Micro-fluidic chip and application thereof

Abstract

The invention discloses a micro-fluidic chip and application thereof, the micro-fluidic chip comprises a first channel and a capture branch, and a first purification unit is arranged below the first channel; an inlet of the first channel is communicated with a first sample inlet and a second sample inlet, and the first sample inlet and the second sample inlet are used for introducing different samples; a sample introduced from the first sample inlet is perpendicular to the center line of the first channel and enters the first channel from two sides of the first channel, and a sample introduced from the second sample inlet enters the first channel along the center line of the first channel; an outlet of the first channel is communicated with a sample outlet channel; the sample outlet channel comprises a capturing branch, a first waste liquid branch and a second waste liquid branch; the inlet width of the capture branch is smaller than the width of the first channels on the two sides and the middle width of the capture branch. The first channel and the capturing branch are arranged, the target particles are preliminarily purified in the first channel and enriched into the capturing branch, the second purifying unit is used for further purifying the target particles, and rapid enrichment and accurate separation of the target particles can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of microfluidic chips, and particularly relates to a microfluidic chip and its applications. Background Technology

[0002] In fields such as biomedical detection, environmental microbial monitoring, and food safety control, the efficient separation and enrichment of specific particles (such as cells, bacteria, exosomes, and microorganisms) in complex matrices is a key prerequisite for achieving accurate qualitative and quantitative analysis. Complex matrix samples such as blood, body fluids, soil extracts, and food homogenates have complex compositions and typically contain large amounts of background particles, proteins, nucleic acids, and other interfering substances, making it difficult to directly detect low-abundance target particles.

[0003] Currently, the separation and enrichment of target particles such as microorganisms still face significant challenges. Firstly, microorganisms are diverse and have complex population structures, often coexisting with numerous impurities in real samples, making separation difficult. Traditional methods such as plate culture, selective enrichment, and centrifugation, while widely used, still suffer from cumbersome procedures, long processing times, and high levels of operator expertise. Furthermore, these methods may alter the original state and activity of microorganisms during cultivation, affecting the reliability of the results, and are difficult to automate and integrate, limiting their application in rapid on-site detection.

[0004] Although molecular biology techniques (such as PCR and metagenomic sequencing) have made significant progress in detection sensitivity and specificity in recent years, their effectiveness still largely depends on preliminary sample pretreatment and target enrichment steps. If the concentration of target particles in the sample is too low or the background interference is too strong, the accuracy and stability of the detection signal will be affected. Therefore, developing rapid enrichment and sorting techniques for target particles in complex matrices is fundamental to overcoming the bottleneck in the detection of complex matrix samples and achieving rapid on-site detection. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is that the separation and enrichment process of target particles in complex matrices is cumbersome, time-consuming and difficult to meet the needs of rapid on-site detection. The present invention proposes a microfluidic chip that can achieve rapid enrichment and accurate separation of target particles and its application.

[0006] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows: The present invention provides a microfluidic chip, including a fluid channel layer, the fluid channel layer including a first channel and a capture branch, a first purification unit disposed below the first channel, the first purification unit using electrical, acoustic, magnetic, deterministic lateral displacement or inertial focusing technology to achieve primary purification of target particles, and the capture branch being used to enrich target particles; The inlet of the first channel is connected to a first inlet and a second inlet, which are used to introduce different samples. The sample introduced by the first inlet enters the first channel from both sides of the first channel perpendicular to the center line, and the sample introduced by the second inlet enters the first channel along the center line of the first channel. The outlet of the first channel is connected to a sample outlet channel, which includes a capture branch, a first waste liquid branch, and a second waste liquid branch. The inlets of the first waste liquid branch and the second waste liquid branch are located on both sides of the inlet of the capture branch. The width of the capture branch entrance is smaller than the width of the first channel on both sides and the width of the capture branch in the middle.

[0007] In some embodiments of this application, a second purification unit is provided below the capture branch. The second purification unit uses surface capture, volume capture, microfluidic in-situ array, optical / magnetic traps or dielectric technology to achieve secondary purification of the target particles.

[0008] In some embodiments of this application, a pointed interdigital electrode array is disposed below the first channel, with the pointed corners of the pointed interdigital electrode array facing the capture branch.

