objects α dispersed in liquid; a plurality of pores 12a which are formed on a surface in contact with liquid of the collection substrate 12 to collect the micro objects α and can hold air in liquid; a step 12b which is formed by depression of a surface surrounding a forming region of the plurality of pores 12a; a thin film 13 which is formed on a surface of at least pore forming region, and converts light into heat; and light sources 41 to 49 which irradiate the thin film 13 with light.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a device for collecting minute objects that collects minute objects dispersed in a liquid contained in a holding container onto a collection substrate.

Background Art

[0002] Conventionally, as a device for collecting minute objects of this kind, for example, there is a minute object integration system disclosed in Patent Document 1. This minute object integration system includes a holding device that holds a substrate provided with a photothermal conversion region in a liquid, and a light heating device that emits first and second light rays. The first and second light rays are irradiated on the photothermal conversion region at intervals, and when the liquid is heated, first and second microbubbles are generated at the irradiation positions of the first and second light rays. Convection of the liquid occurs in a specific direction due to the generated first and second microbubbles. On the other hand, a stagnant region where the flow velocity of the convection is almost zero is generated between each of the first and second microbubbles and a thin film that is the photothermal conversion region formed on the substrate. Minute objects carried by the convection stay in this stagnant region and are integrated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the minute object integration device as disclosed in the above-mentioned conventional Patent Document 1, microbubbles may move on the collection substrate due to convection in the liquid or the like. When the microbubbles move on the collection substrate, even if minute objects once stay and are integrated in the stagnant region close to the microbubbles, the minute objects will leave the stagnant region. As a result, the collection efficiency of the minute objects by the minute object integration device decreases.

Means for Solving the Problems

[0005] The present invention has been made to solve such problems, a holding container capable of holding a liquid, a collection substrate disposed in the liquid held in the holding container and collecting a plurality of minute objects dispersed in the liquid, a plurality of pores formed on the surface of the collection substrate in contact with the liquid and capable of holding air in the liquid, for capturing minute objects, a step formed on the surface by the surrounding surface surrounding the formation region of the plurality of pores being recessed, a photothermal conversion region formed at least on the surface of the formation region and converting light into heat, a light source for irradiating light onto the photothermal conversion region, are provided to constitute a collection device for minute objects.

[0006] According to this configuration, a step is formed on the surface of the collection substrate in contact with the liquid, surrounding the formation region of the plurality of pores, where the surface is recessed. When light is irradiated onto the photothermal conversion region formed on the surface of the pore formation region, the microbubbles generated on the surface of the pore formation region have the contact portion around the surface of the pore formation region surrounded by the step. Therefore, even if the microbubbles generated on the surface of the pore formation region try to move on the surface while contacting the surface of the pore formation region due to convection in the liquid or the like, their movement is stopped at the step. For this reason, the movable range of the microbubbles is suppressed within the range of the pore formation region. As a result, the situation where the minute objects once accumulated in the stagnant region close to the microbubbles are separated from the stagnant region due to the movement of the microbubbles is eliminated. Therefore, according to this configuration, it is possible to prevent a decrease in the collection efficiency of minute objects.

Effects of the Invention

[0007] According to the present invention, it is possible to provide a collection device for minute objects that can avoid a situation where the collection efficiency of minute objects is reduced due to the movement of microbubbles.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Next, the embodiments for implementing the micro-object collection device of the present invention will be described.

[0010] In the present invention and its embodiments, the term "micro-object" means an object having a size in the range from the order of nanometers to the order of micrometers. The shape of the micro-object is not particularly limited, and for example, it may be spherical, ellipsoidal, or rod-shaped (oar-shaped). When the micro-object is ellipsoidal, at least one of the length in the major axis direction and the length in the minor axis direction of the ellipsoid may be in the range from the order of nanometers to the order of micrometers. When the micro-object is rod-shaped, at least one of the width and the length of the rod may be in the range from the order of nanometers to the order of micrometers.

[0011] The micro-object may include a bio-derived object. More specifically, the micro-object may include, for example, cells, microorganisms (such as bacteria and fungi), antigens (such as allergens), viruses, and biomaterials. The "biomaterial" may include biopolymers such as proteins, nucleic acids, lipids, and polysaccharides.

[0012] Other examples of the micro-object include metal nanoparticles, metal nanoparticle aggregates, metal nanoparticle integrated structures, semiconductor nanoparticles, organic nanoparticles, resin beads, PM (Particulate Matter), and the like. The "metal nanoparticles" are metal particles having a size on the order of nanometers. The "metal nanoparticle aggregate" is an aggregate formed by aggregation of a plurality of metal nanoparticles. The "metal nanoparticle integrated structure" is, for example, a structure in which a plurality of metal nanoparticles are fixed to the surface of beads via interaction sites, with a gap provided between them and arranged at intervals less than the diameter of the metal nanoparticles. The "semiconductor nanoparticles" are semiconductor particles having a size on the order of nanometers. The "organic nanoparticles" are particles composed of organic compounds having a size on the order of nanometers. The "resin beads" are particles composed of a resin having a size in the range from the order of nanometers to the order of micrometers. The "PM" is particulate matter having a size on the order of micrometers.

