KR20230032806A - Droplet generation with integrated 3d pneumatic actuator for orifice control, and menufacturing method of the same - Google Patents

Abstract

The present invention is to provide a droplet generator capable of adjusting the size of droplets in a wide range according to needs with a single element. Embodiments provide an orifice-variable micro droplet generator integrated with a three-dimensional pneumatic actuator and a manufacturing method thereof. According to the embodiments, the droplet generator comprises a variable orifice which determines the size of droplets to be generated, and a three-dimensional pneumatic actuator which surrounds the variable orifice and is transformed by pneumatic pressure to adjust the size of the variable orifice.

Description

Orifice variable micro droplet generator with integrated three-dimensional pneumatic actuator and manufacturing method thereof

Various embodiments relate to microfluidic devices, and more particularly, to a variable-orifice micro-droplet generator integrated with a three-dimensional pneumatic actuator and a manufacturing method thereof using a 3D printing mold removal technique.

A microfluidic system is a fluid system having a micro-sized channel, and has the advantage of reducing the consumption of reagents, shortening the reaction time, and performing experiments under various conditions in one system. It is widely used in chemical and biological fields such as DNA analysis, cell culture, cell analysis, biopsy, and drug delivery.

A droplet generator composed of complex microfluidic elements such as microchannels and junctions is a microfluidic device that provides a cost-effective, powerful, and high-throughput platform by producing droplets having a desired volume and composition with a small amount of reagents. Droplets are formed by interrupting the flow of the dispersed phase fluid by the continuous phase fluid when two or more immiscible liquids injected from different inlets, the disperse phase fluid and the continuous phase fluid, meet at a junction. The formed droplets are classified and collected through the outlet channel and used according to the purpose. In addition to the characteristics of the fluids themselves and the velocity of the fluids, the size and shape of the microfluidic channel that provides the fluid flow boundary has a fundamental effect on the formation of droplets.

Materials such as glass, silicon, polydimethylsiloxane (PDMS), and polymethyl methacrylate (PMMA) have been mainly used to fabricate microfluidic devices. PDMS, which has high biocompatibility and non-toxicity, is a widely used material for fabricating microfluidic devices because it is suitable for cell culture, which is one of the major applications of microfluidic devices. In addition, there are advantages such as chemical inertness based on low surface energy, high optical transparency, low electrical conductivity, low unit cost, and easy manufacturing method using casting.

Microfluidic systems are mainly fabricated through soft lithography, a type of lithography, using PDMS. Soft lithography is a technique of casting a soft polymer such as PDMS by using a photoresist mold manufactured in a semiconductor process, and a microfluidic device is a technique in which a molded PDMS device is exposed to oxygen plasma. It is implemented by exposing to and bonding to a glass substrate.

Soft lithography technology has limitations in fabrication possible structures due to the technical limitations of fabricating 2D flat layers in order to fabricate 3D devices and then aligning and bonding them. However, with the recent introduction of 3D printing technology to the manufacture of microfluidic devices, it has become possible to manufacture various types of structures that were considered almost impossible in the past. However, the direct 3D printing technology of PDMS, a material mainly used to fabricate microfluidic devices, has difficulties in manufacturing micro devices due to its resolution limitations.

Therefore, a manufacturing method using casting technology by outputting a mold for manufacturing a microfluidic device with a high-resolution 3D printer has been developed. In casting a microfluidic device, it is important to smoothly remove the mold so as not to damage the cast polymer, and the mold removal method can be divided into a physical removal method and a chemical removal method. The physical mold removal method, which is a method of fixing the cast polymer and extracting the inner mold from the polymer, may cause physical damage in a complex shape such as a curved channel rather than a straight channel, so the structure of the mold is limited for smooth extraction.

The chemical template removal method melts the template by applying heat to the mold or immersing it in a soluble solution, so it is possible to implement a micro-sized PDMS device suitable for a microfluidic device without limiting the shape of the mold. However, the chemical mold removal method is difficult to apply to ABS (Acrylonitrile butadiene styrene), PLA (Polylactic acid), and PP (Polypropylene), which are widely used 3D printer materials and have thermal and chemically relatively stable properties, so PVA (polyvinyl alcohol) Materials such as or wax are applied.

The precise droplet formation control of the droplet generator is divided into a passive method and an active method. Passive droplet generators use the interfacial tension and shear forces of two immiscible fluids. When the shear force becomes larger than the interfacial tension due to the tendency of the interfacial tension to minimize the interfacial area, the dispersed phase liquid is separated from the channel wall and forms droplets due to capillary instability. Manual droplet generators can control the size of droplets by controlling the flow rate of the two fluids, but there is a limit to quickly and flexibly manipulating the size of droplets in a wide range. In contrast, active droplet generators can utilize an additional operating source outside the channel to produce droplets of various sizes.

