Transporter, transport device for micro-object, transport system for micro-object, and transport method for micro-object

Abstract

To provide a transporter that can easily and simply transport fine objects such as fine liquid and fine solid, and has excellent transporting performance, and a transport device or a transport system of fine objects which can easily and simply transport fine objects, and has excellent transporting performance, and a transport method of fine objects.SOLUTION: A transport fluid 10 includes: liquid or semisolid fluid 11; and a photoisomerization compound 13 which is present in the fluid 11 and is photoisomerized by light irradiation of a specific wavelength, where the fluid 11 flows by photoisomerizing the photoisomerization compound 13 to move a fine object 20 on a fluid surface. Further, a transport fluid 10 may be provided on a substrate 15 to constitute the transport device 1 of the fine object 20. Furthermore, a transport system comprising the transport device 1 and a lamp which irradiates fluid with light may be constructed. Further, a transport method of fine objects in which the fine object 20 on a fluid surface is transported by holding the transport fluid 10 and irradiating the fluid 11 with light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transporter for moving minute objects such as minute liquids and minute solids, a minute object transport device or minute object transport system including the transporter, and a minute object transport method using the transporter, and more particularly to a transporter, a minute object transport device, transport system, and transport method used in a microchannel device, a microreactor, etc. [Background technology]

[0002] With the development of high-mix, low-volume production, as exemplified by Industry 4.0, miniaturization of equipment and the use of microfactories are being promoted, placing a premium on establishing technologies for precisely controlling the movement of liquids and microsolids within these devices. In particular, the transport of materials at interfaces is expected to be put to practical use in many application fields, including micro- and nanofluidics, which do not require flow channels, microreactors that control local chemical reactions, and bioanalysis. For example, Patent Document 1 discloses a microchannel device that transports samples using gravity as a driving force, without the need for external sources such as pumps or aspirators. This utilizes a physical structure that forms a flow channel in the direction of gravity, thereby utilizing the driving force of a gradient. Regarding material transport, the following technologies also exist as methods for achieving transport using external energy.

[0003] For example, methods have been proposed that combine typical external energies, such as electric fields, magnetic fields, vibrations, ultrasound, heat, and light, with responsive materials. For example, with regard to the transport of minute liquids, methods such as photothermal reactive surfaces (Non-Patent Document 1), photoinduced molecular surfaces (Non-Patent Document 2), and thermotropic liquid crystals (Non-Patent Document 3) have been proposed. These methods are driven by irradiation with light of specific wavelengths, such as infrared or ultraviolet light. Furthermore, with regard to the transport of minute solids, methods such as the use of photoinduced crystals (Non-Patent Document 4), which are driven by simultaneous irradiation with ultraviolet and visible light, have been proposed.

[0004] In particular, research and development of systems that use light as an energy input (optical input systems) has been promoted due to their advantage of being able to remotely and reversibly control movement in a non-contact, non-invasive manner. For these optical input systems, methods have been proposed that incorporate photoresponsive molecules that can generate macroscopic movement from molecular movement (Non-Patent Document 5), or transport methods that utilize photothermal reactions composed of carbon, etc. (Non-Patent Document 6). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2010 / 061598 [Non-patent literature]

[0006] [Non-Patent Document 1] Chunlei Gao, et al. 'Droplets Manipulated on Photothermal Organogel Surfaces', Adv. Funct. Mater. (2018) Volume 28, 1803072 [Non-patent document 2] Kunihiro Ichimura, et al. 'Light-Driven Motion of Liquids on a Photoresponsive Surface', Science 2000. (2000) vol 288, p.1624-1626 [Non-patent document 3] Yang Xu, et al. 'Liquid Crystal-based Open Surface Microfluidics Manipulate Liquid Mobility and Chemical Composition on Demand', Science Advances (2021) vol 7, eabi7607 [Non-patent document 4] Emi Uchida, et al. 'Light-Induced Crawling of Crystals on a Glass Surface', Nature Communications (2015) vol 6, 7310 [Non-patent document 5] Yang Xu, et al. 'Modularizable Liquid-Crystal-Based Open Surfaces Enable Programmable Chemical Transport and Feeding Using Liquid Droplets', Advance Materials (2022) Volume 34, 2108788 [Non-patent document 6] Chao Chen, et al. 'Remote Photothermal Actuation of Underwater Bubble toward Arbitrary Direction on Planar Slippery Fe3O4-Doped Surfaces', Adv. Funct. Mater. (2019) Volume 29, 1904766 [Non-Patent Document 7] Hujun Wang, et al. 'Improved dynamic stability of superomniphobic surfaces and droplet transport on slippery surfaces by dual-scale re-entrant structures', Chemical Engineering Journal (2020) volume 394, 124871 Summary of the Invention [Problem to be solved by the invention]

[0007] However, these methods have the following problems. Passive methods such as those using gravity have problems such as short transport distances, slow transport speeds, and transport of only specific substances (droplets or bubbles excluding solids) due to the limited transport of substances due to the energy gradient mentioned above. In addition, active methods using external energy, such as those using photoinduced molecular surfaces (Non-Patent Document 2) and thermotropic liquid crystals (Non-Patent Document 3), can transport liquids with high accuracy, but have the problem that the transport speed is slow and the range of transportable liquid volumes is small because the capillary driving force is extremely weak.

[0008] Furthermore, in the transport of microsolids, for example, the phenomenon in which azobenzene derivative crystals move across a glass plate upon simultaneous irradiation with visible and ultraviolet light (Non-Patent Document 4), not only is the transport speed slow, but the transported object itself must be a photoinduced crystal, i.e., a substance that responds to light stimuli, limiting the types of substances that can be transported. This is also true for technologies incorporating photoresponsive molecules (Non-Patent Document 5). Furthermore, when using photothermal as the driving source (Non-Patent Documents 1 and 6), localized high temperatures are required, which increases the risk of evaporation of the transported droplets and damage to the microsolids, making them inapplicable in general atmospheric environments (Non-Patent Document 7). Thus, previous light-input systems required low output or high energy input for transport, and also had problems such as thermal instability of the interface surface.