[0013] In the present invention and its embodiments, the "nanometer order" includes the range from 1 nm to 1000 nm (= 1 μm). The "micrometer order" includes the range from 1 μm to 1000 μm (= 1 mm). Therefore, the term "range from the nanometer order to the micrometer order" includes the range from 1 nm to 1000 μm. The term "range from the nanometer order to the micrometer order" typically indicates 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.

[0014] In the present invention and its embodiments, a "pore" is a hole having an opening in the range from the nanometer order to the micrometer order. The shape of the pore is not particularly limited and may include any shape such as a cylindrical shape, a prismatic shape, and a spherical shape other than a true spherical shape (for example, a hemispherical shape or a semi-elliptical spherical shape).

[0015] In the present invention and its embodiments, a "microbubble" is a bubble in the micrometer order.

[0016] FIG. 1 is a block diagram showing a schematic configuration of a micro-object collection device 1 according to a first embodiment of the present invention. In the following figures, the same or corresponding parts are denoted by the same reference numerals, and overlapping explanations are omitted.

[0017] The collection device 1 includes a collection kit 10, an XYZ-axis stage 20, an adjustment mechanism 30, laser light sources 41 to 49, an optical component 50, an objective lens 60, an illumination device 70, a photographing device 80, and a control device 90. Hereinafter, the x-direction and the y-direction represent the horizontal direction. 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.

[0018] The collection kit 10 holds the sample S. In the present embodiment, the sample S is a liquid in which the micro-objects α are dispersed. The detailed configuration of the collection kit 10 will be described with reference to FIG. 2. The collection kit 10 is placed on the XYZ-axis stage 20.

[0019] The adjustment mechanism 30 adjusts the positions of the XYZ-axis stage 20 on which the collection kit 10 is mounted in the x-direction, y-direction, and z-direction in response to a command from the control device 90. In the present embodiment, since the position of the objective lens 60 is fixed, by adjusting the position of the XYZ-axis stage 20, the relative positional relationship between the collection kit 10 and the objective lens 60 is adjusted. As the adjustment mechanism 30, for example, a drive mechanism such as a servo motor and a focusing handle attached to a microscope can be used, but the specific configuration of the adjustment mechanism 30 is not particularly limited. Note that the adjustment mechanism 30 may adjust the position of the objective lens 60 with respect to the fixed collection kit 10.

[0020] Each of the nine laser light sources 41 to 49 emits laser lights L1 to L9 of, for example, near-infrared (for example, wavelength 1064 nm) in response to a command from the control device 90. However, the wavelengths of the laser lights L1 to L9 are not limited to this as long as they are wavelengths included in the light absorption band of the material of the thin film 13 (see FIG. 3) described later.

[0021] The optical component 50 includes, for example, a mirror, a dichroic mirror, or a prism. The optical system of the collection device 1 is adjusted such that the laser lights L1 to L9 from the laser light sources 41 to 49 are guided to the objective lens 60 by the optical component 50.

[0022] The objective lens 60 condenses the laser lights L1 to L9 from the laser light sources 41 to 49. The light condensed by the objective lens 60 is irradiated onto the collection kit 10. Here, "irradiate" includes the case where the laser lights L1 to L9 pass through the collection kit 10. That is, it is not limited to the case where the beam waist of the light condensed by the objective lens 60 is located within the collection kit 10. Note that the optical component 50 and the objective lens 60 can be incorporated into, for example, an inverted microscope main body or an upright microscope main body.

[0023] The illumination device 70 emits white light WL for illuminating the sample S in the collection kit 10 in accordance with a command from the control device 90. As one example, a halogen lamp can be used for the illumination device 70. The objective lens 60 is also used to capture the white light WL irradiated from the illumination device 70 onto the collection kit 10. The white light WL captured by the objective lens 60 is guided to the imaging device 80 by the optical component 50.

[0024] The imaging device 80 captures an image of the sample S (see Figure 2) in the collection kit 10 irradiated with the white light WL in accordance with a command from the control device 90, and outputs the captured image to the control device 90. A video camera including a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor is used for the imaging device 80.

[0025] The control device 90 controls the adjustment mechanism 30, the laser light sources 41 to 49, the illumination device 70, and the imaging device 80. Further, the control device 90 performs predetermined image processing on the image captured by the imaging device 80. The control device 90 is realized by a microcomputer including a CPU (Central Processing Unit), a memory, an input / output buffer, etc., which are not shown in the figure.

[0026] Note that the optical system of the collection device 1 is not limited to the configuration shown in FIG. 1 as long as it can irradiate the collection kit 10 with the laser beams L1 to L9 from the laser light sources 41 to 49 and can capture the white light WL from the collection kit 10 into the imaging device 80, and it may include an optical fiber or the like. Further, in the collection device 1, the illumination device 70 and the imaging device 80 are merely devices for photographing the state of the sample S and are not essential components for collecting the micro-objects by the collection device 1. Further, the laser light sources 41 to 49 do not necessarily have to be provided in nine units, and at least one unit may be provided.

