Droplet generation device using electrowetting phenomenon

Abstract

The present invention relates to a droplet generation device using an electrowetting phenomenon, wherein droplets with a wide range of sizes can be generated on the basis of an electrowetting control environment, and the droplets can be changed to desired droplet sizes and generated with ease and rapid responsiveness without changing a mechanical structure. The present invention provides a droplet generation device comprising: an electrical control application module for generating electrical control; a droplet generation module provided on the upper surface of the electrical control application module and configured to generate droplets by using the electrical control generated by the electrical control application module; and a negative pressure formation means for forming a negative pressure on opposite surfaces between the electrical control application module and the droplet generation module.

Description

Droplet generation device using electrowetting phenomenon

[0001] The invention relates to a droplet generating device used in polymerase chain reaction (PCR), etc., and more specifically, to a droplet generating device utilizing an electrowetting phenomenon that can form a wide range of droplet sizes based on an electrowetting control environment, and can easily and quickly change and generate a desired droplet size without changing a mechanical structure.

[0002] Microdroplet technology is a technology field that has recently received significant attention due to its relatively simple preparation process, uniformity of droplets, controllability of droplet size and volume, and high productivity.

[0003] Microdroplets can be used as reactors in various fields, including cell biology, DNA or nucleic acid analysis, and more. Among microdroplet technologies, microfluidics utilizes the physical phenomena that occur when fluids flow within microscale structures.

[0004] Recently, particle generation technologies using micro-scale droplets are being studied.

[0005] Microdroplets have a volume on the nanoliter level, and each can be used as a microreactor. Therefore, by using them, uniform particle synthesis conditions different from the irregular particle synthesis conditions of bulk scale can be provided, and thus research using microdroplets is actively being conducted.

[0006] For example, compared to the conventional PCR method (1st generation) that uses polymerase chain reaction (PCR) and agarose gel electrophoresis to confirm the presence of a target gene, and the real-time PCR method (2nd generation) that uses fluorescent substances to confirm the amplification of a target gene in real time, the digital PCR method is evaluated as a next-generation PCR detection method with high sensitivity because it enables absolute quantitative detection of a target gene in real time without a standard substance.

[0007] There are currently only a few commercially available technologies for implementing digital PCR, and these digital PCR implementation methods are broadly divided into two types: micro-barrier type using chips and open-array plates, and droplet type for emulsion PCR.

[0008] However, the problem with the currently commercialized digital PCR technology is that its introduction to general university laboratories or public research facilities is limited due to the high cost of equipment (KRW 200-500 million) and consumable chips (KRW 300-1 million), and the manual droplet generation makes it impossible to monitor the number of droplets generated.

[0009] In the case of this type of manual droplet generation method, the accuracy of the experimental results is reduced due to non-uniformity in droplet size caused by air bubbles in the channel or environmental changes, and there is a problem in that self-diagnosis to determine whether there is an abnormality in operation during manual droplet generation is impossible.

[0010] Additionally, there is a problem of contamination between bio samples when expensive flow sensors are repeatedly used for active droplet generation.

[0011] This problem applies not only to microfluidic-based digital PCR technology but also to most high-performance lab-on-a-chips, which must be developed and used for single-use purposes because contamination between biosamples can lead to errors in analysis results when reused.

[0012] However, in many cases, lab-on-a-chip requires complex functions to implement diverse and precise performance, which complicates the manufacturing process and increases the manufacturing cost of the chip, which is a major obstacle to the commercialization of lab-on-a-chip, which must be used only once.

[0013] In addition, micro-air bubbles that can occur within microfluidic channels interfere with precise fluid control and flow, reducing the reproducibility of lab-on-a-chip, which is one of the main reasons making automation and commercialization of lab-on-a-chip difficult.

[0014] Currently, technology development is underway worldwide to solve the problems of existing manual droplet generation chips (lab-on-a-chip), reduce the economic burden of using microfluidic chips, and fundamentally prevent contamination between bio-samples. However, it is still in its initial stages of technology.

[0015] In particular, in order to overcome the limitations of existing proposed droplet generation methods, research and development are needed to easily generate droplet sizes without mechanical changes or physical configuration combinations of devices for droplet generation, and to enable various changes in droplet sizes over a wide range.

[0016] Accordingly, the present invention, which aims to solve the above-mentioned conventional problems, provides a droplet generation device using an electrowetting phenomenon, which can form a wide range of droplet sizes based on an electrowetting control environment, and can easily and quickly change and generate a desired droplet size without changing a mechanical structure.

