KR20210058435A - Free-energy droplet mixing and flow control method - Google Patents

Abstract

According to the present invention, a free-energy droplet mixing and flow control method is provided. A capillary filled with a volatile material having lower surface tension than a target droplet is disposed around the target droplet located inside a sealed case. The size and intensity of the internal flow field of the target droplet can be adjusted while the distance between the center of the target droplet and the capillary, and the size of the capillary are adjusted. It is possible to use a vapor-driven solutal Marangoni effect.

Description

Non-powered micro-droplet mixing and flow control technique {FREE-ENERGY DROPLET MIXING AND FLOW CONTROL METHOD}

The present invention relates to a non-powered microdroplet mixing and flow control technique, and specifically, using a vapor-driven solutal Marangoni effect without applying external forces such as electric force, magnetic force, acoustic force, etc. It relates to a non-powered microdroplet mixing and flow control technique.

Research on microscopic droplets on a substrate can be applied to various biochemical fields such as disease diagnosis (non-patent documents 1 to 3), cell separation (non-patent documents 4 and 5), and inkjet printing (non-patent documents 6).

Such a system has advantages in that it is inexpensive and simple in configuration compared to a continuous fluid-based system. In order to maximize such advantages, it is necessary to minimize the energy required to form a flow in a droplet.

Conventionally, external devices were used to generate electric force (Non-Patent Document 7), acoustic force (Non-Patent Document 8), magnetic force (Non-Patent Document 9), and the like to control the flow in the droplet.

As described above, since the flow control method in a droplet using an external energy source inevitably requires an external accessory, the overall size of the microfluidic system increases and the configuration is complicated.

This leads to an increase in manufacturing cost, and there is a problem in that it is difficult to make a portable microfluidic system required in the market.

On the other hand, the flow inside the droplet can also be induced by using the Marangoni effect.

The factors that cause the marangoni effect can be roughly classified into three types: a temperature gradient, a surfactant, and a solute. (Non-Patent Documents 10 to 12)

Among them, the solute marangoni effect has the advantage of not requiring a separate external device and not contaminating the droplet sample.

Recently, research has been conducted on forming a flow in droplets using the vapor-type solute marangoni effect and controlling the final deposition pattern (Non-Patent Document 13).

In addition, research is being conducted to observe the flow change in the droplet according to the change in boundary conditions generated from the external volatile solution that evaporates relatively quickly (Non-Patent Document 14).

However, studies on the flow control in droplets using the vapor-type solute marangoni effect have not been conducted yet.