[0027] FIG. 2(a) is a side sectional view showing the detailed configuration of the collection kit 10. The collection kit 10 includes a collection container 11 that houses the sample S in which the micro-objects α are dispersed, and a collection substrate 12. The collection container 11 has a holding container in which the shape of the inner circumference of the housing portion 11a is circular, or similar to a circle, or a polygon having a number of sides close to a circle, or an ellipse, or similar to an ellipse in plan view, and can hold a liquid in the housing portion 11a. The collection container 11 is formed of, for example, a transparent resin or glass. The collection substrate 12 is disposed in the liquid of the sample S held in the housing portion 11a and collects a plurality of micro-objects α dispersed in the liquid.

[0028] FIG. 3 shows the schematic configuration of the collection substrate 12. FIG. 3(a) is a plan view of the collection substrate 12, FIG. 3(b) is a partial perspective view of the portion surrounded by the broken line of the collection substrate 12 shown in FIG. 3(a), and FIG. 3(c) is a side sectional view of the collection substrate 12 taken along the line IIIc-IIIc shown in FIG. 3(a).

[0029] On the substrate surface of the collection substrate 12 in contact with the liquid of the sample S, protrusions are formed at nine positions corresponding to the number of the laser light sources 41 to 49, where the end surface on the upper surface is formed one step higher than the substrate surface. On the circular end surface in plan view of each protrusion, a large number of pores 12a for capturing micro-objects are formed in contact with the liquid of the sample S. Each pore 12a has a shape such as a diameter and a depth that can hold air 16 in the liquid of the sample S.

[0030] There is a height difference in the Z direction between the substrate surface of the collection substrate 12 and the end face surfaces of the respective protrusions, and a step 12b in which the substrate surface is recessed is formed on the surrounding substrate surface surrounding the formation region of the plurality of pores 12a. Further, a thin film 13 is formed on the substrate surface of the collection substrate 12 and the end face surfaces of the respective protrusions. The thin film 13 constitutes a photothermal conversion region that converts the laser light L1 to L9 irradiated from the laser light sources 41 to 49 into heat. The laser light sources 41 to 49 constitute a light source that irradiates the thin film 13 of the collection substrate 12 with light.

[0031] In the present embodiment, the collection substrate 12 is formed using photolithography technology with a translucent glass substrate 14 made of temper pack glass as a base. That is, a resist film 15 is formed on the glass substrate 14, and by selectively removing the resist film 15 by exposure using a photomask, raised protrusions are formed at nine locations on the glass substrate 14 where there is no resist film 15, and a plurality of pores 12a are selectively formed on the end face surfaces of the respective protrusions. In the present embodiment, SU-8 is used as the material of the resist film 15.

[0032] Thereafter, the thin film 13 is formed on the entire surface of the substrate surface of the collection substrate 12 using a method such as vapor deposition, sputtering, or electroless plating. As a result, as shown in FIG. 3, the thin film 13 is formed on the upper surfaces of the glass substrate 14 and the resist film 15, and the bottom surfaces of the pores 12a. The material of the thin film 13 is preferably a material having high light absorptivity (for example, photothermal conversion efficiency) with respect to the wavelength band of the laser light L1 to L9 (near-infrared band in the present embodiment). In the present embodiment, a gold (Au) thin film having a thickness on the order of nanometers is used as the material of the thin film 13 and is formed by vapor deposition. However, other metal elements (for example, silver) or metal nanoparticle integrated structures (for example, structures using gold nanoparticles or silver nanoparticles) may also be used. Alternatively, a material other than a metal having a high light absorption rate in the wavelength band of the laser light L1 to L9 may be used. Examples of such materials include materials close to a black body (for example, carbon nanotube black body).

[0033] FIG. 4 is a graph showing the heat conversion efficiency due to the photothermal effect of the thin film 13 constituting the photothermal conversion region. The horizontal axis of the graph is the film thickness [nm] of the gold thin film used as the thin film 13, and the vertical axis is the substrate temperature [° C.] of the collection substrate 12.

[0034] When the laser beams L1 to L9 are irradiated onto the thin film 13 through the light transmission region of the glass substrate 14, heat is generated at the light-irradiated portion of the collection substrate 12 and microbubbles MB are generated as will be described later. From the graph, it is considered that when the film thickness of the gold thin film is 4 [nm] or less, the laser beams L1 to L9 pass through the thin film 13, the heat conversion efficiency decreases, and no microbubbles MB are generated. Also, when the film thickness of the gold thin film is 20 [nm] or more, the heat conduction of the thin film 13 is high, the heat conversion efficiency decreases, and it is considered that no microbubbles MB are generated. For this reason, the thin film 13 is preferably formed from a gold thin film having a thickness of 4 [nm] to 20 [nm].

