Microfluidic devices and their fabrication methods

Abstract

A microfluidic device and its fabrication method are proposed. The device includes a droplet channel and a droplet supply section, an optical detection section, a droplet sorting section, and a droplet collection section arranged laterally therein. The droplet supply section is connected to one end of the droplet channel and is used to supply the droplet to be tested. The optical detection section includes an optical signal acquisition device disposed in an alignment channel, configured to acquire optical signals representing the optical characteristics of the droplet to be tested passing through the optical signal acquisition device. The droplet sorting section includes a deflection electrode disposed in a deflection electrode channel, configured to be activated when the optical signal meets predetermined conditions, thereby deflecting the droplet to be tested passing through the optical signal acquisition device and sorting it out as a target droplet. The droplet collection section is connected to the other end of the droplet channel and is configured to collect the sorted target droplets. This invention has advantages such as reducing the lower limit of detection light intensity, optimizing the signal-to-noise ratio, and improving detection sensitivity.

Description

Technical Field

[0001] The invention relates to the field of microfluidics, and more specifically, to a microfluidic device and a method for manufacturing the microfluidic device. Background Technology

[0002] Microfluidics is a technology that uses microchannels with dimensions ranging from tens to hundreds of micrometers to process and manipulate droplets smaller than a picoliter. It is an emerging interdisciplinary field involving multiple disciplines, including fluid physics, chemistry, biology and biomedicine, and electronics. Microfluidics is characterized by miniaturization, integration, ease of fabrication, and wide applicability.

[0003] Microfluidic chips, also known as lab-on-a-chip, integrate common microfluidic channel systems within a few square centimeters to perform specific biochemical reactions. One application is as follows: cells or bacteria and their reactants are encapsulated in picoliter-sized droplets through micrometer-level channels, creating tiny, undisturbed reaction systems. After thorough mixing and reaction, cells or bacteria are detected via an optical system. The detection results are quantified to obtain comparable peak information, which is then fed back to a waveform generator and amplifier to screen single cells or bacteria. Microfluidic droplets require very little reaction reagent to achieve ultra-high throughput unattainable by traditional slab screening techniques, thus holding significant applications in directed enzyme evolution.

[0004] An existing optical detection microfluidic sorting chip is as follows: a droplet channel is integrated into the microfluidic device, and the optical characteristics of the droplet are detected by an optical system independent of the microfluidic device. This optical detection microfluidic sorting chip utilizes a complex optical system for detection, the detection area is far from the objective lens, and the complex optical structure is easily affected by the environment, which reduces the accuracy of the detection system and results in a low signal-to-noise ratio. This optical detection microfluidic sorting chip can only detect biochemical samples with strong signals and is ineffective for biochemical samples with weak signals, thus limiting its application.

[0005] Another existing fiber optic detection microfluidic chip integrates optical fibers into the microfluidic chip for the detection of biochemical samples. However, it lacks a sorting structure design and cannot perform sorting operations, thus failing to achieve the sorting function.

[0006] Another existing microfluidic sorting chip uses the physical properties of sample flow to sort samples of different sizes and shapes through the structural design of microfluidic channels. It can only sort samples based on their different flow characteristics during the flow process, and cannot detect the optical feature signals of the samples. Therefore, it cannot sort biochemical samples that only contain optical feature information. Summary of the Invention

[0007] The object of the present invention is to provide an improved microfluidic device to solve or at least alleviate some of the problems of the prior art described above.

[0008] According to one aspect of the present invention, a microfluidic device is provided, the microfluidic device may include a droplet channel and a droplet providing section, an optical detection section, a droplet sorting section and a droplet collecting section arranged sequentially along the lateral direction of the microfluidic device, wherein:

[0009] The droplet providing section is connected to one end of the droplet channel through the droplet providing section outlet, and is used to provide the droplet to be tested;

[0010] The optical detection unit is disposed on one side of the droplet channel, including an optical signal acquisition device disposed in the alignment channel, and is configured to acquire optical signals representing the optical characteristics of the droplet under test passing through the optical signal acquisition device.

[0011] The droplet sorting unit includes a deflection electrode disposed in the deflection electrode channel. The deflection electrode is configured to be activated when the optical signal meets a predetermined condition, so as to deflect the droplet to be tested passing through the optical signal acquisition device and sort it out as the target droplet.

[0012] The droplet collection section is connected to the other end of the droplet channel and is configured to collect the sorted target droplets.

[0013] According to another aspect of the present invention, a method for manufacturing a microfluidic device according to the first aspect of the present invention is provided, the method comprising:

[0014] Fabricate a microfluidic device body corresponding to the microfluidic device. The microfluidic device body includes an open droplet providing part, a droplet channel, an alignment channel, a deflection electrode channel, a shielding electrode channel, and a droplet collecting part on one side.

[0015] Cut the body of the microfluidic device to expose the end of the alignment channel that is opposite to the droplet channel;

[0016] Drill holes in the main body of the microfluidic device to form multiple orifices on the main body of the microfluidic device;

[0017] The cover is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, the shielding electrode channel, and the droplet collection section from the corresponding side;

[0018] The deflection electrode and the shielding electrode are fabricated respectively within the sealed deflection electrode channel and shielding electrode channel;

[0019] The optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel.

[0020] According to another aspect of the present invention, a method is provided for manufacturing a microfluidic device according to the first aspect of the present invention, which also includes a shielding electrode portion located between the droplet supply portion and the optical detection portion and comprising shielding electrodes disposed in pairs of shielding electrode channels located on both sides of the droplet channel, the method comprising:

[0021] Fabricate a microfluidic device body corresponding to the microfluidic device. The microfluidic device body includes an open droplet providing part, a droplet channel, an alignment channel, a deflection electrode channel, a shielding electrode channel, and a droplet collecting part on one side.

[0022] Cut the body of the microfluidic device to expose the end of the alignment channel that is opposite to the droplet channel;

[0023] Drill holes in the main body of the microfluidic device to form multiple orifices on the main body of the microfluidic device;

[0024] The cover is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, the shielding electrode channel, and the droplet collection section from the corresponding side;

[0025] The deflection electrode and the shielding electrode are fabricated respectively within the sealed deflection electrode channel and shielding electrode channel;

[0026] The optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel.

[0027] Compared to existing technologies, this invention offers advantages such as lowering the detection light intensity limit, optimizing the signal-to-noise ratio, and improving detection sensitivity, along with additional benefits. The microfluidic device of this invention integrates an optical signal acquisition device, which can detect the test droplet and acquire optical signals representing the optical characteristics of the test droplet. The acquired optical signals thus have a better signal-to-noise ratio. Therefore, the microfluidic device of this invention has a stronger detection capability for biochemical samples and can be used to detect biochemical samples with weaker optical signals, such as fluorescence signals. It can be widely used for the detection of various biochemical samples that are self-luminous or require excitation light. Furthermore, due to the improved signal-to-noise ratio, the microfluidic device of this invention facilitates the use of optimized screening thresholds for desired sorting. Simultaneously, the microfluidic device of this invention has a droplet sorting section for sorting the test droplets.