J. R. Trantum, D. W. Wright, F. R. Haselton, “Biomarker-mediated disruption of coffee-ring formation as a low resource diagnostic indicator”, Langmuir, 28(4) (2011), 2187-2193. D. Brutin, B. Sobac, B. Loquet, J. Sampol, “Pattern formation in drying drops of blood”, Journal of Fluid Mechanics 667 (2011) 85-95. R. Hernandez-Perez, Z. H. Fan, J. L. Garcia-Cordero, “Evaporation-driven bioassays in suspended droplets”, Analytical Chemistry, 88(14) (2016) 7312-7317. T.-S. Wong, T.-H. Chen, X. Shen, C.-M Ho, “Nanochromatography driven by the coffee ring effect”, Analytical Chemistry, 83(6) (2011) 1871-1873. J.-Y. Jung, H.-Y. Kwak, “Separation of microparticles and biological cells inside an evaporating droplet using dielectrophoresis”, Analytical Chemistry, 79(13) (2007) 5087-5092. D. Kim, S. Jeong, B. K. Park, J. Moon, “Direct writing of silver conductive patterns: Improvement of film morphology and conductance by controlling solvent compositions”, Applied Physics Letters, 89(26) (2006) 264101. D. Mampallil, B. van den Ende, F. Mugele, “Controlling flow patterns in oscillating sessile drops by breaking azimuthal symmetry”, Applied Physics Letters, 99(15) (2011) 154102. G. Destgeer, H. Cho, BH Ha, JH Jung, J. Park, HJ Sung, “Acoustofluidic particle manipulation inside a sessile droplet: four distinct regimes of particle concentration”, Lab on a Chip, 16(4) (2016) 660-667. T. Takei, S. Sakoguchi, M. Yoshida, “Efficient mixing of microliter droplets as micro-bioreactors using paramagnetic microparticles manipulated by external magnetic field”, Jouranl of Bioscience and Bioengineering, 126(5) (2018) 649-652. W. Sempels, R. De Dier, H. Mizuno, J. Hofkens, J. Vermant, “Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system”, Nature Communication, 4 (2013) 1757. B. D. MacDonald, C. Ward, “Onset of Marangoni convection for evaporating sessile droplets”, Journal of Colloid and Interface Science, 383(1) (2012) 198-207. A. Marin, S. Karpitschka, D. Noguera-Marin, MA Cabrerizo-Vilchez, M. Rossi, CJ Kahler, MAR Valverde, “Solutal Marangoni flow as the cause of ring stains from drying salty colloidal drops”, Physical Review Fluids, 4(4) (2019) 041601. R. Malinowski, G. Volpe, I. P. Parkin, G. Volpe, “Dynamic control of particle deposition in evaporating droplets by an external point source of vapor”, Journal of Physical Chemistry Letters, 9(3) (2018) 659-664. O. Hegde, S. Chakraborty, P. Kabi, S. Basu, “Vapor mediated control of microscale flow in sessile droplets”, Physics of Fluids, 30(12) (2018) 122 103. M. A. Wilson, A. Pohorille, “Adsorption and solvation of ethanol at the water liquid-vapor interface: a molecular dynamics study”, Journal of Physical Chemistry B, 101 (16) (1997) 3130-3135. G. Vazquez, E. Alvarez, J. M. Navaza, “Surface tension of alcohol water+ water from 20 to 50°C”, Journal of Chemical & Engineering Data, 40 (3) (1995) 611-614.

The present invention has been devised to solve the various problems of the prior art as described above, and provides vapor-driven solutal Marangoni effects without applying external forces such as electric force, magnetic force, and acoustic force. Its purpose is to provide a non-powered microdroplet mixing and flow control technique used.

In order to achieve the above objects, according to the first embodiment of the present invention, a capillary tube filled with a volatile material having a lower surface tension than the target droplet is disposed around a target droplet located inside a sealed case, and the target liquid It provides a non-powered microdroplet mixing and flow control technique, characterized in that the size and intensity of the flow field inside the target droplet are controlled while adjusting the distance between the center of the enemy and the capillary tube and the size of the capillary tube.

In addition, a plurality of capillaries filled with a volatile material having a lower surface tension than the target droplet may be spaced apart from each other around the target droplet.

In addition, the target droplet is positioned on a glass substrate, the capillary is disposed on the glass substrate by being spaced apart from the target droplet by a predetermined distance, and the vapor of the volatile material evaporated from the capillary is diffused in the direction of the target droplet along the glass substrate. It is characterized by being.

According to a second embodiment of the present invention, a target droplet is located inside a sealed case, and a volatile material having a lower surface tension than the target droplet is attached to the inside of the case, and the distance between the target droplet and the volatile material It provides a non-powered micro-droplet mixing and flow control technique, characterized in that the size and intensity of the flow field inside the target droplet are controlled while controlling.

According to the above-described problem solving means, the present invention has the following effects.

In the present invention, when a volatile solution (ethanol, acetone, etc.) having a lower surface tension than the target droplet is exposed around the target droplet to form a flow inside the target droplet, external forces such as electric force, magnetic force, and acoustic force are applied. It is possible to use the vapor-driven solutal Marangoni effects without doing so, so that the system can be simply configured and the target droplets and samples are prevented from being contaminated.