Conventionally, soft lithography has been used to create channel steering devices, which has inherent structural constraints that limit control of droplets. In general, since a microfluidic device is manufactured by stacking two or more 2D layers pre-formed through a soft lithography process, the final device has no choice but to have a limited shape of 2.5 dimensions in the stacking direction. In addition, this method has a complicated manufacturing process, and there is a risk of fluid leakage at the bonding surface between the layers at high pressure. On the other hand, a microfluidic chip manufactured by a relatively simple process of casting an elastomer in a 3D printed mold has a three-dimensional structure with no interlayer interface and at the same time an unrestricted shape in all directions. In addition, 3D printing technology enables rapid prototyping compared to processes using photolithography.

Achieving a full 3D structure has additional advantages: First, the 2.5D droplet generator fabricated using soft lithography consists of a rectangular cross-section channel with stagnant fluid flow at the channel edges, whereas in the 3D droplet generator mainly composed of circular cross-section channels, the fluid has a uniform velocity in the cross-sectional direction of the channel. have a profile Also, in 2.5D rectangular channels, the dispersed phase fluid can adhere to the relatively short-sided wall surfaces of the rectangle, whereas in 3D circular channels, the dispersed phase fluid is uniformly surrounded by the continuous phase fluid, reducing the wettability of the dispersed phase fluid. Wetting of fluids not only hinders droplet breakup, but also causes unwanted adsorption or damage of cells in biological applications.

Various embodiments provide a variable-orifice micro-droplet generator integrated with a three-dimensional pneumatic actuator and a manufacturing method thereof.

A droplet generator according to various embodiments includes a variable orifice that determines the size of the generated droplet, and a three-dimensional pneumatic actuator that surrounds the variable orifice and adjusts the size of the variable orifice by being deformed by pneumatic pressure.

A method of manufacturing a droplet generator according to various embodiments includes preparing a mold, applying an elastic material to the mold, and forming the droplet generator; and removing the mold from the droplet generator in a chemical manner to obtain the droplet generator.

According to various embodiments, in order to adjust the size of a droplet in a wide range as needed with a single element, a three-dimensional pneumatic actuator of triangular cross section is built around a flow-focusing joint to adjust the size of a variable orifice. A droplet generator capable of controlling , has been realized, and can be used for cell analysis and encapsulation of various sizes, production of functional microparticles, and the like.

According to various embodiments, a three-dimensional pneumatic actuator surrounding the variable orifice controls the size of the variable orifice and, consequently, the size of the droplet formed by causing geometrical deformation of the membrane through expansion by air pressure. The variable orifice and three-dimensional pneumatic actuator were designed with a triangular cross section that reduces the hydraulic diameter the most under the same pneumatic pressure among several geometrical structures. As a result, it was experimentally proven that the droplet generator with a variable orifice can reduce the droplet size without changing the flow rate, and that the droplet can be controlled in a wider range of 259.3% compared to the conventional fixed orifice structure.

According to various embodiments, the 3D micro-droplet generator is fabricated by 3D printing dissolvable mold technology to have a complete 3D structure within a single body of PDMS, which could not be achieved with conventional microprocessing techniques, as well as Even a structure without joint surfaces has been realized.

1 is a diagram illustrating a drop generator with a typical fixed orifice.
2 is a diagram illustrating a droplet generator with a variable orifice incorporating a three-dimensional pneumatic actuator according to various embodiments.
FIG. 3 is an enlarged view of a variable orifice in a droplet generator 100 in which a three-dimensional pneumatic actuator is integrated according to various embodiments.
4 is a view for explaining a change in cross-sectional shape of a variable orifice and a fluid channel in a droplet generator in which a three-dimensional pneumatic actuator is integrated according to various embodiments.
5 is diagrams illustrating a manufacturing method of a droplet generator integrated with a three-dimensional pneumatic actuator according to various embodiments.
6 are diagrams illustrating manufacturing results of a droplet generator in which a three-dimensional pneumatic actuator is integrated according to various embodiments.
7 is diagrams illustrating an experimental configuration for a droplet generator in which a three-dimensional pneumatic actuator is integrated according to various embodiments.
8 is a diagram showing experimental results for a droplet generator in which a three-dimensional pneumatic actuator is integrated according to various embodiments.
9 and 10 are diagrams for describing performance of a droplet generator integrated with a 3D pneumatic actuator according to various embodiments.