[0028] Furthermore, through its ingenious construction, this invention integrates droplet supply, droplet detection, and droplet sorting into a single microfluidic device, enabling the detection and screening of biochemical samples to be completed directly in one step, offering advantages in simplicity and ease of operation. Attached Figure Description

[0029] Non-limiting and non-exhaustive embodiments of the invention are described by way of example with reference to the following figures, wherein:

[0030] Figure 1 and Figure 2 This is a schematic diagram illustrating a microfluidic device according to a preferred embodiment of the present invention;

[0031] Figure 3 It is shown schematically. Figure 1 and Figure 2 A partial enlarged view of a part of the microfluidic device;

[0032] Figure 4A and Figure 4B It is shown schematically. Figure 1 and 2 A partial schematic diagram of a microfluidic device;

[0033] Figure 5 This is a schematic diagram illustrating a microfluidic device according to another preferred embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram illustrating a microfluidic device according to yet another preferred embodiment of the present invention;

[0035] Figure 7 The diagram shows the waveforms of the optical signals of the droplet being tested, acquired using the microfluidic device of the present invention, and the waveforms of the optical signals of the droplet being tested, acquired using a microscope objective.

[0036] Figure 8 , Figures 9A-9F and Figure 10 An example method is shown that can be used to fabricate the microfluidic device of the present invention. Detailed Implementation

[0037] To make the above and other features and advantages of the present invention clearer, the invention is further described below in conjunction with the accompanying drawings. The drawings form a part of this application and, together with the embodiments of the invention, serve to illustrate the invention. For clarity and simplicity, detailed descriptions of the known functions and structures of the devices described herein will be omitted where they might obscure the subject matter of the invention. It should be understood that the specific embodiments given herein are for the purpose of explanation to those skilled in the art and are exemplary only, not restrictive.

[0038] The features described herein may be embodied in different forms and should not be construed as limited to the examples described herein. Rather, the embodiments described herein are provided merely to illustrate some of the many possible ways in which the apparatus and / or systems described herein will become apparent upon understanding the disclosure of this application.

[0039] As used herein, the term “and / or” includes any one of the associated listed items and any combination of any two or more of the associated listed items.

[0040] Although terms such as “first,” “second,” and “third” may be used herein to describe various components, parts, sections, or elements, these components, parts, sections, or elements are not limited by these terms. Rather, these terms are used only to distinguish one component, part, section, or element from another. Therefore, without departing from the teachings of the invention, a first component, part, section, or element referred to herein may also be referred to as a second component, part, section, or element.

[0041] Spatial relative terms such as “up,” “down,” “left,” “right,” “above,” “upper,” “above,” “below,” “lower,” and “below” are used herein for the purpose of describing the relationship between one component, part, section, or element as shown in the figures and another component, part, section, or element. In addition to the orientations depicted in the figures, such spatial relative terms are intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is flipped, an element described as “up,” “above,” “upper,” or “above” relative to another component, part, section, or element will be “down,” “below,” “lower,” or “below” relative to that other element. Thus, the term “up” encompasses both upper and lower orientations, depending on the spatial orientation of the device. The device may also be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0042] The terminology used herein is for the purpose of describing various embodiments only and is not intended to limit the scope of this disclosure. Unless the context clearly indicates otherwise, "a," "an," and "the" are intended to also include plural forms. The terms "comprising," "including," and "having" specify the presence of the stated features, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, operations, components, elements, and / or combinations thereof.

[0043] In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not required to practice the invention. In other instances, well-known steps or operations have not been described in detail to avoid obscuring the invention.

[0044] The preferred embodiments of the microfluidic device according to the present invention are described in detail below by way of example only, in conjunction with the accompanying drawings.

[0045] Reference Figure 1 and Figure 2 A microfluidic device according to a preferred embodiment of the present invention is described, which may be in the form of a chip.

[0046] like Figure 1 As shown, arrow X indicates the lateral direction of the microfluidic device, and arrow Y indicates the longitudinal direction. The microfluidic device includes a droplet channel and, arranged sequentially along the lateral direction X, a droplet supply section, a shielding electrode section 3, an optical detection section 4, a droplet sorting section 5, and a droplet collection section 6. Here, the droplet channel refers to the channel between the outlet 2-2 of the droplet supply section and the inlet 6-6 of the droplet collection section. The droplet channel can extend along the lateral direction X. The droplet supply section includes a droplet generation section 1 and a droplet mixing section 2; in other embodiments, the droplet supply section may not include the droplet mixing section 2. The droplet supply section, the shielding electrode section 3, the optical detection section 4, the droplet sorting section 5, and the droplet collection section 6 are components of the microfluidic device.

[0047] exist Figure 1 The image also shows double-lined and dashed-lined frames, which serve only as markers during the fabrication of the microfluidic device and are not part of the microfluidic device itself.

[0048] The mechanism by which the droplet supply section of this microfluidic device provides droplets is known in the prior art. The droplet supply section can adopt various possible structures, such as T-shaped structures, Y-shaped structures, cross-shaped structures, etc., and only a few examples are given below. In this preferred embodiment, the droplet generation section 1 includes a continuous phase inlet 1-1, a first dispersed phase inlet 1-2, a second dispersed phase inlet 1-3, a converging port 1-4, and a droplet generation section outlet 1-5 (not shown). Figure 1 In, and shown in Figure 2(In the image). A continuous phase inlet 1-1 is connected to a confluence port 1-4 via a continuous phase inlet channel for inputting a continuous phase fluid. A first dispersed phase inlet 1-2 is connected to a confluence port 1-4 via a first dispersed phase inlet channel for inputting the dispersed phase fluid of the sample to be tested. A second dispersed phase inlet 1-3 is connected to a confluence port 1-4 via a second dispersed phase inlet channel for inputting the dispersed phase fluid of a reactant intended to react with the sample to be tested. The first and second dispersed phase inlet channels are symmetrical about the extension line of the droplet channel; the continuous phase inlet channel includes a pair of continuous phase inlet branches symmetrically located on both sides of the extension line of the droplet channel. Each continuous phase inlet branch includes a first branch portion extending from the continuous phase inlet 1-1, a second branch portion extending from the confluence port 1-4, and an intermediate branch portion located between the first and second branch portions, both of which are orthogonal to the extension line of the droplet channel. For example, the continuous phase can be an oil phase, and the dispersed phase can be an aqueous phase. Each of the continuous phase inlet 1-1, the first dispersed phase inlet 1-2, and the second dispersed phase inlet 1-3 has a filter structure disposed therein, as indicated by the dotted portions therein. For example, the first dispersed phase inlet 1-2 can be used as a cell or bacterial dispersed phase inlet, and the second dispersed phase inlet 1-3 can be used as a substrate reactant dispersed phase inlet. The dispersed phase fluids from the first dispersed phase inlet 1-2 and the second dispersed phase inlet 1-3 converge at the converging port 1-4 with the continuous phase fluid from the continuous phase inlet 1-1 to form a test droplet. Specifically, the dispersed phase fluids from the first dispersed phase inlet 1-2 and the second dispersed phase inlet 1-3 can be sheared by the continuous phase fluid from the continuous phase inlet 1-1 at the converging port 1-4 to form a test droplet. The generated test droplet flows out of the droplet generating section 1 through the droplet generating section outlet 1-5. At least a portion of the channel of the liquid supply section—in this preferred embodiment, referring to the channel of the droplet generation section 1 (including the continuous phase input channel, the first dispersed phase input channel, the second dispersed phase input channel, and the channel between the converging port 1-4 and the droplet mixing section inlet 2-1 of the droplet mixing section 2)—may have a first height, which may be designed to be 40 micrometers. The generated test droplets may have a diameter of 10-40 micrometers. The droplet mixing section 2 includes a droplet mixing section inlet 2-1, a droplet supply section outlet 2-2, and a droplet mixing channel between the droplet mixing section inlet 2-1 and the droplet supply section outlet 2-2, for receiving test droplets from the droplet generation section outlet 1-5 via the droplet mixing section inlet 2-1 and outputting the test droplets via the droplet mixing channel and then through the droplet supply section outlet 2-2. A portion of the droplet mixing channel is curved, resulting in a uniform spacing between the droplets. The droplet mixing channel of the droplet mixing section 2 may have a second height, which may be designed to be adapted to the diameter of the optical fiber (it should be understood that the optical fiber is a preferred example of an optical signal acquisition device).For example, the height of the droplet mixing channel could be 125 micrometers.

