Microfluidic concentration control system and method of operation thereof

Abstract

A microfluidic concentration control system according to an embodiment of the present invention may include a sample concentration unit including a microchannel into which a sample solution containing a sample is injected so as to form an ion depletion zone by an ion concentration polarization (ICP) phenomenon, an ion-selective membrane connected to the microchannel, and electrodes capable of applying a voltage to each end of the microchannel; an observation unit that observes the concentration state of the sample injected into the microchannel; and a control unit that controls the sample concentration unit to adjust the position of a concentration plug formed in the microchannel based on information observed by the observation unit.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a microfluidic concentration control system and method of operation. [Background technology]

[0002] In bio-environmental fields such as medicine, pharmaceuticals, drug testing, water quality testing, and clinical diagnostics, the concentrations of the samples to be detected are extremely low, so techniques for concentrating samples to improve the efficiency of detection and analysis are of great importance.

[0003] In order to detect target substances such as biological materials, biodiesel, and heavy metals in a sample, an expensive detector must be used, or the concentration of the target substance must be amplified in the sample preparation stage.

[0004] There are various methods for concentrating cellular-level substances, but there is a particular need for a non-destructive method for concentrating target substances. However, methods for concentrating small target substances such as cells have problems such as low detection sensitivity, limited accessibility, and limited ability to be used by experienced researchers.

[0005] Therefore, it is necessary to develop a new type of enrichment control system for minute-scale target materials. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2011 / 0198225 (published August 18, 2011) [Patent Document 2] Lee JeongHun, et al., Korean Society of Mechanical Engineers, October 1, 2017, Vol. 57, No. 10, pp. 43-47 Summary of the Invention [Problem to be solved by the invention]

[0007] Embodiments of the present invention provide a novel microfluidic concentration control system and method of operation that utilizes the ion concentration polarization (ICP) phenomenon. [Means for solving the problem]

[0008] A microfluidic concentration control system according to an embodiment of the present invention may include a sample concentration unit including a microchannel into which a sample solution containing a sample is injected so as to form an ion depletion zone by an ion concentration polarization (ICP) phenomenon, an ion-selective membrane connected to the microchannel, and electrodes capable of applying a voltage to each end of the microchannel; an observation unit that observes the concentration state of the sample injected into the microchannel; and a control unit that controls the sample concentration unit to adjust the position of a concentration plug formed in the microchannel based on information observed by the observation unit.

[0009] An operating method of a microfluidic concentration control system according to an embodiment of the present invention includes the steps of: forming an ion depletion zone by applying a voltage to both ends of a microchannel through which a sample solution containing a sample flows (step 1); acquiring an image of the concentration state of the sample solution (step 2); calculating the center position of a concentrated plug in the microchannel based on the image (step 3); and adjusting the center position of the concentrated plug based on a preset target position (step 4). [Effects of the Invention]

[0010] According to this technology, a novel microfluidic concentration control system and its operating method that are relatively easy to control are provided by utilizing the ion concentration polarization (ICP) phenomenon. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a microfluidic concentration control system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram for explaining the sample concentrating unit in FIG. 1 in more detail. [Figure 3] 1A-1C are diagrams illustrating the generation and movement of ion depletion regions and concentrate plugs within a microfluidic concentration control system according to an embodiment of the present invention. [Figure 4] 4 is an image showing in more detail the movement of the concentrated plug of FIG. 3. [Figure 5] 1 is a flowchart illustrating a method of operating a microfluidic concentration control system according to an embodiment of the present invention. [Figure 6] 6 is a flowchart for explaining step S400 in FIG. 5 in more detail. [Figure 7] 10 is a graph showing the operation results of a microfluidic concentration control system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Best Mode for Carrying Out the Invention> A microfluidic concentration control system according to an embodiment of the present invention may include a sample concentration unit including a microchannel into which a sample solution containing a sample is injected so as to form an ion depletion zone by an ion concentration polarization (ICP) phenomenon, an ion-selective membrane connected to the microchannel, and electrodes capable of applying a voltage to each end of the microchannel; an observation unit that observes the concentration state of the sample injected into the microchannel; and a control unit that controls the sample concentration unit to adjust the position of a concentration plug formed in the microchannel based on information observed by the observation unit.

[0013] In one embodiment, the sample concentrator can include one or more microchannels.

[0014] In one embodiment, the sample concentrator may include a main microchannel into which the sample solution is injected, one end of which is applied with a reference voltage and the other end of which is applied with a control voltage that is changed according to the control of the controller, and a buffer microchannel into which a buffer solution is injected, both ends of which are connected to ground voltages.

