Microscopic object accumulation device and microscopic object stirring device

Abstract

A microscopic object accumulation device (10) is provided with a container (20) and three or more heat sources (30). The container (20) has a bottom wall (21) and a side wall (26). In a space (SP) demarcated by the bottom wall (21) and the side wall (26), a liquid containing microscopic objects (CE) can be stored. The heat sources (30) can heat the bottom wall (21). When a virtual line (TL) is drawn, the virtual line passing through, from among the heat centers (HC) of the three or more heat sources (30) , two discretionary heat centers (HC) of the heat sources (30), the heat center (HC) of the other one or more heat sources (30) is located at a position diverging from the virtual straight line (TL).

Description

Micro-object accumulation device and micro-object stirring device

[0001] The present disclosure relates to a micro-object accumulation device and a micro-object agitation device.

[0002] The micro-object accumulation device described in Patent Document 1 includes a substrate and a laser device. The substrate is plate-shaped. The substrate has a plurality of depressions on its surface. A liquid can be placed on the surface of the substrate. The laser device can irradiate the substrate with light from the back side, the side opposite the depressions. When the substrate is heated by the laser device, the heat of the substrate is transferred to the liquid. As a result, thermal convection occurs within the liquid. Furthermore, when the substrate is heated by the laser device, gas present inside the plurality of depressions is warmed and expands. Then, multiple expanded gases combine to form bubbles on the surface of the substrate. In areas surrounding these bubbles, the flow of liquid due to the thermal convection described above stagnates. Objects of several microns or less contained in the liquid accumulate in areas where the flow stagnates.

[0003] International Publication No. 2020 / 218347

[0004] In the micro-object accumulation device described in Patent Document 1, the size and amount of objects that can be accumulated depend on the size of bubbles that form on the surface of the substrate. The size of the bubbles depends on several factors, including the output of the laser device, the viscosity and temperature of the liquid, the amount of air dissolved in the liquid, the amount of gas contained in the depressions in the substrate, and the amount of objects dispersed in the liquid. Therefore, in the micro-object accumulation device described in Patent Document 1, it is difficult to precisely control the size and amount of objects that can be accumulated by controlling the size of the bubbles.

[0005] In order to solve the above problems, the present disclosure provides a micro-object accumulation device comprising a container having a bottom wall and side walls rising from the bottom wall, capable of storing a liquid containing micro-objects in a space partitioned by the bottom wall and the side walls, and three or more heat sources capable of heating the bottom wall, wherein when the center of the area heated by the heat sources is defined as the heating center, and an imaginary line is drawn passing through the heating centers of any two of the heating centers of the three or more heat sources, the heating center of one or more other heat sources is located at a location outside the imaginary line.

[0006] The present disclosure also provides a micro-object stirring device comprising a container having a bottom wall and side walls rising from the bottom wall, capable of storing a liquid containing micro-objects in a space partitioned by the bottom wall and the side walls, and three or more heat sources capable of heating the bottom wall, wherein when the center of the area heated by the heat sources is defined as the heating center, and an imaginary line is drawn passing through the heating centers of any two of the heating centers of the three or more heat sources, the heating center of one or more other heat sources is located at a location outside the imaginary line.

[0007] It is easier to collect larger objects than when using bubbles.

[0008] FIG. 1 is a perspective view of a micro-object accumulation device of a first embodiment. FIG. 2 is a top view of a micro-object accumulation device of the first embodiment. FIG. 3 is a side view of a micro-object accumulation device of the first embodiment. FIG. 4 is a top view of a micro-object accumulation device of a second embodiment. FIG. 5 is a side view of a micro-object accumulation device of the second embodiment. FIG. 6 is a top view of a micro-object accumulation device of a third embodiment. FIG. 7 is a side view of a micro-object accumulation device of the third embodiment. FIG. 8 is a top view of a micro-object accumulation device of a fourth embodiment. FIG. 9 is a side view of a micro-object accumulation device of the fourth embodiment. FIG. 10 is a top view of a micro-object accumulation device of a fifth embodiment. FIG. 11 is a side view of a micro-object accumulation device of the fifth embodiment. FIG. 12 is a top view of a micro-object accumulation device of a sixth embodiment. FIG. 13 is a side view of a micro-object accumulation device of the sixth embodiment. FIG. 14 is a side view of a micro-object accumulation device of a seventh embodiment.

[0009] Hereinafter, first, second, third, fourth, fifth, sixth, and seventh embodiments of the micro-object accumulation device will be described. Note that the drawings are schematic diagrams for ease of understanding, and some components may be enlarged or omitted. Therefore, the dimensional ratios of the components may differ from those of the actual components.

[0010] First Embodiment of Micro-Object Accumulation Apparatus (Overall Configuration) As shown in FIG. 1, a micro-object accumulation apparatus 10 includes a container 20 and three or more heat sources 30. The container 20 includes a heat source 30, which is a heat source for accumulating micro-objects.

[0011] The container 20 has a bottom wall 21 and a side wall 26. The bottom wall 21 is circular in a plan view. In the following, an axis that passes through the center of the bottom wall 21 in a plan view and is perpendicular to the bottom wall 21 is referred to as a central axis CA. One of the two surfaces of the bottom wall 21 that face in a direction along the central axis CA is referred to as a bottom surface BS. As will be described later, a space SP defined by the bottom wall 21 and the side wall 26 is located in the direction in which the bottom surface BS of the bottom wall 21 faces. The direction in which the space SP is located relative to the bottom wall 21, i.e., the direction in which the bottom surface BS faces, is referred to as an upward direction UD. The direction opposite to the upward direction UD is referred to as a downward direction DD.

[0012] As shown in FIG. 2 , the bottom wall 21 includes an outer peripheral portion 22, a transmission portion 23, a photothermal conversion portion 24, and a coating layer 25. The outer peripheral portion 22 has a circular shape centered on the central axis CA of the bottom wall 21 in a plan view when viewed in the downward direction DD. The outer peripheral portion 22 has a through-hole that penetrates in a direction along the central axis CA. The through-hole is located approximately in the center of the outer peripheral portion 22 in a plan view when viewed in the downward direction DD. In other words, the geometric center point of the through-hole is located on the central axis CA. The edge of the through-hole has an approximately square shape.

[0013] The transmitting portion 23 has a substantially square plate shape. The transmitting portion 23 is fitted tightly into the through-hole of the outer peripheral portion 22. The transmitting portion 23 is made of, for example, acrylic resin. That is, the transmitting portion 23 is capable of transmitting light.

[0014] The photothermal conversion unit 24 is a substantially square plate. The photothermal conversion unit 24 is tightly fitted into the through-hole of the outer peripheral portion 22. As shown in FIG. 3 , the photothermal conversion unit 24 is located on the upward direction UD side of the transmissive portion 23. The photothermal conversion unit 24 is also tightly superimposed on the transmissive portion 23. In the direction along the central axis CA of the bottom wall 21, the surface of the photothermal conversion unit 24 facing the upward direction UD is at the same position as the surface of the outer peripheral portion 22 facing the upward direction UD. In other words, the surface of the bottom wall 21 facing the upward direction UD, i.e., the bottom surface BS, is a flat surface without any clear steps. In other words, "flat" refers to a planar surface when ignoring minute irregularities and steps that can only be seen by magnifying and observing the bottom surface BS with a microscope, etc.

[0015] The photothermal conversion unit 24 includes a photothermal conversion material. The photothermal conversion material has the property of absorbing light of a specific wavelength and converting the light of that wavelength into heat. Specifically, the photothermal conversion material is metal nanoparticles, carbon nanotubes, graphene, a thin film of titanium nitride, or the like.

[0016] The coating layer 25 covers the surface of the photothermal conversion unit 24 on the upward UD side. The coating layer 25 is a chemical substance applied to the photothermal conversion unit 24. The chemical substance of the coating layer 25 has a higher affinity for a specific substance than the surface on the bottom surface BS side of the outer circumferential portion 22. In the first embodiment, the chemical substance is an antibody. That is, the coating layer 25 has a higher affinity for a specific protein that is an antigen. The coating layer 25 is an extremely thin layer compared to the thickness of the photothermal conversion unit 24, etc. Therefore, in FIG. 3, the coating layer 25 is designated by the same symbol as the photothermal conversion unit 24.