Hereinafter, various embodiments of this document will be described with reference to the accompanying drawings.

1 is a diagram showing a droplet generator 10 having a conventional fixed orifice 11 . FIG. 2 is a diagram illustrating a droplet generator 100 having a variable orifice 110 incorporating a three-dimensional pneumatic actuator 120 according to various embodiments.

1 and 2, in the droplet generators 10 and 100, two channels through which the continuous-phase fluid flows and one channel through which the dispersed-phase fluid flows form a joint, pass through narrow orifices 11 and 110, and It forms a fluid focusing structure in which enemies are formed. The diameter D _d of a droplet generated in the fluid focusing structure is proportional to a number of variables as shown in [Equation 1] below.

where γ is the interfacial tension, d _h is the hydraulic diameter of the orifice (11, 110), and η _c and u _c are the viscosity and velocity of the continuous phase, respectively.

As shown in FIG. 1, the existing droplet generator 10 has an orifice 11 of a fixed size in the design stage, so the size of the generated droplet mainly depends on the speed of the injected fluids, and therefore changes. quantity is limited. In other words, to obtain droplets of various sizes, multiple droplet generators 10 each having orifices 11 of different diameters are required.

On the other hand, in the droplet generator 100 according to various embodiments, as shown in FIG. 2, the variable orifice 110 and the three-dimensional pneumatic actuator 120 surrounding the center of the variable orifice 110 along the downstream channel includes Since the droplet generator 100 has the variable orifice 110 controlled by the three-dimensional pneumatic actuator 120, the size of the droplet can be adjusted with a large change width according to the changing hydraulic diameter as well as the speed of the fluid. Therefore, the functions of the droplet generators 10 each having a plurality of fixed orifices 11 are covered with only a single element.

According to various embodiments, the droplet generator 100 includes a variable orifice 110 , a three-dimensional pneumatic actuator 120 , an abutment 130 , and a fluid channel 140 . The variable orifice 110 determines the size of the droplet. That is, the size of the droplet is determined according to the size of the variable orifice 110 . The three-dimensional pneumatic actuator 120 surrounds the variable orifice 110 and is deformed by air pressure to adjust the size of the variable orifice 110 . Specifically, the three-dimensional pneumatic actuator 120 surrounds the variable orifice 110 with a membrane interposed therebetween and contracts the diameter of the variable orifice 110 while being expanded by air pressure. Through this, the size of the variable orifice 110 is reduced, thereby reducing the size of the droplet. The junction 130 communicates with the variable orifice 110 at the front end of the variable orifice 110, and fluids used to generate droplets meet. Specifically, at the junction 130, two channels through which the continuous-phase fluid flows and one channel through which the disperse-phase fluid flows meet. The fluid channel 140 communicates with the variable orifice 110 and forms a uniform flow of fluids. At this time, the variable orifice 110 and the joint 130 are coupled to the fluid channel 140 .

FIG. 3 is an enlarged view of a variable orifice 110 in a droplet generator 100 in which a three-dimensional pneumatic actuator 120 is integrated according to various embodiments. In FIG. 3, the inside of the three-dimensional pneumatic actuator 120 and the variable orifice 110 is empty, and the area (white) between the three-dimensional pneumatic actuator 120 and the variable orifice 110 is a film filled with PDMS. is considered to be

Referring to FIG. 3 , a mechanism of a variable orifice 110 for adjusting the size of a droplet is shown. At this time, the diameter of the variable orifice 110 is changed according to the air pressure applied to the three-dimensional pneumatic actuator 120 . Specifically, the three-dimensional pneumatic actuator 120 is expanded by applying air pressure using an external pump, and as a result, the diameter of the variable orifice 110 in contact with the inner membrane is contracted. Since it is possible to manufacture a complete three-dimensional microstructure by applying the 3D printing dissolution molding technique, the triangular cross-section variable orifice 110 and the variable orifice 110 in all directions, which could not be achieved with conventional manufacturing techniques, surround the variable orifice 110 The realization of a three-dimensional pneumatic actuator 120 was possible. In addition to the variable orifice 110 portion, the fluid channel 140 is designed with a circular cross section to form a uniform flow of fluid flowing through the fluid channel 140 and to be advantageous in controlling the size of droplets. In addition, it is designed as a tip structure with a circular cross-section in which the tip of the dispersed phase flow protrudes from the junction 130 of the variable orifice 110, and this tip reduces the area of the continuous phase channel at the junction 130, thereby momentarily causing the shear force of the continuous phase. increases and contributes to the stable formation of droplets.