[0015] In one embodiment, the observation unit can observe the sample concentration unit in real time.

[0016] In one embodiment, the control unit can calculate the position of the concentrated plug based on information observed by the observation unit.

[0017] In one embodiment, the controller may control the sample concentrator such that the position of the enrichment plug is adjusted based on the position of the enrichment plug and a preset target position.

[0018] In one embodiment, the controller can control the magnitude of one or more of the voltage and current applied to the sample concentrator.

[0019] An operating method of a microfluidic concentration control system according to an embodiment of the present invention includes the steps of: forming an ion depletion zone by applying a voltage to both ends of a microchannel through which a sample solution containing a sample flows (step 1); acquiring an image of the concentration state of the sample solution (step 2); calculating the center position of a concentrated plug in the microchannel based on the image (step 3); and adjusting the center position of the concentrated plug based on a preset target position (step 4).

[0020] In one embodiment, step 4 may include the steps of calculating an error between the center position of the concentrated plug calculated in step 3 and the target position, determining a control value to be applied to the microchannel based on the error, and applying the determined control value to the microchannel.

[0021] In one embodiment, steps 2 to 4 may be repeatedly performed according to a preset period.

[0022] <Mode for carrying out the invention> Structural or functional descriptions of the embodiments disclosed in this specification or application are merely provided for the purpose of describing embodiments according to the technical concept of the present invention, and embodiments according to the technical concept of the present invention may be implemented in various forms other than the embodiments disclosed in this specification or application, and the technical concept of the present invention should not be construed as being limited to the embodiments described in this specification or application.

[0023] FIG. 1 is a diagram illustrating a microfluidic concentration control system according to an embodiment of the present invention.

[0024] Referring to FIG. 1, a microfluidic concentration control system 1000 can include a sample concentration section 100 , an observation section 200 and a control section 300 .

[0025] The sample concentrator 100 may include one or more microchannels into one or more of which a sample solution containing a sample can be injected.

[0026] The sample is a substance to be concentrated and controlled in position by the microfluidic concentration control system 1000, and the particle diameter may range from several nanometers to several tens of micrometers. For example, the sample may be a protein, a fluorescent particle, a lipid nanoparticle, a microbead, or an exosome, but is not limited to these examples.

[0027] When an electric field is applied to the sample concentrator 100, an ion concentration polarization (ICP) phenomenon may occur, which may result in the formation of an ion depletion zone within the microchannel of the sample concentrator 100. The sample concentrator 100 will be described in more detail below with reference to FIGS. 2 and 3. The sample concentrator 100 may include electrodes for applying a voltage to the microchannel.

[0028] The observation unit 200 can observe the concentration state of the sample injected into the microchannel in the sample concentration unit 100. In one embodiment, the observation unit 200 can acquire an image of a portion of the microchannel in the sample concentration unit 100. More specifically, the observation unit 200 can acquire an image of a portion where a sample plug is formed in the microchannel. In one embodiment, the observation unit 200 can observe the sample concentration unit 100 in real time. In one embodiment, the observation unit 200 can take an image of the sample concentration unit 100 in real time, and can acquire an image of the sample concentration unit 100 by capturing the image at a predetermined period.

[0029] The observation unit 200 may include a light source. In one embodiment, the observation unit 200 can observe fluorescent substances in the sample solution. Therefore, the light source in the observation unit 200 can provide an excitation wavelength of 340 nm to 800 nm, which is suitable for observing fluorescent substances.

[0030] The observation unit 200 may include filters and mirrors, i.e., excitation and emission filters that match the excitation and emission wavelengths to facilitate observation of each fluorescent substance, and may also include a dichroic mirror.

[0031] The observation unit 200 may also include an objective lens for observing the fluorescence, the magnification of which may be between 2X and 100X.

[0032] The observation unit 200 may also include an image sensor capable of converting received visual data into electrical data. The image sensor may be, for example, a charge-coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor.

[0033] The control unit 300 may control the sample concentration unit 100 based on information observed by the observation unit 200. In one embodiment, the control unit 300 may calculate the position of a concentrated plug of the sample formed in the microchannel based on an image acquired by the observation unit 200. For example, if a fluorescent sample to be concentrated in an image acquired by the observation unit 200 is concentrated to a concentration above a certain level and has a brightness above a predetermined threshold, the control unit 300 may recognize this as a concentrated plug and calculate the position of the concentrated plug. In one embodiment, the control unit 300 may calculate the center of gravity of the concentrated plug within the area recognized as the concentrated plug. In one embodiment, the control unit 300 may acquire pixel positions and brightness values ​​from the image acquired by the observation unit 200. The control unit 300 may calculate the position and brightness information of the concentrated plug from the pixel positions and brightness values.