In addition, according to the present invention, by controlling the distance between the target droplet and the volatile material, and the size of the surface area at which the volatile material is exposed to the target droplet, there is an effect of efficiently controlling the flow in the target droplet.

Accordingly, the present invention is expected to be used in various biochemical fields such as disease diagnosis industry, cosmetics industry, chemical process, and coating industry.

In addition, it can be a technology that can compensate for the limitation that a microtiter plate is unsuitable for a small volume of solution.

Microplates for small volumes (less than 1 µl) are difficult to commercialize because it is difficult to secure a sufficient time until reaction due to the fact that the evaporation of the solution occurs quickly and the surface ratio to volume is high.

In order to suppress evaporation of the solution to be observed, if volatile substances are attached to the cover used to block the inside of the micro-quantity plate from external effects, it can cause a smooth mixing of the observed solution and cause a reaction within a limited time, thereby limiting the limitations of existing technologies. You will be able to overcome it.

1 is a diagram schematically showing a system for implementing a first embodiment of a non-powered microdroplet mixing and flow control technique according to the present invention.
FIG. 2 is a view showing a target droplet and a capillary tube viewed from above in FIG. 1.
3 is a view showing a state as viewed from the side of the target droplet and the capillary in FIG. 1.
4 is a photograph of observing the inside of a target droplet when there is no vapor spot due to a volatile substance around the target droplet.
5 is a photograph of observing the inside of a target droplet when there is one vapor point due to a volatile substance around the target droplet.
6 is a diagram schematically showing a theoretical model for explaining a non-powered microdroplet mixing and flow control technique according to the present invention.
7 is a photograph showing a state in which a marangoni flow occurs inside a target droplet when there is one vapor point due to a volatile substance around the target droplet.
8 is a graph showing the relationship between the mass fraction of ethanol and the surface tension.
9 is a graph comparing experimental and theoretical values showing the maximum velocity of flow with respect to the distance between the center of the target droplet and the capillary tube.
10 is a graph comparing an experimental value and a theoretical value showing the frequency with respect to the distance between the center of the target droplet and the capillary tube.
11 is a graph comparing the theoretical value and the experimental value of the frequency obtained in FIG. 10.
12 is a photograph showing a flow state inside a target droplet according to the number of vapor points caused by volatile substances located around the target droplet.
13 is a graph showing the number of vortices generated inside the target droplet according to the number of vapor points caused by volatile substances located around the target droplet.
14 is a graph showing the relationship between the difference in local surface tension and the maximum velocity of the flow.
15A to 15D show the cases in which the number of vapor points due to volatile substances located around the target droplet is 1 to 4, respectively, and (e) shows the case where there are no vapor points due to volatile substances located around the target droplet. This is a photograph showing the shape of the flow inside the target droplet and the degree of mixing over time.
16 is a graph showing the standard deviation over time in the cases of FIGS. 15A to 15E.
FIG. 17 is a graph showing the time it takes for the target droplets to be completely mixed in the case of FIGS. 15A to 15E.
18 is a photograph showing the time required for mixing when only diffusion is used when mixing target droplets in a trace quantity plate.
19 is a photograph showing the time required for mixing when a volatile substance is wetted on a filter paper and then exposed to the target droplet when mixing the target droplet in a trace quantity plate.

Hereinafter, a preferred embodiment of a non-powered microdroplet mixing and flow control technique according to the present invention will be described in detail with reference to the accompanying drawings. For reference, terms and words used in the present specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention. In addition, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all the technical ideas of the present invention, so various alternatives that can be substituted for them at the time of application It should be understood that there may be equivalents and variations.

1 is a diagram schematically showing a system for implementing a first embodiment of a non-powered microdroplet mixing and flow control technique according to the present invention.

In the non-powered microdroplet mixing and flow control system according to the present invention, as shown in FIG. 1, when the 532 nm laser (L) is exposed to the droplet (D), the fluorescent particles (F) added to the droplet (D) are 607 Emits a signal (S) of nm.