[0049] The shielding electrode section 3 is located between the droplet supply section (specifically, the droplet mixing section 2 of the droplet supply section) and the optical detection section 4, and includes a first shielding electrode in a first shielding electrode channel 3-5 located between a pair of injection ports 3-1 and 3-2, and a second shielding electrode in a second shielding electrode channel 3-6 located between another pair of injection ports 3-3 and 3-4. Each shielding electrode channel may include an intermediate shielding electrode channel portion extending in the lateral direction X, and two side shielding electrode channel portions extending away from the droplet channel from both ends of the intermediate shielding electrode channel portion. These two shielding electrode channels may constitute a component of the shielding electrode section 3. Injection ports 3-1, 3-2, 3-3, and 3-4 are only used to form shielding electrodes during the fabrication of the microfluidic device. The pair of shielding electrodes, consisting of the first shielding electrode and the second shielding electrode, are symmetrically distributed on both sides of the droplet channel to shield the electric field force exerted on other test droplets (non-currently detected droplets) when the deflection electrode is energized to deflect the droplet of interest (the currently detected droplet). The shielding electrode section 3 (including the shielding electrode channel) may have a second height, which can be designed to be adapted to the diameter of the optical fiber. For example, the height of the shielding electrode section 3 may be 125 micrometers. The principle of shielding by the shielding electrode is as follows: the shielding electrode closer to the deflection electrode to which AC current is applied generates electrostatic induction within itself. Due to the internal resistance of the shielding electrode and its own open-circuit design, the electrostatic energy is dissipated before it acts on the droplet, thereby preventing it from affecting droplets not currently being detected. The function of the shielding electrode is to prevent the test droplet from deforming due to the influence of the deflection electrode when the ion content is high.

[0050] An optical detection unit 4 is disposed on one side of the droplet channel, including an alignment channel 4-2 and an optical signal acquisition device (not shown) disposed within the alignment channel 4-2. Figure 1 and Figure 2In this preferred embodiment, the optical signal acquisition device is an optical fiber (and in this preferred embodiment, an optical fiber) and an insertion port 4-1. The optical signal acquisition device can be various possible optical signal acquisition devices, including, for example, but not limited to, optical fibers, and optical sensing sensors such as photoelectric sensors. Considering that the speed of optical signal acquisition by an optical fiber is generally greater than that of an optical sensing sensor, it is advantageous to use an optical fiber for the optical signal acquisition device where appropriate. The insertion port 4-1 facilitates locating the alignment channel 4-2 when installing the optical fiber. The alignment channel 4-2 and the insertion port 4-1 of the optical detection unit 4 can have a second height, which can be designed to adapt to the diameter of the optical fiber. For example, the height of the optical detection unit 4 can be 125 micrometers. The infusion port 4-3 is located on the side of the alignment channel 4-2 and communicates with the end of the alignment channel 4-2 near the droplet channel via a channel. The infusion port 4-3 is only used during the fabrication of the microfluidic device. During the fabrication of the microfluidic device, the optical fiber can be integrated into the alignment channel 4-2 in such a way that, before bonding, along... Figure 10 Cutting line 12, as shown, exposes insertion port 4-1. An optical fiber is inserted through the exposed insertion port 4-1 such that the end face of the inserted optical fiber contacts the end face of alignment channel 4-2 near the droplet channel, parallel to the droplet channel, enabling the optical fiber to acquire optical signals representing the optical characteristics of the droplet under test passing through the optical fiber. The inserted optical fiber is fixed with silicone resin (e.g., AB glue), and then liquid polymer material (e.g., polydimethylsiloxane (PDMS)) is injected into alignment channel 4-2 through injection port 4-3. The liquid polymer material is then left to cure at room temperature for 24 hours. This eliminates air bubbles, ensuring a tight fit between the optical fiber and the relevant parts, which helps avoid adverse effects on optical signal acquisition.