[0034] The control unit 300 can adjust the position of the enrichment plug in the microchannel of the sample enrichment unit 100 based on the position of the enrichment plug and the preset target position. In an embodiment, the control unit 300 can determine a control value to be applied to the microchannel based on the position of the enrichment plug and the preset target position, and can adjust the position of the enrichment plug in the microchannel by applying the determined control value to the microchannel. In one embodiment, the control value can be one or more of the magnitude of the voltage and the magnitude of the current applied to the microchannel.

[0035] In an embodiment, the control unit 300 can adjust the position of the concentrated plug through feedback control. For example, various feedback control methods such as proportional-integral-differential control (PID control) or adaptive control can be used.

[0036] In some embodiments, the control unit 300 may include a processor that calculates the current position of the enrichment plug and determines a control value to apply to the microchannel. The control unit 300 may also include a variable power supply that provides a control value, such as a voltage or current, to the sample enrichment unit 100.

[0037] FIG. 2 is a diagram for explaining the sample concentrating section of FIG. 1 in more detail.

[0038] Referring to FIG. 2, the sample concentrator 100 can include a main microchannel 110, a buffer microchannel 120, and an ion-selective membrane .

[0039] A sample solution can be injected into the main microchannel 110. The main microchannel 110 can include an inlet at one end for injecting the sample solution. The main microchannel 110 can include an outlet at the other end for discharging the sample solution. In one embodiment, the main microchannel 110 can have a shape that extends long in one direction so that the sample solution can easily move along the path.

[0040] A reference voltage V H A reference voltage V H The other end 112 of the main microchannel 110 is connected to a control voltage V that can be changed under the control of the controller. CTRL The sample concentrating section 100 may include electrodes to which a voltage can be applied to both ends 111 and 112 of the main microchannel 110.

[0041] A buffer solution can be injected into the buffer microchannel 120. In one embodiment, the buffer solution can be an aqueous electrolyte solution having a concentration corresponding to that of the substance injected into the main microchannel 110. The buffer microchannel 120 can be shaped to extend elongated in one direction or It can be in the form of TIFF2025528925000002.tif828, but is not limited to any particular shape.

[0042] Both ends of the buffer microchannel 120 can be connected to a ground voltage. The sample concentrator 100 can include electrodes that can connect both ends of the buffer microchannel 120 to a ground voltage. The buffer microchannel 120 can be used to increase the efficiency of ion exchange through the ion-selective permeable membrane.

[0043] In an embodiment, the width of the microchannels 110, 120 may be 10 μm to 1000 μm, and the height of the microchannels 110, 120 may be 1 μm to 1000 μm. The microchannels 110, 120 may comprise a flexible polymer material or a rigid plastic. For example, a flexible polymer such as PDMS or a rigid plastic such as acrylic or polycarbonate may be used as the material for the microchannels. The microchannels 110, 120 may have a straight or curved shape.

[0044] The ion-selectively permeable membrane 130 may be connected to each of the main microchannel 110 and the buffer microchannel 120 at one or more contact points. The ion-selectively permeable membrane 130 may generate an ion concentration polarization (ICP) phenomenon. The ion-selectively permeable membrane 130 may be a cation-permeable membrane or an anion-permeable membrane. In one embodiment, the ion-selectively permeable membrane 130 may be Nafion.

[0045] FIG. 3 is a diagram illustrating the generation and movement of ion depletion regions and concentrated plugs in a microfluidic concentration control system according to an embodiment of the present invention.

[0046] An electric field V is applied to one end 111 and the other end 112 of the main microchannel 110. H , V CTRL When a voltage is applied, an ion concentration polarization (ICP) phenomenon occurs in the main microchannel 110 adjacent to the ion-selective permeable membrane 130, forming an ion depletion region 114. The ion concentration polarization phenomenon is an electrochemical transport phenomenon observed around a nanomembrane structure. It is theoretically known that when the thickness of the electric double layer is similar to the size of the nanomembrane, the electric double layer overlaps within the nanomembrane, resulting in single-ion permeability. Ions with charges similar to the wall charge cannot pass through the nanomembrane due to diffusion and drift forces, and only ions with charges opposite to the wall charge can pass through, resulting in ion depletion and excess at the nanomembrane interface.