FIG. 4 is a view for explaining changes in cross-sectional shapes of a variable orifice 110 and a fluid channel 140 in a droplet generator 100 in which a three-dimensional pneumatic actuator 120 is integrated according to various embodiments. In FIG. 4 , (a) and (b) show changes in cross-sectional shape of the variable orifice 110, and (c) shows changes in cross-sectional shape of the fluid channel 140.

Referring to FIG. 4, the cross-sectional shape having the largest hydraulic diameter change of the variable orifice 110 by the three-dimensional pneumatic actuator 120 is analyzed using the solid mechanics module of COMSOL Multiphysics, a multiphysics analysis program. It became. The hydraulic diameter is a parameter used to convert a non _- circular channel into a circular channel of equivalent diameter, expressed as d _h =4 A _C / P , where AC is the area of the cross-sectional area inside the channel and P is the circumference of the channel.

As shown in (a) of FIG. 4, considering the performance of the 3D printer used in the process, the deformation of the variable orifice 110 of a circular channel having a diameter of 600 μm and a triangular, quadrangular, or pentagon having the same hydraulic diameter is It was compared according to the pressure applied to the surrounding three-dimensional pneumatic actuator 120. The hydraulic diameter of a circle with a diameter of ω is ω , while the hydraulic diameters of a triangle, square, and pentagon with side length ω are ω /√3, ω , and ω /tan36°, respectively. The film between the variable orifice 110 and the three-dimensional pneumatic actuator 120 has a thickness of 250 μm in consideration of the output state, and as shown in (b) of FIG. 4, the shape of the three-dimensional pneumatic actuator 120 is variable It follows the cross-sectional shape of the orifice 110. The entire volume of the three-dimensional pneumatic actuator 120 is designed identically, and the same pressure is applied to expand. Considering the durability of the elastic polymer constituting the body of the droplet generator 100, the expansion of the three-dimensional pneumatic actuator 120 by the air pressure applied up to 120 kPa evenly compresses the outside of the membrane. This causes a geometrical deformation in the inside direction of the variable orifice 110 and is expressed as a decrease in hydraulic diameter. Regardless of the shape of the cross section, it is confirmed that each variable orifice 110 having the same hydraulic diameter changes greatly in the order of a triangle, a rectangle, a pentagon, and a circle as the pneumatic pressure increases. Due to the external load uniformly distributed around the variable orifice 110, there is no significant change in deformation of the circular variable orifice 110. On the other hand, in the polygonal variable orifice 110, since the vertex serves as a support, it hardly moves, but the deformation is concentrated in the center of each side of the polygon, so that the hydraulic diameter can change more easily than that of the circular variable orifice 110. . In particular, the triangular variable orifice 110 has a hydraulic diameter of 415.1 μm, which is 69.2% of the original size, when a pressure of 120 kPa is applied to the three-dimensional pneumatic actuator 120, which is the largest reduction among several structures. However, the hydraulic diameter difference between the polygonal and circular variable orifices 110 decreases in the order of triangle, quadrangle, and pentagon, so that the hydraulic diameter difference between the pentagonal variable orifice 110 and the circular variable orifice 110 is within 1.7%. It was insignificant. Therefore, analysis of polygons larger than pentagons is unnecessary.

In addition, as shown in (c) of FIG. 4 , numerical analysis was performed on the fluid flow according to the change in the cross-sectional shape of the fluid channel 140 . The circular fluid channel 140 of the designed droplet generator 100 has a diameter of 1000 μm and the triangular variable orifice 110 has a hydraulic diameter of 600 μm. When water was injected at 120 μL/min into the fluid channel 140 under the non-slip condition, the velocity of the fluid was depicted. As the fluid flows from the circular fluid channel 140 to the triangular variable orifice 110, the flow rate at the center increases by 1.62 times due to the decrease in hydraulic diameter. Moreover, since the protruding part of the triangle in the variable orifice 110 is as small as 3.85% of the area of the triangle, it is considered not to have a significant effect on the stagnation of the fluid.

5 is diagrams illustrating a manufacturing method of a droplet generator 100 in which a three-dimensional pneumatic actuator 120 is integrated according to various embodiments. 6 are diagrams showing manufacturing results of a droplet generator 100 in which a three-dimensional pneumatic actuator 120 is integrated according to various embodiments.

