A microfluidic electrophoresis chip for DNA separation and analysis
By using viscous hydrophilic polymer buffer and negative pressure technology in microfluidic electrophoresis chips, combined with reasonable channel design, the problems of high cost and low separation efficiency of existing chip materials are solved, and efficient DNA separation and automated detection are achieved , suitable for mass production.
Patent Information
- Application Number
- CN202410930909.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-12
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2044-07-12
AI Technical Summary
The existing microfluidic electrophoretic chips have problems in DNA separation and analysis, which leads to low separation efficiency and difficult to achieve automated detection of traditional chips.
A microfluidic electrophoresis chip for DNA separation analysis was designed, made of plastic, by filling the microfluidic channel with viscous hydrophilic polymer buffer, and injecting and electrophoretic separation using negative pressure, combining with reasonable channels. Designed for efficient separation.
It realizes low-cost and efficient DNA separation, improves resolution and detection performance, is suitable for mass production and automated detection, reduces single-chip cost, and reduces adsorption of analytes to the inner surface.
Smart Images
Figure CN118477710B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of DNA detection chips, and in particular to a microfluidic electrophoresis chip for DNA separation and analysis. Background Art
[0002] Microchip capillary electrophoresis (MCE) is a separation and analysis method at the microscale. It has the advantages of high speed, low consumption, miniaturization and integration. It perfectly meets the development requirements and trends of future analytical science and can be used in one-stop clinical diagnosis, drug analysis, environmental monitoring, food supervision and other fields. However, due to the lack of cheap, stable and high-performance microfluidic electrophoresis chips, the research and application of MCE in the analytical field have been greatly restricted. This paper invented a microfluidic electrophoresis chip that can realize repeated cycles of vacuum loading, electric clamp injection, and electrophoretic separation. Combined with the glue pressing module and the high-voltage module, it can realize efficient separation and analysis of DNA.
[0003] Microfluidic electrophoresis chips are the operating carriers of MCE, which directly determine the performance of MCE in all aspects. They need to meet the requirements of processability, transparency, chemical inertness, modifiability, etc. Chips made of different materials have different advantages and disadvantages and processing technologies. Among them, the materials used for traditional electrophoresis chips are silicon and glass, but silicon-based chips are brittle, costly and have poor light transmittance; glass chips have poor processability and are expensive.
[0004] Therefore, in recent years, people have gradually turned their attention to low-cost, highly plastic and chemically stable polymer materials, and developed microfluidic chips based on materials such as polydimethylsiloxane (PDMS), cycloolefin copolymer (COC), and polymethacrylate (PMMA), achieving low-cost separation and analysis while meeting MCE performance requirements.
[0005] Polymer material chips are often hydrophobic, which will adsorb the analytes and cause tailing during electrophoresis, affecting the performance of electrophoresis. In addition, the pressure difference flow caused by the pressure difference inside the chip channel will also affect the electrophoresis performance and reduce the electrophoretic separation. Summary of the invention
[0006] The present application provides a microfluidic electrophoresis chip for DNA separation and analysis, which is used to improve the electrophoresis separation degree.
[0007] The first aspect of the present application provides a microfluidic electrophoresis chip for DNA separation and analysis.
[0008] A microfluidic electrophoresis chip for DNA separation and analysis comprises a chip body, wherein the chip body is provided with a microfluidic channel, wherein the microfluidic channel comprises a loading channel, an electro-clamp loading channel and an electrophoresis separation channel, wherein the loading channel, the electro-clamp loading channel and the electrophoresis separation channel intersect with each other to form a cross, wherein the loading channel has a loading end, wherein the loading channel is connected to the cross, wherein the microfluidic channel is filled with a viscous hydrophilic polymer buffer, wherein the loading channel is connected to a negative pressure hole, and wherein the cross is located between the negative pressure hole and the loading end.