[0017] The side wall 26 is connected to the outer edge of the bottom wall 21. The side wall 26 rises from the bottom wall 21 in the upward direction UD. The side wall 26 is cylindrical and centered on the central axis CA of the bottom wall 21. Therefore, a liquid LQ containing micro-objects can be stored in the space SP partitioned by the bottom wall 21 and the side wall 26. The side wall 26 and the outer peripheral portion 22 of the bottom wall 21 are integrally molded. Furthermore, the micro-objects CE in this embodiment are, for example, eukaryotic cells.

[0018] Each heat source 30 is located on the downward direction DD side with respect to the bottom surface BS. In the first embodiment, there are eight heat sources 30. The eight heat sources 30 are fixed to the surface of the transmitting portion 23 on the downward direction DD side. The eight heat sources 30 are light sources capable of irradiating light onto the bottom wall 21 from the downward direction DD side with respect to the bottom wall 21. Specifically, the heat sources 30 are lasers or LEDs (Light Emitting Diodes).

[0019] Light emitted from each heat source 30 passes through the transmitting portion 23. The light that has passed through the transmitting portion 23 is irradiated onto the photothermal conversion portion 24. As described above, the photothermal conversion portion 24, which is the portion that is irradiated with light from the heat source 30, contains a photothermal conversion material. Therefore, the light that has passed through the transmitting portion 23 is converted into heat by the photothermal conversion portion 24. In this way, the positional relationship between the heat source 30, the transmitting portion 23, and the photothermal conversion portion 24 allows the heat source 30 to heat the bottom wall 21 of the container 20.

[0020] As shown in FIG. 3 , the micro-object accumulation device 10 includes a control unit 40. The control unit 40 is located outside the container 20. The control unit 40 can control whether or not light is emitted from each heat source 30, i.e., the on / off of each heat source 30. The control unit 40 can also control the energy output by each heat source 30. Specifically, the control unit 40 can control the light energy per unit time output by each heat source 30. The unit of this physical quantity is, for example, "J / s (Joules per second)." The control unit 40 can individually control each heat source 30.

[0021] (Regarding the Arrangement of Heat Sources) Next, the arrangement of the heat sources 30 will be described. Hereinafter, as shown in FIG. 2 , an axis that is parallel to the bottom wall 21 and that runs along one side of the photothermal conversion unit 24 will be referred to as the first horizontal axis X. An axis that is parallel to the bottom wall 21 and that is perpendicular to the first horizontal axis X will be referred to as the second horizontal axis Y. One of the directions along the first horizontal axis X will be referred to as the first positive direction X1. One of the directions along the first horizontal axis X that is opposite to the first positive direction X1 will be referred to as the first negative direction X2. One of the directions along the second horizontal axis Y will be referred to as the second positive direction Y1. One of the directions along the second horizontal axis Y that is opposite to the second positive direction Y1 will be referred to as the second negative direction Y2.

[0022] As shown in FIG. 2 , when the bottom surface BS is viewed from above in the upward direction UD, the eight heat sources 30 are aligned along each side of the square-shaped photothermal conversion unit 24. Specifically, when the eight heat sources 30 are designated as the first heat source 31 to the eighth heat source 38, the first heat source 31 is located on the first negative direction X2 side and the second positive direction Y1 side of the geometric center GC of the bottom wall 21. The "geometric center GC of the bottom wall 21" refers to the geometric center point of the bottom wall 21 when the bottom wall 21 is viewed from above facing the downward direction DD. The geometric center GC of the bottom wall 21 is also the geometric center GC of the bottom surface BS. In the first embodiment, the bottom surface BS is circular, and therefore the geometric center GC is the center of the circle.

[0023] The second heat source 32 is located on the first positive direction X1 side of the first heat source 31 and on the second positive direction Y1 side of the geometric center GC of the bottom wall 21. The third heat source 33 is located on the first positive direction X1 side of the second heat source 32. The third heat source 33 is located on the first positive direction X1 side and the second positive direction Y1 side of the geometric center GC of the bottom wall 21. The fourth heat source 34 is located on the second negative direction Y2 side of the first heat source 31 and on the first negative direction X2 side of the geometric center GC. The fifth heat source 35 is located on the second negative direction Y2 side of the third heat source 33 and on the first positive direction X1 side of the geometric center GC.

[0024] The sixth heat source 36 is located on the second negative direction Y2 side with respect to the fourth heat source 34. The sixth heat source 36 is located on the first negative direction X2 side and the second negative direction Y2 side with respect to the geometric center GC. The seventh heat source 37 is located on the first positive direction X1 side with respect to the sixth heat source 36 and the second negative direction Y2 side with respect to the geometric center GC. The eighth heat source 38 is located on the first positive direction X1 side with respect to the sixth heat source 36. The eighth heat source 38 is located on the first positive direction X1 side with respect to the geometric center GC and the second negative direction Y2 side.

[0025] Here, the center of the area heated by the heat source 30 is defined as the heating center HC. In the first embodiment, the heating center HC is the geometric center of the area of ​​the bottom wall 21 where light is irradiated from each heat source 30. Three or more heating centers HC are arranged on a circumference centered on the geometric center GC of the bottom wall 21. Specifically, the first heat source 31, the third heat source 33, the sixth heat source 36, and the eighth heat source 38 are arranged on the circumference of a first imaginary circle C1. The second heat source 32, the fourth heat source 34, the fifth heat source 35, and the seventh heat source 37 are arranged on the circumference of a second imaginary circle C2. In FIG. 2 , the first imaginary circle C1 and the second imaginary circle C2 are indicated by dashed lines.

[0026] Suppose an imaginary line TL is drawn that passes through the heating centers HC of any two of the three or more heat sources 30. At this time, the heating centers HC of one or more other heat sources 30 are located at positions that deviate from the imaginary line TL. For example, among the eight heat sources 30, with respect to the imaginary line TL that passes through the heating centers HC of the first heat source 31 and the third heat source 33, the heating centers HC of the fourth heat source 34 to the eighth heat source 38 are located at positions that deviate from the imaginary line TL.

[0027] Furthermore, the area surrounded by the heating centers HC when the bottom wall 21 is viewed in plan is defined as the specific area SA1. Specifically, first, an imaginary line segment SL is drawn that passes through the heating centers HC of any two of the heating centers HC of any three or more heat sources 30. Then, an imaginary line segment SL that passes through one of the heating centers HC of one of the endpoints of the imaginary line segment SL and the heating center HC of another heat source 30 is drawn so that different imaginary line segments SL do not intersect or overlap with each other. The area surrounded by the multiple imaginary line segments SL drawn in this way is defined as the specific area SA1.

[0028] In FIG. 2 , four imaginary line segments SL are illustrated by dashed lines as an example. Specifically, the imaginary line segment SL connecting the heating center HC of the first heat source 31 and the heating center HC of the third heat source 33 is illustrated. The imaginary line segment SL connecting the heating center HC of the third heat source 33 and the heating center HC of the eighth heat source 38 is illustrated. The imaginary line segment SL connecting the heating center HC of the eighth heat source 38 and the heating center HC of the sixth heat source 36 is illustrated. The imaginary line segment SL connecting the heating center HC of the sixth heat source 36 and the heating center HC of the first heat source 31 is illustrated. Therefore, in the first embodiment, the specific area SA1 surrounded by the heating centers HC of the first heat source 31 to the eighth heat source 38 is substantially square in plan view. Furthermore, the geometric center GC of the bottom wall 21 is located within the specific area SA1. Due to this positional relationship, a coating layer 25 having a higher affinity for a specific substance is located on the surface of the specific area SA1 facing the space SP compared to the surface outside the specific area SA1 facing the space SP.

[0029] (Regarding Operation of the First Embodiment) In the above embodiment, a liquid LQ containing micro-objects can be stored in the space SP defined by the bottom wall 21 and side wall 26 of the container 20. Light emitted from the eight heat sources 30 is converted into heat by the photothermal conversion unit 24. As a result, the portions of the bottom wall 21 that are irradiated with light are heated by the heat sources 30. Furthermore, when an imaginary line TL is drawn that passes through the heating centers HC of any two of the heating centers HC of the three or more heat sources 30, the heating centers HC of the other one or more heat sources 30 are located at locations that deviate from the imaginary line TL. In other words, there is a specific area SA1 that is surrounded by three or more heating centers HC.