[0009] The present invention has been made to solve these problems, and aims to provide a transporter that can easily transport minute objects such as minute liquids and minute solids and has excellent transportability. It also aims to provide a transport device, a transport system, and a transport method for minute objects that can easily transport minute objects and have excellent transportability. [Means for solving the problem]

[0010] The above-mentioned problems of the present invention are solved by using a fluid containing a photoisomerizable compound that is isomerized by light as a transporter for minute objects. That is, by controlling the fluid fluidity by utilizing the chemical gradient caused by the isomerization of the photoisomerizable compound, it becomes possible to control the movement of minute objects on the fluid surface. Specifically, the device has the following configuration. (1) A transporter that includes a liquid or semi-solid fluid and a photoisomerizable compound that is present in the fluid and is isomerizes when irradiated with light of a specific wavelength, and that causes the fluid to flow as the photoisomerizable compound is isomerized, thereby moving minute objects on the fluid surface. (2) A device for transporting a minute object, comprising a substrate and the transporter according to (1) above provided on the substrate. (3) A system for transporting a minute object, comprising the device for transporting a minute object according to (2) above and a light irradiation means for irradiating a fluid with light. (4) A method for transporting a minute object, which comprises holding the transporter described in (1) above and irradiating the fluid with light, thereby moving the minute object on the surface of the fluid. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a transport body that can easily transport micro-objects and has excellent transportability, as well as a transport device, transport system, and method for transporting micro-objects that can easily transport micro-objects and has excellent transportability. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a device for transporting a minute object. [Figure 2] This is an enlarged view (schematic diagram) of the micro-object and its surroundings. [Figure 3] This is a photograph showing the movement of tiny objects (water droplets). [Figure 4] This is the absorption spectrum of the liquid layer. [Figure 5] FIG. 1 is a graph showing the relationship between the DMAB concentration and the surface tension of the liquid layer before and after light irradiation. [Figure 6]1 is a graph showing the relationship between irradiation time and surface temperature when ultraviolet light is irradiated onto the surface of a liquid layer to which different concentrations of DMAB have been added. [Figure 7] 1 is a graph showing the relationship between the time elapsed due to light irradiation and the distance traveled by water droplets for each DMAB concentration. [Figure 8] 1 is a graph showing the relationship between light irradiation intensity and transport rate for each DMAB concentration. [Figure 9] 1 is a graph showing the relationship between the amount of water droplets transported and the transport speed for each DMAB concentration. [Figure 10] These are images observed when transporting different amounts of water droplets. [Figure 11] FIG. 10 is a side view illustrating the reciprocating transport of water droplets. [Figure 12] 10 is a graph showing displacement of a water droplet during reciprocating transportation. [Figure 13] FIG. 10 is a configuration diagram showing the state of use of the transport device when the minute object is changed (Example 2). [Figure 14] 10 shows an image observed when a minute object is transported (Example 2). [Figure 15] 10 shows an image observed when multiple water droplets are transported (Example 3). [Figure 16] 10 shows an image observed when multiple water droplets are transported (Example 4). [Figure 17] 10 shows an image observed when multiple water droplets are transported (Example 5). DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail. Note that in the embodiments of the present invention, when a numerical range such as a concentration range or wavelength range is indicated, it is assumed that the upper and lower limits are included.

[0014] The transporter of this embodiment is a transport fluid 10 containing a fluid 11 and a photoisomerizable compound 13 that is present in the fluid 11 and isomerizes upon irradiation with light, and the isomerization of the photoisomerizable compound 13 causes the fluid 11 to flow, thereby moving minute objects 20 on the fluid surface. Note that transport simply means moving minute objects from one position to another on the fluid surface. FIG. 1 shows the configuration (side view) of a transport device 1 for transporting a micro-object 20, in which a transport fluid 10 is provided on a substrate 15. FIG. 1(A) shows the basic configuration of the transport device 1, and FIG. 1(B) shows the transport device 1 in use. Note that the micro-object 20 to be transported (also referred to as the transport target) is a micro-liquid or a micro-solid, but "micro-" does not mean limited to objects too small to be recognized by the naked eye, but refers to objects on the order of about 10 centimeters or less, to the order of millimeters, microns, or nanometers. For example, this includes micro-objects that are the target of microchannel devices and microreactors widely used in chemistry, biochemistry, etc. Most are on the order of nanometers to millimeters, roughly 1 μm-10 mm.

[0015] The principle of transport of minute objects 20 can be explained as follows: For example, when dimethylazobenzene (3,3'-dimethylazobenzene) (hereinafter referred to as DMAB), an azobenzene derivative, is used as the photoisomerizable compound 13, irradiation with ultraviolet or visible light causes a reaction shown in chemical formula (1). [ka]

[0016] When photoisomerizable compounds (also called photoisomerizable molecules) 13 are induced by light in the fluid 11, they undergo isomerization, for example from trans to cis isomers, where the light is irradiating them, causing a chemical gradient (an increase in the cis isomer) due to a change in the structure of the compound. To reduce the chemical gradient, the increased isomers (in this case, the cis isomers) diffuse through the fluid, creating a flow in the fluid that allows the free transport of minute objects 20 (Figure 1(B)) on the fluid surface.

[0017] (Photoisomerizable compound) The photoisomerizable compound 13 can be isomerized reversibly or unidirectionally upon irradiation with light of a specific wavelength. This does not necessarily mean that it is a cis-trans isomer, such as an azobenzene derivative, but it can also be a photochromic or one-way isomerizable isomer. The specific wavelength can be ultraviolet light (280-400 nm), visible light (400-730 nm), or infrared light (780-1200 nm). While this specific wavelength varies depending on the type of photoisomerizable compound, it is typically ultraviolet light of around 300-400 nm. Cis-trans compounds include azobenzene derivatives, olefins, stilbene derivatives, alkylstyrene derivatives, ethyl cinnamate, retinal, vitamin A, indigo derivatives, and hemiindigo derivatives. Photochromic compounds include diarylethene derivatives, spiropyrans, spirooxazines, naphthopyrans, dimethyldihydropyrene, fulgides, DASA (Donor-Acceptor Stenhouse Adducts), binaphthyl-bridged imidazole dimers, and salicylideneanilines.

[0018] The substituents of these derivatives are not particularly limited as long as they are reversibly isomerized by light. Examples of the substituents include linear or branched C1 to C4 alkyl groups (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, etc.), linear or branched C1 to C4 alkoxy groups (methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, etc.), aryloxy (phenyloxy, naphthyloxy, etc.), aralkyloxy (benzyloxy, phenethyloxy, etc.), halogen atoms (F, Cl, Br, I), nitro, cyano, hydroxy, amino, monoalkylamino (methylamino, ethylamino, n-propylamino, isopropylamino, etc.), and the like. Examples of isomerization occurring in only one direction include norbornadiene-quadricyclane derivatives, cis-stilbene-phenanthrene, anthracene- and benzene-substituted olefins, dimethyl olefins, and hydroxychalcones. Among these, those that are isomerized by ultraviolet or visible light, which are safer than laser light and do not require high output energy, are preferred. In particular, azobenzene derivatives such as DMAB are preferred because it is easy to introduce substituents and the wavelength at which they are isomerized and their solubility in fluids can be changed by changing the substituents.

