A microfluidic electrochemical biosensor

Abstract

This invention provides a microfluidic electrochemical biosensor, belonging to the field of antibiotic detection technology. It includes a substrate glass slide and a PDMS chip, with a micron-scale liquid flow channel mechanism on the PDMS chip. The liquid flow channel mechanism includes a flow channel laid in a serpentine pattern on top of the PDMS chip. A delivery tank is located at the port of the flow channel, and the two are connected via a micropump. An electrochemical reaction tank is located at the bend of the flow channel. By setting up a serpentine flow channel on the PDMS chip, and placing an electrochemical reaction tank at each bend of the flow channel, sample liquid can be delivered into each electrochemical reaction tank. Under the delivery of the micropump, the sample liquid can flow into the electrochemical reaction tank at a certain speed, avoiding uneven liquid levels in each electrochemical reaction tank, which could affect the detection of antibiotics in the sample liquid and improve the effectiveness of use.

Description

Technical Field

[0001] This utility model relates to the field of anti-production detection technology, and more specifically, to a microfluidic electrochemical biosensor. Background Technology

[0002] With the widespread use of antibiotics in livestock farming and water environment management, their residues pose a serious threat to food safety and the ecological environment. Antibiotic residues in milk and lake water may not only lead to drug resistance in humans, but also disrupt the balance of the ecosystem. Therefore, rapid, sensitive and accurate antibiotic detection technology has become a research hotspot.

[0003] In recent years, microfluidic technology has shown great potential in the field of biosensing and detection due to its advantages such as low sample and reagent consumption, high integration, and fast analysis speed. Microfluidic chip-based biosensors shorten detection time and reduce detection costs by integrating sample processing, reaction, and detection functions onto a microchip. However, existing microfluidic sensors for antibiotic detection still have technical bottlenecks. The layout of electrochemical reaction regions and channels lacks optimization, and uneven liquid distribution can lead to unstable detection signals, affecting their use. Utility Model Content

[0004] To overcome the above deficiencies, this utility model provides a microfluidic electrochemical biosensor that overcomes or at least partially solves the above technical problems.

[0005] This utility model is implemented as follows:

[0006] This invention provides a microfluidic electrochemical biosensor, comprising a substrate glass slide and a PDMS chip, and a micron-scale liquid flow channel mechanism is provided on the PDMS chip;

[0007] The liquid flow channel mechanism includes:

[0008] The flow channel is laid out in a serpentine shape on top of the PDMS chip;

[0009] An infusion tank is located at the flow channel port, and the two are connected by a micro pump.

[0010] An electrochemical reaction cell is located at a bend in the flow channel, and an electrode assembly is installed inside the electrochemical reaction cell.

[0011] In a preferred embodiment, the micropump is bolted onto the PDMS chip, and a delivery pipe is provided at the inlet end of the micropump, with one end of the delivery pipe communicating with the interior of the delivery tank.

[0012] In a preferred embodiment, the pump end of the micropump is provided with a drain pipe, which is connected to the interior of the flow channel.

[0013] In a preferred embodiment, the material of the flow channel is polydimethylsiloxane.

[0014] In a preferred embodiment, the electrode assembly comprises three electrodes, which are configured as a working electrode, a reference electrode, and a counter electrode in sequence.

[0015] In a preferred embodiment, the electrochemical reaction tank is located at each bend of the flow channel, and each electrochemical reaction tank is equipped with an electrode assembly.

[0016] In a preferred embodiment, a sample collection trough is also provided at the liquid outlet end of the flow channel.

[0017] In a preferred embodiment, the substrate glass slide and the PDMS chip are integrated as a single unit.

[0018] The microfluidic electrochemical biosensor provided by this utility model has the following beneficial effects:

[0019] By setting up a serpentine flow channel on the PDMS chip and setting up an electrochemical reaction tank at each bend of the flow channel, the sample liquid can be delivered into each electrochemical reaction tank. With the delivery of the micro pump, the sample liquid can flow into the electrochemical reaction tank at a certain speed, so as to avoid the liquid in each electrochemical reaction tank being too much or too little, which would affect the detection of antibiotics in the sample liquid and improve the use effect. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of this utility model;

[0022] Figure 2 This is a schematic diagram of the top structure of the PDMS chip of this utility model;

[0023] Figure 3 This is a schematic diagram showing the location of the micropump of this utility model;

[0024] Figure 4 This is a schematic diagram of the connection structure between the micropump and the flow channel of this utility model.