Referring to FIG. 5 , the droplet generator 100 is manufactured using a 3D printing soluble mold technique in which a sacrificial mold is output by a 3D printer and then an elastic polymer is cast. Therefore, unlike typical microfluidic chips manufactured using microfabrication technology and plasma bonding, it is possible to manufacture a three-dimensional three-dimensional shape as a single body without bonding surfaces.

First, in step 210, as shown in (a) of FIG. 5, a structure 201 composed of a mold 213 and a support 205 is formed. For example, the mold 213 is designed using Autodesk inventor (Autodesk Inc., USA), and then output by a 3D printer (3Z STUDIO, Solidscape) having a resolution of 5000 DPI (5.08 µm). Here, the output, that is, the structure 201 is a mold 213 formed of a build material, and a support 205 formed of a support material for supporting the floating part of the mold 213 Roy is made

Subsequently, in step 220, as shown in (b) of FIG. 5, the support 205, that is, the support material is removed from the structure 201 to obtain a mold 203. For example, the structure 201 is immersed in a dewaxing solvent (BIOACT ^™ VSO, Petroferm) in a flowing state using a hot plate (55 °C, 100 rpm) to selectively remove only the support material.

Subsequently, in step 230 , as shown in FIG. 5(c) , the droplet generator 100 is formed by applying an elastomer material to the mold 203 . Here, the elastomer material is a biocompatible silicone-based elastomer material, and includes, for example, PDMS (Polydimethylsiloxane, Sylgard 184, Dow Corning). For example, a mixture of a base, which is an elastic material, and a curing agent in a mass ratio of 10:1 is poured into the mold 203 after removing air bubbles in a vacuum chamber, and then, after removing air bubbles inside, the mixture is placed in an oven at 75 °C for 6 days. It undergoes a hardening process over time.

Finally, in step 240, as shown in (d) of FIG. 5, the mold 203 is removed from the drop generator 100 in a chemical manner, so that the drop generator 100 is obtained. For example, it is removed by soaking in acetone for 3 hours to dissolve the mold 203 inside the droplet generator 100, that is, the build material. After this, the droplet generator 100 is washed with deionized water and dried.

Through this, as shown in (a) of FIG. 6, after printing, dewaxing is completed to create a mold 203 in which only the build material remains, and then, as shown in (b) of FIG. 6, the mold With optional removal of 203, droplet generator 100 is complete. Considering the performance of the 3D printer, the channel diameters of the continuous phase fluid and the dispersed phase fluid are designed to be 400 μm and 200 μm, respectively. The diameter of the outlet channel is designed to be as wide as 1000 μm in order to reduce the flow resistance near the outlet considering the flow rate flowing in from the inlet. 6(c) is an enlargement of the variable orifice 110 of the manufactured droplet generator 100, which is composed of a joint 130 designed to increase the shear force of the continuous phase against the dispersed phase flow and a three-dimensional pneumatic actuator 120 Show the picture. Red dye and blue dye were respectively injected into the fluid channel 140 and the three-dimensional pneumatic actuator 120 in order to clearly check the manufactured appearance.

Structure of the variable orifice 110 and the three-dimensional pneumatic actuator 120 fabricated with a film interposed by FIG. is confirmed It should be noted that the chip, that is, all elements of the droplet generator 100 are manufactured as a single body without a bonding surface by a single casting process. The upper vertex of the triangular variable orifice 110 is formed somewhat flat by the 3D printer's own printing mechanism in which one layer is composed of at least two lines. However, according to the analysis using COMSOL, the hydraulic diameter between the trapezoidal and triangular variable orifices 110 reflecting the actual dimensions showed only a negligible difference of 1.0% even when pneumatic pressure was applied up to 120 kPa. On the other hand, the thickness of the film between the variable orifice 110 and the three-dimensional pneumatic actuator 120, which affects the hydraulic diameter according to the applied air pressure, was measured as 256.1 μm, and was manufactured with a relatively small error of 2.4% than the design. As shown in (e) and (f) of FIG. 6 observed in the longitudinal direction of the fluid channel 140, the expansion of the three-dimensional pneumatic actuator 120 is not only the hydraulic diameter of the variable orifice 110, but also the protruding tip and the variable orifice The spacing between (110) is also reduced to make the size of the droplets smaller.

7 are diagrams illustrating an experimental configuration for a droplet generator 100 in which a three-dimensional pneumatic actuator 120 is integrated according to various embodiments. 8 is a diagram showing experimental results for a droplet generator 100 in which a three-dimensional pneumatic actuator 120 is integrated according to various embodiments.