[0019] If these photoisomerizable compounds 13 are liquid (including syrup-like compounds) at room temperature, they may be used as they are, but if they are solid, they may be in the form of powder, particles, or other particulates, which can be mixed and stirred with fluid 11 so that they exist in a dispersed, dissolved, or complexed (solidified) state in the fluid. Note that, for ease of understanding, Figure 1 shows a plurality of particulate photoisomerizable compounds 13 (schematic diagram), but in reality, they exist in various forms, such as when dissolved or when complexed.

[0020] (fluid) The fluid 11 is a liquid, sol, semi-solid, or semi-fluid (for example, with a viscosity of 30 Pa·s or more or a consistency of 220 or more) that is flowable at room temperature (15-35°C) or near room temperature. Examples of semi-solid or semi-fluid materials include grease and paraffin. The flow of the fluid causes the movement of minute objects 20 present on the surface. For example, mineral oil, synthetic oil, vegetable oil, animal oil, alcohols, aqueous solutions, water, etc. can be selected as the fluid. Specifically, various silicone oils (decamethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, dodecamethylcyclohexasiloxane, methylsilicone, methylphenylsilicone, methylhydroxysilicone, amino-modified silicone oil, epoxy-modified silicone oil, carboxy-modified silicone oil, carbinol-modified silicone oil, methacrylic-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, alkyl-modified silicone oil, fatty acid ester-modified silicone oil, partially fluorinated silicone oil), lower saturated fatty acids, higher saturated fatty acids, lower unsaturated fatty acids, higher unsaturated fatty acids, higher alcohols, fatty acid compounds (sesame oil, , rapeseed oil, almond oil, cottonseed oil, salad oil, etc.), fluoroalkylethoxysilane, fluoroalkylmethoxysilane, alkylethoxysilane, alkylmethoxysilane, CnHx (n>4 or more) alkanes, alkenes, alkynes, oils and fats (beef tallow, lard, castor oil, palm oil, etc.), polyoxyalkylenated oils and fats (castor oil, hydrogenated castor oil), chlorinated oil, sulfurized oil (soybean oil, lard), polymerized oil (soybean oil, fish oil), other liquids containing fatty acid derivatives (fatty acids, soaps, esters, amides, polyoxyalkylene adducts, chlorinated / sulfurized / polymerized fatty acid alkyl esters), lubricating fluids with aromatic rings, such as phenyltriethoxysilane, phenyltrimethoxysilane, phenylchlorosilane, phenylmethylchlorosilane, 2-(4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl)oxy] -phenol, 1-[2-{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy}ethyl]-4-{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy}-2,2,6,6-tetramethylpiperidine, 4,4'-bis(α,α-dimethyl-benzyl)diphenylamine, 2,4-diamino-phenyl-1,3,5-Triazine, tris(nonylphenyl)phosphite, tris(mixed, mono- and dinonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecylphosphite), 1,1,3-tris(2-methyl-4-di-tridecylphosphite-5-t-butyl-phenyl)butane and diphenylphosphite mixture, 4,4'biphenylenediphosphinic acid tetrakis(2,4-di-t-butylphenyl), cyclic neopentanetetraylbis(2,4-di-t-butylphenylphosphite), tris(cyclohexylphenyl)phosphite, 2-t-butyl-α-(3-t-butyl-4-hydroxyphenyl) -P-Cumenylbis(P-nonylphenyl)phosphite, bis-[2-methyl-4,6-bis-(1,1-dimethylethyl)phenyl]ethyl phosphite, 3,9-bis{2,4-bis(1-methyl-1-phenylethyl)phenoxy}-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy-2,4,8,10-tetra-t-butylbenz[d, f] [1,3,2]dioxaphosphepin, n-octadecyl-β-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, 4,4'-butylidenebis(6-t-butyl-m-cresol) or 1,1-bis(2'-methyl-4'-hydroxy-5'-t-butyl-phenyl)butane, triethylene glycol bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate, 2,2'-oxamidobis[ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane), 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, tetrakis[methylene-3-(3',5)di-t-butyl-4'-hydroxyphenyl]propionate]methane, bis[3,3-bis(4'-hydroxy-3'-t-butylphenyl)butanoic acid]glycol ester, 1,4-Benzenedicarboxylic acid bis[2-(1,1-dimethylethyl)-6-[[3-(1,dimethylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-methylphenyl] ester, N,N-bis{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl}hydrazine, 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methyl phenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate, pt-butylphenyl salicylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, phenyl salicylate or phenyl salicylate, 2-(2H-benzotriazole- 2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2'hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole and methyl methacrylate copolymer, 2-cyano-3,3-diphenylacrylate-2-ethylhexyl, poly(oxy-1,2-ethanediyl), α-[4-(3-butoxy-2-cyano-3-oxo-1-propen-1-yl)-2-methoxyphenyl]-ω-hydroxy-2-(2'-hydroxy-3'5'-di)-t-amylphenyl)benzotriazole, polyoxyethylene (4 to 50 moles) alkyl (C7 or higher) phenyl ether, polyoxyethylene (4 to 50 moles) Alkyl (C7 or higher) phenyl ether sulfate (Na, NH4), polyoxyethylene (5 to 55 moles) nonylphenyl phosphate, α(p-nonylphenyl)-ω-hydroxypoly(oxyethylene) dihydrogen phosphate ester,Examples of suitable additives include monohydrogen phosphate ester mixtures, methylphenyl polysiloxanes, polyorgano (C1-C32 alkyl and / or phenyl) siloxane and polyalkylene (C2-C3) glycol condensates, benzene-1,2-dimethyl-4,5-bis(1-phenylethyl), benzene-4-(1,3-diphenylbutyl)-1,2-dimethyl, benzene [1-(3,4-dimethylphenyl)ethyl] (1-phenylethyl) mixtures, branched polycarbonates, sodium bis(4-t-butylphenyl) phosphate, sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate, zinc(II) phenylphosphonate, 7,8,9-trideoxy-3,5:4,6-O-bis(4-propylphenyl)methylene=D-glycero-L-gulononitol, paraffin, and grease. These may be used alone or in combination of two or more. Among these, silicone oils containing methyl groups, phenyl groups, or hydrogen in the side chains or terminals of their molecular structure, and oils such as fatty acids with 6 or more carbon atoms are preferred because they are particularly good at dissolving compounds with a benzene ring, such as azobenzene derivatives.

