A sequential micromixer based on sinusoidal vortex flow and working method thereof

Abstract

The application provides a sequential micro-mixer based on sinusoidal vortex flow, comprising a glass substrate, a PDMS cover plate with a micro-channel arranged on the glass substrate, two 3D electrodes arranged on two sides of the micro-channel respectively, a planar electrode connected with one end of the 3D electrode and connected with an external power supply at the other end, so as to form a uniform electric field in the micro-channel through the 3D electrode, and two suspended electrodes arranged in the micro-channel and asymmetrically arranged along the fluid flow direction of the micro-channel in sequence. The sequential micro-mixer has a high-efficiency and controllable mixing effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microfluidic technology, and in particular to a sequential micro-mixer based on sinusoidal vortex flow and a working method thereof. BACKGROUND

[0002] Lab on a chip (LOC) technology has been steadily developed in the fields of chemistry, biology, and material analysis, and has played an important role in laboratory applications. Traditional experimental methods often rely on culture dishes or cell culture flasks, but these methods have some limitations, such as difficulty in batch processing, difficulty in simulating real in vivo conditions for cell growth environment, etc. In order to overcome these limitations and improve experimental efficiency and accuracy, microfluidic technology has emerged.

[0003] Among them, micro-mixing technology, as one of the important research directions in the field of microfluidics, aims to rapidly contact molecules from different reagents in a microchannel, thereby achieving efficient reaction and analysis. Especially for multi-component reactions, organic synthesis and highly complex biological macromolecule detection, multiple micro-mixing is crucial for successful experiments. However, in past research, most of the research has focused on two-fluid mixing in a single channel, or multi-fluid mixing in a segmented channel, and there is little research on sequential mixing of parallel flows.

[0004] Traditional sequential mixing methods usually require multiple steps of mechanical stirring, which not only poses a risk of reagent consumption and uneven concentration, but also, especially for rapid reactions or quantitative detection, cannot accurately control the amount of reactants due to insufficient mixing process. In order to overcome the limitations of traditional mixing, passive and active fluid mixing in microchannels has attracted great attention and has been proven to effectively enhance mass transfer. Passive micro-mixing usually relies on special geometric shapes or complex microchannel structures embedded in the microchannel. In addition to the complex manufacturing process, this method is usually used to achieve multi-step or simultaneous micro-mixing in three or more fluids. In terms of multi-fluid parallel mixing, there are still challenges. In contrast, active micro-mixing is driven by external energy sources, such as magnetic fields, acoustic energy, electrical stimulation, and optical fields, etc. Active mixers can quickly and uniformly perform micro-mixing in simple channels and complete in a short time. More importantly, through the design achieved by external stimulation, the mixing position and mixing time can be easily controlled. SUMMARY

[0005] The technical idea of the present application: In the active micro-mixer, electrokinetic methods such as induced charge electroosmotic flow (ICEO) and alternating current electrothermal coupling (ACET) have the characteristics of simple electrode structure, no moving parts and low voltage, making them attractive mixing mechanisms in various biological analysis applications. Interestingly, ICEO is generated on a floating electrode, which exhibits ICEO-based micro-vortex flow that can occur at any desired location by inducing a voltage rather than directly applying an electrical signal. It seems that ICEO flow is promising to meet the needs of multi-fluid micro-mixing.

[0006] Therefore, the present application provides a sequential micro-mixer based on sinusoidal vortex flow and a working method thereof, which adopts the principle of sinusoidal vortex flow, and realizes sequential micro-mixing by using reconfigurable micro-vortex based on ICEO.

[0007] One aspect of the embodiments of the present application discloses a sequential micro-mixer based on sinusoidal vortex flow, comprising:

[0008] a glass substrate;

[0009] a PDMS cover plate with a micro-channel, arranged on the glass substrate;

[0010] two 3D electrodes, respectively arranged on both sides of the micro-channel;

[0011] a planar electrode, one end of which is connected with the 3D electrode, and the other end of which is connected with an external power supply, so as to form a uniform electric field in the micro-channel through the 3D electrode;

[0012] two floating electrodes, both of which are arranged in the micro-channel and are asymmetrically arranged along the fluid flow direction of the micro-channel.