Referring to FIG. 7 , mineral oil having a viscosity of 25 cSt and deionized water were used as the continuous phase fluid and the dispersed phase fluid, respectively, in consideration of the hydrophobic characteristics of PDMS. The continuous and dispersed phase fluids are supplied at flow rates of 100-500 μL/min and 20 μL/min, respectively, using a syringe pump, and form droplets as they meet at the junction. The formed droplets are monitored with an optical microscope (HRM-300, HUVITZ), exited and stored in storage. In addition, a pressure regulator was configured to adjust the air pressure applied to the three-dimensional pneumatic actuator. The pressure regulator consists of a linear actuator (L16-R, Actuonix Motion Devices), a syringe, a microcontroller (MCU, Arduino UNO, Arduino), and a pressure sensor (33A-015G-2210, SHIBA KOREA). The pressure sensor senses the pressure supplied to the three-dimensional pneumatic actuator 120 and changes the pressure by moving a syringe connected to the linear actuator through a control signal from the microcontroller. The pressure supplied to the three-dimensional pneumatic actuator 100 is adjusted according to the observed droplet size to control the hydraulic diameter of the variable orifice 110 . Pressure is applied up to 120 kPa so that leakage between the tube connected to the droplet generator 100 does not occur due to excessive pressure.

Through this, as shown in FIG. 8, using the droplet generator 100 equipped with the variable orifice 110 controlled by the 3-dimensional pneumatic actuator 120, the flow rate of the continuous fluid and the 3-dimensional pneumatic actuator 120 By changing the air pressure applied to the droplets, droplets were generated. The flow rate of the dispersed phase was fixed at 20 μL/min. The size of the droplet decreased as the flow rate of the continuous phase fluid increased and as the pressure of the three-dimensional pneumatic actuator 120 increased and the hydraulic diameter of the variable orifice 110 decreased.

9 and 10 are diagrams for explaining the performance of the droplet generator 100 in which the 3D pneumatic actuator 120 is integrated according to various embodiments.

Referring to FIG. 9 , the diameters of droplets generated by the droplet generators 10 having a general fixed orifice 11 and the droplet generators 100 having a variable orifice 110 according to various embodiments have been compared. The ratio of the flow rate ( Q _w ) of the dispersed phase fluid to the flow rate ( Q _o ) of the continuous phase fluid was set from 0.04 to 0.2 so that droplets could be stably formed.

Figure 9 (a) shows the change in droplet size produced by the droplet generators 100 having three sizes of fixed orifices 11 with hydraulic diameters increased from 400 μm to 600 μm at 100 μm intervals. The droplet generator 10 with a fixed orifice 11 having a diameter of 600 μm has droplets in the range of 505.3-647.7 μm, and the droplet generator 10 with the smallest fixed orifice 11 having a diameter of 400 μm has a droplet in the range of 369.6-507.3 μm. of droplets were observed. The general droplet generator 10 has no additional control elements other than the change in the velocity ratio of the fluid, allowing droplet size adjustment in a range of up to 72.9%.

In (b) of FIG. 9, the droplet generator 100 having a triangular variable orifice 110 having a hydraulic diameter of 600 μm can generate droplets in the range of 513.5-700.8 μm when there is no contraction of the variable orifice 110. On the other hand, when a pneumatic pressure of 120 kPa was applied to the three-dimensional pneumatic actuator 120, smaller droplets in the range of 372.1-559.0 μm could be generated. At 0 Pa, a droplet generator 100 with a variable orifice 110 has a similar range of droplet sizes that a droplet generator 10 with a fixed orifice 11 of the same hydraulic diameter can produce. On the other hand, the hydraulic diameter of the variable orifice 110 at a pressure of 120 kPa was calculated to be 415.1 μm, but the droplet size was similar to that of the fixed orifice 11 with a hydraulic diameter of 400 μm at a flow rate of 0.04. This is because, as shown in (e) and (f) of FIG. 6 , the distance between the protruding tip and the variable orifice 110 is reduced so that the droplet is separated from the fluid flow before growing larger. Therefore, as the applied pressure increases, not only the hydraulic diameter of the variable orifice 110 but also the droplet diameter is adjusted to an additional range according to the narrowing of the gap. In addition, by applying a negative pressure of -60 kPa to the three-dimensional pneumatic actuator 120, the size of the droplet could be further increased. As a result, it has been experimentally demonstrated that the droplet generator with the three-dimensional pneumatic actuator 120 can reduce the droplet size and adjust it over a wide range of 259.3% without changing the flow rate.