[0051] The droplet sorting section 5 includes a first deflecting electrode in a first deflecting electrode channel located between a pair of inlet ports 5-1 and 5-2, and a second deflecting electrode in a second deflecting electrode channel located between another pair of inlet ports 5-3 and 5-4. Each deflecting electrode channel includes an end near the droplet channel and an inner deflecting electrode channel portion and an outer deflecting electrode channel portion that intersect and communicate at the end and extend away from the droplet channel from the end. The inner deflecting electrode channel portions of the two deflecting electrode channels are opposite and adjacent to each other and located between the outer deflecting electrode portions of the two deflecting electrode channels. These two deflecting electrode channels can constitute part of the droplet sorting section 5. Inlet ports 5-1, 5-2, 5-3, and 5-4 are only used for forming deflecting electrodes during the fabrication of the microfluidic device. In this preferred embodiment, the droplet sorting section 5 is disposed on one side of the droplet channel, opposite to the side where the optical detection section 4 is located. It should be understood that in other embodiments, the droplet sorting section 5 may be on the same side of the droplet channel as the optical detection section 4. Furthermore, in this preferred embodiment, the droplet sorting unit 5 includes two deflection electrodes. It should be understood that in other embodiments, the droplet sorting unit 5 may include a single deflection electrode. A pair of deflection electrodes, consisting of a first deflection electrode and a second deflection electrode, are arranged opposite each other along the lateral direction X of the microfluidic device, located on the same side of the droplet channel, and are configured to be activated when an optical signal representing the optical characteristics of a test droplet passing through the optical fiber meets predetermined conditions, thereby deflecting the test droplet passing through the optical fiber and sorting it as a target droplet. The droplet sorting unit 5 (including the first deflection electrode channel and the second deflection electrode channel) may have a second height, which may be designed to be adapted to the diameter of the optical fiber. For example, the height of the droplet sorting unit 5 may be 125 micrometers. Here, the optical fiber may be coupled to external associated hardware to realize optical signal control of the deflection electrodes for droplet deflection and sorting based on optical signals acquired by the optical fiber. This hardware may include, for example, but not limited to, filters, photomultiplier tubes, comparators, waveform generators, amplifiers, etc. The specific process can be described as follows: The optical signal acquired by the optical fiber is processed by optical components such as filters and then input into a photomultiplier tube to obtain a corresponding electrical signal. This electrical signal is then compared with a set threshold. In response to the comparison result indicating that the electrical signal exceeds the threshold, a deflection trigger signal is generated (e.g., a binarized signal to trigger sorting). Then, in response to this deflection trigger signal, alternating current is applied to the deflection electrodes to control the deflection of the droplet. During this process, relevant signals, such as optical signals, electrical signals, and / or the deflection trigger signal, can be processed as needed, for example, but not limited to, filtering and amplification.

[0052] The droplet collection unit 6 includes a first collection outlet 6-1, a second collection outlet 6-2, a first collection channel 6-3, and a second collection channel 6-4. The first collection outlet 6-1 communicates with the first collection channel 6-3, and the second collection outlet 6-2 communicates with the second collection channel 6-4. The first collection channel 6-3 and the second collection channel 6-4 converge at the droplet collection unit inlet 6-6, where the droplet channel communicates with the droplet collection unit 6. Here, the first collection channel 6-3 and the first collection outlet 6-1 are inclined relative to the droplet channel towards the side where the droplet sorting unit 5 is located, for receiving and discharging droplets deflected by the deflection electrode, i.e., target droplets. The second collection channel 6-4 and the second collection outlet 6-2 are inclined relative to the droplet channel towards the side where the optical detection unit 4 is located, for receiving and discharging waste liquid, including droplets not deflected by the deflection electrode. In this document, the first collection outlet 6-1 and the second collection outlet 6-2 may also be referred to as the "target droplet collection outlet" and the "waste liquid collection outlet," respectively, and the first collection channel 6-3 and the second collection channel 6-4 may also be referred to as the "target droplet collection channel" and the "waste liquid collection channel," respectively. The droplet collection section 6 (including the first collection channel 6-3 and the second collection channel 6-4) may have a second height, which may be designed to be adapted to the diameter of the optical fiber. For example, the height of the droplet collection section 6 may be 125 micrometers.

[0053] As in Figure 2 As clearly visible, the droplet collection unit 6 also includes one or more pressure relief channels 6-5 located between the first collection channel 6-3 and the second collection channel 6-4. Each of the pressure relief channels connects the first collection channel 6-3 and the second collection channel 6-4. The function of the pressure relief channels is to reduce the increased fluid resistance caused by the droplets entering the first collection channel 6-3 when they are sorted into the first collection channel 6-3 by the deflection electrode. Increased fluid resistance affects the effectiveness of sorting multiple consecutive droplets into the first collection channel 6-3.

[0054] In use, the test droplet flows out of the droplet supply outlet 2-2 and enters the section where the shielded electrode section 3 is located along the droplet channel, automatically returning to a central flow during the flow process. As the test droplet passes through the optical detection section 4, the optical signal representing the optical characteristics of the test droplet is acquired by the optical fiber and converted into an electrical signal after related hardware processing. The electrical signal is compared with a threshold by a comparator. If the electrical signal exceeds the threshold, a deflection trigger signal is generated. The generated deflection trigger signal controls the waveform generator to emit a deflection signal. The deflection signal is amplified by an amplifier and provided to the deflection electrode for energization. The energized deflection electrode causes the corresponding droplet to deflect and flow into the target droplet collection channel 6-3, and finally out of the microfluidic device from the target droplet collection outlet 6-1. The undeflected droplets flow into the waste liquid collection channel 6-4 under the action of flow resistance, and finally out of the microfluidic device from the waste liquid collection outlet 6-2.

[0055] exist Figure 1 and Figure 2 In microfluidic devices, there are two channel heights: 40 micrometers and 125 micrometers. The channels and pressure relief channels are part of the droplet supply section—the droplet generation section. Figure 2 The portion shown in dark black has a height of 40 micrometers, while the remaining portion has a height of 125 micrometers, adapted to the selected fiber diameter. Figure 2 In the magnified portion H1, the boundary is defined by the intersection of the droplet generation section outlet 1-5 and the droplet mixing section inlet 2-1. To the left of this boundary, shown in dark black (i.e., the droplet generation section channel), the height of the portion (including the droplet mixing section channel) is 40 micrometers, while to the right of this boundary, shown in light gray (including the droplet mixing section channel), the height is 125 micrometers. Figure 2 In the magnified portion H2, the pressure relief channel 6-5, shown in dark black, has a height of 40 micrometers. It connects to the target droplet collection channel 6-3 and the waste liquid collection channel 6-4, both with a height of 125 micrometers. Reducing the height of a portion of the droplet supply section—the droplet generation section—is advantageous. This allows the size (diameter) of the generated test droplets to be controlled within the range of 10-40 micrometers, and maintains a suitable droplet sorting spacing (the distance between test droplets) within the range of 100-200 micrometers, meeting the basic requirements of the droplet sorting section for sorting parameters. Reducing the height of the pressure relief channel helps meet relevant process requirements, such as the aspect ratio requirements during photolithography. Furthermore, the pressure relief channel should not be too large, lest droplets enter and clog it, rendering it ineffective for pressure relief.

[0056] Many advantages can be achieved by configuring the microfluidic device of the present invention with two channel heights (i.e., a first height and a second height). For example, by splitting at least a portion of the droplet supply section—i.e., the droplet generation section—and the electrode channel of the droplet sorting section into two heights, the controllability of the size and spacing of the test droplets can be ensured, and in particular, the stability of the sorting time interval can be guaranteed. As another example, by splitting at least a portion of the droplet supply section—i.e., the droplet generation section—and the alignment channel of the optical detection section into two heights, a test droplet suitable for sorting can be generated using a smaller channel (especially in height), and the test droplet can pass through the detection center of the optical signal acquisition device by the automatic focusing characteristic of the test droplet in flow.