[0009] In some embodiments of this application, a sawtooth electrode array is disposed below the second channel, surrounding the entrance of the capture branch, and the sawtooth electrode array includes at least two sawtooth units.

[0010] In some embodiments of this application, the fluid channel layer further includes a square annular channel, and the first inlet is disposed at one end of the square annular channel; The first channel is configured as a straight line, and the first channel is connected to the end of the square annular channel away from the first injection port; The second injection port is located at the junction of the annular channel and the first channel; the first injection port, the second injection port, and the first channel are located in the same horizontal direction; Let the width of the first channel be a, the inlet width of the capture branch be b, and the flow resistances of the capture branch, the first waste liquid branch, and the second waste liquid branch be c, d, and e, respectively; then a, b, c, d, and e satisfy the following relationship: .

[0011] In some embodiments of this application, the capture branch inlet is on the same horizontal line as the first channel, and the first waste liquid branch inlet and the second waste liquid branch inlet are vertically arranged on both sides of the capture branch inlet.

[0012] In some embodiments of this application, the microfluidic chip further includes a substrate layer disposed below the fluid channel layer. The substrate layer has through holes that communicate with the first inlet, the second inlet, the outlet of the capture branch, the outlet of the first waste liquid branch, and the outlet of the second waste liquid branch, respectively, for fluid transport. The angular interdigitated electrode array is etched on the substrate layer below the first channel; the sawtooth electrode array is etched on the substrate layer below the capture branch.

[0013] In some embodiments of this application, the microfluidic chip further includes a cover layer disposed on the side of the fluid channel layer away from the substrate layer, and the cover layer, the fluid channel layer, and the substrate layer are connected together.

[0014] In some embodiments of this application, the cover layer is made of glass, and the substrate layer is made of ITO glass.

[0015] In some embodiments of this application, the fluid channel layer is made of a perforated thin film, and the perforated portion of the perforated thin film forms a microfluidic channel.

[0016] Another aspect of the present invention provides the application of the above-mentioned microfluidic chip in the detection of complex matrix samples.

[0017] In some embodiments of this application, the complex matrix sample includes blood, urine, body fluids, soil extracts, and food homogenates.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a microfluidic chip. By precisely setting the structure of the fluid channel layer, the liquids from the two inlets in the first channel are in a laminar flow state. The two-phase fluids from the first inlet flow to the waste liquid branches on both sides, while the fluid from the second inlet is constrained in the middle and covers the inlet of the capture branch, acting as a physical barrier to prevent the sample from the first inlet from entering the capture branch. This achieves path isolation of the liquids introduced from the two inlets, which is beneficial for removing matrix interference compared to single injection. By setting up a first purification unit, the target particles are purified in one step using electrical, acoustic, magnetic, deterministic lateral displacement, or inertial focusing techniques. The target particles are directionally guided to the capture branch and efficiently enriched. The entire process does not rely on labeling or complex pretreatment. The precise screening of target particles can be achieved solely through structural design and electrical, acoustic, magnetic, deterministic lateral displacement, or inertial focusing techniques. It is highly adaptable and easy to operate. By adjusting the flow resistance of the three branches, the flow rate of the capture branch is reduced. Then, by increasing the width of the capture branch, the flow velocity in the capture branch channel is reduced, thereby achieving the capture of the target particle. By setting a contraction-expansion structure for the capture branch, the particle stream enriched by the sharp interdigitated electrodes exhibits differences in motion trajectory, achieving separation. Large / high-density particles move towards the center, while small / low-density particles move towards the sidewall, resulting in differences in particle trajectory due to different inertial forces. By designing a serrated electrode array surrounding the inlet of the capture branch, particles moving in different directions are captured by the corresponding electrodes, achieving targeted capture of "one type of particle corresponding to one set of electrodes". Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the microfluidic chip provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the fluid channel layer provided in an embodiment of the present invention; Explanation of reference numerals in the attached figures: 100. Fluid channel layer; 101. Square annular channel; 102. First injection port; 103. First channel; 104. Second injection port; 105. Capture branch; 106. First waste liquid branch; 107. Second waste liquid branch; 200. Cover sheet layer; 300. Substrate layer; 301. Sharp-angled interdigitated electrode array; 302. Serrated electrode array. Detailed Implementation