10 is a result of measuring the performance of the triangular three-dimensional pneumatic actuator 120 at a continuous phase flow rate of 100 μL/min and a dispersed phase flow rate of 20 μL/min. 10(a) shows the droplet size and droplet generation frequency measured by applying a pressure in the range of 0-120 kPa to the triangular three-dimensional pneumatic actuator 120. Since the change in the size of the variable orifice 110 according to the applied pressure rapidly increased the flow rate, the frequency of droplet generation also increased, resulting in an average of 176 droplets per minute at 120 kPa. In (b) of FIG. 10 , when the applied pressure was 120 kPa, droplet size was statistically analyzed to evaluate droplet uniformity. Droplets were formed in the range of 545.5–576.4 μm, and the standard deviation was calculated as 7.0 μm. Accordingly, it was confirmed that droplets having a high uniformity with a coefficient of variation of 1.25% were formed. In addition, at the applied pressure of -60, 0 and 60 kPa, the coefficient of variation was measured as 0.79, 0.35 and 0.90%, respectively. for detecting and providing feedback.

In short, the triangular three-dimensional pneumatic actuator 120 and the variable orifice 110 have a fluid channel 140 having a free-form cross section including a triangle and a circle by using a chemical template removal method based on 3D printing technology, effective It consists of an abutment 130 containing an additional tip for droplet formation, and an orifice 110 sized by a three-dimensional pneumatic actuator 120. The three-dimensional pneumatic actuator 120 expanded by the injected air pressure induces intentional deformation of the surrounding inner membrane, and thus the diameter of the variable orifice 110 is controlled by the air pressure. In order to evaluate the cross-sectional area and circumference of the deformed variable orifice 110, hydraulic diameter was introduced to compare the performance of the three-dimensional pneumatic actuator 120 and the variable orifice 110 having various cross-sections, and as a result, the same pressure A three-dimensional pneumatic actuator 120 and a variable orifice 110 of a triangular cross section showing the largest change in hydraulic diameter under the pressure can be designed and realized.

In addition, since the droplet generator 100 having the variable orifice 110 increases the shear force on the flowing fluid as the pressure applied to the variable orifice 110 increases, the droplet generation rate increases with the decrease in the diameter of the droplet at the same flow rate ratio. It increases. By applying a negative pressure (-60 kPa) to a positive pressure (120 kPa) to the three-dimensional pneumatic actuator 120 to change the size of the droplet, a plurality of droplet generators 10 having a fixed orifice 11 can be converted to a single variable orifice ( 110) was experimentally verified that it could be effectively replaced with the droplet generator 100 equipped with it.

In a microfluidic system, it is expected that the droplet generator 100 will be used for DNA replication by being used for manufacturing a PCR device. Drug release is proportional to the size of the microparticles, and the technology that can vary the size of the particles is expected to be used in the synthesis of microfluidic polymer capsules for drug delivery. It is expected to be directly applied to the development of microfluidic devices composed of biocompatible materials and used as devices for molecular diagnostics and immunoassay diagnostics in the field of biochemistry.

The droplet generator 100 according to various embodiments surrounds the variable orifice 110 that determines the size of the generated droplet, and the variable orifice 110 is deformed by air pressure to change the size of the variable orifice 110. It includes a three-dimensional pneumatic actuator 120 for adjusting.

According to various embodiments, the three-dimensional pneumatic actuator 120 surrounds the variable orifice 110 with a membrane interposed therebetween, and expands by pneumatic pressure, thereby contracting the diameter of the variable orifice 110 through the membrane, thereby, The droplet size is reduced.

According to various embodiments, the shape of the three-dimensional pneumatic actuator 120 corresponds to the cross-sectional shape of the variable orifice 110 .

According to various embodiments, the cross-sectional shape of the variable orifice 110 is one of triangular, quadrangular, or pentagonal.

According to various embodiments, the droplet generator 100 further includes a junction 130 communicating with the variable orifice 110 at a front end of the variable orifice 110 and meeting fluids used to generate droplets. .

According to various embodiments, when the three-dimensional pneumatic actuator 120 is inflated, the distance between the abutment 130 and the variable orifice 110 is reduced, thereby further reducing the size of the droplet.

According to various embodiments, the droplet generator 100 further includes a fluid channel 140 that communicates with the variable orifice 110 and forms a uniform flow of fluids.

According to various embodiments, the cross-sectional shape of the fluid channel 140 is circular.

In the manufacturing method of the droplet generator 100 according to various embodiments, the mold 203 is prepared (steps 210 and 220), and an elastic material is applied to the mold 203 to form the droplet generator 100. (step 230), and removing the mold 203 from the droplet generator 100 in a chemical manner to obtain the droplet generator 100 (step 240).