[0057] Below, refer to Figure 3 describe Figure 1 and Figure 2 Example dimensions and parameters of the microfluidic device. Figure 3 It is shown that the point of the shielded electrode closest to the droplet channel is in the longitudinal direction Y of the microfluidic device (e.g., Figure 1 The distance m from the droplet channel shown in the figure, the width n of the droplet channel, the projection point d of the point of the shielding electrode channel furthest from the droplet feeder in the lateral direction X of the microfluidic device on the droplet channel, the distance r of the end of the alignment channel closest to the droplet channel in the longitudinal direction Y from the droplet channel, the width s of the first alignment channel portion of the alignment channel, the projection point c of the central axis of the alignment channel on the droplet channel, the distance x of the point of the droplet sorting section closest to the droplet channel in the longitudinal direction Y from the droplet channel, the intersection point a of the extension lines of the outer edges of the two deflection electrode channels in the lateral direction X, the intersection point b of the extension lines of the inner edges of the first collection channel and the second collection channel, the pressure relief area A where the pressure relief channel is located, the non-pressure relief area B between the pressure relief channels, the width t of the pressure relief channel in the lateral direction X, the spacing u of adjacent pressure relief channels in the lateral direction X, the width v of the first collection channel, and the width w of the second collection channel.

[0058] According to the present invention, the distance m can be determined based on the height of the shielding electrode section, and the distance x can be determined based on the height of the droplet sorting section. The distance m can be equal to the distance x. Figure 1 and Figure 2 In this case, the range is 35-70 micrometers. The distance r can be in the range of 40-80 micrometers.

[0059] Furthermore, according to the present invention, the distance q between projection point d and projection point c in the lateral direction X can be in the range of 100-200 micrometers; the distance p between projection point c and intersection point a in the lateral direction X can be in the range of 40-80 micrometers; the distance o between intersection point a and intersection point b in the lateral direction X can be in the range of 70-150 micrometers; and the distance l between intersection point a and intersection point b in the longitudinal direction Y can be in the range of 5-10 micrometers.

[0060] In one embodiment, the width t can be 20-35 micrometers, the spacing u can be 20-35 micrometers, the width v can be in the range of 35-65 micrometers, the width w can be in the range of 46-70 micrometers, and the width n can be in the range of 25-60 micrometers. A width w to width v ratio in the range of 1.05-1.15 is advantageous.

[0061] Below, refer to Figure 4A and Figure 4B An exemplary description is provided. Among other things, Figure 4A Insertion port 4-1 and alignment channel 4-2 are shown. Figure 4B A partial enlarged view of alignment channel 4-2 is shown.

[0062] The insertion port 4-1 has a maximum width g1 in the lateral direction X of the microfluidic device. The planes containing each of the two opposite sidewalls of the insertion port 4-1 in the lateral direction X form an angle k1 with respect to the lateral direction X. The insertion port 4-1 has a length g2 in the longitudinal direction Y of the microfluidic device. The maximum width g1 can be on the order of millimeters; thus, the exposed insertion port 4-1 is easily visible to the naked eye and readily locatable during fiber optic installation, facilitating fiber installation. Furthermore, the angle k1 can be appropriately designed so that the fiber optic cable can be inserted into the alignment channel 4-2 through the insertion port 4-1 regardless of the insertion angle; this facilitates fiber optic installation. In one embodiment, the maximum width g1 is 3 millimeters, and the angle k1 is 60 degrees. The length g2 can be determined based on associated dimensions, including, but not limited to, the maximum width g1 and the angle k1.

[0063] Alignment channel 4-2 ensures that the end face of the optical fiber installed therein aligns with the end face 4-5 of alignment channel 4-2 (shown in...). Figure 4BThe alignment channel 4-2 is closely fitted and parallel to the droplet channel. The alignment channel 4-2 includes: a first alignment channel portion adjacent to the droplet channel, without alignment microstructures, designated as having a length h1 and a width s; and a second alignment channel portion extending from the first alignment channel portion away from the droplet channel, having alignment microstructures. The insertion port 4-1 extends from the second alignment channel portion away from the droplet channel. The alignment channel 4-2 has a length g3 in the longitudinal direction Y of the microfluidic device. The maximum width s1 of the second alignment channel portion in the transverse direction X is greater than the width s of the first alignment channel portion in the transverse direction X, the latter being adapted to the diameter of the selected optical fiber.

[0064] The two opposing sidewalls of the second alignment channel portion in the lateral direction X of the microfluidic device are configured to form a plurality of aligned microstructures 4-4 that are symmetrical about the central axis (axis of symmetry) LL of the alignment channel 4-2 and are paired. Each aligned microstructure includes a recess formed by the sidewall of the second alignment channel portion recessed toward the central axis. Each recess includes a top 4-8, two ramp portions 4-6 and 4-7, and two lateral portions 4-9 and 4-10. The top 4-8 is located between the two ramp portions 4-6 and 4-7 and is parallel to the longitudinal direction Y of the microfluidic device. Each of the two lateral portions (4-9 or 4-10) is connected to the sidewall at one end and to the corresponding ramp portion (4-6 or 4-7) of the two ramp portions at the other end. Each recess is symmetrical about a line parallel to the lateral direction X passing through the center of the top 4-8. The recess can be configured such that its top is closer to the central axis than the corresponding sidewall of the first alignment channel portion, such that the minimum width of the second alignment channel portion in the lateral direction X is less than the width s of the first alignment channel portion in the lateral direction X. Each alignment microstructure can also take other possible shapes, such as semicircular, semi-elliptical, or arcuate. In any case, the width of the second alignment channel portion in the lateral direction X is minimized at the top of the paired alignment microstructures. The alignment microstructure 4-4 has the following function: when the optical fiber is inserted into the alignment channel 4-2, the deformation of the paired alignment microstructures 4-4, whose spacing is smaller than the diameter of the optical fiber, causes the axis of symmetry of the optical fiber to coincide with the central axis LL of the alignment channel 4-2, so that the end face of the optical fiber is aligned with the end face 4-5 of the alignment channel 4-2 near the droplet channel.

[0065] In one embodiment, the length g2 is determined based on the following equation:

[0066]

[0067] like Figure 4BAs shown, the first fiber alignment channel portion has a length h1 in the longitudinal direction Y, which can be in the range of 150-300 micrometers; the first fiber alignment channel portion has a width s in the transverse direction X, which is smaller than the size of the optical signal acquisition device (e.g., smaller than the diameter of the fiber, specifically the diameter of the fiber minus 0-5 micrometers); the second fiber alignment channel portion has a maximum width s1 in the transverse direction X, which is greater than the diameter of the fiber, specifically the diameter of the fiber plus 5-20 micrometers; the tops of the recesses of the paired alignment microstructures have a distance s2, specifically, the distance s2 is the diameter of the fiber minus 5-10 micrometers, where s2 < s < s1; the alignment microstructures formed on the same sidewall have a spacing h2 in the longitudinal direction Y; each alignment microstructure has a length h3 in the longitudinal direction Y, and each alignment microstructure has a width h4 in the transverse direction X. In the case where each alignment microstructure includes the recess, the top has a width h5 in the longitudinal direction Y, and the slope forms an angle k2 with the central axis, which is less than 90°.