[0035] By forming the thin film 13 from a gold thin film having a thickness of 4 [nm] or more, it is possible to avoid the laser beams L1 to L9 irradiated from the laser light sources 41 to 49 passing through the gold thin film and the heat conversion efficiency decreasing and no microbubbles MB being generated. Also, by forming the thin film 13 from a gold thin film having a thickness of 20 [nm] or less, it is possible to avoid the heat conduction of the thin film 13 becoming too high and the heat conversion efficiency decreasing and no microbubbles MB being generated.

[0036] In the present embodiment, a resist film 15 having a thickness of 5 [μm] is formed on a glass substrate 14 having a square shape in plan view with a side of 5 [mm] and a thickness of 0.2 [mm]. The thin film 13 is deposited aiming at a thickness of 10 [nm]. The pores 12a are formed in a cylindrical shape with a diameter φ of 5 [μm] and a depth of 5 [μm], and are arranged in the x direction and the y direction at a pitch of 10 [μm]. Each pore 12a having such a size can hold air 16 in the liquid of the sample S as shown in FIG. 2.

[0037] In addition, the pores 12a are preferably cylindrical in shape in terms of photolithography technology. However, in order to store the air 16, as shown in the partially enlarged side sectional view of FIG. 5, it is desirable that the pores 12c have a substantially cylindrical shape with a reverse taper-shaped side surface whose opening area is smaller than the bottom area. According to this configuration, it is possible to make it difficult for the air 16 accumulated in the pores 12c to escape.

[0038] FIG. 6 is a perspective view showing the holding container positioning mechanism of the collection device 1. The holding container positioning mechanism positions the relative position between the collection container 11 and the XYZ-axis stage 20 which is a mounting plate on which the collection container 11 is placed.

[0039] In the present embodiment, the collection container 11 has a bottomed cylindrical shape, and on the outer periphery having a cylindrical shape, a pair of convex portions 11b, 11b are formed protruding from the outer periphery at opposing positions. On the other hand, a circular through-hole 20a is formed in the XYZ-axis stage 20. A step 20b is formed on the inner periphery of the circular through-hole 20a so that the outer peripheral edge of the circular bottom of the collection container 11 fits and is received, and a pair of grooves 20c, 20c having a shape into which the convex portions 11b, 11b fit are formed at opposing positions of the step 20b. The convex portions 11b, 11b constitute engaging portions formed on the outer periphery of the collection container 11, and the grooves 20c, 20c constitute engaged portions that engage with these engaging portions. The holding container positioning mechanism according to the present embodiment is composed of the convex portions 11b, 11b and the grooves 20c, 20c. When the pair of convex portions 11b, 11b of the collection container 11 fit into the grooves 20c, 20c of the XYZ-axis stage 20 and the collection container 11 is placed on the XYZ-axis stage 20, the relative position between the collection container 11 and the XYZ-axis stage 20 is positioned.

[0040] The holding container positioning mechanism is not limited to this configuration. For example, it may be the configuration shown in FIG. 7. In this configuration, the collection container 11' has a cylindrical inner periphery of the housing portion 11a and a rectangular outer periphery 11c. A rectangular through-hole 20e is formed in the XYZ-axis stage 20'. A step 20f into which the outer peripheral edge of the rectangular bottom of the collection container 11' fits is formed in a rectangular shape around the inner periphery of this rectangular through-hole 20e. The outer periphery 11c of the collection container 11' constitutes an engaging portion, and the step 20f of the XYZ-axis stage 20' constitutes an engaged portion that engages with this engaging portion. The holding container positioning mechanism according to this modification is composed of the outer periphery 11c of the collection container 11' and the step 20f of the XYZ-axis stage 20'. When the outer periphery 11c of the collection container 11' fits into the step 20f of the XYZ-axis stage 20' and the collection container 11' is placed on the XYZ-axis stage 20', the relative position between the collection container 11' and the XYZ-axis stage 20' is positioned.

[0041] Note that the holding container positioning mechanism on the XYZ-axis stage 20, 20' side may be configured not as the XYZ-axis stage 20, 20' itself but as a jig, and the jig may be configured to be attached to the XYZ-axis stage 20, 20'. Also, in the holding container positioning mechanism shown in FIG. 6, instead of the convex portion 11b on the outer periphery of the collection container 11, a groove may be formed as the engaged portion, and a convex portion having a shape that fits into this groove may be formed as the engaging portion instead of the groove 20c at a position facing the step 20b.

[0042] In addition, the collection device 1 has a substrate positioning mechanism for positioning the relative position between the collection substrate 12 and the collection container 11. In this embodiment, this substrate positioning mechanism is composed of the four sides of the collection substrate 12 having a rectangular outer shape as shown in FIG. 3(a) and a rectangular step 11d (see FIG. 2) formed on the bottom surface of the housing portion 11a of the collection container 11. When the four outer peripheral sides of the rectangular bottom of the collection substrate 12 fit into and are accommodated in the rectangular step 11d, the relative position between the collection substrate 12 and the collection container 11 is positioned.