[0013] In one embodiment disclosed by the present application, along the fluid flow direction of the micro-channel, the two floating electrodes are a rectangular floating electrode and a sinusoidal floating electrode in sequence.

[0014] In one embodiment disclosed by the present application, the micro-channel comprises a first channel, a second channel, a third channel and a mixing channel connected in sequence, the first channel has a first aqueous phase inlet, the second channel has a second aqueous phase inlet, the third channel has a third aqueous phase inlet, and the mixing channel has an outlet, and the first aqueous phase inlet, the second aqueous phase inlet, the third aqueous phase inlet and the outlet are all arranged on the PDMS cover plate.

[0015] In one embodiment disclosed by the present application, the two 3D electrodes are respectively arranged on both sides of the mixing channel.

[0016] In one embodiment disclosed by the present application, the rectangular floating electrode and the sinusoidal floating electrode are arranged in the mixing channel.

[0017] Another aspect of the embodiments of the present specification discloses a working method of a sequential micro-mixer based on sinusoidal vortex flow, which is realized by the sequential micro-mixer based on sinusoidal vortex flow described above;

[0018] The working method of the sequential micro-mixer based on sinusoidal vortex flow comprises the following steps.

[0019] Injecting the solution to be mixed into the micro-channel;

[0020] Turning on the external power supply, forming a uniform electric field in the micro-channel through the 3D electrode, inducing a double electric layer through the suspended electrode, and then forming an asymmetric fluid vortex in the micro-channel to realize rapid micro-mixing between different fluids.

[0021] In one embodiment of the present specification, the working method of the sequential micro-mixer based on sinusoidal vortex flow further comprises the following steps.

[0022] Configuring the buffer: a buffer with a pH value of 9.2 and a conductivity of 0.2 S / m is configured by adding potassium chloride and ammonia;

[0023] Configuring a fluorescein solution with a concentration of 1.32×10-5 mol / L;

[0024] Mixing anhydrous ethanol and Tween solution in a volume ratio of 9:1 to configure an active agent solution;

[0025] Adding the active agent solution to the buffer and the fluorescein solution in a volume ratio of 1:99, respectively, to complete the configuration of the solution to be mixed.

[0026] In one embodiment of the present specification, the working method of the sequential micro-mixer based on sinusoidal vortex flow further comprises the following steps.

[0027] Installing the syringes containing the buffer and the fluorescein solution on three syringe pumps, respectively, wherein the buffer syringe pump is installed at the two side inlets of the micro-channel, and the fluorescein solution syringe pump is installed at the middle inlet of the micro-channel;

[0028] Turning on the buffer syringe pump to inject the buffer into the micro-channel to soak the channel;

[0029] Turning on the fluorescein solution syringe pump to inject the fluorescein solution into the micro-channel.

[0030] The embodiments of the present specification can at least achieve the following beneficial effects:

[0031] The present application forms a uniform electric field in the microchannel through the planar electrode and the two 3D electrodes, and forms an asymmetric fluid vortex in the microchannel through the two suspended electrodes, so as to promote the rapid micro-mixing between different fluids and have a high-efficiency and controllable mixing effect.

[0032] The present application promotes the rapid mixing of different reagents in the fluid, is suitable for chemical reactions, biological experiments and other laboratory applications, and provides a new driving force for the application and development of microfluidic technology in the biomedical field. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0034] Figure 1 The exploded view of the sequential micro-mixer based on the sinusoidal vortex flow involved in some embodiments of the present application.