[0068] The droplet supply section of the microfluidic device of the present invention can be appropriately adjusted according to the situation to meet the needs of various target samples. Figure 5 The diagram schematically illustrates a microfluidic device according to another preferred embodiment of the invention. Instead of a simple droplet input module shown in dark black on the left, which includes a continuous phase inlet L1 and a dispersed phase inlet L2... Figure 1 and Figure 2 In addition to the droplet generation section 1 and droplet mixing section 2 serving as droplet supply sections, Figure 5 Microfluidic devices in Figure 1 and Figure 2 The microfluidic devices in these systems are basically the same. Figure 5 In the droplet input module shown, the dispersed phase input port L2 is connected to the converging port via a single dispersed phase input channel (see [link]). Figure 1 1-4 in the middle; Figure 5 (Not shown in the text) is used to input droplets obtained beforehand from the test sample and reactants reacting with the test sample. A continuous phase inlet L1 is connected to a converging port via a continuous phase inlet channel for inputting a continuous phase fluid. This continuous phase inlet channel includes a pair of continuous phase inlet branches symmetrically located on either side of the single dispersed phase inlet channel. Each continuous phase inlet branch includes a first branch extending from the continuous phase inlet L1, a second branch extending from the converging port, and an intermediate branch located between the first branch and the second branch, the second branch forming an angle with the single dispersed phase inlet channel. The droplet input module, which serves as a droplet supply unit, also includes a converging port and a droplet supply unit outlet (see...). Figure 1 2-2 in the middle; Figure 5The channel between (not shown in the image) is where droplets from the dispersed phase inlet L2 converge with the continuous phase fluid from the continuous phase inlet L1 at the converging port to form the test droplet. Specifically, droplets from the dispersed phase inlet L2 can be dispersed by the continuous phase fluid from the continuous phase inlet L1 at the converging port to form the test droplet. The formed test droplet is provided to the droplet channel through the droplet supply outlet.

[0069] exist Figure 5 In the embodiment shown, it is advantageous to design the pressure relief channel and the droplet supply section to have the same height (i.e., a first height) and to design the other parts of the microfluidic device—including the droplet channel, the shielding electrode section, the optical detection section, the droplet sorting section, and the droplet collection section—to have a height adapted to the diameter of the optical fiber (i.e., a second height different from the first height) to facilitate the fabrication process of two exposures. Figure 5 The microfluidic device is suitable for situations where test droplets are generated offline, such as samples requiring long-term incubation before sorting. In this embodiment, preferably, the height and width of the single dispersed phase input channel do not exceed 1.5 times the diameter of the test droplet to ensure the droplet spacing when the droplet is dispersed into the droplet sorting section by the continuous phase. Taking a 20-micrometer diameter droplet sample after sorting and incubation as an example, the height and width of the single dispersed phase input channel should be designed to be below 30 micrometers, preferably 15-30 micrometers; the height of other channels in the droplet supply section besides the single dispersed phase input channel and the pressure relief channel should be designed to be below 30 micrometers, preferably 15-30 micrometers.

[0070] The height of the electrode section (including the shielding electrode section and the sorting electrode section as the droplet sorting section) of the microfluidic device of the present invention can be appropriately adjusted according to the situation to meet the needs of various target samples. Figure 6 The illustration schematically shows a microfluidic device according to yet another preferred embodiment of the invention. Figure 6 Microfluidic devices in Figure 1 and Figure 2 The microfluidic device is essentially the same as the one shown in the image, except that the height of the droplet sorting section and the shielding electrode section, indicated in dark black, has been adjusted to be the same as the height of the droplet generating section. By making this adjustment, the height of the droplet sorting section and the shielding electrode section is reduced, allowing for a smaller channel distance during the fabrication of the microfluidic device template—that is, a smaller minimum distance (distances m and x) between the deflection electrode channel and the shielding electrode channel and the droplet channel. Correspondingly, a smaller deflection voltage can be used. Using a lower voltage can prevent electrolytic lysis of cells or bacteria, which is advantageous. For example, in… Figure 6 In the case where the channel height of the electrode section is adjusted to 40 micrometers, the distances m and x can be reduced to 20 micrometers, and the deflection voltage can be reduced to 800 volts. In contrast, in... Figure 1 and Figure 2 In this case, the distances m and x need to be larger, and the deflection voltage needs to reach 1200 volts.

[0071] The applications and advantages of the present invention are illustrated below.

[0072] Taking DNA polymerase screening as an example, a droplet microfluidic device is used to produce E. coli expressing DNA polymerase and the corresponding reaction substrate. One phase of the generated droplet is the E. coli expressing DNA polymerase, and the other phase is a DNA strand terminally labeled with Cy3 fluorescent molecules and a deoxyribonucleotide terminally labeled with Cy5 fluorescent molecules. The droplet microfluidic device mixes the two aqueous phases and encapsulates them in a dispersed oil phase, forming droplets with a diameter of 20 micrometers. After collecting the droplets, they are incubated at 58 degrees Celsius for 2 hours. During this time, the DNA polymerase in the droplets links the deoxyribonucleotides labeled with Cy5 fluorescent molecules to the paired strands of the DNA strand labeled with Cy3 fluorescent molecules. When irradiated with Cy3 fluorescent excitation light, fluorescence resonance energy transfer occurs, and Cy5 emits excited light.

[0073] Introduce droplets as Figure 5 The microfluidic device of the present invention, as shown, provides a light source environment for Cy3 excitation light, and the excitation light of Cy5 is simultaneously collected by a microscope objective and an optical fiber integrated in the chip, obtaining the following... Figure 7 The results are shown. Figure 7 In the diagram, waveform W1 displayed on the oscilloscope represents the optical signal of the droplet, amplified by a photomultiplier tube and acquired by the microscope objective lens, with a peak-to-valley value of 0.8 volts and a noise range of 0.4 volts. Waveform W2, also displayed on the oscilloscope, represents the optical signal of the droplet, amplified by a photomultiplier tube and acquired by the optical fiber integrated into the microfluidic device, with a peak-to-valley value of 3 volts and a noise range of 0.2 volts. Therefore, the microfluidic device of this invention reduces system noise, improves the signal-to-noise ratio, raises the detection threshold, and significantly enhances detection sensitivity.

[0074] This invention can be widely used for the detection and sorting of various biochemical samples that are self-luminous or stimulated to emit light.

[0075] In general, the method for fabricating the microfluidic device of the present invention may include the following steps:

[0076] Fabricate a microfluidic device body corresponding to the microfluidic device, the microfluidic device body including the droplet providing part, the droplet channel, the alignment channel, the deflection electrode channel and the droplet collecting part with an opening on one side thereon;

[0077] Cut the body of the microfluidic device to expose the end of the alignment channel that is opposite to the droplet channel;

[0078] Drill holes in the main body of the microfluidic device to form multiple orifices on the main body of the microfluidic device;

[0079] A cover plate is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, and the droplet collection section from the corresponding side;

[0080] The deflection electrode is fabricated within the sealed deflection electrode channel;

[0081] The optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel.