[0043] FIG. 8 is a plan view of the collection substrate 12 of the present embodiment, showing irradiation regions (hereinafter referred to as laser spots) LS1 to LS9 on which laser beams L1 to L9 are irradiated with black dots. In the present embodiment, laser spots LS1 to LS9 are formed at nine locations on the thin film 13 on the surface of the collection substrate 12. Laser spots LS1 to LS3 are formed at the center of each formation region of the pores 12a formed at three locations in the lower part of the figure, laser spots LS4 to LS6 are formed at the center of each formation region of the pores 12a formed at three locations in the middle part of the figure, and laser spots LS7 to LS9 are formed at the center of each formation region of the pores 12a formed at three locations in the upper part of the figure.

[0044] When collecting the micro-objects α, first, the control device 90 places the collection container 11 on the XYZ-axis stage 20 such that the bottom of the collection container 11 fits into the step 20b of the XYZ-axis stage 20 and the convex portions 11b, 11b of the collection container 11 engage with the grooves 20c, 20c of the XYZ-axis stage 20. This process is realized, for example, by a feeding mechanism (not shown) of the collection kit 10. At this time, on the inner bottom surface of the collection container 11, the four outer peripheral sides of the rectangular bottom of the collection substrate 12 fit into the rectangular step 11d, and the collection substrate 12 is accommodated.

[0045] Next, the control device 90 controls the illumination device 70 to emit white light WL for irradiating the sample S on the collection kit 10, and controls the imaging device 80 to start imaging the sample S.

[0046] Next, the control device 90 adjusts the position of the XYZ-axis stage 20 by controlling the adjustment mechanism 30 so that the laser beams L1 to L9 from the laser light sources 41 to 49 are irradiated to appropriate positions on the collection substrate 12, for example, the positions where the laser spots LS1 to LS9 in FIG. 8 are formed. This position adjustment can be realized by extracting the pattern of the pores 12a from the image captured by the imaging device 80 using, for example, image processing techniques for pattern recognition.

[0047] Next, the control device 90 controls the laser light sources 41 to 49 so as to emit the laser lights L1 to L9. The laser lights L1 to L9 are condensed by the objective lens 60, and the condensed light is irradiated onto the thin film 13 of the collection substrate 12. As a result, convection occurs in the liquid of the sample S, and the minute objects α dispersed in the liquid are collected in the stagnant regions near the respective laser spots LS1 to LS9 and captured in the pores 12a. Thereafter, the control device 90 controls the laser light sources 41 to 49 to stop the irradiation of the laser lights L1 to L9 onto the thin film 13 of the collection substrate 12.

[0048] The state in which the minute objects α are collected and the mechanism thereof will be described as follows.

[0049] FIG. 2(b) shows the collection state of the minute objects α from the sample S when the laser spot LS2 is formed at one location in the center of the lower stage of the collection substrate 12 as shown in FIG. 8.

[0050] Before the start of the irradiation of the laser light L2 from the laser light source 42, as shown in FIG. 2(a), the minute objects α can move freely in the liquid of the sample S. Almost no minute objects α are captured in the pores 12a of the collection substrate 12.

[0051] However, when the irradiation of the laser light L2 (hereinafter also abbreviated as "light irradiation") is started, due to the photothermal effect of the thin film 13 of the laser spot LS2, the vicinity of the laser spot LS2 is locally heated. As a result, microbubbles MB are generated at the laser spot LS2.

[0052] At this time, when heat is locally generated in the pores 12a that hold the air 16, microbubbles MB are generated with the air 16 held in the pores 12a as nuclei, and their generation is promoted. Since the locally generated heat increases the temperature of the liquid more in the areas closer to the light irradiation location, a temperature gradient occurs in the liquid. Due to this temperature gradient, convection occurs in the liquid held in the housing portion 11a of the collection container 11. Since this convection is promoted by the generation of microbubbles MB, it occurs efficiently. The minute objects α dispersed in the liquid are efficiently collected by the microbubbles MB formed on the surface of the collection substrate 12 by this efficiently occurring convection and are captured in the pores 12a.

[0053] More specifically, a region where the flow velocity of the convection becomes zero is generated as a stagnant region between the microbubbles MB and the thin film 13. The minute objects α carried by the convection stay in this stagnant region and are collected. Here, "collection" means the action of collecting the minute objects α in the stagnant region near the microbubbles MB. As a result, compared with the case where there is no light irradiation, the frequency (the number of times per unit time) of the minute objects α passing above the pores 12a around the microbubbles MB increases. The minute objects α are captured in the pores 12a when passing above the pores 12a. Here, "capture" means the action of catching the minute objects α in the space inside the pores 12a.

[0054] According to the collection device 1 of the present embodiment, on the surface of the collection substrate 12 in contact with the liquid of the sample S around the formation region of the plurality of pores 12a, a step 12b in which the surface sinks is formed as shown in FIG. 3. Light is irradiated onto the thin film 13, which is a photothermal conversion region formed on the surface of the pore formation region, through the light-transmissive glass substrate 14 as shown in FIG. 2(b). The microbubbles MB generated on the surface of the pore formation region are surrounded by the step 12b around the contact portion with the surface of the pore formation region.