[0020] The technical solutions in specific embodiments of the present invention will now be described in detail and completely with reference to the accompanying drawings. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0021] This invention provides a microfluidic chip, such as Figure 1 , 2 As shown, it includes a fluid channel layer, which includes a first channel and a capture branch. A first purification unit is arranged below the first channel. The first purification unit uses electrical, acoustic, magnetic, deterministic lateral displacement or inertial focusing technology to achieve primary purification of target particles. The capture branch is used to enrich target particles. The inlet of the first channel is connected to a first injection port and a second injection port. The first injection port and the second injection port are used to introduce different samples. The sample introduced by the first injection port enters the first channel from both sides of the first channel perpendicular to the center line of the first channel, and the sample introduced by the second injection port enters the first channel along the center line of the first channel. The outlet of the first channel is connected to a sample outlet channel, which includes a capture branch, a first waste liquid branch, and a second waste liquid branch. The inlets of the first waste liquid branch and the second waste liquid branch are located on both sides of the inlet of the capture branch. The width of the capture branch entrance is less than the width of the first channel on both sides and the width of the capture branch in the middle.

[0022] It is important to note that in fields such as biomedical detection, environmental microbial monitoring, and food safety control, the efficient separation and enrichment of specific particles (such as cells, bacteria, exosomes, and microorganisms) in complex matrices is a crucial prerequisite for achieving accurate qualitative and quantitative analysis. Currently, the core technical challenge in detecting target particles such as microorganisms lies in how to achieve rapid enrichment and separation of microorganisms from complex matrices. Firstly, microorganisms are diverse, have complex population structures, and often coexist with a large number of impurities in real samples, making separation difficult. Traditional methods such as plate culture, selective enrichment, and centrifugation, while widely used, still suffer from cumbersome procedures, long processing times, and high requirements for operator expertise. Current rapid detection methods, such as nucleic acid amplification and bioluminescence methods, are severely interfered with by the sample's cellular matrix, resulting in inaccurate detection. Solid-phase imaging methods use filtration to remove the cellular matrix for bacterial enrichment, but this suffers from filter clogging and insufficient detection limits.

[0023] To address the aforementioned issues, the microfluidic chip of this invention employs a precisely designed fluid channel layer structure. Within the first channel, the liquids from the two inlets are in a laminar flow state. Liquid from the first inlet enters the first channel from both sides and, driven by the velocity gradient of the Poiseuille flow field, undergoes lateral migration under shear stress, merging into the first / second waste liquid branches on both sides. Within the first channel, the liquid from the second inlet forms a core flow due to the laminar flow effect. Through fluid dynamic constraints, it occupies the central region of the first channel, covers the middle outlet, and enters the capture branch. This design utilizes the viscous isolation mechanism of the laminar interface and employs the buffer core flow to construct a physical barrier, effectively preventing the sample from the first inlet from entering the rear capture branch through diffusion or convection, thus achieving path isolation between the sample from the first inlet and the buffer solution from the second inlet. Compared to single-inlet sampling, this design is beneficial for removing matrix interference. By setting up a first purification unit, the target particles are purified in one step using electrical, acoustic, magnetic, deterministic lateral displacement, or inertial focusing techniques. The target particles are directionally guided to the capture branch and efficiently enriched. The entire process does not rely on labeling or complex pretreatment. The precise screening of target particles can be achieved solely through structural design and electrical, acoustic, magnetic, deterministic lateral displacement, or inertial focusing techniques. It is highly adaptable and easy to operate. By diverting the flow through three branches, the flow rate in the capture branch is reduced. Then, by increasing the width of the capture branch, the flow velocity in the capture branch channel is reduced, thereby achieving the capture of the target particle.

[0024] In one embodiment, a second purification unit is provided below the capture branch. The second purification unit uses surface capture, volume capture, microfluidic in-situ array, optical / magnetic traps or dielectric technology to achieve secondary purification of the target particles.

[0025] By adopting the above technical solution, a second purification unit is set below the capture branch, which can further purify the particles entering the capture branch.

[0026] In one embodiment, a pointed interdigital electrode array is disposed below the first channel, with the pointed corners of the pointed interdigital electrode array facing the capture branch.