[0009] Through the above scheme, a viscous hydrophilic polymer buffer is filled in the microfluidic channel and negative pressure is used for feeding. This can not only achieve hydrophilic modification of the inner surface of the channel by pre-packaging the buffer and reduce the adsorption of the analyte on the inner surface, but also slow down the effect of pressure difference flow on the electrophoresis performance, and can better screen DNA fragments of different sizes with fixed charge-to-mass ratio to achieve efficient separation.
[0010] Preferably, the chip body comprises an upper substrate and a lower substrate, the microfluidic channel is located on the upper substrate, and the upper substrate is bonded to the lower substrate.
[0011] Preferably, it further comprises a capillary, wherein the capillary is connected to the sample loading end.
[0012] Preferably, the chip body is adhesively connected to the capillary.
[0013] Preferably, the chip body is made of plastic.
[0014] Preferably, the flow resistance of the electrophoresis separation channel is more than one thousand times the flow resistance of the loading channel.
[0015] Preferably, the width of the loading channel is w 1 ,length L 1 And depth h 1 , the width of the electrophoresis separation channel w 2 , length L2 and depth h2, viscosity of the viscous hydrophilic polymer buffer Satisfy between:
[0016] .
[0017] Preferably, the width of the electrophoresis separation channel is 20 microns to 50 microns.
[0018] Preferably, the depth of the electrophoresis separation channel is 50 microns to 75 microns.
[0019] Preferably, the viscous hydrophilic polymer buffer is PVP, PEO, HEC or HPC.
[0020] In summary, this application includes the following beneficial technical effects:
[0021] 1. This application is a plastic microfluidic chip with high transparency and processability, low single-chip cost, and can be used for mass production.
[0022] 2. This application realizes negative pressure sample loading, electric clamp sample injection, and electrophoresis separation process. The sample loading and electrophoresis processes can be carried out simultaneously without affecting each other. Automated detection can be achieved in conjunction with relevant electrophoresis equipment.
[0023] 3. The channel flow resistance derivation and loading channel design of this application: taking into account factors such as cost and processing solution implementation, gel viscosity, etc., the width ratio of the negative pressure loading channel and the electrophoresis separation channel is reasonably designed to achieve a thousand-fold flow resistance difference.
[0024] 4. The depth and width of the electrophoresis separation channel of the present application are designed through actual measurement and theoretical calculation, and the channel depth with a lower detection limit and the channel width with a higher separation degree are designed respectively, which can achieve better detection performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a schematic structural diagram of a microfluidic electrophoresis chip for DNA separation and analysis according to an embodiment of the present application;
[0026] Figure 2 It is a schematic diagram of the flow direction of DNA in a microfluidic channel of a microfluidic electrophoresis chip for DNA separation and analysis according to an embodiment of the present application;
[0027] Figure 3 It is an exploded schematic diagram of a microfluidic electrophoresis chip for DNA separation and analysis according to an embodiment of the present application;
[0028] Figure 4 It is an electrophoretic spectrum of a microfluidic electrophoresis chip for DNA separation analysis with an electrophoretic separation channel depth of 50-75 μm;
[0029] Figure 5 It is a table of theoretical plate numbers corresponding to the width of each electrophoretic separation channel;
[0030] Explanation of the reference numerals: 1. Chip body; 11. Upper substrate; 12. Lower substrate; 2. Microfluidic channel; 21. Sample loading channel; 22. Electro-clamp injection channel; 23. Electrophoresis separation channel; 24. Cross; 3. Liquid reservoir hole; 31. Negative pressure hole; 4. Capillary. DETAILED DESCRIPTION
[0031] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments.
[0032] In the description of the embodiments of the present application, words such as "illustrative", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "illustrative", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "illustrative", "for example" or "for example" is intended to present related concepts in a concrete way.
[0033] In the description of the embodiments of the present application, the term "and / or" is only a kind of association relationship describing the associated objects, indicating that there may be three kinds of relationships, for example, A and / or B, which can represent: A exists alone, B exists alone, and A and B exist at the same time. In addition, unless otherwise specified, the meaning of the term "multiple" refers to two or more. For example, multiple systems refer to two or more systems, and multiple screen terminals refer to two or more screen terminals. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. The terms "include", "comprise", "have" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.