[0047] The ion depletion region 114 can be used as a concentration mechanism for the sample material by utilizing the property that sample material with the same polarity as the nanomembrane cannot pass through the ion depletion region 114. The sample material can be concentrated starting from the boundary of the ion depletion region 114 to form a concentrated plug 113. The sample material can reach a concentration equilibrium point between advection, which is transported according to flow, and electromigration, which occurs due to electrophoresis. The concentration pattern of the sample material can vary depending on the dominance of advection or electrotransport.

[0048] Specifically, the concentration mode can be determined by comparing the absolute value of the electrophoretic mobility of the sample substance with the critical mobility. If the absolute value of the electrophoretic mobility of the sample substance is smaller than the critical mobility, the advection mechanism is dominant. If the absolute value of the electrophoretic mobility of the sample substance is larger than the critical mobility, the electrotransport mechanism is dominant. Sample substances with an absolute value of electrophoretic mobility smaller than the critical mobility can be concentrated (stacking) at a specific point, and the area of ​​the concentrated plug can increase. Sample substances with a larger absolute value of electrophoretic mobility can propagate toward one end (inlet or outlet) while changing the position of the concentrated plug toward the concentration equilibrium point.

[0049] The size of the ion depletion region 114 may vary depending on the type of ion-selective permeable membrane 130, the potential difference between the two ends 111 and 112 of the main microchannel 110, and the concentration distribution of ions. For example, when the potential difference between the two ends 111 and 112 of the main microchannel 110 increases under a specific initial condition, i.e., when the control voltage V CTRL When the potential difference decreases, i.e., when the control voltage V CTRL As ρ increases, the size of the ion depletion region 114 decreases, causing the concentrated plug to move toward the ion-selective permeable membrane 130.

[0050] The size and position of the concentrated plug 113 due to the ion concentration polarization phenomenon can be changed depending on the potential difference, current amount, flow rate, concentration time, channel shape, electrolyte type and concentration, etc. The microfluidic concentration control system according to an embodiment of the present invention can fix the concentrated plug 113 at a set position by adjusting factors that determine the size and position of the concentrated plug 113 in real time.

[0051] FIG. 4 is an image showing the movement of the concentrated plug of FIG. 3 in more detail.

[0052] FIG. 4 is an image showing part A of FIG. 3, which is an observation result when the absolute value of the electrophoretic mobility of the sample substance is greater than the critical mobility.

[0053] 3 and 4, it can be seen that even though control values ​​such as the magnitude of the applied voltage or the magnitude of the current are fixed when a voltage is applied to the main microchannel 110, the center position 113a of the concentrated plug moves toward one end 111 of the main microchannel over time (t0 to t3). In other words, in order to fix the position of the concentrated plug at a specific position, the control values ​​for the microchannel must be appropriately changed taking into account the movement of the concentrated plug.

[0054] FIG. 5 is a flowchart illustrating a method of operation of a microfluidic concentration control system according to an embodiment of the present invention.

[0055] 5, in step S100, a voltage may be applied to both ends of a microchannel through which a sample solution containing a sample flows. The applied voltage may be a voltage for implementing an ion concentration polarization (ICP) phenomenon. The initial voltage may be determined in consideration of the type of sample solution, the type of ion-selectively permeable membrane, a preset target position, the flow rate of the sample solution in the microchannel, and other factors. The microchannel may be connected to the ion-selectively permeable membrane at one or more contact points, thereby forming an ion depletion zone in the microchannel due to the ion concentration polarization (ICP) phenomenon.

[0056] In step S200, an image of the concentrated state of the sample solution can be acquired. In one embodiment, the observation unit can use an optical device to observe the vicinity of an ion depletion region where a concentrated plug may be generated, and can acquire an image of the vicinity of the ion depletion region according to a preset cycle. For example, the observation unit can use an optical device such as a microscope to acquire an image of the portion of the microchannel where the sample is concentrated, and can capture an image of the portion of the sample where the sample is concentrated in real time from the image.