[0017] The problems solved by the present invention are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0018] According to one aspect of the present invention for achieving the above objects and other features of the present invention, a droplet generating device is provided, characterized by including: an electric control applying module that causes electrical control; a droplet generating module that is provided on an upper surface of the electric control applying module and is configured to generate droplets by the electrical control generated from the electric control applying module; and a negative pressure forming means that forms negative pressure on an opposing surface between the electric control applying module and the droplet generating module.

[0019] In the present invention, the electric control application module includes a patterning electrode formed on the upper surface of the base substrate, and the electric control application module may further include a protective film covering the upper surface of the patterning electrode.

[0020] In the present invention, the droplet generation module may include a base block; a sample inlet formed in the base block and through which a sample is introduced; an oil inlet and an oil outlet formed at each end of the base block; and a microchannel through which a fluid introduced through the oil inlet and a sample introduced through the sample inlet pass and are discharged through the oil outlet.

[0021] In the present invention, the oil inlet, the sample inlet, and the oil outlet are provided on the same line, and the microchannel is formed so that the sample flowing in from the sample inlet and the oil flowing in from the oil inlet can meet in a orthogonal direction at a point where they join, and the point where the sample and the oil join can be provided to be located on the upper side of one of the patterning electrodes.

[0022] In the present invention, the microchannel may further include a high-flow resistance channel section.

[0023] In the present invention, the high-flow resistance channel section can be formed as a wave channel forming a zigzag U-shaped flow.

[0024] In the present invention, the negative pressure forming means may include a negative pressure applying portion formed on one side of the base block; and a negative pressure forming channel formed around the lower surface of the base block and connected to the negative pressure applying portion.

[0025] The droplet generating device using the electrowetting phenomenon according to the present invention provides the following effects.

[0026] First, the present invention can form a relatively wide range of droplet sizes compared to existing droplet formation methods, and thus has the effect of being usefully utilized in microdroplet formation technologies such as cell biology, DNA, and nucleic acid analysis.

[0027] Second, the present invention has the effect of easily and quickly generating droplets of a desired size through control of electrical environmental factors such as voltage without changing the mechanical structure.

[0028] The effects of the present invention are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0029] FIG. 1 is a drawing showing a droplet generating device using an electrowetting phenomenon according to the present invention, and is a perspective view showing the state before (A) and after (B) separation of an electric control application module and a droplet generating module.

[0030] Fig. 2 is a cross-sectional view showing a droplet generating device using an electrowetting phenomenon according to the present invention.

[0031] Figure 3 is a plan view showing an example of the structure of a droplet generation module included in a droplet generation device using an electrowetting phenomenon according to the present invention.

[0032] Figure 4 is a drawing showing an example of manufacturing a droplet generating device using an electrowetting phenomenon according to the present invention.

[0033] FIG. 5 is a drawing showing part “A” of FIG. 1, which is a cross-sectional view (A) and a plan view (B) of a microchannel showing active droplet generation of an electrowetting electrode using a droplet generation device utilizing an electrowetting phenomenon according to the present invention.

[0034] Figure 6 shows snapshots of droplets generated by an electrowetting (EW) voltage of 330 Vpp and 30 kHz, taken at 1.25 ms intervals.

[0035] Figure 7 shows a graph and snapshot photographs showing the reproducibility of droplet size using five identical disposable microchannels, showing droplet size as a function of electrowetting voltage.

[0036] Figure 8 is a graph showing the stepwise modulated droplet size using a square wave amplitude modulated EW voltage with a peak-to-peak (pp) range of 150 V and 330 V (sample and oil flow rates were set to 1 and 1.5 μL / min, respectively).

[0037] Hereinafter, a droplet generating device utilizing an electrowetting phenomenon according to a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0038]

[0039] FIG. 1 is a drawing showing a droplet generating device using an electrowetting phenomenon according to the present invention, and is a perspective view showing a state before (A) and after (B) separation of an electric control application module and a droplet generating module, FIG. 2 is a cross-sectional view showing a droplet generating device using an electrowetting phenomenon according to the present invention, FIG. 3 is a plan view showing an example of the structure of a droplet generating module included in a droplet generating device using an electrowetting phenomenon according to the present invention, and FIG. 4 is a drawing showing an example of manufacturing a droplet generating device using an electrowetting phenomenon according to the present invention. FIG. 5 is a cross-sectional view (A) and a plan view (B) of a microchannel showing active droplet generation of an electrowetting electrode using a droplet generating device using an electrowetting phenomenon according to the present invention.

[0040]

[0041] The droplet generation device using the electrowetting phenomenon according to the present invention, as shown in FIGS. 1 to 5, largely includes an electric control application module (100), a droplet generation module (200), and a negative pressure forming means (300).