[0034] Scenario: The microfluidic electrophoresis chip described in the present invention is used for separation and analysis of DNA. Its separation mode is gel-free sieving electrophoresis. The hydrophilic modification of the inner surface of the channel can be achieved by pre-packaging the buffer, reducing the adsorption of the analyte on the inner surface, and also slowing down the effect of differential pressure flow on the electrophoresis performance. It can better sieve DNA fragments of different sizes with fixed charge-to-mass ratio to achieve efficient separation;
[0035] The capillary electrophoresis chip and electrophoresis device for optical detection disclosed in announcement number CN203170343U can realize the process of electrophoresis injection and electrophoresis separation, but manual operation is required to replace samples, and there is interference between samples. It is only suitable for laboratory testing and cannot be used for automated chip electrophoresis equipment;
[0036] Another micro capillary electrophoresis chip and its preparation method disclosed in the announcement number CN110308195B is made of glass chip, which has a complex manufacturing process, limits the depth and aspect ratio of the channel size, has a high single chip cost, is not suitable for mass production, and is only suitable for laboratory testing;
[0037] The design of the technical solution of the present application enables the electrophoresis chip to have the characteristics of high processability, low single-chip cost, high degree of integration, and can be used for automated equipment detection, and has high market economic value.
[0038] Reference Figure 1 and Figure 2 A microfluidic electrophoresis chip for DNA separation and analysis includes a chip body 1 and a capillary 4. The chip body 1 is provided with a microfluidic channel 2. The microfluidic channel 2 includes a loading channel 21, an electric clamp injection channel 22 and an electrophoresis separation channel 23. The loading channel 21, the electric clamp injection channel 22 and the electrophoresis separation channel 23 are interconnected. The electric clamp injection channel 22 and the electrophoresis separation channel 23 intersect with each other to form a cross 24. The cross 24 is a conventional structure of the electrophoresis chip and is not described in detail herein.
[0039] Reference Figure 2 and Figure 3 The chip body 1 is made of plastic. The chip body 1 includes an upper substrate 11 and a lower substrate 12. The upper substrate 11 and the lower substrate 12 are bonded together by hot pressing.
[0040] The capillary 4 is disposed on the lower substrate 12 , and the lower substrate 12 and the capillary 4 are glued together; specifically, the lower substrate 12 and the capillary 4 can be glued together by ultraviolet glue, and the capillary 4 is connected to the sample loading channel 21 to transfer the sample DNA to the cross 24 .
[0041] The microfluidic channel 2 is located on the upper substrate 11, and the upper substrate 11 is also provided with a liquid reservoir hole 3 and an optical focus mark. The liquid reservoir hole 3 is connected to the microfluidic channel 2. The microfluidic channel 2 is filled with a viscous hydrophilic polymer buffer, which is a hydrophilic polymer buffer with a relatively high viscosity. In this embodiment, the viscous hydrophilic polymer buffer is PVP. In other embodiments, the viscous hydrophilic polymer buffer can also be PEO, HEC or HPC. Pre-packaging the buffer in the microfluidic channel 2 can achieve hydrophilic modification of the inner surface of the channel, reduce the adsorption of the analyte on the inner surface, and also slow down the influence of the pressure difference flow on the electrophoretic performance, and can better screen DNA fragments of different sizes with a fixed charge-to-mass ratio to achieve efficient separation.