[0030] The density of the liquid LQ heated by the heat sources 30 decreases. Therefore, the liquid LQ located near the portion of the bottom wall 21 where light from each heat source 30 is irradiated rises in the upward direction UD from the bottom wall 21 side toward the water surface. The liquid LQ located near the side wall 26 descends in the downward direction DD from the water surface side toward the bottom wall 21 side. Therefore, as shown by the arrows in FIG. 3 , thermal convection occurs in the liquid LQ within the container 20. Micro-objects CE contained in the liquid LQ move within the liquid LQ due to thermal convection. Specifically, in the liquid LQ near the side wall 26, i.e., in the portion where the liquid LQ descends, the micro-objects CE are transported from the water surface side toward the bottom wall 21 side. Next, the micro-objects CE are transported in the upward direction UD of the heat source 30, i.e., to the portion where the liquid LQ ascends. At this time, depending on the size and density of the minute objects CE, the force causing the minute objects CE to fall toward the bottom wall 21 due to gravity becomes greater than the force pushing the minute objects CE toward the water surface due to thermal convection. Therefore, minute objects CE of a specific size and density are accumulated in a specific area SA1 on the bottom wall 21. Furthermore, within the liquid LQ, the upward direction UD side of the specific area SA1 and near the bottom wall 21 are less susceptible to the flow of thermal convection. Therefore, minute objects CE carried within the liquid LQ by thermal convection tend to accumulate in the specific area SA1.

[0031] (Effects of the First Embodiment) (1-1) In the first embodiment described above, the heating centers HC of all heat sources 30 are not located on the same imaginary straight line TL. As a result, the bottom wall 21 of the container 20 has a specific area SA1 surrounded by three or more heating centers HC. As described above, minute objects CE carried within the liquid LQ by thermal convection tend to accumulate within the specific area SA1. In this series of accumulation processes of minute objects CE, the presence of air bubbles within the liquid LQ is unnecessary. Therefore, it is not necessary to control the size of the air bubbles generated within the liquid LQ, and there is no variation in the size of the minute objects CE that can be accumulated depending on the size of the air bubbles. In other words, minute objects CE of a specific size can be accumulated by simple control without the need for difficult control such as controlling the size of the air bubbles.

[0032] (1-2) In the first embodiment described above, the geometric center GC of the bottom wall 21 is located within the specific area SA1. Because the specific area SA1 is located near the geometric center GC of the bottom wall 21, the entire liquid LQ is likely to circulate due to thermal convection. Therefore, minute objects CE are likely to accumulate in the specific area SA1 contained in the liquid LQ.

[0033] (1-3) In the first embodiment described above, the three or more heat sources 30 are arranged on the circumference of a first imaginary circle C1 and a second imaginary circle C2, each having a center point at the geometric center GC. As a result, the flow of the liquid LQ due to thermal convection tends to be symmetrical with respect to the central axis CA of the bottom wall 21. In other words, since the liquid LQ circulates more easily within the container 20, minute objects CE tend to accumulate more easily within the specific area SA1.

[0034] (1-4) In the first embodiment described above, the bottom surface BS is a flat surface. That is, the surface of the bottom wall 21 facing the upward direction UD is a flat surface, and the heat source 30 is located below the bottom surface BS. If the heat source 30 were located above the bottom surface BS in the upward direction UD, there is a risk that the circulated liquid LQ would collide with the heat source 30, thereby hindering the circulation of the liquid LQ due to thermal convection. With the above configuration, such an effect can be prevented.

[0035] (1-5) In the first embodiment, the heat source 30 is a light source capable of irradiating the bottom wall 21 with light from the downward direction DD. The portion of the bottom wall 21 that is irradiated with light from the heat source 30 contains a photothermal conversion material. Because the heat source 30 is a light source, it is easy to control the spot diameter of the light. In other words, it is easy to control the range and position of the area that can be heated by one heat source 30.

[0036] Furthermore, since the bottom wall 21 contains a photothermal conversion material, light is more easily converted into heat, thereby increasing the efficiency of converting the light energy output by the heat source 30 into heat compared to when the bottom wall 21 does not have the photothermal conversion section 24.

[0037] (1-6) In the first embodiment, the micro-object accumulation device 10 has a control unit 40 that can control the energy output by the heat source 30. This makes it possible to adjust the viscosity and buoyancy of the liquid LQ when generating thermal convection, depending on the size of the micro-object CE, etc.

[0038] (1-7) In the first embodiment, the minute object accumulation device 10 has a coating layer 25. By coating with a substance that has a high affinity for the minute objects CE, the minute objects CE are more likely to remain in the specific area SA1.

[0039] (1-8) In the first embodiment described above, the side wall 26 is cylindrical. That is, the bottom surface BS is circular. If the bottom surface BS is polygonal, the flow of the liquid LQ is likely to stagnate at the corners near the vertices of the polygon. That is, there is a risk that minute objects CE may stagnate at the corners of the polygonal shape. With the above configuration, such a situation can be prevented, and the liquid LQ is more likely to circulate within the container 20.

[0040] (1-9) In the first embodiment described above, the locations where minute objects CE accumulate are locations where thermal convection currents collide. Therefore, the minute objects CE accumulate in a relatively large area, rather than in a limited area such as around a bubble in the liquid LQ. Therefore, depending on the physical properties of the liquid LQ and the light energy from the heat source 30, it is also possible to accumulate relatively large minute objects CE of several tens of μm or more.

[0041] <Second embodiment of micro-object accumulation device> Next, a second embodiment of the micro-object accumulation device will be described. The micro-object accumulation device 100 according to the second embodiment further comprises a cooling unit CS compared to the micro-object accumulation device 10 according to the first embodiment. The arrangement of each heat source 30 is also different. In the following, among the components of the micro-object accumulation device 100 according to the second embodiment, the same components as those in the first embodiment will be assigned the same reference numerals and will not be described again.

[0042] 4, in the micro-object accumulation device 100 according to the second embodiment, the first heat source 31 to the eighth heat source 38 are all located on the circumference of a third imaginary circle C3 whose center is the geometric center GC of the bottom wall 21. Specifically, the heat sources 30 are arranged so that when the heating centers HC of the heat sources 30 are connected so that all the imaginary line segments SL are the shortest distance, the shape of the specific area SA2 is a substantially regular octagon.

[0043] Therefore, also in the second embodiment, when an imaginary line TL is drawn that passes through the heating centers HC of any two of the heating centers HC of the three or more heat sources 30, the heating centers HC of one or more other heat sources 30 are located at positions that deviate from the imaginary line TL. For example, with respect to the imaginary line TL that passes through the heating centers HC of the first heat source 31 and the heating centers HC of the second heat source 32, the heating centers HC of the third heat source 33 to the eighth heat source 38 are located at positions that deviate from the imaginary line TL.

[0044] 5, each heat source 30 is embedded inside the bottom wall 21, specifically inside the photothermal conversion section 24. Therefore, the micro-object accumulation device 100 according to the second embodiment does not include the transmission section 23.

[0045] The micro-object accumulation device 100 according to the second embodiment is equipped with four cooling units CS. The cooling units CS are capable of cooling the bottom wall 21. Specifically, the cooling units CS are Peltier elements. When the bottom wall 21 is viewed in a plan view from the upward direction UD, the cooling units CS are located outside the specific area SA2. In other words, when viewed in a plan view, the cooling units CS are located in locations that are not surrounded by any specific area SA2. Specifically, the four cooling units CS are located on the first positive direction X1 side, the first negative direction X2 side, the second positive direction Y1 side, and the second negative direction Y2 side, respectively, relative to the geometric center GC of the bottom wall 21.

[0046] (Effects of the Second Embodiment) According to the second embodiment, in addition to the effects (1-1) to (1-8) of the first embodiment, the following effects can be obtained.

[0047] (2-1) In the second embodiment described above, the minute object accumulation device 100 is equipped with a cooling unit CS. The cooling unit CS is located outside the specific area SA2. This increases the temperature difference between the part of the liquid LQ that is heated by the heat source 30 and the part that is cooled by the cooling unit CS. This makes it easier for thermal convection to occur within the liquid LQ. Therefore, it is easier for minute objects CE to accumulate in the specific area SA2.

[0048] <Third Embodiment of Micro-Object Stacking Device> Next, a third embodiment of a micro-object Stacking device will be described. In a micro-object Stacking device 200 according to the third embodiment, the bottom wall 221 is provided with a recess R, unlike the micro-object Stacking device 10 according to the first embodiment. Also, the arrangement of each heat source 30 relative to the bottom wall 221 is different. In the following, among the components of the micro-object Stacking device 200 according to the third embodiment, the same components as those in the first embodiment will be assigned the same reference numerals and will not be described again.