[0057] In step S300, the center position of the concentrated plug formed in the microchannel may be calculated based on the image acquired in step S200. In one embodiment, the controller may identify the concentrated plug from the image acquired by the observation unit. For example, the controller may recognize pixels having a brightness greater than a predetermined threshold value or a specific color as the concentrated plug. To this end, a brightness value greater than the brightness of the background may be set as the threshold value for recognizing the concentrated plug. Alternatively, a specific wavelength range may be set as the color range for identifying the concentrated plug. As a result, pixels having a brightness greater than the threshold value or pixels having a color within a specific wavelength range may be separated from the background and recognized as the concentrated plug. In this case, various image processing techniques may be additionally applied to reduce noise and increase sensitivity. The controller may calculate the center position of the concentrated plug from the region recognized as the concentrated plug, i.e., the pixels recognized as the concentrated plug. The controller may calculate the center position of the concentrated plug by calculating a center of gravity that reflects the concentration level of each region within the concentrated plug. In one embodiment, the center of gravity of the concentrated plug may be calculated by weighting the brightness of each pixel recognized as the concentrated plug. Alternatively, the center of gravity of the concentrated plug can be calculated by taking into account the color of the pixel recognized as the concentrated plug, thereby allowing the control unit to obtain the center position and cumulative concentration of the concentrated plug.

[0058] In step S400, the control unit may adjust the center position of the concentrate plug in the microchannel based on a preset target position. In one embodiment, the center position of the concentrate plug may be adjusted based on the difference between the preset target position and the current center position of the concentrate plug calculated in step S300. In one embodiment, the control unit may adjust the center position of the concentrate plug using various feedback control methods. The control unit may turn on / off the application of feedback control in response to a user instruction or at its own discretion. The control unit may adjust the center position of the concentrate plug by changing a control value applied to the microchannel. In one embodiment, the control value changed to adjust the center position of the concentrate plug may be the magnitude of the voltage or current applied to the microchannel. Step S400 will be described in more detail below in the description of FIG. 6. The target position may also be changed after the generation of the concentrate plug in accordance with a user instruction.

[0059] In an embodiment, steps S200 to S400 may be repeatedly performed according to a preset cycle, thereby fixing the position of the concentrated plug at a preset target position. Here, fixing the position of the concentrated plug at the target position may mean that the center position of the concentrated plug is located within a certain error range from the target position.

[0060] FIG. 6 is a flowchart for explaining step S400 in FIG. 5 in more detail.

[0061] 6, in step S410, the control unit can calculate the error between the center position of the concentrated plug calculated in step S300 of FIG. 5 and a preset target position. The target position can be preset as a target position for the concentrated plug, and the target position can also be changed after the concentrated plug is formed.

[0062] In step S420, the controller may determine a control value to be applied to the microchannel based on the error calculated in step S410. For example, the magnitude of the voltage or current to be applied to the microchannel may be determined to move the center position of the concentrated plug to a preset target position according to the calculated error. Various feedback control methods may be applied to determine the control value. For example, proportional-integral-differential control (PID control) or adaptive control may be applied, and a set value for such feedback control may be preset.

[0063] In step S430, the controller can apply the determined control value to the microchannel, and then perform steps S200 and S300 of Figure 5 again to calculate the center position of the concentrated plug, and then perform steps S410 to S430 again.

[0064] A microfluidic concentration control system and an operating method thereof according to embodiments of the present invention may implement separation and concentration of a microfluid containing a sample using ion concentration polarization. The position of the concentration plug may be actively controlled by incorporating an observation unit that monitors the concentration state of the sample in real time and a control unit that adjusts the electrical driving conditions of the sample concentration unit in real time. More specifically, the position of the concentration plug of the sample material generated by the ion concentration polarization phenomenon may be fixed or moved to another position using feedback control, thereby enabling large-volume separation and concentration over a long period of time, and effectively performing operations such as moving the concentration plug to a desired outlet to extract the concentrated sample without user intervention. Therefore, even non-expert users can easily operate the concentration control system, facilitating commercialization in ion concentration polarization-based diagnostics, water quality testing, protein concentration devices, and the like. Furthermore, since the concentration plug can be easily moved to a position where a collection channel is formed, the concentration control system may also be used as a system for recovering concentrated sample material.

[0065] FIG. 7 is a graph showing the operation results of a microfluidic concentration control system according to an embodiment of the present invention.

[0066] Referring to Figure 7, a demonstration was carried out to demonstrate the position control of the concentration plug. A sample concentration section was prepared, including a microchannel with a channel width of 150 μm and a height of 15 μm. A sample solution containing the fluorescent substance Alexa Fluor 430 and 2.5 mM potassium chloride (KCl) as an electrolyte was injected into the main microchannel. The ion-selective permeable membrane of the device was a cation-permeable membrane called Nafion, and the buffer microchannel was filled with a 2.5 mM potassium chloride aqueous solution.