[0021] (base material) The substrate 15 is a hydrophobic substrate unless an aqueous solution or water is used as the fluid. It may be hydrophobic itself, but it is sufficient that the surface is hydrophobic. For example, if the substrate surface is hydrophilic, such as glass, it is preferable to subject the substrate surface to hydrophobic treatment. When an aqueous solution or water is used as the fluid, it is sufficient that the surface is hydrophilic, and a hydrophilic substrate or a substrate that has been subjected to hydrophilic treatment is used. When performing hydrophobic treatment, a criterion for hydrophobicity is preferably, for example, a contact angle with water of 90 degrees or more. Materials for the substrate 15 include inorganic substrates such as stainless steel, silicon, quartz, or glass, organic substrates such as resin or rubber, plastic, concrete, wood, metal, and leather. Furthermore, the substrate 15 may be made of a deformable material (for example, rubber that can be deformed by pinching it with fingers) as long as it can hold a fluid. The size of the substrate 15 depends on the size and application of the minute object 20 to be transported, but for example, when used in a microchannel device, a plate-like shape of approximately 10 x 10 cm is expected. The shape is not limited to a plate, and various shapes such as a dish, box, or cylinder may be used as long as the substrate can hold a fluid on its surface or inside.

[0022] (Method for manufacturing a device for transporting micro-objects) The transport device 1 can be produced by the following method. First, except when an aqueous solution or water is used as the fluid, a substrate 15 with a hydrophobic surface is prepared. Here, the substrate itself may be hydrophobic, or the substrate surface may be hydrophobic. In the case of a substrate with a hydrophilic surface, a hydrophobization treatment is performed on the substrate surface. For example, when coating the substrate with a hydrophobic substance to form a thin film, this is done by contacting a hydrophobizing agent with the substrate surface. The hydrophobizing agent can be selected without particular limitation from hydrophobizing agents that have traditionally been used to hydrophobize various materials. Preferred hydrophobizing agents include various silane coupling agents, N,N-dialkylaminosilane compounds, acyclic disilazane compounds, and cyclic silazane compounds, which are used for hydrophobization. Fluorine-based compounds may also be used.

[0023] A hydrophobic substrate 15 can be fabricated by contacting the surface of the substrate with these hydrophobic agents using methods such as spin coating, dipping, roll-to-roll coating, squeegee coating, doctor blade coating, coating, spraying, casting, and layer-by-layer deposition (layer-by-layer adsorption). These methods may be used alone or in combination. For example, the substrate surface may be hydrophobized by dipping, and then a fluid may be sprayed onto the substrate to form a thin film. These methods can also be used to deposit a fluid 11 on a substrate or thin film. When using an aqueous solution or water as the fluid, the substrate itself must be hydrophilic, or a substrate 15 with a hydrophilic surface must be prepared. For example, ion implantation is a typical surface treatment method for hydrophilization. Alternatively, the substrate surface may be hydrophilized using a hydrophilic polymer such as polyvinylpyrrolidone or a hydrophilizing agent such as titanium oxide, using a method similar to the hydrophobization treatment described above.

[0024] Next, the transport fluid 10 to be held on the substrate 15 is prepared. It does not matter whether this step or the substrate preparation step is carried out first. The transport fluid 10 can be easily prepared by mixing and stirring the photoisomerizable compound 13 with the fluid 11. The fluid 11 can be selected based on its compatibility with the photoisomerizable compound 13 and the substrate 15, as well as the intended use and purpose. For example, if the fluid's fluidity needs to be increased, such as to increase the transport speed, a low-viscosity liquid, particularly a fatty acid-containing oil, can be used. Furthermore, many fatty acid-containing oils (especially those containing methyl groups, phenyl groups, hydrogen, or a benzene ring) are easily soluble in the photoisomerizable compound 13, making it easier to handle and disperse the photoisomerizable compound 13 evenly throughout the fluid. On the other hand, if the fluid's fluidity needs to be reduced, such as to precisely control the transport position, a high-viscosity liquid, sol, or semi-solid or semi-liquid substance, such as paraffin or grease, can be used.

[0025] In addition, when using a fluid other than an aqueous solution or water, the compatibility of the hydrophobizing agent with the substrate itself or the substrate surface must first be such that it does not react with the substrate surface. Furthermore, to allow the fluid to spread over the entire substrate surface, the hydrophobizing treatment is preferably performed so that the contact angle of the fluid with the substrate surface is 45° or less, preferably 20° or less, and more preferably 10° or less. Note that when the fluid is an aqueous solution or water, the contact angle of the fluid is applied as is, so it is preferable that the substrate surface is hydrophilized. In this case, too, a fluid that does not react with the substrate surface is selected. Furthermore, if the photoisomerizable compound 13 is solid at room temperature, it is preferable to prepare it in a powdered or granular form (e.g., approximately 10-100 μm in diameter) for rapid dissolution. Furthermore, since the dispersed or dissolved state of the photoisomerizable compound 13 allows for more effective utilization of the range of movement of objects on the substrate 15, it is advisable to select a compound that is easily dispersed and dissolved in the fluid 11. Alternatively, a fluid 11 that is easily dispersed and dissolved in the photoisomerizable compound 13 may be selected. For example, the photoisomerizable compound 13 may be present in the fluid 11 at a concentration of 0.1 mM or more, preferably approximately 1-100 mM. If the amount of photoisomerizable compound 13 is too large, the amount of heat generated by isomerization increases, which may affect the surface tension of the micro-object 20 being transported and the fluid, or may cause Marangoni convection due to the temperature increase, making it difficult for localized flow to occur. On the other hand, if the amount is too small, the effect of flow due to isomerization is reduced. The fluid 11 is selected to have a density greater than that of the minute objects 20 to be transported (satisfying the conditions for the minute objects 20 to float), and to be non-disintegrating, non-decomposing, non-dissolving, and non-reactive with the minute objects 20.