[0049] In the third embodiment, when an imaginary straight line TL is drawn passing through the heating centers HC of any two of the heating centers HC of three or more heat sources 30, the heating centers HC of one or more other heat sources 30 are located at locations that are off the imaginary straight line TL.

[0050] As shown in Fig. 6, in the micro-object accumulation device 200 according to the third embodiment, the bottom wall 221 has a recess R recessed in the downward direction DD relative to the space SP within a specific area SA3 of the bottom wall 221. The outer edge shape of the recess R is approximately square. In a plan view looking toward the downward direction DD, the center of the outer edge shape of the recess R approximately coincides with the geometric center GC of the bottom wall 221. Furthermore, as shown in Fig. 7, the recess R is recessed in a rectangular shape in a cross-sectional view along the central axis CA of the bottom wall 221.

[0051] In the micro-object accumulation device 200 according to the third embodiment, each heat source 30 is installed on the surface of the bottom wall 221 on the upward direction UD side. Each heat source 30 is also located near the outer edge of the recess R. Therefore, in the third embodiment, the bottom wall 221 does not have either the transmitting portion 23 or the photothermal conversion portion 24.

[0052] (Effects of the Third Embodiment) According to the third embodiment, in addition to the effects (1-1) to (1-3) and (1-6) to (1-8) of the first embodiment, the following effects can be obtained.

[0053] (3-1) In the third embodiment, the bottom wall 221 has a recess R within the specific area SA3. This makes it easier for minute objects CE carried in the upward direction UD of the specific area SA3 to fall and enter the recess R. Because the effect of thermal convection is small inside the recess R, minute objects CE that have entered the recess R are less likely to move out of the recess R. This makes it easier for minute objects CE to accumulate.

[0054] <Fourth embodiment of micro-object accumulation device> (Overall configuration) Next, a fourth embodiment of a micro-object accumulation device will be described. In a micro-object accumulation device 300 according to the fourth embodiment, the bottom wall 321 is provided with a hole R2, unlike the micro-object accumulation device 10 according to the first embodiment. The micro-object accumulation device 300 also includes a first electrode 110 and a second electrode 120. In the following, among the configuration of the micro-object accumulation device 300 according to the fourth embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted.

[0055] In the fourth embodiment, when an imaginary straight line TL is drawn passing through the heating centers HC of any two of the heating centers HC of three or more heat sources 30, the heating centers HC of one or more other heat sources 30 are located at locations that are off the imaginary straight line TL.

[0056] As shown in Figure 9, in the micro-object accumulation device 300 according to the fourth embodiment, the bottom wall 321 has a hole R2 penetrating from the surface of the bottom wall 321 on the downward direction DD side to the surface on the upward direction UD side. As shown in Figure 8, the outer edge shape of the hole R2 is approximately square. In a plan view looking toward the upward direction UD side, the center of the outer edge shape of the hole R2 approximately coincides with the geometric center GC of the bottom wall 321. A transmitting portion 23 is fitted tightly inside the hole R2. The material of the transmitting portion 23 is the same as in the first embodiment.

[0057] As shown in Figure 8, the micro-object collecting device 300 according to the fourth embodiment has four heat sources 30. Specifically, the micro-object collecting device 300 has a first heat source 31, a third heat source 33, a sixth heat source 36, and an eighth heat source 38. In the micro-object collecting device 300 according to the fourth embodiment, each heat source 30 is fixed to the surface of the transmitting section 23 on the downward direction DD side. The arrangement of each heat source 30 is the same as in the first embodiment.

[0058] 8 , the bottom wall 321 includes a first electrode 110 and a second electrode 120. The first electrode 110 has a first base portion 111, a first support portion 112, and a first end portion 113.

[0059] The first base portion 111 has a substantially rectangular parallelepiped shape. The first base portion 111 is located on the outer edge of the bottom wall 321. The first base portion 111 is located on the first positive direction X1 side with respect to the geometric center GC. The first base portion 111 is embedded inside the container 20.

[0060] The first base 111 is connected to a DC power supply (not shown) located outside the container 20. More specifically, the first base 111 is connected to the positive electrode of the DC electrode. That is, a positive voltage from the DC power supply can be applied to the first electrode 110. The inter-terminal voltage applied from the DC power supply is, for example, about several mV to several hundred mV.

[0061] The first support portion 112 is strip-shaped. A first end of the first support portion 112 is connected to the first base portion 111. The first support portion 112 extends from the first base portion 111 toward the geometric center GC. The first support portion 112 constitutes a portion of the bottom wall 321 on the bottom surface BS side. A portion of the first support portion 112 on the geometric center GC side is attached to a surface of the transmitting portion 23 facing the upward direction UD. The surface of the first support portion 112 on the upward direction UD side is exposed to the space SP.

[0062] The first end 113 is disk-shaped. In other words, the main surface of the first end 113 is circular. Note that the main surface here refers to the flat surface with the largest area among the outer surfaces of a plate-shaped object. The diameter of the main surface of the first end 113 is shorter than the length of one side of the square that constitutes the specific area SA1. Furthermore, the center of the circle of the first end 113 coincides with the geometric center GC.

[0063] The outer peripheral edge of the first end 113 is connected to a second end of the first support portion 112, which is the opposite end to the first end connected to the first base portion 111. The first end 113 is attached to a surface of the transmitting portion 23 facing the upward direction UD. Therefore, the direction in which one of the main surfaces of the first end 113 faces coincides with the direction in which the bottom surface BS faces. The surface of the first support portion 112 facing the upward direction UD is exposed to the space SP.

[0064] The first end 113 contains a photothermal conversion material. As described above, the first end 113 is attached to the surface of the transmitting portion 23 facing the upward direction UD. In other words, the first end 113 has a portion that is irradiated with light from the heat source 30. Therefore, the first end 113 also functions as a photothermal conversion portion.

[0065] 9 , in the direction along the central axis CA of the bottom wall 321, the surfaces of the first support portion 112 and the first end portion 113 facing in the upward direction UD are at the same position as the surface of the outer circumferential portion 22 facing in the upward direction UD. In other words, the surfaces of the first support portion 112 and the first end portion 113 facing in the upward direction UD are flush with the surface of the outer circumferential portion 22 facing in the upward direction UD, and there is no clear step between them.

[0066] 8 , the second electrode 120 has a second base 121, a second support 122, and a second end 123. The second base 121 has a substantially rectangular parallelepiped shape. The second base 121 is located at a location on the outer edge of the bottom wall 321, away from the first base 111. The second base 121 is embedded inside the container 20. In this embodiment, the second base 121 is located on the opposite side of the geometric center GC from the first base 111.

[0067] The second base 121 is connected to a DC power supply (not shown) that is located outside the container 20. More specifically, the second base 121 is connected to the negative electrode of the DC electrode. That is, a negative voltage from the DC power supply can be applied to the second electrode 120.

[0068] The second support portion 122 is strip-shaped. A first end of the second support portion 122 is connected to the second base portion 121. The second support portion 122 extends from the second base portion 121 toward the geometric center GC. The second support portion 122 forms a part of the bottom wall 321 on the bottom surface BS side. In other words, the surface of the second support portion 122 on the upward direction UD side is exposed to the space SP.

[0069] The second end 123 has an overall annular shape in a plan view. Specifically, the outer diameter of the second end 123 is smaller than the inner diameter of the side wall 26. The inner diameter of the second end 123 is larger than the outer diameter of the first end 113 of the first electrode 110. The center of the outer diameter and the center of the inner diameter of the second end 123 coincide with the geometric center GC. Therefore, the first end 113 of the first electrode 110 is located in a region inside the inner periphery of the second end 123.

[0070] The second end portion 123 also has a slit 123A. The slit 123A extends from the end of the inner peripheral edge of the second end portion 123 on the first positive direction X1 side toward the first positive direction X1 side and reaches the outer peripheral edge of the second end portion 123. The width of the slit 123A is larger than the width of the first support portion 112 of the first electrode 110. The first support portion 112 of the first electrode 110 is located in the portion of the slit 123A.

[0071] The outer peripheral edge of the second end 123 is connected to the second end of the second support portion 122, which is opposite the first end connected to the second base portion 121. The second end 123 forms a part of the bottom wall 321 on the bottom surface BS side in an area where the first electrode 110 is not present. A part of the second end 123, including the inner peripheral edge, is attached to a surface of the transmissive portion 23 facing the upward direction UD. Therefore, the direction in which one of the main surfaces of the second end 123 faces coincides with the direction in which the bottom surface BS faces. The surface of the second electrode 120 facing the upward direction UD is exposed to the space SP.