[0055] Therefore, even if the microbubbles MB generated on the surface of the pore formation region attempt to move on the surface while in contact with the surface of the pore formation region due to convection in the liquid of the sample S, their movement is stopped at the step 12b. For this reason, the movable range of the microbubbles MB is suppressed within the extremely narrow range of the pore formation region. As a result, the fine objects α once accumulated in the stagnant region close to the microbubbles MB will not be separated from the stagnant region due to the movement of the microbubbles MB. Therefore, according to the configuration of the collection device 1 of the present embodiment, a decrease in the collection efficiency of the fine objects α can be prevented.

[0056] In addition, the pores 12a are formed limited to the end face surfaces of the respective protrusions, and by forming the laser spots LS1 to LS9 only in the pore formation region, microbubbles MB are surely formed only at the locations irradiated with the laser beams L1 to L9, and the generation of unnecessary noise bubbles is suppressed.

[0057] In addition, the periphery of the contact portion of the microbubbles MB with the surface of the pore formation region is annular. Therefore, according to the collection device 1 of the present embodiment in which the step 12b has a circular shape in plan view, the step 12b has a shape similar to the circle drawn by the periphery of the contact portion in plan view. Therefore, no matter where the microbubbles MB are generated on the surface of the pore formation region, the annular contact portion of the microbubbles MB reaches the step 12b most quickly. For this reason, the movement of the microbubbles MB in all directions horizontal to the surface of the collection substrate 12 is quickly stopped.

[0058] In the above-described embodiment, the case where the thin film 13 is provided on the entire surface of the collection substrate 12 has been described. However, the thin film 13 only needs to be formed on at least the surface of the formation region of the pores 12a. As in the collection substrate 12A shown in FIGS. 9 and 10(a) and (b), the region where the thin film 13 is formed may be configured to be limited to the end face surfaces of the protrusions where a plurality of pores 12a are formed. FIG. 9 is a plan view of the collection substrate 12A, FIG. 10(a) is a partial perspective view of a portion surrounded by a broken line of the collection substrate 12A shown in FIG. 9, and FIG. 10(b) is a side cross-sectional view of the collection substrate 12A taken along the line Xb-Xb shown in FIG. 9.

[0059] Also in this configuration, the laser beams L1 to L9 from the laser light sources 41 to 49 are irradiated onto the formation region of the pores 12a as shown in the plan view of the collection substrate 12A in FIG. 10(c), forming laser spots LS1 to LS9. According to this configuration, by arranging the thin film 13 only in the region where the laser spots LS1 to LS9 are formed, the amount of heat dissipation when the light is thermally converted is suppressed, and microbubbles MB can be generated with light of less power.

[0060] In the above-described embodiment, the case where the pores 12a are formed on the end face surfaces of the protrusions raised on the surface of the collection substrate 12 and the step 12b has a circular shape in plan view has been described. However, the pores 12a may be formed on the end face surfaces of a polygonal prism having a number of sides close to a circle and raised on the surface of the collection substrate 12, and the step 12b may have a polygonal shape having a number of sides close to a circle in plan view. The step 12b is not limited to a perfect circle in plan view, and may be configured to be somewhat distorted in plan view or to have an elliptical shape in plan view. Even with such a configuration, the step 12b has a shape close to a shape similar to the circle drawn by the periphery of the contact portion with the surface of the pore formation region of the microbubble MB in plan view. Therefore, no matter where the microbubble MB is generated on the surface of the pore formation region, the annular contact portion of the microbubble MB reaches the step 12b most quickly. For this reason, the movement of the microbubble MB in all horizontal directions on the surface of the collection substrate 12 can be quickly stopped.

[0061] FIG. 11(a) is a plan view of a collection substrate 12B constituting a micro-object collection device according to the second embodiment of the present invention, FIG. 11(b) is a partial perspective view of a portion surrounded by a broken line of the collection substrate 12B shown in FIG. 11(a), and FIG. 11(c) is a side cross-sectional view of the collection substrate 12B taken along line XIc-XIc shown in FIG. 11(a).

[0062] The micro-object collection device according to the second embodiment is different from the micro-object collection device 1 according to the first embodiment in that a groove 12d is formed in the collection substrate 12B such that a step 12b surrounds a pore formation region. Other configurations are the same as those of the micro-object collection device 1 according to the first embodiment.

[0063] According to the micro-object collection device according to the second embodiment, the movement of the micro-bubbles MB generated on the surface of the pore formation region in the direction toward the outside of the pore formation region is resisted by the corner 12e of the wall constituting the groove 12d, which stands upright with the bottom surface of the groove 12d sandwiched between the outer periphery of the step 12b in addition to the step 12b. For this reason, the movement of the micro-bubbles MB in the direction toward the outside of the pore formation region requires more energy, and the movement of the micro-bubbles MB in the horizontal direction on the surface of the collection substrate 12B is more effectively stopped.

[0064] Also in the micro-object collection device according to the second embodiment, the laser beams L1 to L9 from the laser light sources 41 to 49 are irradiated onto the formation region of the pores 12a surrounded by the groove 12d as shown in the plan view of the collection substrate 12B in FIG. 12(a) to form laser spots LS1 to LS9.