[0082] As described above, the microfluidic device of the present invention may optionally include a shielding electrode portion, which may be located between the droplet providing portion and the optical detection portion and include shielding electrodes disposed in pairs of shielding electrode channels located on both sides of the droplet channel. In this case, the method of manufacturing the microfluidic device may include the following steps:

[0083] Fabricate a microfluidic device body corresponding to the microfluidic device. The microfluidic device body includes an open droplet providing part, a droplet channel, an alignment channel, a deflection electrode channel, a shielding electrode channel, and a droplet collecting part on one side.

[0084] Cut the body of the microfluidic device to expose the end of the alignment channel that is opposite to the droplet channel;

[0085] Drill holes in the main body of the microfluidic device to form multiple orifices on the main body of the microfluidic device;

[0086] The cover is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, the shielding electrode channel, and the droplet collection section from the corresponding side;

[0087] The deflection electrode and the shielding electrode are fabricated respectively within the sealed deflection electrode channel and shielding electrode channel;

[0088] The optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel.

[0089] The above steps can be performed in various possible ways. The following text only combines them with... Figure 8 , Figures 9A-9F as well as Figure 10 Example embodiments of the method for fabricating a microfluidic device according to the present invention are described.

[0090] Fabricating the microfluidic device body corresponding to the microfluidic device may include a photolithography step, a casting step, a demolding step, and a first cutting step, as detailed below:

[0091] In the photolithography step, a template with two heights for the microfluidic device (e.g., using negative photoresist overlay) is fabricated. Figure 9A (a)

[0092] In the casting step, liquid polymer materials (e.g., polydimethylsiloxane (PDMS)) are used (e.g.) Figure 9A (b) The mold is poured to solidify the polymer material.

[0093] In the demolding step, the template is removed from the cured polymer material through a demolding process.

[0094] In the first cutting step, by Figure 1 The double-line frame shown is outside, specifically along Figure 10 The cutting frame 11 shown in the figure cuts the demolded polymer material to obtain the body of the microfluidic device (e.g., Figure 9B c) The main body of the microfluidic device includes an open droplet supply section, a droplet channel, an alignment channel, a deflection electrode channel, a shielding electrode channel, and a droplet collection section on one side.

[0095] In the second cutting step, a cutting blade made of polymer material (such as...) is used. Figure 9C (d) along Figure 10 The solid black line 12 in the middle cuts through the body of the microfluidic device to expose the end of the alignment channel opposite to the droplet channel—in this embodiment, the insertion port for inserting the optical signal acquisition device (e.g., Figure 9D (e) is exposed from the side to facilitate the subsequent installation of an optical signal acquisition device, which is preferably an optical fiber.

[0096] The first and second cutting steps mentioned above are in Figure 8 The overall structure is shown in a cutting step.

[0097] In the drilling step, a drilling tool is used to drill holes in the cut microfluidic device body to form multiple orifices on the microfluidic device body. These orifices can be located at the desired drilling positions on the microfluidic device body and may include: an inlet for a droplet supply section for inputting fluid to obtain a test droplet provided by the droplet supply section; and an outlet for a droplet collection section for the droplet to flow out of the microfluidic device. Depending on the need, the multiple orifices may also include other possible orifices, such as orifices communicating with a deflection electrode channel for forming a deflection electrode within the deflection electrode channel, orifices communicating with a shielding electrode channel for forming a shielding electrode within the shielding electrode channel, or orifices communicating with an alignment channel for integrating an optical signal acquisition device within the alignment channel. For example, in the fabrication of... Figure 1 In the case of the microfluidic device shown, the plurality of orifices on the main body of the microfluidic device correspond to the continuous phase inlet 1-1, the first dispersed phase inlet 1-2, the second dispersed phase inlet 1-3, the first collection outlet 6-1, the second collection outlet 6-2, the injection ports 3-1 to 3-4, the injection ports 5-1 to 5-4, and the infusion port 4-3. In the fabrication... Figure 5 In the case of the microfluidic device shown, the plurality of orifices on the main body of the microfluidic device can correspond to the continuous phase inlet L1, the dispersed phase inlet L2, and the first collection outlet (e.g., Figure 1 6-1 in the middle), second collection outlet (such as Figure 1 6-2 in the middle), injection port (such as Figure 1 3-1 to 3-4 and 5-1 to 5-4) and injection port (e.g. Figure 1 (4-3 in the middle).

[0098] In the bonding step, the cover plate (such as...) is subjected to a plasma treatment method. Figure 9D f) is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, the shielding electrode channel, and the droplet collection section from the corresponding side. This cover plate can be, for example, a glass slide.

[0099] In the electrode fabrication step, a deflection electrode is fabricated within a sealed deflection electrode channel, and a shielding electrode is fabricated within a sealed shielding electrode channel. Specifically, the process for fabricating the deflection electrode is as follows: First, a low-melting-point metal wire (such as...) is polished using 1000-grit sandpaper. Figure 9E (g) until shiny, use needle-nose pliers to cut the low-melting-point metal into 1 cm lengths for later use; use wire cutters and wire strippers to cut the copper core wire into 5 cm lengths and strip 0.5 cm of bare portion from each end (e.g.) Figure 9E (h); Place the bonded microfluidic device body on a 120°C hot plate and heat for 5 minutes. Insert one end of the copper wire into the injection port (e.g., connected to one end of the deflection electrode channel). Figure 9E In section i, corresponding to the injection port 5-1 of the deflection electrode, the low-melting-point metal is inserted into the injection port at the other end of the deflection electrode channel (e.g., ...). Figure 9E In the middle j, corresponding to the injection port 5-2 of the deflection electrode, pressure is continuously applied downwards (e.g., Figure 9E In the process of fabricating the shielding electrode, the low-melting-point metal is heated and melts, flowing into the deflection electrode channel. The microfluidic device body is then removed from the hot plate and cooled to room temperature. The inserted copper wire and the flowing-in and cooled low-melting-point metal then integrate within the deflection electrode channel, forming the deflection electrode. Specifically, the process of fabricating the shielding electrode is as follows: The bonded microfluidic device body is heated on a 120°C hot plate for 5 minutes. The low-melting-point metal is inserted into the corresponding injection port (e.g., injection ports 3-1 to 3-4) connected to the end of the shielding electrode channel. Pressure is continuously applied downwards, causing the low-melting-point metal to melt and flow into the shielding electrode channel. The microfluidic device body is then removed from the hot plate and cooled to room temperature. The flowing-in and cooled low-melting-point metal then forms the shielding electrode within the shielding electrode channel. The fabrication of the deflection electrode and the shielding electrode can be performed simultaneously. Optionally, silicone resin can be applied to the exposed metal parts of the electrode to prevent leakage and electric shock during use.