[0072] The second end 123 contains a photothermal conversion material. As described above, the second end 123 has a portion attached to the surface of the transmitting portion 23 facing the upward direction UD. In other words, the second end 123 has a portion that is irradiated with light from the heat source 30. Therefore, a portion of the second end 123 also functions as a photothermal conversion portion.

[0073] 9 , in the direction along the central axis CA of the bottom wall 321, the surfaces of the second support portion 122 and the second end portion 123 facing in the upward direction UD are at the same position as the surface of the outer circumferential portion 22 facing in the upward direction UD. In other words, the surfaces of the second support portion 122 and the second end portion 123 facing in the upward direction UD are flush with the surface of the outer circumferential portion 22 facing in the upward direction UD, and there is no clear step between them.

[0074] (Effects of the Fourth Embodiment) According to the fourth embodiment, in addition to the effects (1-1) to (1-8) of the first embodiment, the following effects can be obtained.

[0075] (4-1) In the fourth embodiment, the micro-object assembly device 300 has a first electrode 110 and a second electrode 120. The first electrode 110 can receive a positive voltage from a DC power supply, while the second electrode 120 can receive a negative voltage from a DC power supply.

[0076] Here, let us assume that the micro-object CE is a eukaryotic cell or a bacterium. The surfaces of eukaryotic cells and bacteria are often negatively charged. This makes the micro-object CE more likely to be attracted to the positively charged first electrode 110. On the other hand, the micro-object CE is less likely to be attracted to the negatively charged second electrode 120. Furthermore, the first end 113 of the first electrode 110 is located inside the specific area SA1 in a planar view.

[0077] Therefore, in addition to the circulation of the liquid LQ due to thermal convection, the minute objects CE can be accumulated in the specific area SA1 due to electrical interaction. In other words, the minute objects CE can be efficiently accumulated in the specific area SA1.

[0078] (4-2) In the fourth embodiment, the first end 113 of the first electrode 110 and the second end 123 of the second electrode 120 contain a photothermal conversion material. Furthermore, the first end 113 and the second end 123 are attached to portions of the bottom wall 321 that are irradiated with light from the heat source 30. That is, the areas of the first end 113 and the second end 123 that are irradiated with the heat source 30 also function as photothermal conversion units. Therefore, it is not necessary to separately provide the photothermal conversion unit 24, the first end 113, and the second end 123 on the bottom wall 321. Therefore, the micro-object accumulation device 300 according to the fourth embodiment can be manufactured without a complex design.

[0079] <Fifth embodiment of micro-object accumulation device> (Overall configuration) Next, a fifth embodiment of a micro-object accumulation device will be described. In a micro-object accumulation device 400 according to the fifth embodiment, the shapes and arrangement of the first electrode 110 and the second electrode 120 are different from those of the micro-object accumulation device 300 according to the fourth embodiment. Furthermore, in the following, among the configurations of the micro-object accumulation device 400 according to the fifth embodiment, the same components as those in the first embodiment are assigned the same reference numerals and their description will be omitted.

[0080] In the fifth embodiment, when an imaginary straight line TL is drawn passing through the heating centers HC of any two of the heating centers HC of three or more heat sources 30, the heating centers HC of one or more other heat sources 30 are located at locations that are off the imaginary straight line TL.

[0081] 10 , the first end 113 of the first electrode 110 is disk-shaped. The diameter of the first end 113 is slightly smaller than the inner diameter of the side wall 26. The center of the circle of the first end 113 coincides with the geometric center GC. The first end 113 is attached to a surface of the bottom wall 421 facing the upward direction UD and a surface of the transmissive portion 23 facing the upward direction UD. Therefore, in this embodiment, the surface of the first end 113 facing the upward direction UD occupies most of the bottom surface BS. The surface of the first end 113 facing the upward direction UD is exposed to the space SP.

[0082] The second end 123 of the second electrode 120 is cylindrical. The outer diameter of the second end 123 is approximately the same as the inner diameter of the side wall 26. As shown in FIG. 11 , the second end 123 is attached to the surface of the side wall 26 on the space SP side. When viewed in the downward direction DD, the second end 123 does not overlap with the first electrode 110. Therefore, the second electrode 120 and the first electrode 110 are disposed in different positions.

[0083] (Regarding the Effects of the Fifth Embodiment) According to the fifth embodiment, in addition to the effects (1-1) to (1-8) of the first embodiment and the effects (4-1) and (4-2) of the fourth embodiment, the following effects can be obtained.

[0084] (5-1) In the fifth embodiment, the second end 123 of the second electrode 120 is attached to the surface of the side wall 26 facing the space SP, while the first end 113 of the first electrode 110 is attached to the bottom wall 421. In this case, minute objects CE that are electrically repelled from the second end 123 move toward the first end 113. That is, the electrical repulsive force generated between the second end 123 and the minute objects CE also contributes to accumulating the minute objects CE toward the first end 113. Therefore, the efficiency of accumulating the minute objects CE toward the first end 113 can be improved.

[0085] <Sixth Embodiment of Micro-Object Stacking Device> Next, a sixth embodiment of a micro-object Stacking device will be described. In a micro-object Stacking device 500 according to the sixth embodiment, the shape and arrangement of the first electrode 110 and the second electrode 120 are different from those of the micro-object Stacking device 300 according to the fourth embodiment. The micro-object Stacking device 500 also has the same photothermal conversion unit 24 as in the first embodiment. In the following, the same components of the micro-object Stacking device 500 according to the sixth embodiment as those in the fourth embodiment will be assigned the same reference numerals and will not be described again.

[0086] In the sixth embodiment, when an imaginary straight line TL is drawn passing through the heating centers HC of any two of the heating centers HC of three or more heat sources 30, the heating centers HC of one or more other heat sources 30 are located at locations that are off the imaginary straight line TL.

[0087] As shown in FIG. 12 , the first end 113 of the first electrode 110 is semi-cylindrical. The semi-cylinder here refers to a shape obtained by dividing a cylinder into two halves along a plane including the central axis. The outer diameter of the first end 113 is approximately the same as the inner diameter of the side wall 26. As shown in FIG. 13 , the first end 113 is attached to the surface of the side wall 26 on the space SP side. In this embodiment, the first end 113 extends over approximately 180 degrees in the circumferential direction around the central axis CA on the side closer to the first base 111. The first end 113 is removable from the micro-object accumulation device 500. That is, the first electrode 110 is separable from the container 20.

[0088] The second end 123 of the second electrode 120 is semi-cylindrical. The outer diameter of the second end 123 is approximately the same as the inner diameter of the side wall 26. As shown in FIG. 13 , the second end 123 is attached to the surface of the side wall 26 facing the space SP. In this embodiment, the second end 123 extends over approximately 180 degrees on the side closer to the second base 121 in the circumferential direction around the central axis CA. The second end 123 is not in direct contact with the first end 113. Therefore, the second electrode 120 is attached to a location on the surface of the side wall 26 facing the space SP, different from the location where the first electrode 110 is located.

[0089] 13 , the length of the second end 123 in the direction of the central axis CA is substantially the same as the length of the first end 113 in the direction of the central axis CA. Furthermore, the position of the second end 123 in the direction of the central axis CA is substantially the same as the position of the first end 113 in the direction of the central axis CA. In other words, the first electrode 110 and the second electrode 120 face each other. More specifically, substantially the entire first end 113 faces the second end 123.

[0090] As shown in FIG. 12 , the bottom wall 521 of the micro-object accumulation device 500 has a photothermal conversion unit 24. In this embodiment, the photothermal conversion unit 24 is disk-shaped. The diameter of the photothermal conversion unit 24 is slightly smaller than the diameter of the bottom surface BS. The geometric center of the photothermal conversion unit 24 coincides with the geometric center GC of the bottom wall 521. The photothermal conversion unit 24 forms part of the bottom surface BS of the bottom wall 521. Furthermore, the central portion of the photothermal conversion unit 24 is attached to the surface of the transmitting portion 23 facing the upward direction UD. Therefore, in this embodiment, the surface of the photothermal conversion unit 24 facing the upward direction UD occupies most of the bottom surface BS. Furthermore, the surface of the photothermal conversion unit 24 facing the upward direction UD is exposed to the space SP.

[0091] (Regarding the Effects of the Sixth Embodiment) According to the sixth embodiment, in addition to the effects (1-1) to (1-8) of the first embodiment and the effects (4-1) and (4-2) of the fourth embodiment, the following effects can be obtained.