[0042] Refer to Figure 1 and Figure 2In this embodiment, there are 6 liquid reservoir holes 3, and 3 liquid reservoir holes 3 are distributed on both sides of the cross 24; wherein, the liquid reservoir holes 3 include the first liquid reservoir, the second liquid reservoir, the third liquid reservoir, the fourth liquid reservoir, the fifth liquid reservoir and the sixth liquid reservoir; the loading channel 21 has two loading ends, the first loading end is the third liquid reservoir for loading sample-labeled DNA, the second loading end is located at the bottom of the cross 24 and is connected to the capillary 4 for loading sample DNA, and the third liquid reservoir is used to add sample-labeled DNA; the first liquid reservoir is a negative pressure hole 31, and the cross 24 is located between the negative pressure hole 31 and the loading end of the loading channel 21, which is used to apply a negative pressure of 20-30psi to allow the sample DNA and the DNA used for sample labeling to enter the loading channel 21. The second liquid reservoir, the fourth liquid reservoir, the fifth liquid reservoir and the sixth liquid reservoir are used to apply different voltages to complete the injection and DNA separation;
[0043] In order to reduce the impact of negative pressure during negative pressure loading on the results caused by the sample DNA and the DNA used for sample labeling entering the electrophoresis separation channel 23; the present application solves this problem by increasing the flow resistance between the sample loading channel 21 and the electrophoresis separation channel 23, specifically:
[0044] In the laminar flow of microfluidic experiments, it is sometimes not necessary to perform such accurate calculations on the fluid. A simplified equation can be used to describe the flow of the fluid, namely the Hagen-Poiseuille equation: , pressure difference loss ; Among them, the resistance coefficient f=64 / Re , Reynolds number Re=ρvd / μ , for a rectangular channel, its characteristic diameter d= 2wh / (w+h) , after the above equation is calculated, the channel flow resistance can be finally calculated R=8𝜇𝐿(w+h) 2 / (w 3 h 3 ) ; Wherein, μ is the viscosity of the liquid in the channel, L is the channel length, w is the channel width, and h is the channel height.
[0045] Therefore, when the flow resistance of the electrophoretic separation channel 23 reaches more than one thousand times that of the loading channel 21, it can be considered that during negative pressure injection, the flow of the gel in the electrophoretic separation channel 23 caused by pressure can be ignored; accordingly, the width of the loading channel 21 and the width of the electrophoretic separation channel 23 are calculated by the following formula:
[0046] ;
[0047] Wherein, w1, L1, and h1 are respectively the width, length, and depth of the loading channel 21, and w2, L2, and h2 are respectively the width, length, and depth of the electrophoresis separation channel 23. is the viscosity of the viscous hydrophilic polymer buffer; after actual measurement, its viscosity is 234.7mpas, which is more than 200 times the viscosity of water. Under the condition of controlling the same depth and determining the channel length, the width of the loading channel 21 is configured to be 5 times the width of the electrophoresis separation channel 23, so that the flow resistance of the electrophoresis separation channel 23 is more than one thousand times that of the negative pressure loading channel 21.
[0048] The specific dimensions of the electrophoresis separation channel 23 in this embodiment are designed as follows:
[0049] Reference Figure 4 and Figure 5 , the relationship and derivation between electrophoresis performance and channel depth and width: the depth of the electrophoresis separation channel 23 directly affects the lowest DNA concentration that the chip can detect, that is, the detection limit. The width of the electrophoresis injection channel 22 directly determines the width of the injection channel, affecting the separation efficiency of the electrophoresis signal. Therefore, the channel cross-sectional size of the electrophoresis chip directly determines the performance of the electrophoresis spectrum. The deeper the channel, the lower the detection limit of the chip; the narrower the channel, the higher the detection and separation efficiency of the chip.
[0050] Due to the limitation of the depth-to-width ratio during channel processing, the channel cannot achieve a larger depth and a narrower width at the same time; for example, in machining, the depth-to-width ratio may only be 1:1, and in injection molding, the maximum depth-to-width ratio can only be 3:1.