At this time, the size of the fluorescent particles (F) is 1.9 μm and the density is 1.05 g/cm 3.

Using the optical filter 5, only the signal S emitted from the fluorescent particles F is read from the ultra-high-speed camera 6 connected to the inverted microscope 4, and the particle image velocimetry experiment is conducted.

In order to prevent external influences, the entire system is wrapped using a case (1) made of acrylic.

In the photograph of FIG. 5 to be described later, a vapor-type solute marangoni flow field can be seen, and the yellow mark indicates the location (vapor point) of the capillary tube 2 containing ethanol.

Due to the high solubility of ethanol in water, marangoni flow occurs until the ethanol or water droplets completely evaporate.

FIG. 2 is a view showing a state viewed from above of a target droplet and a capillary tube in FIG. 1, and FIG. 3 is a view illustrating a state viewed from a side of the target droplet and a capillary tube in FIG. 1.

As a method for generating a flow inside the microdroplet D on the substrate 3, there is a method of placing ethanol in the capillary tube 2 using a capillary effect and placing it around the droplet D.

At this time, ethanol evaporates from the tip of the capillary tube (2). Since ethanol vapor has a higher molecular weight than the atmosphere, most of the ethanol vapor evaporated from the capillary tube (2) diffuses along the glass substrate (3).

The ethanol vapor is distributed in a relatively large amount compared to a region near the capillary tube 2 and far away.

Therefore, in the region close to the capillary tube 2, the surface tension is low due to the relatively large amount of ethanol vapor. Since the marangoni flow occurs from a region having a low surface tension to a region having a high surface tension, the flow occurs as shown in the arrow direction of FIG. 2.

In this experiment, the flow field was observed while controlling two variables. The first variable is the distance (l) between the capillary and the center of the droplet, and the second is the size of the capillary.

By changing these two parameters, the ethanol concentration at the droplet interface was controlled and the flow within the droplet was controlled.

The flow in the section where the distance (l) between the capillary tube and the droplet is 1.5 to 4 mm was observed through this experiment.

In addition, the ethanol vapor flow rate was adjusted using capillary tubes of three sizes (r ₀ is 0.25, 0.375, 0.55 mm).

In addition, the volume of the droplet is 2.0±0.2 μl, the radius (R) is 1.3 to 1.6 mm), and the height (h) is 0.52 to 0.73 mm.

FIG. 4 is a photograph of observing the inside of a target droplet when there is no vapor spot due to a volatile substance around the target droplet, and FIG. 5 is a photograph of observing the inside of a target droplet when there is one vapor spot due to a volatile substance around the target droplet.

Through the pictures, we checked whether the flow field was created according to the presence or absence of an external steam point. In this and subsequent photos, the visibility was improved by using a contrast-limited adaptive histogram smoothing (CLAHE) and a highpass filter.

As shown in FIG. 4, when there is no vapor point, it can be seen that internal flow hardly occurs. In addition, no flow due to the thermal Marangoni effect was observed even when the laser was used.

6 is a diagram schematically showing a theoretical model for explaining the non-powered microdroplet mixing and flow control technique according to the present invention. This is a photograph showing the state where the swine flow occurred.

here,

c _A is the concentration of ethanol in the air,

r ₀ is the radius of the capillary tube,

c ₀ is the initial concentration of ethanol at the capillary tip,

l is the distance between the droplet center and the capillary tip,

R is the radius of the droplet.

This is an explanation of the theoretical model used to analyze the vapor-type solute Marangoni flow field. To calculate the local surface tension difference, the ethanol concentration in air was first calculated using the one-dimensional steady-state Poisson diffusion equation in a spherical coordinate system.

According to molecular dynamics studies, when ethanol molecules dissolve in water, they reach a state of thermal equilibrium in supicoseconds, and then cannot escape from the surface due to lack of kinetic energy.

In other words, since the ethanol molecule dissolves rapidly into water, the ethanol concentration in water and air is almost the same.