[0065] In the micro-object collection device according to the second embodiment as well, the case where the thin film 13 is formed on the entire surface of the collection substrate 12B has been described. However, the thin film 13 only needs to be formed on at least the surface of the pore 12a formation region. As shown in the plan view of the collection substrate 12C in FIG. 12(b), the region where the thin film 13 is formed may be limited to the surface of the pore 12a formation region surrounded by the groove 12d. According to this configuration, by disposing the thin film 13 only in the region where the laser spots LS1 to LS9 are formed, the amount of heat dissipation when the light is thermally converted is suppressed, and microbubbles MB can be generated with light of less power.

[0066] FIG. 13(a) is a plan view of a collection substrate 12D constituting a micro-object collection device according to the third embodiment of the present invention, and FIG. 13(b) is a cross-sectional view taken along the line XIIIb-XIIIb shown in FIG. 13(a) of the collection substrate 12D.

[0067] The micro-object collection device according to the third embodiment differs from the micro-object collection device according to the second embodiment in that a plurality of grooves 12d in the collection substrate 12D surround the pore formation region and are formed on the surface of the collection substrate 12D. Other configurations are the same as those of the micro-object collection device according to the second embodiment.

[0068] Microbubbles MB of various sizes are generated in the pore formation region, and the annular contact portion with the surface of the pore formation region also has various sizes. According to the micro-object collection device according to the third embodiment, since a plurality of grooves 12d of various sizes surround the pore formation region, the horizontal movement of the microbubbles MB on the surface of the collection substrate 12D can be effectively stopped by the grooves 12d of a size corresponding to the size of each microbubble MB.

[0069] Also in the micro-object collection device according to the third embodiment, the laser beams L1 to L9 from the laser light sources 41 to 49 are irradiated onto the pore 12a formation region surrounded by the groove 12d as shown in the plan view of the collection substrate 12D in FIG. 14(a) to form the laser spots LS1 to LS9.

[0070] In each of the above-described second and third embodiments, pores 12a are formed on the end face surface of the protrusions protruding from the surface of the collection substrate 12, and the groove 12d has a circular shape in plan view. Therefore, the groove 12d has a shape similar to a circle drawn by the periphery of the contact portion with the surface of the pore formation region of the microbubble MB in plan view. Therefore, no matter where the microbubble MB is generated on the surface of the pore formation region, the annular contact portion of the microbubble MB reaches the groove 12d most quickly. For this reason, the movement of the microbubble MB in all horizontal directions on the surfaces of the collection substrates 12B and 12D can be stopped quickly and more effectively.

[0071] In addition, in the micro-object collection device according to the third embodiment, the case where the thin film 13 is formed on the entire surface of the collection substrate 12D has been described. However, the thin film 13 may be formed at least on the surface of the region where the pores 12a are formed. As shown in the plan view of the collection substrate 12E in FIG. 14(b), the region where the thin film 13 is formed may be limited to the surfaces of the groove 12d formation region and the pore 12a formation region and provided. Further, as shown in the plan view of the collection substrate 12F in FIG. 15, the region where the thin film 13 is formed may be limited to the surface of the region where the pores 12a are formed and provided. According to these configurations, by disposing the thin film 13 only in the region where the groove 12d and the pores 12a are formed, or only in the region where the pores 12a are formed, the amount of heat radiation when light is thermally converted is suppressed, and the microbubble MB can be generated with light of less power.

[0072] Also, in each of the above-described second and third embodiments, the case where the pores 12a are formed on the end face surface of the protrusions that bulge in a columnar shape on the surface of the collection substrate 12 and the groove 12d has a circular shape in plan view has been described. However, the pores 12a may be formed on the end face surface of a polygonal prism that bulges on the surface of the collection substrate 12 and has the number of sides close to a circle, and the groove 12d may be configured to have a polygonal shape with the number of sides close to a circle in plan view. The groove 12d is not limited to a perfect circle in plan view, and may be configured to be somewhat distorted in plan view or to have an elliptical shape in plan view. Even with such a configuration, the groove 12d has a shape close to a shape similar to the circle drawn by the periphery of the contact portion with the surface of the pore formation region of the microbubble MB in plan view. Therefore, no matter where the microbubble MB is generated on the surface of the pore formation region, the annular contact portion of the microbubble MB can reach the groove 12d most quickly. For this reason, the movement of the microbubble MB in all horizontal directions on the surfaces of the collection substrates 12B and 12D can be quickly stopped.

[0073] Also, in the micro-object collection device according to each of the second and third embodiments, the groove 12d may be configured to be divided into a plurality of parts in the circumferential direction surrounding the pore formation region. For example, in the micro-object collection device according to the third embodiment, as shown in the partial plan view of the collection substrate 12D shown in FIG. 16(a), each groove 12d may be divided into three regions.

[0074] According to this configuration, since the groove 12d is divided into a plurality of parts in the circumferential direction, the amount of air accumulated in the groove 12d becomes smaller by the amount of division. Since the amount of air accumulated in the divided groove 12d becomes small, it is difficult for the air to become noise bubbles. For this reason, it is difficult for the collection of micro-objects by the collection device to be inhibited by noise bubbles.