[0051] The depth of the electrophoresis separation channel 23 of the present application is set to 50 microns to 75 microns. Figure 4 As shown, the detection limit that can be achieved by electrophoresis is 10-30pg / μL. The width of the electrophoresis separation channel 23 is set to 20 microns-50 microns. The above values can be used to obtain the theoretical plate number of DNA of each size through theoretical calculation, which has a good separation effect. The detailed description is as follows:
[0052] Theoretical plate number calculation of DNA of different sizes in electrophoresis separation channel 23 of different widths: According to the theory of capillary electrophoresis, the separation efficiency of different samples is related to the initial zone width of the sample and the diffusion coefficient of the sample, which can be specifically expressed by the formula: Perform theoretical calculations, namely: ; where L is the separation length, Δ is the initial zone width, Dt is the diffusion coefficient, and N is the number of theoretical plates. This formula can be obtained by N=5.54(t R / W 1 / 2)² is calculated; it should be noted that the initial zone width is approximately equal to the width of the electric clamp injection channel 22, and the width of the electric clamp injection channel 22 is proportional to the width of the loading channel 21. The voltage setting can be adjusted so that the width of the electric clamp injection channel 22 is equal to the width of the loading channel 21;
[0053] Therefore, the electrophoresis of small-size channels can be inferred from the relatively easy-to-obtain data, for example:
[0054] Reference Figure 5 This patent detects the electrophoresis spectrum data of two existing electrophoresis chips, where the width of the electrophoresis separation channel 23 of the former is 50 microns, and the width of the channel of the latter is 75 microns. R / W 1 / 2 )² Calculate the theoretical plate number N for each peak in the spectrum, and use 1 / N and The linear relationship of is used to infer the theoretical plate numbers of the peaks of the remaining sizes. Finally, the width of the electrophoresis separation channel 23 of the electrophoresis chip can be selected according to the theoretical plate numbers of the respective widths, thereby obtaining the size of the electrophoresis separation channel 23 of the present application.
[0055] Continue to refer to Figure 1 and Figure 2 The implementation principle of a microfluidic electrophoresis chip for DNA separation and analysis provided in this embodiment is:
[0056] S1: When the electrophoresis chip of the present application is used, it is first cleaned and glued. After cleaning and wetting all the microfluidic channels 2, glue is added to the second liquid reservoir, the fourth liquid reservoir, the fifth liquid reservoir and the sixth liquid reservoir and glue is pressed to fill the channels with glue;
[0057] S2: After adding the sample-labeled DNA to the third liquid reservoir and controlling the capillary 4 to be inserted below the liquid surface of the DNA sample, a negative pressure of 20-30 psi is applied to the first liquid reservoir, so that the sample DNA and the sample-labeled DNA flow into the loading channel 21 along the flow channel;
[0058] S3: After negative pressure loading is completed, voltage is applied to the second liquid reservoir, the fourth liquid reservoir, the fifth liquid reservoir and the sixth liquid reservoir, so that the DNA in the microfluidic channel 2 flows to the cross 24 by electrophoresis, forming an electric clamp, and the loading is completed in a very short time;
[0059] S4: After the electric clamp is formed at the cross 24, the voltages of the second liquid reservoir, the fourth liquid reservoir, the fifth liquid reservoir and the sixth liquid reservoir are quickly switched to the separation voltage, and the DNA samples at the cross enter the electrophoresis separation channel 23 for separation under the action of the electric field force, and the DNA samples on the left and right sides flow toward the second liquid reservoir and the fifth liquid reservoir under the action of the electric field. At the same time, negative pressure loading is carried out synchronously without affecting the electrophoresis separation process;
[0060] It should be noted here that the voltage setting needs to be adjusted by the flow of DNA. By adjusting the voltage, the DNA flows in the direction shown by the arrow in the figure. The specific voltage value is related to the channel size and the buffer in the channel, and can be adjusted according to the actual usage scenario. The relative size of the voltage of each reservoir is: to form an electric clamp, V5>V2 when injecting, and the voltage of V4 and V6 needs to satisfy the output current of the two holes to be a negative value (such as -0.1μA). During electrophoresis separation, the separation voltage is: V6>V4, and the voltage of V5 and V2 needs to satisfy the output current of the two holes to be a positive value (such as 0.1μA). V2, V4, V5, and V6 represent the voltages applied to the second reservoir, the fourth reservoir, the fifth reservoir, and the sixth reservoir, respectively.