[0026] The transport fluid 10 is then placed on the substrate 15 by injection, application, dripping, or other methods. The transport fluid 10 may also be placed on the substrate 15 using the hydrophobic treatment method described above. The amount of transport fluid 10 on the substrate 15 is set to 0.01 μL / cm, depending on the physical properties of the minute objects 20, such as their size and density. 2 or more, preferably 0.1 μL / cm 2That is, it is sufficient that the amount is large enough to allow the minute object 20 to move. According to this embodiment, a transport device can be produced simply and easily.

[0027] The fluid 11, the photoisomerizable compound 13, the substrate 15, etc. can be selected, for example, as follows. First, the object to be transported is identified, and then the fluid 11 is selected. As described above, the fluid 11 is selected to basically satisfy the conditions for floating the minute objects 20, and is one that does not disintegrate, decompose, or dissolve the minute objects 20, and is non-reactive. The photoisomerizable compound 13 to be added to the fluid 11 is also selected to be easily dispersed and dissolved in the fluid 11, and the substrate 15 is also prepared to match the properties of the fluid 11 (whether it is an aqueous solution or water, or other). While this selection process is basic, priority may be given to the selection of other materials or substances. Even if the object to be transported is difficult to float in the fluid 11 or is highly reactive, transport is possible by forming a layered structure using floating materials, etc. (see Figure 13).

[0028] (Method of using a device for transporting small objects) FIG. 2 shows an enlarged view (schematic diagram) of the periphery of the minute object 20. In FIG. When the transport device 1 is used, a minute object 20 to be transported is placed on the transport fluid 10. The minute object 20 may be either liquid or solid, as long as it floats on the transport fluid 10 (has low density), does not disintegrate, decompose, or dissolve, and is not reactive with the fluid. In the case of liquids, examples include liquids such as syrup and solid masses such as droplets. The size of the minute object 20 can also be selected from tens or a few centimeters to micron or nano orders. If the minute object 20 is liquid, it is preferable to select one that has a large surface tension with respect to the transport fluid 10 (fluid 11) so that it can move on the transport fluid 10.

[0029] The transport fluid 10 around the minute object 20 is then irradiated with light of a wavelength that causes isomerization of the photoisomerizable compound 13. The irradiation method depends on the wavelength at which photoisomerization occurs. For compounds that undergo isomerization between ultraviolet and visible light, an LED light 30 capable of irradiating visible or ultraviolet light is recommended for its ease of use. As shown in Figures 1(B) and 2, the LED light 30 is preferably used to illuminate the transport fluid 10 from an oblique angle (e.g., between 40 and 80°). When light 33 from the LED light 30 strikes the transport fluid 10, that area (irradiated area 35) heats up, and the photoisomerizable compound 13 in the transport fluid 10 undergoes isomerization. For example, in the case of DMAB mentioned above, the reaction shown in chemical formula (1) occurs, causing isomerization from the trans isomer to the cis isomer. This isomerization causes the transport fluid 10 (fluid 11) at the irradiated area 35 to flow, and the minute object moves in the direction of arrow D, opposite the irradiated area 35. When the minute object 20 moves, the irradiation area 35 can be changed accordingly, allowing the object to move in the intended direction. For example, when transporting millimeter-order water droplets using a small LED light, the irradiation intensity is 5-25 mW / cm, depending on the concentration of the photoisomerizable compound 13 and the amount of fluid. 2 A moderate strength is sufficient.

[0030] The LED light 30 may be operated manually, or it may be automatically controlled by providing a sensor for detecting the position of the micro object 20 and a device for moving the LED light 30. In the case of manual operation, the LED light 30 may be held by hand or fixed to a stage and moved by a screw. The direction, distance, and speed of movement of the micro object 20 can be controlled by changing the light irradiation method (irradiation conditions) of the LED light 30, such as the irradiation position, direction, angle, duration, and intensity, thereby transporting the micro object 20 to the desired location. The speed of movement of the micro object 20 can also be controlled by changing the concentration of the photoisomerizable compound 13 in the transport fluid 10. These irradiation methods and conditions, such as the concentration of the photoisomerizable compound 13, may be combined as appropriate. The LED light 30 may also be automatically turned on and off, and the wavelength and intensity of the irradiated light may be automatically controlled. In this way, a transportation system is constructed using the transport device 1 and the LED light 30. If the micro object 20 is a microscopic liquid or solid containing a chemical substance, or the chemical substance itself, various chemical substances can be transported. For example, it can be applied to transporting and combining acidic and basic droplets to generate neutralized droplets. [Example]

[0031] Example 1 A glass substrate (manufactured by Matsunami Glass Industrial Co., Ltd., product number S9111, size 52 × 76 mm, thickness 1 mm) was used as the substrate 15, and its surface was coated with a hydrophobic alkylsilane. The coating solution was prepared by mixing decyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), tetraethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), ethanol (manufactured by Kanto Chemical Co., Ltd.), water, and hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) (decyltrimethoxysilane:tetraethoxysilane:ethanol:hydrochloric acid:water = molar ratio 0.95 × 10 -3 :7.2 × 10 -3 : 206 × 10 -3 :222 × 10 -3 :7.7 × 10 -6) was dip-coated onto a glass substrate (dip speed 1.0 mm / sec) to perform hydrophobic treatment.

[0032] Next, the wettability (hydrophilicity) of the hydrophobized glass substrate surface was evaluated as follows: A 10 μL droplet was dropped onto the substrate 15 placed horizontally, and the contact angle with the substrate 15 was measured. Due to the action of hydrophobic decyltrimethoxysilane, after coating, the surface exhibited a contact angle of 108.6° with water, indicating non-wetting with water.

[0033] A transport fluid 10 containing photoisomerizable molecules was then retained as a liquid layer on the hydrophobized glass substrate surface (hereinafter, this transport fluid 10 will be referred to as the liquid layer), and a transport device 1 was fabricated and used in the following experiments. The transport fluid 10 used silicone oil (dimethyl silicone, KF-96, manufactured by Shin-Etsu Chemical Co., Ltd.) as the base lubricating fluid 11, and DMAB (manufactured by Tokyo Chemical Industry Co., Ltd.) as the photoisomerizable compound 13 (photoisomerizable molecule). Specifically, DMAB powder was added to silicone oil, and the mixture was mixed and stirred to prepare a transport fluid 10 with a DMAB concentration of 10 mM. The transport fluid 10 was then applied to the glass substrate surface at a concentration of 0.4 μL / cm. 2 It was added dropwise and held.