Therefore, the assumption that the ethanol concentration is the same in air and water at the same location can be used.

It can be seen from the photograph of FIG. 7 that marangoni flow hardly occurs in the region located opposite to the capillary tube. This shows that it is difficult for the ethanol vapor to reach the region opposite where the capillary is located.

In this experimental configuration, the point at which the concentration of ethanol is maximized is on the left side based on FIG. 6, and the portion at which the concentration becomes minimum is at the top or bottom.

here,

c _w is the concentration of ethanol at the droplet interface,

Re is the Reynolds number,

ε is the aspect ratio (height/radius) of the droplet,

ρ is the density of water,

V is the velocity of the flow,

μ is the viscosity of the water,

Δγ (delta gamma) is the local surface tension difference,

β is the proportionality constant.

The difference in maximum ethanol concentration can be calculated using the maximum and minimum values of the ethanol concentration.

The difference in the maximum ethanol concentration is an index that can confirm the ethanol distribution at the droplet interface and has a proportional relationship with the local surface tension difference.

In this study, the product of the Reynolds number and the aspect ratio of the droplet shape is less than 1. From this, it can be seen that the viscous force is mainly balanced with the marangoni force.

The theoretical speed equation was obtained through a simple similarity law of marangoni force and viscous force. It is possible to check how _{the constants β and c 0} used in this study were calculated through FIG. 8 to be described later.

8 is a graph showing the relationship between the mass fraction of ethanol and the surface tension.

(Non-patent document 16)

First, the proportionality constant was calculated using the relationship between the mass fraction of ethanol and the surface tension. Here, it was calculated using the assumption that the change in surface tension is linear at low mass fractions.

Second, it is the initial concentration value at the capillary surface. This constant was calculated using Dalton's law of partial pressure in a closed system.

9 is a graph comparing experimental and theoretical values showing the maximum velocity of flow with respect to the distance between the center of the target droplet and the capillary tube.

The Marangoni flow field was analyzed by varying two variables, the distance between the droplet center and the capillary tube and the size of the capillary tube.

As shown in FIG. 9, it can be seen that the maximum speed decreases as the distance l increases.

From the ethanol concentration equation, it can be confirmed that the ethanol concentration at the droplet surface is inversely proportional to the distance between the capillary tube and the droplet interface.

If the capillary is placed at a relatively long distance from the droplet, the difference in maximum ethanol concentration decreases.

The decrease in the difference in the maximum ethanol concentration leads to a decrease in the difference in local surface tension, which decreases the intensity of the marangoni flow in the droplet.

Another variable, the size of the capillary, can be adjusted to control the flow of ethanol vapor that diffuses from the capillary.

Increasing the diffused ethanol vapor flow rate causes the dissolution of relatively more ethanol molecules at the droplet interface, which causes an increase in the difference in the maximum ethanol concentration, thereby increasing the intensity of the marangoni flow.

In FIG. 9, error bars represent a vibrating marangoni flow pattern. The solid lines were calculated using the theoretical velocity equation obtained earlier. The colored area is shown in the graph taking into account the change in droplet radius and height.

10 is a graph comparing an experimental value and a theoretical value showing the frequency with respect to the distance between the center of the target droplet and the capillary tube.

In this study, the frequency was calculated using a fast Fourier transform. It can be seen that the frequency also decreases as the distance l between the capillary tube and the center of the droplet increases.

The solid line and the colored area represent the theoretical model of the frequency. The theoretical frequency value was calculated by dividing the theoretical velocity by the radius of the droplet.

The reason for dividing by the radius of the droplet is that the dominant flow within the droplet moves in the x direction from the center of the droplet, that is, by a distance R based on FIG. 2.

11 is a graph comparing the theoretical value and the experimental value of the frequency obtained in FIG. 10.

The theoretical frequency obtained in FIG. 10 and the frequency obtained by experiment were compared through a graph. Through this graph, you can check the matching trend.