[0035] Figure 2 The exploded view of the sequential micro-mixer based on the sinusoidal vortex flow involved in some embodiments of the present application. Figure 1

[0036] Figure 3 The internal structure diagram of the sequential micro-mixer based on the sinusoidal vortex flow involved in some embodiments of the present application.

[0037] Figure 4 The internal size structure diagram of the sequential micro-mixer based on the sinusoidal vortex flow involved in some embodiments of the present application.

[0038] Figure 5 The sectional size structure diagram of the sequential micro-mixer based on the sinusoidal vortex flow involved in some embodiments of the present application.

[0039] Reference signs:

[0040] ​1, PDMS cover plate; 2, first aqueous phase inlet; 3, outlet; 4, planar electrode; 5, second aqueous phase inlet; 6, third aqueous phase inlet; 7, glass substrate; 8, 3D electrode; 9, suspended electrode; 91, rectangular suspended electrode; 92, sinusoidal suspended electrode; 10, first channel; 11, second channel; 12, third channel; 13, mixing channel. DETAILED DESCRIPTION

[0041] Hereinafter, only certain exemplary embodiments are described simply. As can be recognized by those skilled in the art, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are to be regarded as illustrative in nature rather than restrictive.

[0042] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship commonly understood by those skilled in the art, only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0043] The terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0044] In addition, the terms "mounting", "connecting", "connecting", "fixing" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] As Figure 1 and Figure 2As shown, one aspect of the embodiment of the present specification discloses a sequential micro-mixer based on sinusoidal vortex flow, comprising:

[0047] a glass substrate 7;

[0048] a PDMS cover plate 1 with micro-channels, arranged on the glass substrate 7;

[0049] two 3D electrodes 8, respectively arranged on both sides of the micro-channels;

[0050] a planar electrode 4, one end of which is connected to the 3D electrode 8, and the other end is connected to an external power supply, so as to form a uniform electric field in the micro-channels through the 3D electrode 8;

[0051] two floating electrodes 9, both of which are arranged in the micro-channels and are asymmetrically arranged along the fluid flow direction of the micro-channels.

[0052] In some embodiments, along the fluid flow direction of the micro-channels, the two floating electrodes 9 are sequentially a rectangular floating electrode 91 and a sinusoidal floating electrode 92. The upper and lower surfaces of the sinusoidal floating electrode 92 are sinusoidal surfaces composed of sinusoidal curves.

[0053] In some embodiments, the micro-channels include a first channel, a second channel, a third channel and a mixing channel connected in series, the first channel has a first aqueous phase inlet 2, the second channel has a second aqueous phase inlet 5, the third channel has a third aqueous phase inlet 6, and the mixing channel has an outlet 3, the first aqueous phase inlet 2, the second aqueous phase inlet 5, the third aqueous phase inlet 6 and the outlet 3 are all arranged on the PDMS cover plate 1.

[0054] In some embodiments, the two 3D electrodes 8 are respectively arranged on both sides of the mixing channel.

[0055] In some embodiments, the rectangular floating electrode 91 and the sinusoidal floating electrode 92 are arranged in the mixing channel.

[0056] Another aspect of the embodiment of the present specification discloses a working method of a sequential micro-mixer based on sinusoidal vortex flow, which is realized by the above-mentioned sequential micro-mixer based on sinusoidal vortex flow.

[0057] The working method of the sequential micro-mixer based on sinusoidal vortex flow comprises:

[0058] injecting the solution to be mixed into the micro-channels;

[0059] Opening the external power supply, forming a uniform electric field in the microchannel through the 3D electrode 8, inducing a double electric layer through the suspended electrode 9, and then forming an asymmetric fluid vortex in the microchannel to realize rapid micro-mixing between different fluids.