[0034] In addition to the transport fluid 10 containing DMAB, the fluid 11 alone was applied to the surface of a hydrophobic glass substrate at 0.4 μL / cm 2 The sliding angle and contact angle of water on the surface were measured using the same method and conditions as those used in the evaluation of wettability. On the liquid layer surface, a sliding angle of less than 2° was observed for water (a water droplet (10 μL)). In addition, the contact angle hysteresis (cosθRec - cosθAdv), calculated from the advancing (Adv) and receding (Rec) contact angles, was less than 1 / 10 of that before and after the liquid layer was retained. The smaller the contact angle hysteresis, the more the shape of the water droplet can be maintained. These results confirmed that by converting the hydrophobic surface of the glass substrate into a liquid layer surface, deformation of the shape of the micro-object 20 when it is a water droplet is suppressed.

[0035] (Transportation of Micro-Objects 1) Then, a water droplet as a micro-object 20 was placed on the liquid layer (DMAB concentration 10 mM) of the fabricated transport device 1, and ultraviolet light (25 mW / cm ) with a wavelength of 365 nm was applied using an LED light (UV light, manufactured by CCS Inc., HLV-24UV365) 30. 2 ) was irradiated onto the liquid layer around the water droplet (see Figure 2). These conditions were also used for the transportation of micro-objects 2-5 below unless otherwise noted. The water droplets moved immediately when exposed to light, so the light was irradiated from an oblique angle (maintained at a nearly constant angle between approximately 40-60°) while held by hand so as to follow the movement of the water droplets (see Figure 1(B) and Figure 2). Figure 3 shows photographs of water droplet movement. Figure 3(A) shows a water droplet (100 μL) moving horizontally in a straight line, and Figure 3(B) shows a water droplet (10 μL) moving horizontally in a zigzag pattern. As shown in these photographs, the LED light 30 allowed the water droplet to move in any direction. Furthermore, by moving the LED light 30 and shining light from any direction, we were able to achieve not only linear transport but also transport along a zigzag trajectory. As described above, when irradiated with UV light, DMAB isomerizes from the trans form to the cis form. This isomerization creates a chemical gradient within the fluid (and also generates heat due to light absorption), promoting the formation of a surface tension gradient in the fluid. Therefore, it is believed that the diffusion of DMAB induced localized flow, which led to the movement of the water droplets.

[0036] To investigate whether DMAB isomerization was occurring in the liquid layer, the absorption spectrum was measured while shining an LED light 30 on the liquid layer of the transport device 1 (DMAB concentration 10 mM). An Ocean Insight spectrometer (Ocean Optics Flame) was used for the measurements. The results are shown in Figure 4. The LED light 30 was fixed at an angle of 50° on a horizontally moving optical stage. The peak between 260 and 370 nm, with a central peak around 320 nm, decreased upon light irradiation, while the peak between 400 and 500 nm increased (see the enlarged portion in the right frame). This confirmed that isomerization from the trans form to the cis form occurs even when DMAB is dispersed in silicone oil. This tendency became more pronounced with longer irradiation times.

[0037] Furthermore, we investigated whether the surface tension of the liquid layer changes with light irradiation using silicone oil droplets to which different concentrations of DMAB were added. Specifically, we created multiple transport devices 1 by changing the amount of DMAB added to the fluid 11 (silicone oil). All other conditions were the same as those for the transport device 1 used in the above (Transportation of Micro-Objects 1). This transport device 1 (with different DMAB concentrations) was also used in the later sections (Transportation of Micro-Objects 2-4). The results are shown in Figure 5. The LED light 30 was fixed at an angle of 50° on an optical horizontal moving stage and emitted ultraviolet light with a wavelength of 365 nm (25 mW / cm 2 ) was irradiated. Figure 5 shows that when DMAB was added, the rate of decrease in surface tension increased as the concentration of DMAB added increased. Furthermore, the rate of decrease in surface tension for silicone oil droplets containing 1, 10, and 100 mM DMAB was 2, 3, and 10%, respectively. The addition of DMAB reduces surface tension, but it is presumed that heat generation due to light absorption also plays a role, particularly at high concentrations.

[0038] In addition, ultraviolet light (25 mW / cm ) with a wavelength of 365 nm was applied to the surface of the liquid layer to which the above-mentioned different concentrations of DMAB had been added. 2) was irradiated (for 5-45 seconds), and the change in surface temperature was evaluated. The results are shown in Figure 6. The irradiation method was the same as in Figure 5. The surface temperature was measured using a thermograph (manufactured by FLIR Systems) installed vertically above the transportation device 1. In the case of the 0 mM liquid layer without added DMAB, the temperature did not change because it was not affected by light. On the other hand, in the liquid layers with added DMAB, the temperature began to rise immediately after light irradiation, reached saturation about 10 seconds after irradiation, and remained constant thereafter. Furthermore, the time it took to return to a steady state (temperature before light irradiation) after the LED light was turned off (45 seconds) was about 15 seconds, independent of the DMAB concentration. With a high DMAB concentration, the surface temperature of the liquid layer rose, and it is thought that the micro-object 20 being transported would also be affected by the heat. On the other hand, with a DMAB concentration of about 10 mM, the temperature change due to heat was about +5°C, indicating that there was almost no heat generation.

[0039] (Transportation of Micro-Objects 2) Furthermore, using the transport device 1 with different concentrations of DMAB in the liquid layer, ultraviolet light (wavelength 365 nm, 25 mW / cm 2We investigated the transport of a water droplet (10 μL) on the liquid layer surface when DMAB was irradiated with light. The LED light 30 was fixed to an optical horizontal stage and moved by a screw feed, maintaining an angle of 50°. This irradiation method was also used in the transport of micro-objects 3-4 described below. Figure 7 shows the results of the time course of light irradiation and the water droplet movement distance (displacement) for various DMAB concentrations. These results show that the movement distance increases dramatically when the DMAB concentration is 10 mM. Furthermore, in liquid layers with DMAB concentrations of 0, 1, 10, and 100 mM, the average speeds of the water droplet transport were 0, 0.0008, 0.2704, and 0.0282 mm / s, respectively. Figure 7 also indicates that the water droplet can be transported at a nearly constant speed regardless of the DMAB concentration. This suggests that, when the irradiation intensity is constant, transport efficiency can be improved by adjusting the DMAB concentration within an appropriate range, for example, 5-50 mM, preferably around 10 mM. Furthermore, by changing the DMAB concentration, the speed and distance of water droplet movement can be controlled.