[0067] As an initial condition, a reference voltage V is applied to one end of the main microchannel. HAn initial concentrated plug was formed by applying 60 V as the voltage. After the concentrated plug was formed, when it became concentrated to a brightness equal to or greater than a preset critical brightness, the plug could be recognized by a control unit including feedback control software, and feedback control was initiated.

[0068] When feedback control is initiated, V is applied to the other end of the main microchannel to which the floating electrode is connected. CTRL In this case, the PID control method was used to determine the control value, and the P gain for PID control was set to 0.004, the I gain to 0, and the D gain to 0.04.

[0069] The target position at which the concentrated plug was to be fixed was initially set to 500px, and after it was stabilized at 500px, the target position was changed sequentially to 400px, 600px, and 500px.

[0070] The results can be seen in Figure 7. After generating the initial plug, the target positions were set sequentially as 500px (Target 1), 400px (Target 2), 600px (Target 3), and 500px (Target 1). It can be seen that the positions of the concentrated plugs converged within the error range of the target positions within a short time from the time the target positions were set.

[0071] More specifically, it took an average of 4 seconds for the position difference of the concentrated plug relative to the target position to converge to within 5% of the full screen scale, and the magnitude of the ripple converged to an error range of 1.6% of the full screen. [Explanation of symbols]

[0072] 100 Sample Concentration Unit 110 Main Microchannel 120 Buffer Microchannel 130 Ion-selective permeable membrane 200 Observation Section 300 control section

Claims

1. a sample concentration unit including a microchannel into which a sample solution containing a sample is injected so as to form an ion depletion zone by an ion concentration polarization (ICP) phenomenon; an ion-selective membrane connected to the microchannel; and first and second electrodes to which voltages can be applied to both ends of the microchannel, wherein a predetermined reference value is applied to the first electrode and a first control value is applied to the second electrode; an observation unit that observes the concentration state of the sample injected into the microchannel; a control unit that calculates a current position of the concentrated plug formed in the microchannel based on information observed by the observation unit, and determines a second control value to be applied to the second electrode based on the current position of the concentrated plug and a predetermined target position; Including, The observation unit The concentration state of the sample is repeatedly observed according to a preset cycle. The control unit A microfluidic concentration control system that repeatedly calculates the current position of the concentration plug according to a preset period and repeatedly determines a second control value to be applied to the second electrode based on the current position.

2. The sample concentrating unit includes: The microfluidic concentration control system of claim 1 , comprising one or more microchannels.

3. The sample concentrating unit includes: a main microchannel into which the sample solution is injected and which includes the first electrode and the second electrode at both ends; The microfluidic concentration control system according to claim 2 , further comprising: a buffer microchannel into which a buffer solution is injected and whose both ends are connected to a ground voltage.

4. The observation unit The microfluidic concentration control system according to claim 1 , wherein the sample concentration section is monitored in real time.

5. The microfluidic concentration control system of claim 1 , wherein once the second control value is determined, the determined second control value is applied to the second electrode.

6. The reference value is 10. The microfluidic concentration control system of claim 1, wherein the control value is a constant or a time-varying control value.

7. The reference value is one or more of a voltage and a current applied to the first electrode; The first control value and the second control value are The microfluidic concentration control system of claim 1 , wherein the second electrode is one or more of a voltage and a current.

8. Step 1: applying a predetermined reference value to a first electrode located at one end of a microchannel through which a sample solution containing a sample flows, and applying a first control value to a second electrode located at the other end of the microchannel, thereby forming an ion depletion zone due to an ion concentration polarization (ICP) phenomenon; Step 2: Obtaining an image of the concentrated state of the sample solution; Calculating the center position of the concentrated plug in the microchannel based on the image (step 3); and (4) adjusting the center position of the concentrated plug by determining a second control value to be applied to the second electrode based on a preset target position and the center position of the concentrated plug; A method for operating a microfluidic concentration control system that repeatedly executes steps 2 to 4 according to a preset cycle.

9. Step 4 calculating an error between the center position of the concentrated plug calculated in step 3 and the target position; determining the second control value to be applied to the second electrode based on the error; and applying the determined second control value to the second electrode.

10. The reference value is one or more of a voltage and a current applied to the first electrode; The first control value and the second control value are 9. The method of claim 8, wherein the second electrode is one or more of a voltage and a current.

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