12 is a photograph showing a flow state inside a target droplet according to the number of vapor points caused by volatile substances located around the target droplet.

Up to 8 vortices were created using 1 to 4 capillaries. In FIG. 12, the red arrow indicates the direction of the marangoni flow, and the yellow mark indicates the position (vapor point) of the capillary tube.

It can be seen that when the number of vapor points is increased, the area where no flow occurs gradually decreases.

13 is a graph showing the number of vortices generated inside the target droplet according to the number of vapor points caused by volatile substances located around the target droplet.

The measurement result of the vapor-type solute marangoni flow field according to the number of capillaries can be seen through FIG. 13.

In this experiment, the distance between the droplet center and the capillary was maintained at 2.1 mm, and the radius of the capillary was also fixed at 0.25 mm.

One ethanol vapor point creates a pair of vortices. This is due to the symmetric boundary condition when the ethanol component diffuses in the gas phase. The relationship between the number of vortices (M) and the number of external vapor points (N) is M=2N.

14 is a graph showing the relationship between the difference in local surface tension and the maximum velocity of the flow.

The initial concentration and proportionality constant at the capillary cross section change the local surface tension difference and maximum velocity.

In order to confirm the change of the internal flow rate according to the type of volatile solution, five or more experiments were performed on each volatile solution with a capillary tube size and a capillary tube size having a constant distance between the capillary tube and the center of the droplet.

It can be seen that the relationship between the local surface tension difference and the maximum velocity is proportional.

15A to 15D show the cases in which the number of vapor points due to volatile substances located around the target droplet is 1 to 4, respectively, and (e) shows the case where there is no vapor points due to volatile substances located around the target droplet. As, it is a photograph showing the shape of the flow inside the target droplet and the degree of mixing over time, FIG. 16 is a graph showing the standard deviation over time in the cases of FIGS. 15A to 15E, and FIG. In the cases (a) to (e), it is a graph showing the time it takes for the target droplet to be completely mixed.

This flow control technique was applied to the mixing in droplets. 15 shows the flow shape in the droplet and the degree of mixing over time when the number of external vapor points (N) is adjusted to 1-4. The time taken for the droplets to be completely mixed when ethanol and acetone are used is shown in FIG. 17.

FIG. 18 is a photograph showing the time required for mixing when only diffusion is used when mixing target droplets in a trace quantitative plate, and FIG. 19 is a case where volatile substances are wetted in filter paper and exposed to target droplets when mixing target droplets in a trace quantitative plate This is a picture showing the time it takes to mix.

For practical application, the mixing of droplets in a micro-quantity plate was tested.

The difference in time required for mixing was compared when using only diffusion when mixing a droplet sample in a trace quantity plate (FIG. 18) and when using the vapor-type solute marangoni effect (FIG. 19).

18 shows only the droplets are placed on the trace quantity plate, and in FIG. 19, the filter paper was soaked with acetone and exposed to the droplets for about 7 seconds, and then the filter paper was removed. It can be seen that sample mixing proceeds about 5 times faster when the cover is used.

[Application and application field]

The droplet-based microfluidic system on a substrate is applied in various fields such as bioassays, disease diagnosis, coating and printing due to its economical and simple configuration.

The performance of the microfluidic system described above largely depends on how effectively flow control can be achieved.

Therefore, a precise analysis of the internal flow field in the droplet must be carried out in advance.

Therefore, the technology for controlling the internal flow field of stationary droplets is a technology that can be applied to the development of mixing, particle separation, and uniform coating methods.

In the flow control method using an external volatile substance proposed in the present invention, since the vapor supplied from the outside is automatically disappeared by evaporation after the marangoni effect occurs, the change of the final sample can be minimized.

Because of these characteristics, the solute marangoni effect can be applied to processes that require handling samples sensitive to temperature or external conditions, such as cell separation and bioassay.

If the method proposed in the present invention is used in the coating and printing process, it is possible to reduce the cost incurred during initial system design.