[0092] (6-1) If the density of the minute objects CE is lower than the density of the liquid LQ, it is not easy to accumulate the minute objects CE on the bottom wall 521. If the minute objects CE are attracted to the bottom wall 521 against the buoyancy of the minute objects CE, a high voltage may be required. In particular, if the minute objects CE are eukaryotic cells or bacteria, the eukaryotic cells or bacteria may be damaged by the high voltage.

[0093] In contrast to this, in the sixth embodiment, the first end 113 of the first electrode 110 is attached along the inner circumferential surface of the side wall 26. This means that, for example, a voltage high enough to attract minute objects CE near the water surface to the bottom wall 521 is not required. Therefore, minute objects CE can be accumulated at the first end 113 without requiring an excessively high voltage to the minute objects CE. Note that in Figures 12 and 13, only some of the multiple minute objects CE are labeled with symbols.

[0094] (6-2) Regarding the arrangement of the first electrode 110 and the second electrode 120, it is also possible to attach the first end 113 of the first electrode 110 to the side wall 26 and the second end 123 of the second electrode 120 to the bottom wall 521. However, if the density of the minute objects CE is lower than the density of the liquid LQ, the buoyancy of the minute objects CE prevents them from approaching the second end 123 on the bottom wall 521. Therefore, the repulsive force between the minute objects CE and the second end 123 makes almost no contribution to accumulating the minute objects CE on the first electrode 110.

[0095] In contrast to this, in the sixth embodiment, the surface of the side wall 26 on the side of the space SP is divided into two. The first end 113 is attached to one surface, and the second end 123 is attached to the other surface. In this way, minute objects CE that flow toward the first end 113 are adsorbed. On the other hand, minute objects CE that flow toward the second end 123 are directed toward the first end 113 due to the repulsive force with the second end 123. Therefore, the efficiency of accumulating minute objects CE at the first end 113 can be improved.

[0096] (6-3) In the sixth embodiment, the first end 113 of the first electrode 110 is detachable from the container 20. Therefore, the minute objects CE accumulated at the first end 113 can be easily removed from the liquid LQ.

[0097] <Seventh embodiment of micro-object accumulation device> Next, a seventh embodiment of a micro-object accumulation device will be described. A micro-object accumulation device 600 according to the seventh embodiment differs from the micro-object accumulation device 10 according to the first embodiment in the configuration of the bottom wall 210. In the following, among the configurations of the micro-object accumulation device 600 according to the seventh embodiment, the same components as those in the first embodiment will be assigned the same reference numerals and will not be described again.

[0098] In the seventh embodiment, when an imaginary straight line TL is drawn passing through the heating centers HC of any two of the heating centers HC of three or more heat sources 30, the heating centers HC of one or more other heat sources 30 are located at locations that are off the imaginary straight line TL.

[0099] 14, the container 20 of the micro-object collecting device 600 has a bottom wall 210 and a side wall 26. Furthermore, the bottom wall 210 has a bottom wall main body 211, a coating layer 205, a support plate 203, and a photothermal conversion unit 204.

[0100] The bottom wall main body 211 is plate-shaped. The bottom wall main body 211 is circular in plan view. The surface of the bottom wall main body 211 facing the upward direction UD, i.e., the bottom surface BS, is a flat surface without any clear steps.

[0101] The coating layer 205 covers a portion of the surface of the bottom wall main body 211 facing in the upward direction UD. More specifically, the coating layer 205 covers a central portion of the surface of the bottom wall main body 211 facing in the upward direction UD. The material, etc. of the coating layer 205 is the same as that of the micro-object accumulation device 10 of the first embodiment. The coating layer 205 is an extremely thin layer compared to the thickness of the bottom wall main body 211, etc. Therefore, in Figure 14, the coating layer 205 is given the same symbol as the bottom wall main body 211, assuming that it is the same as the bottom wall main body 211.

[0102] The support plate 203 is plate-shaped. In plan view, the support plate 203 has a circular shape with the same dimensions as the bottom wall main body 211. The support plate 203 is made of, for example, acrylic resin. That is, the support plate 203 is light-transmitting.

[0103] The photothermal conversion unit 204 is plate-shaped. In plan view, the photothermal conversion unit 204 is circular and has the same dimensions as the support plate 203. The photothermal conversion unit 204 is attached to one main surface of the support plate 203. The photothermal conversion unit 204 cannot be separated from the support plate 203. The photothermal conversion unit 204 contains a photothermal conversion material. The photothermal conversion material is the same as that of the micro-object accumulation device 10 of the first embodiment.

[0104] The photothermal conversion unit 204 and the support plate 203 are detachably attached to the bottom wall main body 211 from the downward direction DD. Note that in Figure 14, the photothermal conversion unit 204 and the support plate 203 in a state removed from the bottom wall main body 211 are shown imaginary by two-dot chain lines. When attached to the bottom wall main body 211, the photothermal conversion unit 204 is located on the upward direction UD side, and the support plate 203 is located on the downward direction DD side. The surface of the photothermal conversion unit 204 facing the upward direction UD is in contact with the surface of the bottom wall main body 211 facing the downward direction DD. Note that "the photothermal conversion unit 204 is detachable from the downward direction DD from the bottom wall main body 211" here means that the photothermal conversion unit 204 and the bottom wall main body 211 can be attached and detached without irreversible deformation or damage. Furthermore, the state in which the photothermal conversion unit 204 is attached to the bottom wall main body 211 does not only mean that the two are completely fixed so as to be unable to move relative to each other, but also means that the positional relationship between the two is maintained when the micro-object accumulation device 600 is left stationary. Therefore, the state in which the bottom wall main body 211 is placed on the photothermal conversion unit 204 can also be included in the state in which the photothermal conversion unit 204 is attached to the bottom wall main body 211.

[0105] The side wall 26 is connected to the outer edge of the bottom wall main body 211. The side wall 26 rises in the upward direction UD from the bottom wall main body 211. The side wall 26 is cylindrical and has its center on the central axis CA of the bottom wall 21. Therefore, a liquid LQ containing minute objects can be stored in the space SP defined by the bottom wall main body 211 and the side wall 26. The side wall 26 and the bottom wall main body 211 are integrally molded.

[0106] The micro-object accumulation device 600 includes three or more heat sources 30, more specifically, the first heat source 31 to the eighth heat source 38. The first heat source 31 to the eighth heat source 38 are fixed to the surface of the support plate 203 on the downward direction DD side. Note that FIG. 14 illustrates only three heat sources 30, specifically, the second heat source 32, the fourth heat source 34, and the fifth heat source 35. The arrangement of the first heat source 31 to the eighth heat source 38 on the surface of the support plate 203 on the downward direction DD side is the same as that of the micro-object accumulation device 10 of the first embodiment. That is, when attached to the bottom wall main body 211, the first heat source 31 to the eighth heat source 38 are arranged to surround a point on the central axis CA of the support plate 203. Note that the control unit 40 is not shown in FIG. 14.

[0107] Light emitted from each heat source 30 passes through the support plate 203. The light that has passed through the support plate 203 is irradiated onto the photothermal conversion section 204. As described above, the photothermal conversion section 204, which is the portion that is irradiated with light from the heat source 30, contains a photothermal conversion material. Therefore, the light that has passed through the support plate 203 is converted into heat by the photothermal conversion section 204. The heat from the portion of the photothermal conversion section 204 that is irradiated with light is transferred to the bottom wall main body 211 that is in contact with the photothermal conversion section 204. In this way, the heat source 30 can heat the bottom wall main body 211 of the bottom wall 210 of the container 20.

[0108] (Effects of the Seventh Embodiment) According to the seventh embodiment, in addition to the effects (1-1) to (1-9) of the first embodiment, the following effects can be obtained.

[0109] (7-1) In the seventh embodiment, the photothermal conversion unit 204 and the support plate 203 are detachable from the bottom wall main body 211 from the downward direction DD. Therefore, a single set of photothermal conversion unit 204 and support plate 203 can be shared by multiple containers 20 that do not have the photothermal conversion unit 204 and support plate 203. Furthermore, even a container 20 that does not have the photothermal conversion unit 204 and support plate 203 can store liquid or the like in the space SP. Therefore, when micro-objects are not being accumulated, part of the container 20 can be removed from the photothermal conversion unit 204 and support plate 203, and the container 20 can be operated with no wiring or the like connected.