[0075] Also, in the micro-object collection device according to each of the second and third embodiments, each groove 12d may be replaced with a groove 12f having a tapered cross-sectional shape in which the opening side is wider than the groove bottom side, as shown in the partial side cross-sectional view of FIG. 16(b). According to this configuration, since the opening side of the groove 12f is widened, it is difficult for air to accumulate in the groove 12f. For this reason, noise bubbles caused by the air accumulating in the groove 12f are less likely to occur, and the collection of micro-objects by the collection device is less likely to be inhibited by the noise bubbles.

[0076] In addition, in each of the above-described embodiments and each modification, the case where a plurality of pores 12a are arranged in a line in the x-direction and the y-direction as shown in the plan view of FIG. 17(a) has been described. However, the plurality of pores 12a may be configured to be arranged in a two-dimensional hexagonal lattice (honeycomb shape) as shown in the plan view of FIG. 17(b). According to this configuration, the length in the x-direction and the length in the y-direction of the region where the plurality of pores 12a are distributed can be reduced, and more pores 12a can be arranged in a region of the same area, and more air 16 that triggers micro-bubble generation can be stored in the pores 12a.

[0077] In addition, in each of the above-described embodiments and each modification, the resist film 15 may be formed of the same material as the glass substrate 14. Even with this configuration, the same operational effects as those of each of the above-described embodiments and each modification are exhibited.

[0078] Summarizing the above, the present invention is expressed as follows.

[0079] <1>A holding container capable of holding a liquid, A collection substrate disposed in the liquid held in the holding container and collecting a plurality of micro-objects dispersed in the liquid, A plurality of pores formed on the surface of the collection substrate in contact with the liquid and capable of holding air in the liquid, for capturing the micro-objects, A step formed on the surface where the surrounding surface surrounding the formation region of the plurality of pores sinks, At least formed on the surface of the formation region, a photothermal conversion region that converts light into heat, and a light source that irradiates light onto the photothermal conversion region A micro-object collection device comprising the same.

[0080] <2>The micro-object collection device according to <1>, wherein the step has a shape of a circle in plan view or a polygon having a number of sides close to a circle.

[0081] <3>The micro-object collection device according to <1>, wherein the step forms a groove surrounding the formation region.

[0082] <4>The micro-object collection device according to <3>, wherein the groove has a shape of a circle in plan view or a polygon having a number of sides close to a circle.

[0083] <5>The micro-object collection device according to <3> or <4>, wherein a plurality of the grooves are formed on the surface surrounding the formation region.

[0084] <6>The micro-object collection device according to any one of <3> to <5>, wherein the groove is divided into a plurality in the circumferential direction surrounding the formation region.

[0085] <7>The micro-object collection device according to any one of <3> to <6>, wherein the groove has a tapered cross-sectional shape with an opening side wider than a groove bottom side.

Explanation of Signs

[0086] 1... Collection device 10... Collection kit 11, 11’... Collection container (holding container) 11a... Accommodation part 11b... Convex part 11c... Outer circumference 11d... Rectangular step 12, 12A to 12F... Collection substrate 12a, 12c... Pores 12b... Step 12d, 12f... Grooves 12e…angle 13…thin film (photothermal conversion region) 14…glass substrate 15…resist film 16…air 20, 20’…XYZ-axis stage 20a…circular through-hole 20b…step 20c…groove 20e…rectangular through-hole 20f…step 30…adjustment mechanism 41~49…laser light source 50…optical component 60…objective lens 70…illumination device 80…imaging device 90…control device S…sample α…microscopic object MB…microbubble LS1~LS9…laser spot (light irradiation region)

Claims

1. A holding container capable of holding a liquid, A collection substrate disposed in the liquid held in the holding container to collect a plurality of minute objects dispersed in the liquid, A plurality of pores formed on the surface of the collection substrate in contact with the liquid to capture the minute objects and capable of holding air in the liquid, A step formed by the surrounding surface surrounding the formation region of the plurality of pores sinking into the surface, A photothermal conversion region formed at least on the surface of the formation region to convert light into heat, A light source for irradiating light onto the photothermal conversion region A device for collecting minute objects comprising the above.

2. The device for collecting minute objects according to Claim 1, wherein the step has a circular shape in plan view or a polygonal shape having a number of sides close to a circle.

3. The device for collecting minute objects according to Claim 1, wherein the step forms a groove surrounding the formation region.

4. The device for collecting minute objects according to Claim 3, wherein the groove has a circular shape in plan view or a polygonal shape having a number of sides close to a circle.

5. The device for collecting minute objects according to Claim 3, wherein a plurality of the grooves are formed on the surface surrounding the formation region.

6. The device for collecting minute objects according to any one of Claims 3 to 5, wherein the groove is divided into a plurality in the circumferential direction surrounding the formation region.

7. The device for collecting minute objects according to any one of Claims 3 to 5, wherein the groove has a tapered cross-sectional shape with an opening side wider than a groove bottom side.

Images