[0061] The electrophoresis chip of the present application uses a viscous hydrophilic polymer buffer with a relatively high viscosity as a buffer for DNA screening. After accurate calculation of the channel flow resistance inside the chip, the flow resistance of the electrophoresis separation channel 23 is more than one thousand times the flow resistance of the negative pressure loading channel 21, which can realize negative pressure loading and electrophoresis separation at the same time, preventing the influence of negative pressure loading on the electrophoresis separation channel 23, and increasing the detection efficiency and accuracy; in addition, the present application reasonably integrates the loading channel 21, the electric clamp injection channel 22 and the electrophoresis separation channel 23, and combines the assembly of the liquid storage tank shell to realize the functions of loading, injection and separation. By detecting cross-chips of the same material and theoretical calculations, the chip can achieve a lower detection limit and a higher separation efficiency, which has an important role in promoting the development of chip electrophoresis instruments.
[0062] It should be noted that: when the device provided in the above embodiment realizes its function, only the division of the above functional modules is used as an example. In actual application, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the device and method embodiments provided in the above embodiment belong to the same concept, and the specific implementation process is detailed in the method embodiment, which will not be repeated here.
[0063] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.
[0064] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0065] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are only regarded as exemplary, and the scope and spirit of the present disclosure are defined by the claims.
Claims
1. A microfluidic electrophoresis chip for DNA separation and analysis, comprising a chip body (1), wherein the chip body (1) is provided with a microfluidic channel (2), wherein the microfluidic channel (2) comprises a sample loading channel (21), an electric clamp sample injection channel (22) and an electrophoresis separation channel (23), wherein the electric clamp sample injection channel (22) and the electrophoresis separation channel (23) intersect with each other to form a cross intersection (24), wherein the sample loading channel (21) has a sample loading end, wherein the sample loading channel (21) is connected to the cross intersection (24), and wherein: The microfluidic channel (2) is filled with a viscous hydrophilic polymer buffer, the sample loading channel (21) is connected to a negative pressure hole (31), and the cross intersection (24) is located between the negative pressure hole (31) and the sample loading end; The flow resistance of the electrophoresis separation channel (23) is more than one thousand times the flow resistance of the loading channel (21); The width w1, length L1 and depth h1 of the sample loading channel (21), the width w2, length L2 and depth h2 of the electrophoresis separation channel (23), and the viscosity μ of the viscous hydrophilic polymer buffer satisfy the following relationship:
2. A microfluidic electrophoresis chip for DNA separation and analysis according to claim 1, characterized in that: The chip body (1) comprises an upper substrate (11) and a lower substrate (12); the microfluidic channel (2) is located on the upper substrate (11); and the upper substrate (11) and the lower substrate (12) are bonded to each other.
3. A microfluidic electrophoresis chip for DNA separation and analysis according to claim 1, characterized in that: It also includes a capillary (4), wherein the capillary (4) is connected to the sample loading end.
4. A microfluidic electrophoresis chip for DNA separation and analysis according to claim 3, characterized in that: The chip body (1) is adhesively connected to the capillary (4).
5. A microfluidic electrophoresis chip for DNA separation and analysis according to claim 1, characterized in that: The chip body (1) is made of plastic.
6. A microfluidic electrophoresis chip for DNA separation and analysis according to claim 1, characterized in that: The width of the electrophoresis separation channel (23) is 20 microns to 50 microns.
7. A microfluidic electrophoresis chip for DNA separation and analysis according to claim 6, characterized in that: The depth of the electrophoresis separation channel (23) is 50 microns to 75 microns.
8. The microfluidic electrophoresis chip for DNA separation and analysis according to claim 1, characterized in that: The viscous hydrophilic polymer buffer is PVP, PEO, HEC or HPC.