[0042] Specifically, a droplet generating device utilizing an electrowetting phenomenon according to the present invention comprises, as shown in FIGS. 1 to 5, an electric control applying module (100) having a patterning electrode (120) for generating droplets formed therein; a droplet generating module (200) provided on an upper surface of the electric control applying module (100) and configured to generate droplets by electrical control applied from the electric control applying module (100); and a negative pressure forming means (300) for forming negative pressure (vacuum) on an opposing surface between the electric control applying module (100) and the droplet generating module (200).

[0043] The above electric control application module (100) is a component that forms a patterning electrode (120) for generating droplets and applies a predetermined voltage to the patterning electrode (120) to generate droplets of a predetermined size in the droplet generation module (200).

[0044] Specifically, the electric control application module (100) includes a base substrate (110) and a patterning electrode (120) formed in a predetermined pattern on the upper surface of the base substrate (110).

[0045] The above base material (110) is formed of a glass material.

[0046] The above patterning electrode (120) is composed of a pair of electrodes, a negative (-) electrode and a positive (+) electrode, formed in the width direction (vertical direction in the drawing) of the base substrate (110).

[0047] In addition, the electric control application module (100) further includes a protective film (130) for protecting the patterning electrode (120).

[0048] The above protective film (130) may be composed of a polymer material, for example, SU-8 photoresist.

[0049] The above-mentioned electric control authorization module (100) can be reused for the disposable droplet generation module (200).

[0050] In other words, the above electric control authorization module (100) is a component that can be used permanently and is separated from the disposable droplet generation module (200).

[0051] Next, the droplet generation module (200) is a component provided on the upper surface of the electric control application module (100) and configured to generate a fluid introduced into a microchannel into droplets of a predetermined size by electrical control applied from the electric control application module (100).

[0052] Specifically, the droplet generation module (200) includes a base block (210), a sample inlet (220) formed in the base block (210) and through which a sample is introduced, an oil inlet (231) and an oil outlet (232) formed at each end of the base block (210), and a microchannel (240) through which a fluid introduced through the oil inlet (231) and a sample introduced through the sample inlet (220) pass and are discharged through the oil outlet (232).

[0053] The above base block (210) may be composed of PDMS (polydimethylsiloxane).

[0054] The above oil inlet (231) and oil outlet (232) are formed on the imaginary center line in the longitudinal direction of the base block (210).

[0055] The above sample inlet (220) is formed on the virtual center line, but is formed at a position close to the oil inlet (231).

[0056] The above microchannel (240) is formed so that the sample flowing in from the sample inlet (220) and the oil flowing in from the oil inlet (231) can meet in a direction perpendicular to each other at the point where they join.

[0057] In other words, the microchannel (240) is formed at the point where the oil and the sample meet, and the direction in which the sample flows and the direction in which the oil merge become orthogonal to each other at the point of confluence, thereby allowing the formation of droplets.

[0058] Specifically, the microchannel (240) includes an oil inlet linear channel portion (241) extending a predetermined length along an imaginary center line from an oil inlet (231), a branch channel portion (242) branching in a V shape from an extended end of the oil inlet linear channel portion (241), a parallel channel portion (243) extending in parallel from each end of the branch channel portion (242), an orthogonal channel portion (244) extending in an facing direction from each end of the parallel extension portion (243), a confluence channel portion (245) joining in a V shape at each end of the orthogonal channel portions (244), an outflow channel portion (246) connected to an oil outlet (232) at the joining end of the confluence channel portion (245), and a sample channel portion (247) having one end connected to the sample inlet portion (220) and the other end joined to the confluence channel portion (245).

[0059] The above orthogonal channel portion (244) and the joining channel portion (245) are positioned on the upper side of one electrode among a pair of patterning electrodes (120).

[0060] Additionally, the microchannel (240) may further include a high-flow resistance channel section (248).

[0061] The above high-flow resistance channel section (248) can be formed as a waveform channel that forms a zigzag waveform in a direction orthogonal to the main channel, i.e., a waveform channel that forms a zigzag U-shaped flow.

[0062] The above high-flow resistance channel section (248) can be formed in the orthogonal channel section (244), the outflow channel section (246), and the sample channel section (247).

[0063] Here, the channel size of the high-flow resistance channel section (248) is formed smaller than the channel sizes of other channel sections.

[0064] Additionally, a droplet length measurement area capable of measuring the length of the droplet can be configured in the above-mentioned outlet channel section (246).

[0065] Next, the negative pressure forming means (300) is a component that forms negative pressure (vacuum) on the opposing surface between the electric control application module (100) and the droplet generating module (200).