[0025] In the figure: 1. Substrate slide; 2. PDMS chip; 3. Liquid flow channel mechanism; 31. Flow channel; 32. Infusion tank; 321. Micropump; 33. Electrochemical reaction tank; 331. Electrode assembly; 4. Delivery tube; 5. Drain tube; 6. Working electrode; 7. Reference electrode; 8. Counter electrode; 9. Sample collection tank; 10. Liquid outlet. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0027] Example

[0028] Reference Figures 1-4 This utility model provides a technical solution: a microfluidic electrochemical biosensor, including a substrate glass slide 1 and a PDMS chip 2, with a micron-scale liquid flow channel mechanism 3 disposed on the PDMS chip 2. The liquid flow channel mechanism 3 includes a flow channel 31, which is laid in a serpentine shape on top of the PDMS chip 2. The surface of the flow channel 31 is treated with oxygen plasma and then bonded to the PDMS chip 2, with a bonding strength of 0.8 MPa. An infusion tank 32 is opened at the port of the flow channel 31, and the two are connected by a micropump 321. The infusion tank 32 adopts a flared design with an inlet diameter of 2 mm to facilitate the injection of micro-sample liquids, making it easy to use. Furthermore, the micropump 321 in this device is a piezoelectric driven diaphragm pump with an operating voltage of 5V-15V and a flow rate range of 0.1. The flow rate is between μL / min and 10μL / min, and the micropump 321 is connected to the flow channel 31 using a Luer connector to ensure no leakage. The electrochemical reaction tank 33 is located at the bend of the flow channel 31. The electrochemical reaction tank 33 is equipped with an electrode assembly 331, which includes a working electrode 6, a reference electrode 7, and a counter electrode 8. The working electrode 6 is a glassy carbon electrode because glassy carbon electrodes have good conductivity, chemical stability, and low background current, making them suitable for substrate modification. The reference electrode 7 is an Ag / AgCl electrode, whose electrode potential is stable at the standard electrode potential of +0.222V vs SHE, making it suitable for electrochemical detection in aqueous systems. The counter electrode 8 is a platinum electrode (Pt) because it has high catalytic activity and chemical stability, and can effectively promote redox reactions.

[0029] Reference Figures 1-4In a preferred embodiment, the micropump 321 is bolted onto the PDMS chip 2, and a delivery pipe 4 is provided at the inlet end of the micropump 321. One end of the delivery pipe 4 is connected to the inside of the delivery tank 32. A stainless steel stud is embedded in the corresponding position of the PDMS chip 2. The stud has a diameter of 1.5 mm and a embedding depth of 2 mm. It is solidified by PDMS casting to form an integral structure with the chip, avoiding the risk of chip cracking caused by traditional direct drilling installation. A silicone rubber buffer pad with a thickness of 0.3 mm is installed between the micropump 321 and the PDMS chip 2 to effectively absorb the vibration of the micropump 321 during operation, prevent the vibration from affecting the stable transmission of liquid in the flow channel 31, and avoid rigid contact damage to the chip.

[0030] Reference Figures 1-4 In a preferred embodiment, the pump 321 is provided with a drain pipe 5 at the pumping end. The drain pipe 5 is connected to the interior of the flow channel 31. The drain pipe 5 is connected to the outlet end of the pump 321 by a quick-connect coupling. The interface has a built-in sealing ring to ensure the sealing performance during connection and prevent liquid leakage and air bubbles from entering. Fluororubber tubing is selected as the material of the drain pipe 5, which has excellent chemical stability and can withstand the corrosion of various reagents that may come into contact with during the detection process, such as TMB and H2O2 solution. At the same time, it does not adsorb or chemically react with the components in milk and lake water samples.

[0031] Reference Figures 1-4 In a preferred embodiment, the material of the flow channel 31 is polydimethylsiloxane.

[0032] Electrode group 331 includes three electrodes, which are arranged in sequence as working electrode 6, reference electrode 7 and counter electrode 8. Electrode group 331 adopts a multi-layer stacked structure, with working electrode 6 located at the bottom layer, reference electrode 7 surrounding it, and counter electrode 8 placed on top. This design shortens the distance between electrodes, reduces the influence of solution resistance, and avoids cross-interference between electrodes. The spacing between adjacent electrodes is designed to be 8 mm. By filling the space between electrodes with polytetrafluoroethylene (PTFE) insulating material, electrochemical signal crosstalk is prevented, ensuring the accuracy of multi-channel independent detection.