[0110] <Modifications> The first to seventh embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0111] The shapes of the bottom wall 21 and the side walls 26 are not limited to those of the above embodiment. For example, the bottom wall 21 may be rectangular, and the side walls 26 may be rectangular tubular with four sides. Furthermore, the side walls 26 do not have to be cylindrical, and may be recesses or the like provided on a substrate.

[0112] The container 20 may be a single well of a microplate. That is, a plurality of side walls 26 may extend from a single bottom wall 21 at different positions, and one of the side walls 26 may be the container 20.

[0113] In the first embodiment, the shapes of the transmission sections 23 and the photothermal conversion sections 24 do not have to be square. For example, a plurality of transmission sections 23 and a plurality of photothermal conversion sections 24 may be provided in one-to-one correspondence with each heat source 30.

[0114] The chemical substance applied as the coating layer 25 is not limited to the example of the first embodiment. For example, the chemical substance may be a protein coating. That is, a protein that promotes intercellular adhesion may be applied as the coating layer 25. Alternatively, the bottom surface BS may be subjected to plasma treatment to form the coating layer 25. That is, the presence of functional groups such as hydroxyl groups or carboxyl groups on the bottom surface BS improves the hydrophilicity of the bottom surface BS. The coating layer 25 may also contain a silane coupling agent. The presence of functional groups such as amino groups or epoxy groups on the bottom surface BS improves the hydrophilicity of the bottom surface BS. Coating the coating layer 25 with these chemical substances makes it easier for cells, as micro-objects CE, to adhere to the specific area SA1. The micro-object accumulation device 10 does not necessarily have to include the coating layer 25.

[0115] The heat source 30 is not limited to the light source exemplified in the above embodiment. In other words, the heat source 30 is not limited to a laser or an LED, and may be another type of light source. For example, the heat source 30 may be an electric heater that generates heat when electricity is applied. Note that, when the size of the minute objects CE to be accumulated is small, it is preferable that the heat source 30 be one that can locally heat a relatively narrow area of ​​several millimeters square. Furthermore, the types of heat sources 30 may be different, and for example, the heat source 30 may include both a laser and an LED.

[0116] The heat source 30 does not have to be fixed to the bottom wall 21. For example, in the first embodiment, the heat source 30 does not have to be fixed to the downward direction DD side of the container 20. Also, for example, another container 20 capable of transferring heat may be fitted into the space SP of the container 20 of the first embodiment. Then, the fitted container 20 may store the liquid LQ containing the minute objects CE. This makes it possible to suppress contamination of the liquid LQ as a container 20.

[0117] In the above embodiments, the control unit 40 does not have to be able to control the energy output by each heat source 30. Furthermore, the micro object accumulation device 10 does not have to be equipped with a control unit 40. In each of the above embodiments, the number of heat sources 30 may be seven or less, or nine or more, as long as it is three or more. Furthermore, the shape of the heat source 30 does not have to be circular in plan view. For example, the shape of the heat source 30 may be rod-shaped. Even in this case, the heating center HC of the heat source 30 can be identified.

[0118] The arrangement of the heat sources 30 is not limited to the examples in the above embodiments. For example, the heat sources 30 may be arranged so that the geometric center GC of the bottom wall 21 is located outside the specific area SA1. Furthermore, none of the heat sources 30 may be arranged on a circumference with the geometric center GC as the center point.

[0119] The shape of the specific area SA1 is not limited to the example in the above embodiment. For example, the specific area SA1 may be an isosceles triangular area surrounded by the second heat source 32, the sixth heat source 36, and the eighth heat source 38. For example, in the first embodiment, assume that the second heat source 32, the sixth heat source 36, and the eighth heat source 38 are controlled to emit light, and the first heat source 31, the third heat source 33, the fourth heat source 34, the fifth heat source 35, and the seventh heat source 37 are controlled not to emit light. In this case, the specific area SA1 is likely to accumulate in the isosceles triangular area surrounded by the second heat source 32, the sixth heat source 36, and the eighth heat source 38.

[0120] In the second embodiment, the cooling unit CS does not have to be a Peltier element. For example, the cooling unit CS may be a cooling fan or a coolant. In the third embodiment, the shape and size of the recess R are not limited to those of the embodiment. For example, the size of the recess R may be larger than the specific area SA3 in a plan view. The same applies to the hole R2 in the fourth embodiment.

[0121] In the fourth embodiment, the shapes of the first electrode 110 and the second electrode 120 are not limited to those of the above-described embodiments. For example, the shape of the main surface of the first end 113 of the first electrode 110 does not have to be circular. Accordingly, the shape of the second end 123 of the second electrode 120 may be different. Furthermore, the diameter of the main surface of the first end 113 may be longer than the length of one side of the square that constitutes the specific area SA1. Furthermore, the first end 113 may be shaped so as to be present on both the bottom wall 321 and the side wall 26. The same applies to the second end 123.

[0122] In the fourth embodiment, a part or all of the first end 113 may be outside the specific area SA1 when the bottom wall 321 is viewed from above. Also, a part or all of the first end 113 may be outside the hole R2 when the bottom wall 321 is viewed from above.

[0123] In the fourth embodiment, only one of the first end 113 and the second end 123 may contain the photothermal conversion material. In such a case, the plurality of heat sources 30 may be attached at positions that irradiate the first end 113 or the second end 123 that contains the photothermal conversion material. In this way, the area of ​​the first end 113 or the second end 123 that is irradiated by the heat source 30 also functions as a photothermal conversion section.

[0124] In other words, if one or more selected from the first electrode 110 and the second electrode 120 contains a photothermal conversion material and is attached to a portion of the bottom wall 321 that is irradiated with light from the heat source 30, the first electrode 110 or the second electrode 120 will also function as a photothermal conversion section.

[0125] The second end 123 does not have to include the photothermal conversion material. For example, the first end 113, the second end 123, and the photothermal conversion material may be prepared separately. In the sixth embodiment, the surface of the first end 113 may be covered with the coating layer 25.

[0126] The shape of the first end 113 in the fifth embodiment is not limited to the example of the above embodiment. It is sufficient that three or more heat sources 30 can irradiate light onto the first end 113. The second end 123 of the second electrode 120 in the fifth embodiment is not limited to the example of the above embodiment. For example, the second end 123 may be attached to a lid that closes the opening on the upward direction UD side of the container 20. Accordingly, the arrangement and shape of the second electrode 120 may be changed. In this case, the second end 123 may be designed to be in contact with the liquid LQ. As a result, the second end 123 and the first end 113 face each other across the liquid LQ. Here, for example, when positively charged micro-objects CE are to be accumulated on the first electrode 110, the micro-objects CE accumulate on the first end 113 of the first electrode 110 due to the force of the thermal convection flow and the repulsive force with the second end. In other words, the micro-objects CE can be efficiently accumulated on the first end 113. Furthermore, the shapes and arrangements of the first electrode 110 and the second electrode 120 may be changed depending on whether the minute object CE is positively or negatively charged.

[0127] Therefore, in the fifth embodiment, one of the first electrode 110 and the second electrode 120 is attached to the bottom wall 421, and the other of the first electrode 110 and the second electrode 120 is attached to a wall that is not the bottom wall 421 among the walls that constitute the container 20.

[0128] In the sixth embodiment, the shapes of the first end 113 and the second end 123 are not limited to those of the above embodiment. For example, the first end 113 may extend over a range wider or narrower than the 180-degree range closer to the first base portion 111 in the circumferential direction around the central axis CA. Accordingly, the area in which the second end 123 exists may change.

[0129] A portion of the first end 113 does not have to face the second end 123. The same applies to the second end 123. In the sixth embodiment, it is sufficient that a portion or all of the first electrode 110 faces a portion or all of the second electrode 120.

[0130] In each of the fourth and fifth embodiments, one or more selected from the first electrode 110 and the second electrode 120 may be separable from the container 20. In addition, in the sixth embodiment, in addition to or instead of the first electrode 110, the second electrode 120 may be separable from the container 20.

[0131] In each of the fourth and sixth embodiments, the arrangement of the first base portion 111 of the first electrode 110 and the second base portion 121 of the second electrode 120 is not limited to the examples in each embodiment. For example, the first base portion 111 and the second base portion 121 do not have to face each other across the geometric center GC. Furthermore, the shapes of the first electrode 110 and the second electrode 120 may change accordingly.