[0066] The negative pressure forming means (300) includes a negative pressure applying portion (310) formed on one side of the base block (210), and a negative pressure forming channel (320) formed around the lower surface of the base block (210).

[0067] This negative pressure forming means (300) applies negative pressure (vacuum formation) to the opposing portion between the electric control application module (100) and the droplet generation module (200), thereby enabling the electric control application module (100) and the droplet generation module (200) to be coupled or separated.

[0068] The above negative pressure applying unit (310) can be connected to an external device to apply negative pressure, and for example, can be connected to a vacuum pump to form negative pressure.

[0069] Meanwhile, an example of manufacturing a droplet generating device using the electrowetting phenomenon according to the present invention is described with reference to FIG. 4.

[0070] A chip structure is patterned using SU-8 (protective film (130)) on a 1.75 T thick glass substrate (base substrate (110)) on which a chromium thin film is deposited, and a 2 mm thick acrylic bar is attached to create a space where a vacuum can be formed, thereby creating a mold capable of creating a PDMS upper plate (process (a)).

[0071] The PDMS top plate is cured using the created mold (process (b)).

[0072] A 2.4 um PET film is attached to the cured PDMS to form a disposable chip channel (process (c)).

[0073] The process of making an electrical control module, which is a reusable component, involves patterning a desired electrode shape on a substrate with a chrome / gold thin film on a 0.7T thick glass (process (d)).

[0074] To protect the electrode from liquid, a layer acting as a protective film is created using SU-8 (process (e)).

[0075] The drawing of process (f) shows a vacuum assembly of a disposable chip, a droplet generation module (100), and a reusable electric control application module (200).

[0076] FIG. 6 is a snapshot of droplets generated by an electrowetting (EW) voltage of 330 Vpp and 30 kHz taken at 1.25 ms intervals, FIG. 7 is a graph and snapshot photographs showing the reproducibility of droplet sizes using five identical disposable microchannels, showing the droplet sizes according to the electrowetting voltage, and FIG. 8 is a graph showing the droplet sizes modulated stepwise using a square wave amplitude modulated EW voltage with a peak-to-peak (pp) range of 150 V and 330 V (the flow rates of the sample and oil were set to 1 and 1.5 μL / min, respectively). The inventors of the present invention experimentally confirmed that satisfactory droplet generation can be achieved by using the electrowetting phenomenon according to the present invention.

[0077]

[0078] According to the droplet generation device utilizing the electrowetting phenomenon according to the present invention as described above, a relatively wide range of droplet sizes can be formed compared to existing droplet formation methods, and thus, it can be usefully used in micro-droplet formation technologies such as cell biology, DNA, and nucleic acid analysis, and has the advantage of being able to easily and quickly generate droplets having a desired size with control of electrical environmental factors such as voltage without changing the mechanical structure.

Claims

1. An electrical control authorization module that causes electrical control; A droplet generation module provided on the upper surface of the electric control application module and configured to generate droplets by electrical control generated from the electric control application module; and It is characterized by including a negative pressure forming means for forming negative pressure on the opposing surface between the electric control application module and the droplet generating module. Droplet generating device.

2. In paragraph 1, The above electric control authorization module includes a patterning electrode formed on the upper surface of the base substrate, The above electric control application module is characterized in that it further includes a protective film covering the upper surface of the patterning electrode. Droplet generating device.

3. In paragraph 1 or 2, The above droplet generation module base block; A sample inlet formed on the above base block and through which a sample is introduced; Oil inlet and oil outlet formed at each end of the base block; and A microchannel through which a fluid flowing in through an oil inlet and a sample flowing in through the sample inlet pass and are discharged to the oil outlet; characterized in that it comprises; Droplet generating device.

4. In paragraph 3, The above oil inlet, sample inlet and oil outlet are provided on the same line, The above microchannel is formed so that the sample flowing in from the sample inlet and the oil flowing in from the oil inlet can meet in a direction perpendicular to the point where they join, The point where the sample and oil meet is characterized in that it is located on the upper side of one of the patterning electrodes. Droplet generating device.

5. In paragraph 4, The above microchannel is characterized in that it further includes a high-flow resistance channel section. Droplet generating device.

6. In paragraph 5, The above high-flow resistance channel section Characterized by being formed by a wave channel that forms a zigzag U-shaped flow. Droplet generating device.

7. In paragraph 1, The above negative pressure forming means A negative pressure applying portion formed on one side of the base block; and characterized in that it includes a negative pressure forming channel that is connected to the negative pressure applying unit and formed around the lower surface of the base block; Droplet generating device.

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