[0060] In some embodiments, the working method of the sequential micro-mixer based on the sinusoidal waveform vortex flow further comprises:

[0061] The buffer solution is configured: the buffer solution with a pH value of 9.2 and a conductivity of 0.2 S / m is configured by adding potassium chloride and ammonia water;

[0062] The concentration of the fluorescein solution is 1.32*10-5 mol / L;

[0063] The anhydrous ethanol and the Tween solution are mixed in a volume ratio of 9:1 to configure the active agent solution;

[0064] The active agent solution is added to the buffer solution and the fluorescein solution in a volume ratio of 1:99 respectively to complete the configuration of the solution to be mixed.

[0065] In some embodiments, the working method of the sequential micro-mixer based on the sinusoidal waveform vortex flow further comprises:

[0066] The injectors containing the buffer solution and the fluorescein solution are respectively installed on the three injection pumps, wherein the buffer solution injection pump is installed on the two side entrances of the microchannel, and the fluorescein solution injection pump is installed on the middle entrance of the microchannel;

[0067] The buffer solution injection pump is opened, and the buffer solution is injected into the microchannel to soak the channel;

[0068] The fluorescein solution injection pump is opened, and the fluorescein solution is injected into the microchannel.

[0069] The principle of the application is as follows:

[0070] The outside of the channel accesses the external power supply by using the planar electrode 4 to connect the 3D electrodes 8 on both sides of the channel to form a uniform electric field in the channel. In the internal structure of the micro-mixer, the channel contains an asymmetrically arranged rectangular floating electrode 91 (RFE) and a subsequent sinusoidal floating electrode 92 (SSFE) in the shape of a sine wave. The alternating current electric field can induce a double electric layer near the floating electrode 9. Under the excitation electric field, the floating electrode 9 generates induced charge electroosmotic flow (ICEO) and alternating current electrothermal coupling (ACET) electrokinetic forces. The surface potential of the floating electrode 9 changes, and the electric charge also changes, affecting the capacitance of the double electric layer, thereby changing the electroosmotic current on the surface of the floating electrode 9, and forming an asymmetric fluid vortex in the channel. At the same time, the position of the floating electrode 9 has a significant effect on the electric field and controls the formation of the double electric layer. Once the position of the floating electrode 9 changes asymmetrically along the width of the channel, the electric field and the double electric layer will be rebuilt. This phenomenon will cause time-varying microfluidic vortexes corresponding to the shape of the floating electrode 9, and alternately interfere with the contact interface between the left and right two fluids, resulting in rapid micro-mixing between different fluids.

[0071] In a specific embodiment, the dimensions of the sequential micro-mixer based on sinusoidal vortex flow can be as shown in Figures 3 to 5 , or can be set according to actual needs. As shown in Figure 5 , the height (thickness) of the glass substrate 7 is 1.1 mm, the height (thickness) of the PDMS cover plate is 4 mm-1.1 mm=2.9 mm, and the height of each channel (first channel 10, second channel 11, third channel 12, mixing channel 13) is 0.8 mm.

[0072] 1. Experimental preparation: (1) Before the experiment, the buffer solution was prepared by adding potassium chloride and ammonia water to prepare a buffer solution with a pH value of 9.2 and an electrical conductivity of 0.2 S / m; (2) A fluorescein solution with a concentration of 1.32×10-5 mol / L was prepared; (3) Anhydrous ethanol and Tween solution were mixed in a volume ratio of 9:1 to prepare an active agent solution; (4) The active agent solution was added to the buffer solution and the fluorescein solution in a volume ratio of 1:99.

[0073] 2. Experimental procedure: (1) Place the microfluidic chip with the Teflon plastic tube inserted on the microscope stage for easy observation and adjustment in subsequent experiments; (2) Install syringes containing buffer solution and fluorescein solution on three syringe pumps respectively, and connect them to the respective inlet positions on the chip (fluorescein solution in the middle and buffer solution on both sides); (3) Turn on the buffer injection pump, inject the buffer solution into the chip, and soak the channel for 10 minutes; (4) Turn on the fluorescein solution injection pump, adjust to a suitable flow rate, and inject the fluorescein solution into the chip; (5) Turn on the power of the signal generator and adjust the external electrical signal voltage, frequency and other parameters; (6) Observe and record the mixing of the solution in the chip channel under the microscope; (7) Adjust the voltage, frequency and flow rate and repeat the above experimental steps.