According to various embodiments, the steps of preparing the mold 203 (steps 210 and 220) include the structure 201 including the mold 203 formed of a build material and the support 205 formed of a support material. Forming step (step 210), and removing the support material from the structure 201 to obtain a mold 203 (step 220).

According to various embodiments, forming the structure 201 (step 210 ) includes outputting the structure 201 using a 3D printer.

According to various embodiments, obtaining (step 240 ) the droplet generator 100 includes removing the mold 203 by dissolving the build material of the mold 203 .

According to various embodiments, the elastomer material is a biocompatible silicone-based elastomer.

According to various embodiments, forming (step 230 ) the droplet generator 100 includes applying a mixture of an elastomeric material and a curing agent to a mold 203 , and curing the mixture in the mold 203 to drop droplets Forming the generator (100).

Various embodiments of this document and terms used therein are not intended to limit the technology described in this document to a specific embodiment, and should be understood to include various modifications, equivalents, and/or substitutes of the embodiment. In connection with the description of the drawings, like reference numerals may be used for like elements. Singular expressions may include plural expressions unless the context clearly dictates otherwise. In this document, expressions such as "A or B", "at least one of A and/or B", "A, B or C" or "at least one of A, B and/or C" refer to all of the items listed together. Possible combinations may be included. Expressions such as "first," "second," "first," or "second" may modify the elements in any order or importance, and are used only to distinguish one element from another. The components are not limited. When a (eg, first) component is referred to as being “connected” or “connected” to another (eg, second) component, the certain component is directly connected to the other component, or It may be connected through another component (eg, a third component).

According to various embodiments, each of the components described above may include a single entity or a plurality of entities. According to various embodiments, one or more components or steps among the aforementioned components may be omitted, or one or more other components or steps may be added. Alternatively or additionally, a plurality of components may be integrated into one component. In this case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to integration. According to various embodiments, the steps may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the steps may be executed in a different order, may be omitted, or one or more other steps may be added. .

Claims (14)

In the droplet generator,
A variable orifice that determines the size of the generated droplet; and
A three-dimensional pneumatic actuator that surrounds the variable orifice and is deformed by air pressure to adjust the size of the variable orifice
including,
droplet generator.
According to claim 1,
The three-dimensional pneumatic actuator,
Surrounding the variable orifice with a membrane interposed therebetween, contracting the diameter of the variable orifice through the membrane while expanding by the pneumatic pressure, thereby reducing the size of the droplet.
droplet generator.
According to claim 1,
The shape of the three-dimensional pneumatic actuator,
Corresponding to the cross-sectional shape of the variable orifice,
droplet generator.
According to claim 1,
The cross-sectional shape of the variable orifice is,
which is either triangular, square, or pentagonal,
droplet generator.
According to claim 2,
A joint portion communicating with the variable orifice at the front end of the variable orifice and meeting fluids used to generate droplets
Including more,
droplet generator.
According to claim 5,
When the three-dimensional pneumatic actuator is inflated, the distance between the junction and the variable orifice is reduced, thereby further reducing the size of the droplet.
droplet generator.
According to claim 1,
A fluid channel communicating with the variable orifice and forming a uniform flow of the fluids
Including more,
droplet generator.
According to claim 7,
The cross-sectional shape of the fluid channel,
circular,
droplet generator.
In the manufacturing method of the droplet generator according to any one of claims 1 to 8,
Preparing a mold;
applying an elastomeric material to the mold to form the droplet generator; and
removing the mold from the droplet generator in a chemical manner to obtain the droplet generator;
including,
A method of manufacturing a droplet generator.
According to claim 9,
The step of preparing the mold is,
forming a structure comprising a mold formed of a build material and a support formed of a support material;
Obtaining the mold by removing the support material from the structure
including,
A method of manufacturing a droplet generator.
According to claim 10,
Forming the structure,
Outputting the structure using a 3D printer
including,
A method of manufacturing a droplet generator.
According to claim 10,
Acquiring the droplet generator,
Dissolving the build material of the mold to remove the mold
including,
A method of manufacturing a droplet generator.
According to claim 9,
The elastic material,
A biocompatible silicone-based elastic chain,
A method of manufacturing a droplet generator.
According to claim 9,
Forming the droplet generator,
applying the mixture of the elastomeric material and curing agent to the mold; and
curing the mixture in the mold to form the droplet generator.
including,
A method of manufacturing a droplet generator.

Images