[0027] By adopting the above technical solution, a sharp-angled interdigital electrode array with its sharp corners facing the capture branch is set below the first channel. By adjusting the dielectric parameters and flow rate, when the fluid force on the particles is greater than the dielectric force, they will flow out from the waste liquid branches on both sides with the fluid. When the dielectric force on the particles is greater than the fluid force, they will be directionally guided to the capture branch and achieve efficient enrichment. The whole process does not rely on labeling or complex pretreatment. The precise screening of target particles can be achieved only through structural design and electric field control. It has strong adaptability and is easy to operate.

[0028] In one embodiment, a sawtooth electrode array is disposed below the second channel, surrounding the entrance of the capture branch, and the sawtooth electrode array includes at least two sawtooth units.

[0029] By reducing the width of the capture branch inlet and increasing the width of the middle channel, based on the principle of squeeze flow separation, the particle flow enriched by the sharp-angled interdigitated electrodes exhibits differences in motion trajectory, thus achieving separation. Large / high-density particles move towards the center, while small / low-density particles move towards the sidewall, resulting in differences in particle trajectory due to different inertial forces. By designing a serrated electrode array surrounding the capture branch inlet, particles moving in different directions are captured by corresponding electrodes, achieving targeted capture of "one type of particle corresponding to one set of electrodes".

[0030] In one embodiment, the fluid channel layer further includes a square annular channel, and the first inlet is disposed at one end of the square annular channel; The first channel is set to be linear, and the first channel is connected to the end of the square annular channel away from the first injection port; The second injection port is located at the junction of the square annular channel and the first channel; the first injection port, the second injection port, and the first channel are located in the same horizontal direction; Let the width of the first channel be *a*, the inlet width of the capture branch be *b*, and the flow resistances of the capture branch, the first waste liquid branch, and the second waste liquid branch be *c*, *d*, and *e*, respectively; then *a*, *b*, *c*, *d*, and *e* satisfy the following relationship: .

[0031] Through the above structural design, the flow rate of the capture branch is reduced by adjusting the flow resistance of the three branches. Then, combined with the increase in the width of the capture branch, the flow velocity in the capture branch channel is reduced, thereby achieving the capture of the target particle.

[0032] In one embodiment, the capture branch inlet is on the same horizontal line as the first channel, and the first waste liquid branch inlet and the second waste liquid branch inlet are vertically arranged on both sides of the capture branch inlet.

[0033] In one embodiment, the microfluidic chip further includes a substrate layer disposed below the fluid channel layer. The substrate layer has through holes that are respectively connected to the first sample inlet, the second sample inlet, the outlet of the capture branch, the outlet of the first waste liquid branch, and the outlet of the second waste liquid branch for fluid transport. The angular interdigitated electrode array is etched on the substrate layer below the first channel; the sawtooth electrode array is etched on the substrate layer below the capture branch.

[0034] In one embodiment, the microfluidic chip further includes a cover layer disposed on the side of the fluid channel layer away from the substrate layer, and the cover layer, the fluid channel layer, and the substrate layer are connected together.

[0035] In one embodiment, the cover layer is made of glass, and the substrate layer is made of ITO glass.

[0036] In one embodiment, the fluid channel layer is made of a perforated film, and the perforated portion in the perforated film forms a microfluidic channel.

[0037] Another aspect of the present invention provides the application of the above-mentioned microfluidic chip in the detection of complex matrix samples.

[0038] In one embodiment, the complex matrix sample includes blood, urine, body fluids, soil extracts, and food homogenates.

[0039] In another aspect, the present invention provides a method of using the above-described microfluidic chip, comprising the following steps: (1) Start dielectric control: Apply dielectric signals to the first channel and the capture branch respectively, wherein the dielectric signal of the first channel is a periodic signal and the dielectric signal of the capture branch is set to normally open; (2) Sample injection: Complex matrix samples are injected through the first injection port, and buffer solution is injected through the second injection port; particles smaller than a certain size in complex matrix samples are separated from large particles because the dielectric force they experience is greater than the fluid force, and they enter the capture branch along with the buffer solution. (3) Within the capture branch, particles smaller than a certain size will be further purified and separated, resulting in differences in motion trajectories to achieve separation. Large / high-density particles move towards the center, while small / low-density particles move towards the sides, forming differences in particle trajectories due to different inertial forces. Thus, different particles will be captured onto the sawtooths at different angles of the sawtooth electrode array, thereby achieving further purification and enrichment of particles smaller than a certain size. (4) After the sample is injected, stop the dielectric signal of the first channel and then stop the two-phase injection. At this time, the flow rate in the channel drops to 0. Adjust the dielectric signal of the capture branch channel to reduce the dielectric force to facilitate optical tweezers to grab the sample, while ensuring that the bacteria are captured on the electrode.