[0033] Electrochemical reaction tanks 33 are located at each bend of the flow channel 31. Each electrochemical reaction tank 33 is equipped with an electrode assembly 331. A sample collection tank 9 is also provided at the liquid outlet of the flow channel 31. The electrochemical reaction tank 33 adopts a rectangular straight channel structure with a diameter of 2 mm and a length of 5 mm. It is smoothly connected to the flow channel 31 to ensure smooth liquid inflow and outflow and reduce eddies and residues. The tank body is integrally molded from polydimethylsiloxane (PDMS). The surface is coated with a hydrophilic silane coating after oxygen plasma treatment to promote liquid spreading and reduce non-specific adsorption of samples and reagents, thereby reducing background interference.

[0034] The substrate glass slide 1 and the PDMS chip 2 are integrated into one unit.

[0035] Specifically, the working process or working principle of a microfluidic electrochemical biosensor is as follows: This device moves the sample inside the flow channel 31 and moves it to the position of the electrochemical reaction tank 33. Based on the electrode group 331 set inside the electrochemical reaction tank 33, the introduction of the sample will generate a current signal, which can detect and analyze the antibiotics in the sample.

[0036] In practical use, connect this device to external detection and analysis equipment and power it on. Drop the sample into the infusion tank 32. For example, milk or lake water samples are diluted 10 times with PBS (pH 7.4), centrifuged at 8000 rpm for 10 minutes, and the supernatant is filtered through a 0.22-micron microporous membrane. Then, take 20 microliters of the filtered supernatant and drop it onto the infusion tank 32 on the PDMS chip 2.

[0037] Next, the micropump 321 is turned on, which can pump the sample into the flow channel 31 and allow it to flow inside the flow channel 31. The device has a liquid outlet 10 at the bend of the flow channel 31 to allow the sample to flow into the electrochemical reaction tank 33. As the sample continues to be transported, it can be transported to other electrochemical reaction tanks 33. Finally, the remaining sample will be transported into the sample collection tank 9 for sample collection.

[0038] The sample flows through channel 31 and sequentially reaches each electrochemical reaction cell 33. Electrochemical reaction cells 33 are pre-prepared with three electrodes (working electrode 6, reference electrode 7, and counter electrode 8). The working electrode 6 is modified with an aptamer corresponding to the antibiotic target. The liquid is incubated in the electrochemical reaction cell 33 for 10 minutes. Then, 20 μL of nanozyme solution modified with complementary DNA is added dropwise to infusion tank 32 and flows sequentially through each electrochemical reaction cell 33 in the same manner. Incubation continues for another 10 minutes. Then, 20 μL of solution containing TMB and H2O2 is added to infusion tank 32 and flows to each electrochemical reaction cell 33 in the same manner for the solution to participate in the reaction. This allows for the subsequent connection of the detection and analysis equipment to the electrochemical reaction cell 33. By detecting the current signal, antibiotics in the sample can be detected.

Claims

1. A microfluidic electrochemical biosensor, characterized in that, It includes a substrate glass slide (1) and a PDMS chip (2), and a micron-scale liquid flow channel mechanism (3) is set on the PDMS chip (2). The liquid flow channel mechanism (3) includes: The flow channel (31) is laid out in a serpentine shape on the top of the PDMS chip (2); An infusion tank (32) is provided at the port of the flow channel (31), and the two are connected by a micro pump (321); An electrochemical reaction tank (33) is located at the bend of the flow channel (31), and an electrode assembly (331) is provided inside the electrochemical reaction tank (33).

2. The microfluidic electrochemical biosensor according to claim 1, characterized in that, The micropump (321) is bolted onto the PDMS chip (2), and a delivery pipe (4) is provided at the inlet end of the micropump (321). One end of the delivery pipe (4) is connected to the inside of the delivery tank (32).

3. A microfluidic electrochemical biosensor according to claim 2, characterized in that, The micropump (321) is provided with a drain pipe (5) at the pumping end, and the drain pipe (5) is connected to the interior of the flow channel (31).

4. A microfluidic electrochemical biosensor according to claim 3, characterized in that, The material of the flow channel (31) is polydimethylsiloxane.

5. A microfluidic electrochemical biosensor according to claim 4, characterized in that, The electrode group (331) includes three electrodes, which are configured as working electrode (6), reference electrode (7) and counter electrode (8) in sequence.

6. A microfluidic electrochemical biosensor according to claim 5, characterized in that, The electrochemical reaction tank (33) is located at each bend of the flow channel (31), and each electrochemical reaction tank (33) is provided with an electrode assembly (331).

7. A microfluidic electrochemical biosensor according to claim 6, characterized in that, A sample collection trough (9) is also provided at the liquid outlet end of the flow channel (31).

8. A microfluidic electrochemical biosensor according to claim 7, characterized in that, The substrate glass slide (1) and the PDMS chip (2) are integrated into one unit.

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