[0132] In the seventh embodiment, if sufficient strength can be obtained with the photothermal conversion unit 204 alone, the support plate 203 may be omitted. Also, in addition to the support plate 203, another layer may be interposed on the downward direction DD side of the photothermal conversion unit 204. In this case, however, it is necessary to select a light-transmitting material for the other layer so that light from the downward direction DD can reach the photothermal conversion unit 204.

[0133] In the seventh embodiment, the heat source 30 does not have to be fixed to a surface of the support plate 203 facing the downward direction DD. For example, the heat source 30 may be embedded inside the support plate 203, or may be located between the support plate 203 and the photothermal conversion unit 204. Furthermore, the heat source 30 may be fixed to a member separate from the photothermal conversion unit 204 and the support plate 203. For example, the heat source 30 may be fixed to a device on which the photothermal conversion unit 204 and the support plate 203 are to be placed when the micro-object accumulation device 600 is used.

[0134] In the seventh embodiment, a structure may be employed in which the photothermal conversion unit 204 and the bottom wall main body 211 cannot move relative to each other when they are attached to each other. An example of such a structure is a structure in which the photothermal conversion unit 204 and the bottom wall main body 211 cannot move relative to each other due to a concave-convex relationship between the two.

[0135] Incidentally, Japanese Patent Application Laid-Open No. 2008-161132 discloses a microorganism culture device. This microorganism culture device includes an electric heater and an open / close type pressure-resistant sealed container. The electric heater heats the inside of the open / close type pressure-resistant sealed container. The open / close type pressure-resistant sealed container has a culture tank and a stirrer. The culture tank stores a culture solution. The stirrer stirs the culture solution in the culture tank by rotating a stirring bar.

[0136] In the above-mentioned microbial culture device, a fairly strong water current is generated in the culture tank by the stirrer, which causes impacts on the microorganisms in the culture solution. In addition, the microorganisms may collide with the rotating stirrer. Therefore, in the above-mentioned microbial culture device, the microorganisms in the culture solution are damaged.

[0137] In this regard, in each of the above embodiments, convection can be generated in the solution in the container 20. Therefore, depending on the size of the container 20, the viscosity of the solution, the size and specific gravity of the micro-objects contained in the solution, and the like, the micro-object accumulation device of each of the above embodiments can be used as a micro-object agitator. In particular, when the micro-objects are small, such as viruses, it is preferable to use it as a micro-object agitator. With this micro-object agitator, micro-objects can be agitated without a rotating stirrer inside the container 20, and micro-objects can be agitated without external impact such as ultrasonic waves. Therefore, with this micro-object agitator, micro-objects can be agitated while minimizing damage to the micro-objects.

[0138] LQ...liquid CE...micro-object 10...micro-object accumulation device 20...container 21...bottom wall CA...central axis GC...geometric center 22...periphery 23...transmitting portion 24...photothermal conversion portion 25...coating layer BS...bottom surface 26...side wall 30...heat source 31...first heat source 32...second heat source 33...third heat source 34...fourth heat source 35...fifth heat source 36...sixth heat source 37...seventh heat source 38...eighth heat source HC...heating center 40...controller SP...space SA1...specific area SA2...specific area SA3...specific area C1...first virtual circle C2...second virtual circle SL...virtual line segment TL...virtual line UD...upward direction DD...downward direction 100...micro-object accumulation device 110...first electrode 120... Second electrode CS... Cooling section C3... Third imaginary circle 200... Micro-object accumulating device 221... Bottom wall 300... Micro-object accumulating device 321... Bottom wall 400... Micro-object accumulating device 421... Bottom wall 500... Micro-object accumulating device 521... Bottom wall R... Recess

Claims

1. A micro-object accumulation device comprising: a container having a bottom wall and side walls rising from the bottom wall, capable of storing a liquid containing micro-objects in a space partitioned by the bottom wall and the side walls; and three or more heat sources capable of heating the bottom wall, wherein, when the center of the area heated by the heat sources is defined as the heating center, and an imaginary line is drawn passing through the heating centers of any two of the heating centers of the three or more heat sources, the heating centers of one or more other heat sources are located at a location outside the imaginary line.

2. A micro-object accumulation device as described in claim 1, wherein when the area surrounded by the heating center is defined as a specific area when the bottom wall is viewed in a plane, the geometric center of the bottom wall is located within the specific area.

3. The minute object accumulation device according to claim 2, wherein the three or more heat sources are arranged on a circumference with the geometric center as the center point.

4. A micro-object accumulation device as described in any one of claims 1 to 3, wherein when the direction in which the space is located relative to the bottom wall is defined as the upward direction and the direction opposite to the upward direction is defined as the downward direction, the surface of the bottom wall facing the upward direction is a flat surface, and the heat source is located on the downward side of the surface of the bottom wall facing the upward direction.

5. A micro-object accumulation device as described in claim 4, wherein the heat source is a light source capable of irradiating light onto the bottom wall from the downward side, the heating center is the center of an area of ​​the bottom wall irradiated with light from the heat source, and the portion of the bottom wall irradiated with light from the heat source contains a photothermal conversion material.

6. A micro-object assembly device according to any one of claims 1 to 5, further comprising a control unit capable of controlling the energy output by the heat source.

7. A micro-object accumulation device as described in any one of claims 1 to 6, further comprising a cooling unit capable of cooling the bottom wall, and when the area surrounded by the heating center is defined as a specific area when the bottom wall is viewed in a plane, the cooling unit is located outside the specific area when the bottom wall is viewed in a plane.

8. A micro-object accumulation device as described in any one of claims 1 to 7, wherein when the area surrounded by the heating center is defined as a specific area when the bottom wall is viewed in a plane, the surface of the specific area facing the space has a coating layer that has a higher affinity for a specific substance than the surface of the outside of the specific area facing the space.

9. A micro-object accumulation device as described in any one of claims 1 to 8, wherein when the area surrounded by the heating center is defined as a specific area when the bottom wall is viewed in a plane, the direction in which the space is located relative to the bottom wall is defined as an upward direction, and the direction opposite to the upward direction is defined as a downward direction, the bottom wall has a recess within the specific area of ​​the bottom wall that is recessed downward relative to the space.

10. A minute object collecting device according to any one of claims 1 to 9, wherein the side wall is cylindrical.

11. A micro-object accumulation device as described in any one of claims 1 to 10, comprising: a first electrode exposed to the space and capable of applying a positive voltage from a DC power supply; and a second electrode exposed to the space and positioned away from the first electrode and capable of applying a negative voltage from a DC power supply.

12. A micro-object accumulation device as described in claim 11, wherein, when the direction in which the space is positioned relative to the bottom wall is defined as an upward direction and the direction opposite to the upward direction is defined as a downward direction, the surface of the bottom wall facing the upward direction is a flat surface, the heat source is a light source capable of irradiating light from the downward side of the bottom wall, and one or more selected from the first electrode and the second electrode contain a photothermal conversion material and are attached to a portion of the bottom wall that is irradiated with light from the heat source.

13. A micro-object accumulation device as described in claim 11 or claim 12, wherein one of the first electrode and the second electrode is attached to the bottom wall, and the other of the first electrode and the second electrode is attached to a wall that is not the bottom wall among the walls that constitute the container.

14. A micro-object accumulation device according to any one of claims 11 to 13, wherein one or more selected from the first electrode and the second electrode are attached to the surface of the side wall facing the space.

15. A micro-object accumulation device as described in any one of claims 11 to 14, wherein the first electrode is attached to the surface of the side wall facing the space, the second electrode is attached to a location on the surface of the side wall facing the space different from the location of the first electrode, and part or all of the first electrode and part or all of the second electrode face each other.

16. A micro-object collecting device according to any one of claims 11 to 15, wherein one or more selected from the first electrode and the second electrode are separable from the container.

17. A micro-object accumulation device as described in claim 5, wherein the bottom wall comprises a bottom wall body having the flat surface and a photothermal conversion unit containing the photothermal conversion material, the photothermal conversion unit is detachably attached to the bottom wall body from the downward side, and the heat source is located on the downward side of the photothermal conversion unit.

18. A micro-object stirring device comprising: a container having a bottom wall and side walls rising from the bottom wall, capable of storing a liquid containing micro-objects in a space partitioned by the bottom wall and the side walls; and three or more heat sources capable of heating the bottom wall, wherein when the center of the area heated by the heat sources is defined as the heating center, and when an imaginary line is drawn passing through the heating centers of any two of the heating centers of the three or more heat sources, the heating centers of one or more other heat sources are located at a location outside the imaginary line.

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