[0040] It should be noted that after the target particles are purified and aggregated using the microfluidic chip described above, those skilled in the art can capture the target particles on the corresponding electrodes using optical tweezers or other methods. Then, Raman, fluorescence, and other techniques can be used to identify the target particles and for subsequent qualitative analysis.

[0041] To provide a clearer and more detailed description of the microfluidic chip and its applications provided in the embodiments of the present invention, specific embodiments will be described below.

[0042] Example 1: Microfluidic Chip like Figure 1 , 2 The microfluidic chip includes a fluid channel layer 100, a cover layer 200, and a substrate layer 300. The fluid channel layer 100 is fabricated using a perforated thin film double-sided adhesive, with the perforated portions forming microfluidic channels. The cover layer 200 is made of quartz glass, and the substrate layer 300 is made of ITO quartz glass. The cover layer 200 and the substrate layer 300 are disposed on opposite sides of the fluid channel layer 100. The fluid channel layer 100, cover layer 200, and substrate layer 300 are connected together through the fluid channel layer 100.

[0043] The fluid channel layer 100 includes a square annular channel 101, a first channel 103, and a sample outlet channel. One end of the annular channel 101 is provided with a first sample inlet 102; The first channel 103 is configured as a straight line, which is connected to the end of the square annular channel 101 away from the first injection port 102, and a second injection port 104 is provided at the connection point. The second injection port 104 is located on the center line of the first channel 103. The first injection port 102, the second injection port 104 and the first channel 103 are in the same horizontal direction, and are used to introduce different samples; The sample outlet channel includes a capture branch 105, a first waste liquid branch 106, and a second waste liquid branch 107. The inlet of the capture branch 105 is at the same horizontal line as the first channel 103. The inlets of the first waste liquid branch 106 and the second waste liquid branch 107 are perpendicularly arranged on both sides of the inlet of the capture branch 105. The outlets of the capture branch 105, the first waste liquid branch 106, and the second waste liquid branch 107 are arranged in parallel.

[0044] In this embodiment, the width of the first channel 103 is set to a, the inlet width of the capture branch 105 is set to b, and the flow resistances of the capture branch 105, the first waste liquid branch 106, and the second waste liquid branch 107 are set to c, d, and e, respectively; then a, b, c, d, and e satisfy the following relationship: .

[0045] The substrate layer 300 has through-holes that connect to the first sample inlet 102, the second sample inlet 104, the outlet of the capture branch 105, the outlet of the first waste liquid branch 106, and the outlet of the second waste liquid branch 107, respectively, for fluid transport. An electrode array is etched on the substrate layer 300, comprising a pointed interdigitated electrode array 301 and a serrated electrode array 302. The pointed interdigitated electrode array 301 is disposed below the first channel 103 and points towards the capture branch 105; the sawtooth electrode array 302 is disposed around the entrance of the capture branch 105.

[0046] Example 2: How to use the microfluidic chip in Example 1 Taking macrophage samples containing bacteria as an example of complex matrix samples: (1) First, prepare bacterial samples and buffer solutions, corresponding to the first and second injection ports respectively; (2) Start dielectric control and apply dielectric signals to the first channel and the capture branch respectively. The dielectric signal of the first channel is a periodic signal, capture-release; the dielectric signal of the capture branch is set to normally open. (3) When the bacterial sample is introduced, it forms a laminar flow interface with the buffer in the first channel to prevent the bacterial sample from entering the inlet of the capture branch. The bacteria are subjected to the maximum dielectric force in the sample, thus achieving separation from the sample. They enter the buffer phase from the sample phase and are captured at the electrode tip. Under the action of the periodic signal, they move along the electrode to the capture branch and are captured by the electrode of the capture branch, thus achieving bacterial enrichment. (4) After the sample is injected, stop the dielectric signal of the first channel and then stop the two-phase injection. At this time, the flow rate in the channel drops to 0. Adjust the dielectric signal of the capture branch channel to reduce the dielectric force to facilitate optical tweezers to grasp the sample, while ensuring that the bacteria are captured on the electrode.