[0100] In the fiber integration step, the optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel, for example, via an insertion port and then via the exposed end of the alignment channel. Specifically, fiber strippers are used to remove the structure of the fiber except for the cladding and core, and a fiber cleaver is used to cut the end face of the fiber flat, ensuring that the fiber, after stripping the outer sheath and cutting the end face, has sufficient length to penetrate into the alignment channel; the fiber (e.g.) is then integrated into the alignment channel. Figure 9F After wiping the middle (m) clean with a lint-free cloth, insert it into the insertion port (e.g.) Figure 9D (e) Insert the fiber optic alignment channel, manipulate the end face of the fiber to contact the end face of the designed alignment channel under a microscope, and apply silicone resin (e.g., AB glue, such as...) Figure 9F (n) Fix the optical fiber; after the optical fiber is fixed and stable, use a syringe (e.g., Figure 9F (p) Liquid polymer material is poured from an inlet (e.g., a port connected to the alignment channel) Figure 9F Pour in the middle q (corresponding to the injection port 4-3), and then let it stand at room temperature for 24 hours to cure, thereby realizing the integration of optical fibers.

[0101] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0102] Although the invention has been described in conjunction with embodiments, those skilled in the art will understand that the above description and drawings are exemplary and not restrictive, and the invention is not limited to the disclosed embodiments. Various modifications and variations are possible without departing from the spirit of the invention.

Claims

1. A microfluidic device, comprising a droplet channel and a droplet supply section, an optical detection section, a droplet sorting section, and a droplet collection section arranged sequentially along the transverse direction of the microfluidic device, wherein: The droplet providing section is connected to one end of the droplet channel through the droplet providing section outlet, and is used to provide the droplet to be tested; The optical detection unit is disposed on one side of the droplet channel, including an optical signal acquisition device disposed in the alignment channel, and is configured to acquire optical signals representing the optical characteristics of the droplet under test passing through the optical signal acquisition device. The droplet sorting unit includes a deflection electrode disposed in the deflection electrode channel. The deflection electrode is configured to be activated when the optical signal meets a predetermined condition, so as to deflect the droplet to be tested passing through the optical signal acquisition device and sort it out as the target droplet. The droplet collecting section is connected to the other end of the droplet channel and is configured to collect the sorted target droplets. The droplet collection unit includes: a first collection channel communicating with the other end of the droplet channel and configured to collect sorted target droplets; a second collection channel communicating with the other end of the droplet channel and configured to collect waste liquid; and one or more pressure relief channels between and connecting the first collection channel and the second collection channel.

2. The microfluidic device according to claim 1 further includes a shielding electrode section, the shielding electrode section being located between the droplet supply section and the optical detection section and including shielding electrodes disposed in pairs of shielding electrode channels located on both sides of the droplet channel.

3. The microfluidic device according to claim 2, wherein: At least a portion of the channel of the droplet supply section and the pressure relief channel have a first height; The remaining portion of the droplet providing section, excluding the at least part mentioned above, has a second height greater than the first height. The height of the deflection electrode channel and the shielding electrode channel is equal to the second height or the first height.

4. The microfluidic device according to claim 1, wherein: The ratio of the width (w) of the second collection channel to the width (v) of the first collection channel is in the range of 1.05-1.

15.

5. The microfluidic device according to claim 1 or 2, wherein: The alignment channel includes a first alignment channel portion adjacent to the droplet channel and a second alignment channel portion extending away from the droplet channel from the first alignment channel portion. Two opposing sidewalls of the second alignment channel portion in the lateral direction are configured to form a plurality of alignment microstructures that are symmetrical and paired about the central axis of the alignment channel. Each alignment microstructure includes a recess formed by the sidewall of the second alignment channel portion recessed toward the central axis. The maximum width (s1) of the second alignment channel portion in the lateral direction is greater than the width (s) of the first alignment channel portion in the lateral direction.

6. The microfluidic device according to claim 5, wherein: The optical detection unit also includes an insertion port extending from the second alignment channel portion away from the droplet channel. In the direction from the second alignment channel portion to the insertion port, the width of the insertion port gradually increases in the lateral direction.

7. The microfluidic device according to claim 5, wherein: Each recess includes a top, two ramps, and two transverse portions. The top is located between the two ramps and is parallel to the longitudinal direction of the microfluidic device. Each of the two transverse portions is connected to the sidewall at one end and to the corresponding ramp of the two ramps at the other end. Each recess is symmetrical about a line parallel to the transverse direction passing through the center of the top.

8. The microfluidic device according to claim 1 or 2, wherein: The optical signal acquisition device is an optical fiber or an optical sensing sensor.

9. A method for fabricating a microfluidic device according to claim 1, comprising: Fabricate a microfluidic device body corresponding to the microfluidic device, the microfluidic device body including the droplet providing part, the droplet channel, the alignment channel, the deflection electrode channel and the droplet collecting part with an opening on one side thereon; Cut the body of the microfluidic device to expose the end of the alignment channel that is opposite to the droplet channel; Drill holes in the main body of the microfluidic device to form multiple orifices on the main body of the microfluidic device; A cover plate is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, and the droplet collection section from the corresponding side; The deflection electrode is fabricated within the sealed deflection electrode channel; The optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel.

10. The method according to claim 9, wherein: Integrating the optical signal acquisition device into the alignment channel includes: Insert the optical signal acquisition device into the alignment channel; The optical signal acquisition device is fixed in place using silicone resin. The polymer material is injected into the alignment channel from one of the plurality of orifices, which serves as the injection port; and The polymer material is cured to fix the optical signal acquisition device in the alignment channel.

11. A method for fabricating a microfluidic device according to claim 2, comprising: Fabricate a microfluidic device body corresponding to the microfluidic device. The microfluidic device body includes an open droplet providing part, a droplet channel, an alignment channel, a deflection electrode channel, a shielding electrode channel, and a droplet collecting part on one side. Cut the body of the microfluidic device to expose the end of the alignment channel that is opposite to the droplet channel; Drill holes in the main body of the microfluidic device to form multiple orifices on the main body of the microfluidic device; The cover is bonded to one side of the perforated microfluidic device body to close the openings of the droplet supply section, the droplet channel, the alignment channel, the deflection electrode channel, the shielding electrode channel, and the droplet collection section from the corresponding side; The deflection electrode and the shielding electrode are fabricated respectively within the sealed deflection electrode channel and shielding electrode channel; The optical signal acquisition device is integrated into the alignment channel via the exposed end of the closed alignment channel.

12. The method according to claim 11, wherein: Integrating the optical signal acquisition device into the alignment channel includes: Insert the optical signal acquisition device into the alignment channel; The optical signal acquisition device is fixed in place using silicone resin. The polymer material is injected into the alignment channel from one of the plurality of orifices, which serves as the injection port; and The polymer material is cured to fix the optical signal acquisition device in the alignment channel.

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