Previously, when a mixture material was determined, candidate solutions with various mixing ratios were prepared, and a solution optimized for the process was selected through trial and error.

By using the vapor-type solute marangoni effect, uniform coating can be performed by controlling the vapor exposure area and the distance between the vapor point and the target droplet without having to make a separate mixture.

In addition, the system using the solute marangoni effect is suitable for constructing a portable microfluidic system because it has the advantages of simple configuration and low price.

[marketability]

As we enter an aging society, people's interest in health is constantly increasing.

Accordingly, the demand for technology capable of diagnosing diseases continues to increase.

The global blood diagnostic device market is worth 50 trillion won.

Various blood diagnostic devices such as diabetes meter to cancer diagnostic device are on the market.

When using commercially available blood test methods, it takes 2-3 days to obtain results after the test.

If this is replaced by a portable disease diagnosis device, there is an advantage that users can check their health status from time to time and receive more accurate diagnosis through accumulated data.

Due to these advantages, many domestic and foreign bio companies are increasing their investment in technology for early diagnosis of various diseases with a small amount of blood.

One of the important factors in the mobile healthcare business is a simple system and economics.

Therefore, it is expected that effective disease diagnosis will be possible if the flow control method proposed in the present invention is used.

[Technology commercialization prospect]

This technique is characterized by the ability to form a pair of vortices per vapor point.

It is expected that effective self-mixing and particle separation can be performed by generating a large number of vortices in the droplet.

There are several ways to control the flow of large droplets.

There is a method of forming a flow of alcohol vapor between the droplets to simultaneously cause flow in a large amount of droplets.

In addition, if the container to which the volatile material is attached is covered over the microfluidic system, the flow of marangoni in the droplets may occur.

In addition, if a structural device capable of generating solute marangoni flow is developed, it will be possible to satisfy the flow conditions optimized for the system.

[Companies applicable to the present invention]

The technology for diagnosing diseases through a small amount of blood and making treatments using blood is continuously being developed by healthcare and bio companies such as BBB, GC Green Cross, and Bertis.

In this respect, a technique capable of mixing samples and separating particles without an additional energy source would be useful.

In addition, the vapor-type solute marangoni effect can be applied to OLED manufacturing technology using a solution process.

The solution process has advantages such as low equipment investment cost and high material use efficiency compared to the vacuum deposition process.

If alcohol vapor is exposed when an OLED material is coated using a solution process that forms a thin film through a wet process such as spin coating, inkjet printing, and nozzle printing, a uniform deposition layer can be obtained and the process can be simplified.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those of ordinary skill in the following.

1: case 2: capillary tube
3: glass substrate 4: microscope (lens)
5: optical filter 6: camera
D: droplet F: fluorescent particles

Claims (4)

A capillary tube filled with a volatile substance having a lower surface tension than the target droplet is disposed around the target droplet located inside the sealed case,
A non-powered microdroplet mixing and flow control technique, characterized in that, while adjusting the distance between the center of the target droplet and the capillary tube and the size of the capillary tube, the size and intensity of the flow field inside the target droplet are controlled.
The method according to claim 1,
A non-powered microdroplet mixing and flow control technique, characterized in that a plurality of capillaries filled with a volatile material having a lower surface tension than the target droplet are disposed around the target droplet to be spaced apart.
The method according to claim 1 or 2,
The target droplet is located on the glass substrate, the capillary is disposed on the glass substrate by being spaced apart from the target droplet by a predetermined distance, and the vapor of the volatile material evaporated from the capillary is diffused in the direction of the target droplet along the glass substrate. Non-powered microdroplet mixing and flow control technique characterized.
Place the target droplet inside the sealed case,
A volatile material having a lower surface tension than the target droplet is attached to the inside of the case,
A non-powered microdroplet mixing and flow control technique, characterized in that the size and intensity of the flow field inside the target droplet are controlled while controlling the distance between the target droplet and the volatile material.

Images