[0074] In summary, several specific embodiments of the present invention have been disclosed. Without contradiction, the various embodiments can be freely combined to form new embodiments. That is, embodiments that are alternative solutions can be freely substituted for each other, but cannot be combined with each other; embodiments that are not alternative solutions can be combined with each other. These new embodiments are also part of the substantive content of the present invention.

[0075] The above embodiments describe several specific implementations of the present invention. However, those skilled in the art should understand that various changes or modifications can be made to these implementations without departing from the principles and essence of the present invention, but all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A sequential micro-mixer based on sinusoidal vortex flow, characterized in that, include: Glass substrate; A PDMS cover plate with microchannels is disposed on the glass substrate; Two 3D electrodes are respectively disposed on both sides of the microchannel; A planar electrode, one end of which is connected to the 3D electrode and the other end is connected to an external power source, so as to form a uniform electric field in the microchannel through the 3D electrode; Two suspended electrodes are disposed within the microchannel and are arranged asymmetrically along the fluid flow direction of the microchannel. Along the fluid flow direction of the microchannel, the two suspended electrodes are, in turn, a rectangular suspended electrode and a sinusoidal suspended electrode.

2. The sequential micro-mixer based on sinusoidal vortex flow according to claim 1, characterized in that, The microchannel includes a first channel, a second channel, a third channel, and a mixing channel that are connected to each other. The first channel has a first aqueous phase inlet, the second channel has a second aqueous phase inlet, the third channel has a third aqueous phase inlet, and the mixing channel has an outlet. The first aqueous phase inlet, the second aqueous phase inlet, the third aqueous phase inlet, and the outlet are all located on the PDMS cover plate.

3. The sequential micromixer based on sinusoidal vortex flow according to claim 2, characterized in that, The two 3D electrodes are respectively disposed on both sides of the mixing channel.

4. The sequential micro-mixer based on sinusoidal vortex flow according to claim 3, characterized in that, The rectangular and sinusoidal suspended electrodes are located within the mixing channel.

5. A method for operating a sequential micro-mixer based on sinusoidal vortex flow, characterized in that: This is achieved using a sequential micro-mixer based on sinusoidal vortex flow, as described in any one of claims 1 to 4. The operating method of the sequential micro-mixer based on sinusoidal vortex flow includes: The solution to be mixed is injected into the microchannel; When an external power source is turned on, a uniform electric field is formed in the microchannel through the 3D electrodes, which induces an electric double layer through the suspended electrodes, thereby forming an asymmetric fluid vortex in the microchannel and achieving rapid micro-mixing between different fluids.

6. The operating method of the sequential micromixer based on sinusoidal vortex flow according to claim 5, characterized in that, Also includes: Preparation of the buffer solution: A buffer solution with a pH of 9.2 and a conductivity of 0.2 S / m was prepared by adding potassium chloride and ammonia. Prepare a fluorescein solution with a concentration of 1.32 × 10⁻⁵ mol / L; An activator solution was prepared by mixing anhydrous ethanol and Tween solution in a volume ratio of 9:

1. The surfactant solution was added to the buffer solution and the fluorescein solution at a volume ratio of 1:99 to prepare the solution to be mixed.

7. The operating method of the sequential micromixer based on sinusoidal vortex flow according to claim 5, characterized in that, Also includes: Syringes containing buffer solution and fluorescein solution were respectively installed on three injection pumps, wherein the buffer injection pump was installed at both inlets of the microchannel, and the fluorescein solution injection pump was installed at the middle inlet of the microchannel. Turn on the buffer injection pump and inject buffer into the microchannel to soak the channel; Turn on the fluorescein solution injection pump and inject the fluorescein solution into the microchannel.

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