[0047] (5) The particle position is automatically identified in the capture branch, and then Raman acquisition is performed by optical tweezers in sequence.

[0048] (6) Use Raman model to identify Raman spectra and determine whether bacteria are present in the sample.

[0049] The above are merely exemplary embodiments of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Other embodiments of this disclosure will be readily apparent to those skilled in the art upon consideration of the specification and the disclosure of practical truths.

[0050] This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described in this disclosure. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A microfluidic chip, characterized in that, The system includes a fluid channel layer, which comprises a first channel and a capture branch. A first purification unit is disposed below the first channel. The first purification unit uses electrical, acoustic, magnetic, deterministic lateral displacement, or inertial focusing techniques to achieve primary purification of the target particles. The capture branch is used to enrich the target particles. The inlet of the first channel is connected to a first inlet and a second inlet, which are used to introduce different samples. The sample introduced by the first inlet enters the first channel from both sides of the first channel perpendicular to the center line, and the sample introduced by the second inlet enters the first channel along the center line of the first channel. The outlet of the first channel is connected to a sample outlet channel, which includes a capture branch, a first waste liquid branch, and a second waste liquid branch. The inlets of the first waste liquid branch and the second waste liquid branch are located on both sides of the inlet of the capture branch. The width of the capture branch entrance is smaller than the width of the first channel on both sides and the width of the capture branch in the middle.

2. The microfluidic chip according to claim 1, characterized in that, A second purification unit is provided below the capture branch. The second purification unit uses surface capture, volume capture, microfluidic in-situ array, optical / magnetic traps or dielectric technology to achieve secondary purification of the target particles.

3. The microfluidic chip according to claim 2, characterized in that, A pointed interdigital electrode array is disposed below the first channel, with the pointed corners of the interdigital electrode array facing the capture branch.

4. The microfluidic chip according to claim 2, characterized in that, Below the second channel, a sawtooth electrode array is arranged around the entrance of the capture branch, and the sawtooth electrode array includes at least two sawtooth units.

5. The microfluidic chip according to claim 1, characterized in that, The fluid channel layer further includes a square annular channel, and the first sample inlet is disposed at one end of the square annular channel; The first channel is configured as a straight line, and the first channel is connected to the end of the square annular channel away from the first injection port; The second injection port is located at the junction of the annular channel and the first channel; the first injection port, the second injection port, and the first channel are located in the same horizontal direction; Let the width of the first channel be a, the inlet width of the capture branch be b, and the flow resistances of the capture branch, the first waste liquid branch, and the second waste liquid branch be c, d, and e, respectively; then a, b, c, d, and e satisfy the following relationship: 。 6. The microfluidic chip according to claim 5, characterized in that, The capture branch inlet is on the same horizontal line as the first channel, and the first waste liquid branch inlet and the second waste liquid branch inlet are perpendicularly arranged on both sides of the capture branch inlet.

7. The microfluidic chip according to claim 6, characterized in that, The microfluidic chip also includes a substrate layer disposed below the fluid channel layer. The substrate layer has through holes that are respectively connected to the first sample inlet, the second sample inlet, the capture branch outlet, the first waste liquid branch outlet and the second waste liquid branch outlet for fluid transport. The pointed interdigitated electrode array is etched on the substrate layer below the first channel; The sawtooth electrode array is etched onto the substrate layer beneath the capture branch.

8. The microfluidic chip according to claim 7, characterized in that, The microfluidic chip also includes a cover layer, which is disposed on the side of the fluid channel layer away from the substrate layer, and the cover layer, the fluid channel layer and the substrate layer are connected together.

9. The microfluidic chip according to claim 8, characterized in that, The cover layer is made of glass, and the substrate layer is made of ITO glass; The fluid channel layer is made of a perforated thin film, and the perforated portion of the perforated thin film forms a microfluidic channel.

10. The application of the microfluidic chip according to any one of claims 1-9 in the detection of complex matrix samples.

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