[0040] (Transportation of Micro-Objects 3) Next, we investigated the effect of the irradiation intensity of ultraviolet light (wavelength 365 nm) and the DMAB concentration in the liquid layer on the transport speed of water droplets. Using transport device 1 with different concentrations of DMAB in the liquid layer, we placed a water droplet (10 μL) on the liquid layer and irradiated it with ultraviolet light at an intensity of 5-25 mW / cm. 2 The water droplets were transported while varying the intensity of the ultraviolet light between 100 and 1000 Hz. The results are shown in Figure 8. As is clear from Figure 8, the transport speed increased as the irradiation intensity of the ultraviolet light increased. This tendency was particularly pronounced when the DMAB concentration was 10 mM. This result also indicates that strong light accelerates the photoisomerization reaction, causing the flow of many liquid layers. Therefore, the movement speed of the water droplets can be controlled by changing the intensity of the irradiated light. It is also possible to increase or decrease the irradiation intensity at the irradiated area 35 by shortening or increasing the irradiation distance.

[0041] (Transportation of Micro-Objects 4) Furthermore, we investigated the effect of the amount (size) of water droplets being transported and the DMAB concentration in the liquid layer on the transport speed of water droplets. Using transport device 1 with different DMAB concentrations in the liquid layer, water droplets (10-100 μL) were placed on the liquid layer and exposed to ultraviolet light (wavelength 365 nm) at an irradiation intensity of 25 mW / cm for 40 seconds. 2 The results are shown in Figure 9. As is clear from Figure 9, when the DMAB concentration was 10 mM, the transport phenomenon was reproducibly achieved in the range of droplet volumes from 10 to 100 μL. Although the transport speed tended to decrease as the droplet volume increased, it can be said that even relatively large droplets of 200 μL to 1 mL can be transported sufficiently. Conversely, droplets smaller than 10 μL can also be transported.

[0042] In Figure 10, water droplets of 10 μL (Figure 10(A)), 50 μL (Figure 10(B)), and 100 μL (Figure 10(C)) were transferred using the transport device 1 under the same conditions (DMAB concentration: 10 mM, light intensity: 25 mW / cm 2 ) are shown. As is clear from Figure 10, the smaller the droplet, the faster the transport speed, and the larger the droplet, the slower the transport speed. Furthermore, when UV light was irradiated on the rear side of the droplet (left side in each image) relative to the direction of droplet movement, there was almost no difference in the contact angle between the front and rear. Transport due to heat or photothermal effects also affects the surface tension of the droplet, so in areas where this energy is applied, the surface tension of the droplet decreases, and the contact angle tends to become smaller. However, when the DMAB concentration was 10 mM, the temperature increase due to heat was only about 5°C before and after light irradiation (Figure 6), which means that there was almost no effect on the surface tension of the droplet.

[0043] (Transportation of Micro-Objects 5) FIG. 11 shows a diagram (side view) for explaining the reciprocating transportation of water droplets, and FIG. 12 shows a graph of the displacement during the reciprocating transportation. Next, we performed a round-trip transport of a water droplet (10 μL) using the transport device 1 (the same transport device 1 used in the previous section, "Transportation of Micro-Objects 1") (DMAB concentration: 10 mM) by changing only the irradiation position 35 (Figure 2) while keeping the UV light irradiation angle fixed (50°). The LED light 30 was fixed to an optical horizontal translation stage and moved by a screw feed, maintaining a constant angle. When the light was irradiated past the water droplet (light irradiation from the right, Figure 11(A)), the water droplet moved relatively slowly (Figure 11(B)), with a speed of 0.11 mm / s (Figure 12(A)). On the other hand, when the water droplet was transported in the forward direction of the UV light irradiation (light irradiation from the left, Figure 11(C)), the water droplet moved faster (Figure 11(D)), with a speed of 0.27 mm / s (Figure 12(A)). These results suggest that the direction of UV light irradiation affects the transport speed. Furthermore, when the round-trip transport was repeated, accurate positional movement was repeatedly achieved simply by changing the position of the light irradiation (Figure 12(B)). Therefore, the movement speed of the water droplets can be controlled by changing the position of the light irradiation.

[0044] In this example, the isomerization of DMAB in the liquid layer by UV light irradiation induces a flow in the liquid layer, which transports water droplets floating on the surface. The direction, distance, and speed of water droplet movement can be controlled by changing the light irradiation method (e.g., the light irradiation position, direction, angle, duration, and intensity) and the DMAB concentration.

[0045] Example 2 In Example 1, it was demonstrated that minute objects 20 were water droplets (liquid droplets) and could be transported horizontally without deformation. In this example, a transport device 1 (the transport device 1 used in the above (Transportation of Minute Objects 1)) (DMAB concentration 10 mM) was used to form minute objects 25 by placing multiple minute solids on water droplets 20, as shown in Figure 13(A), and transporting the minute objects 25. This example differs from Example 1 in that a combination of water droplets and minute solids was used as the minute objects, but otherwise the same method and conditions were used as in Example 1. In addition, the LED light 30 was fixed to an optical horizontal movement stage and slid using a screw feed, and moved while maintaining an angle of 50°. The water droplet 20 is sandwiched between a water-repellent mesh (made of polyester, mesh count 39 / cm, wire diameter 55 μm, opening width 199 μm, manufactured by Kureha Co., Ltd.) 21 and the liquid layer of the transport fluid 10. When a water droplet is present between substances, a Laplace pressure is generated due to the difference in surface tension between the water droplet and the surrounding air and liquid layer, resulting in a force F (a force in the opposite direction to the load direction) that lifts the substance placed on the surface (Figure 13(B)). Note that θA in the figure indicates the contact angle of the water droplet 20 with the water-repellent mesh 21. When the water-repellent mesh 21 was placed on the water droplet (50 μL) used as the micro-object 20 in Example 1, the water-repellent mesh 21 had a contact angle θA of 150° or more, and even when placed on the water droplet, the water did not penetrate the water-repellent mesh 21, and the water-repellent mesh 21 was retained on the surface of the water droplet 20 without sinking.

[0046] Furthermore, to transport a minute object 25 (combination) consisting of multiple objects, a polystyrene piece 23 (maximum size 4 × 3 × 3 mm (length × width × height), 0.5 mg) was placed using tweezers on the water-repellent mesh 21. Because the polystyrene piece 23 was blocked by the water-repellent mesh 21, the water droplet 20 did not come into direct contact with the polystyrene piece 23. Then, as in Example 1, ultraviolet light with a wavelength of 365 nm (25 mW / cm ) was applied to the liquid layer surface of the transport fluid 10. 2), the minute objects 25 could be transported while maintaining their stacked state. Figure 14 shows an image observed at this time. As shown in Figure 14, even when multiple minute solids were placed on the water droplet, stable transportation was achieved with almost no effect on the transportation speed. According to this example, by providing a water droplet 20 and a platform such as a water-repellent mesh 21 on top of it, various minute solids and minute liquids (e.g., soft materials, cells, bacteria, viruses, etc.) can be placed on the platform and transported.

[0047] Example 3 A transport device 1 was fabricated in the same manner and under the same conditions as in Example 1, except that the fluid 11 of the transport fluid 10 was changed from silicone oil to oleic acid (manufactured by Kanto Chemical Co., Ltd.) (DMAB concentration 10 mM). The method and conditions for transporting the minute objects 20 were the same as those in Example 1 (Transportation of minute objects 1), except that the minute objects were multiple water droplets 20a, 20b (10 μL, 5 μL) of different volumes. The LED light 30 was handheld and irradiated with ultraviolet light (365 nm, 25 mW / cm) from an oblique angle (maintained at a substantially constant angle within the range of approximately 40-60°). 2 ) was irradiated. Figure 15 shows the observed image at this time. Figure 15(A) shows the observed image when a 5 μL water droplet 20b was transported, Figure 15(B) shows the observed image when a 10 μL water droplet 20a was transported, and Figure 15(C) shows the observed image when the transport of the two water droplets 20a, 20b was completed (dotted line part). In this example as well, as in the other examples, it was confirmed that different water droplets 20a, 20b were able to be transported on the liquid layer surface.

[0048] Example 4 This example is the same as Example 3 in that the minute objects are multiple water droplets 20c and 20d, but differs from Example 3 in that the multiple water droplets 20c and 20d are transported to the same position in the same amount (10 μL). The other conditions were the same as Example 3 (fluid 11 is oleic acid). Assuming the application of the transport device 1 to a microreactor, we attempted to combine two droplets 20c and 20d on the surface of the liquid layer. Figure 16 shows an image of this process. Light (365 nm, 25 mW / cm) was irradiated onto the vicinity of one of the droplets 20c and 20d, droplet 20d. 2 ) and were combined near the center (Fig. 16(C)). Furthermore, by continuing the light irradiation, the two water droplets 20c and 20d could be transported in a combined and linked state without coalescing (Figs. 16(D) and (E)). It is also possible to combine the two water droplets 20c and 20d by irradiating them with light. According to this embodiment, it is possible to transport a plurality of substances to a predetermined location, bind them, and transport them simultaneously. It is also possible to separate the substances after binding.

[0049] Example 5 In this example, a plurality of water droplets 20c and 20d are combined by the method described in Example 4, and then visible light with a wavelength of 465 nm (intensity 25 mW / cm ) is irradiated around the two water droplets 20c and 20d. 2 ) was irradiated obliquely (maintaining a constant angle between approximately 40-60°) using a separate LED light (HLV3-22BL-2C, manufactured by CCS Inc.) that was held by hand. Figure 17 shows the observed image at this time. In this case, the two water droplets 20c and 20d were able to combine and become a single water droplet 20e. As shown in formula (1), visible light reversibly isomerizes DMAB in the liquid layer from cis to trans. At this time, the surface tension of the liquid layer changes (Figure 5), creating conditions that favor the coalescence of the two water droplets 20c and 20d. According to this embodiment, the present invention can be used as a microreactor that does not require a flow path, for example, to combine multiple substances on the surface of a liquid layer. Examples of applications of the microreactor include the development of new drugs and cell culture using a micro-reaction field. [Industrial Applicability]

[0050] The present invention can be used in a variety of technical fields, including microreactors, microchannels, μ-TAS (micro-TAS), microbubbles, bioanalysis, friction control, dirt adhesion prevention, anti-icing, anti-fogging, mist and water collection, nozzle discharge control, water purification, and heat transfer control. [Explanation of symbols]

[0051] 1. Transportation Devices 10 Transport fluid 11 Fluid 13 Photoisomerizable compounds 15 Base material 20 Minute object (water droplet) 21 Water-repellent mesh 23 Polystyrene strips 25 Micro-objects (combinations) 30 LED lights 33 light 35 Irradiation area

Claims

1. A transporter comprising a liquid or semi-solid fluid and a photoisomerizable compound present in the fluid that is isomerized when irradiated with light of a specific wavelength, wherein the isomerization of the photoisomerizable compound causes the fluid to flow, thereby moving micro-objects on the surface of the fluid.

2. 10. The transporter of claim 1, wherein the photoisomerizable compound comprises an azobenzene derivative.

3. A device for transporting a minute object, comprising: a substrate; and the transporter according to claim 1 or 2 provided on the substrate.

4. 4. The device for transporting minute objects according to claim 3, wherein the substrate itself is hydrophobic or the surface of the substrate is subjected to a hydrophobic treatment.

5. 5. The device for transporting minute objects according to claim 4, wherein the fluid has a contact angle of 45 degrees or less with respect to the substrate.

6. 4. The device for transporting minute objects according to claim 3, wherein the minute objects are minute liquid droplets or a combination of minute liquid droplets and minute solids.

7. 4. A transport system for a minute object, comprising: the transport device for a minute object according to claim 3; and light irradiation means for irradiating a fluid with light.

8. 3. A method for transporting a minute object, comprising: holding the transporter according to claim 1 or 2; and irradiating a fluid with light, thereby moving the minute object on the surface of the fluid.

9. A method for transporting micro-objects as described in claim 8, characterized in that at least one of the direction, distance, and speed of movement of the micro-objects on the fluid surface is controlled by changing the method of light irradiation or the concentration of the photoisomerizable compound in the fluid.

10. 9. The method for transporting minute objects according to claim 8, wherein the minute objects are minute liquid droplets or a combination of minute liquid droplets and minute solids.

11. The method for transporting micro-objects described in claim 8, characterized in that the micro-objects include a plurality of micro-droplets, and by irradiating light onto the fluid surrounding at least one of the plurality of micro-droplets, the micro-droplets are moved and two or more micro-droplets are combined together.

12. A method for transporting micro-objects as described in claim 11, characterized in that a photoisomerizable compound that is reversibly isomerized by light of different wavelengths is used as the photoisomerizable compound, and the micro-droplets are bonded together by irradiating them with light of one wavelength, and then the micro-droplets are merged together by irradiating them with light of the other wavelength.

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