Digital microfluidic PCR chip

Abstract

The utility model relates to PCR chip technical field especially, and it is a kind of digital microfluidic PCR chip;Including substrate, droplet, be provided with several electrodes on substrate, at least part electrode is half moon electrode, the arc profile of half moon electrode is matched with the contact circle profile of droplet on the substrate;It further includes spacer between the substrate and the electrode, the side of the substrate is coated with hydrophobic coating where the spacer is located;The utility model half moon electrode makes the effective three-phase contact line of droplet on electrode longer, more uniform.This significantly enhances the electro-wetting driving force, so that droplet can be effectively stretched and separated at lower voltage, reduce the power consumption of the whole system, and reduce the interference of thermal effect generated by high voltage on PCR reaction process, at the same time spacer provides the determined separation position, and is combined with hydrophobic coating, can effectively guide droplet to break at the predetermined path neck.

Description

Technical fields:

[0001] This invention relates to the field of PCR chip technology, and in particular to a digital microfluidic PCR chip. Background technology:

[0002] Digital microfluidics technology, especially digital microfluidic PCR chips, is one of the core components of modern biomedical detection and analysis platforms. It uses programmed control of the voltage on array electrodes to drive nanoliter or picoliter droplets through electrowetting effects, enabling them to move, merge, separate, and react. This integrates traditional laboratory sample preparation, amplification, and detection steps onto a single microchip, achieving high throughput, automation, and low reagent consumption.

[0003] Among the many operations in digital microfluidic chips, the precise and reliable separation of droplets is one of the key and challenging steps. Current technologies commonly employ square electrode designs to drive and separate droplets. However, the geometry of the square electrode does not match the natural contour (circular) of the droplet, resulting in non-uniform three-phase contact lines between the droplet and the electrode edge. This non-uniformity necessitates a higher driving voltage to overcome a significant interfacial energy barrier during droplet separation, increasing system power consumption and thermal effects. Furthermore, it can easily lead to droplet breakage or residue during separation, reducing the success rate and accuracy of the separation. Utility Model Content:

[0004] The purpose of this invention is to provide a digital microfluidic PCR chip that addresses the shortcomings of existing technologies, enabling high-success-rate and high-precision droplet separation without increasing the driving voltage.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: a digital microfluidic PCR chip, including a substrate, a droplet, and a plurality of electrodes disposed on the substrate, at least some of which are crescent-shaped electrodes, the arc contour of the crescent-shaped electrodes matching the contact circle contour of the droplet on the substrate; and further including a spacer disposed between the substrate and the electrodes, the spacer being coated with a hydrophobic coating on one side of the substrate.

[0006] A further improvement to the above scheme is that a plurality of spacers are provided, and the plurality of spacers are respectively provided between two adjacent electrodes.

[0007] A further improvement to the above scheme is that the spacers are arranged symmetrically or asymmetrically along the droplet separation path.

[0008] A further improvement to the above scheme is that the shape of the spacer is set to one of square, circle, or trapezoid.

[0009] A further improvement to the above scheme is that the ratio of the radius of curvature of the crescent-shaped electrode to the diameter of the droplet is 1:1.5.

[0010] A further improvement to the above scheme is that the thickness of the spacer is 0.5 μm to 2 μm.

[0011] A further improvement to the above solution is that the hydrophobic coating is a Teflon or CYTOP material.

[0012] A further improvement to the above scheme is that the substrate includes an upper substrate and a lower substrate, the upper substrate and the lower substrate are arranged in parallel, and the electrode is disposed on the surface of the lower substrate facing the upper substrate.

[0013] A further improvement to the above scheme is that it also includes a heating element and a temperature control sensor for performing the PCR reaction, both of which are disposed on the substrate.

[0014] The advantages of this utility model are as follows: This utility model includes a substrate, a droplet, and a plurality of electrodes disposed on the substrate, at least some of which are crescent-shaped electrodes, and the arc contour of the crescent-shaped electrodes matches the contact circle contour of the droplet on the substrate; it also includes a spacer disposed between the substrate and the electrodes, and the spacer is coated with a hydrophobic coating on one side of the substrate.

[0015] The crescent-shaped electrode of this invention has an arcuate profile that closely matches the circular contact profile of the droplet, resulting in a longer and more uniform effective three-phase contact line on the electrode. This significantly enhances the electrowetting driving force, allowing the droplet to be effectively stretched and separated at lower voltages, reducing the overall system power consumption and minimizing the interference of high-voltage thermal effects on the PCR reaction process. Simultaneously, the spacer provides a defined separation location and, combined with the hydrophobic coating, effectively guides the droplet to break off at the predetermined neck. Even with a large electrode spacing, this structure maintains a high separation success rate, improving the chip's adaptability and reliability in various application scenarios. Attached image description:

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] Figure 2 This is a side sectional view of the present invention.

[0018] Explanation of reference numerals in the attached drawings: substrate 1, upper substrate 11, lower substrate 12, droplet 2, electrode 3, spacer 4, hydrophobic coating 41, heating element 5, temperature sensor 6. Detailed implementation method:

[0019] The present invention will be further described below with reference to the accompanying drawings, such as... Figure 1-2 As shown, this invention provides a digital microfluidic PCR chip, including a substrate 1, a droplet 2, and a plurality of electrodes 3 disposed on the substrate 1. At least some of the electrodes 3 are crescent-shaped electrodes 3, and the arc contour of the electrodes 3 matches the contact circular contour of the droplet 2 on the substrate 1. It also includes a spacer 4 disposed between the substrate 1 and the electrodes 3. The spacer 4 is coated with a hydrophobic coating 41 on one side of the substrate 1. The arc contour of the crescent-shaped electrodes 3 highly matches the circular contact contour of the droplet 2, making the effective three-phase contact line of the droplet 2 on the electrodes 3 longer and more uniform. This significantly enhances the electrowetting driving force, allowing the droplet 2 to be effectively stretched and separated at a lower voltage, reducing the power consumption of the entire system and reducing the interference of the thermal effect caused by high voltage on the PCR reaction process. At the same time, the spacer 4 provides a defined separation position and, combined with the hydrophobic coating 41, can effectively guide the droplet 2 to break at the neck of a predetermined path. Even with a large electrode spacing, this structure can maintain a high separation success rate, improving the chip's adaptability and reliability in different application scenarios. The matched contour makes the droplet 2 more evenly stressed, avoiding stress concentration at the corners of the square electrode 3, thereby reducing the possibility of unexpected breakage or residue of the droplet 2. The separation process is more controllable and more precise.

[0020] This invention provides several spacers 4, which are respectively positioned between two adjacent electrodes 3. By setting multiple spacers 4 and arranging them between adjacent electrodes 3, a stable droplet 2 separation "channel" or "barrier" is formed. This allows for more precise control of the necking and breakage position of the droplet 2, further improving the repeatability and success rate of droplet 2 separation. It is particularly suitable for complex PCR processes that require continuous and repeated droplet 2 separation.

[0021] The spacer 4 of this invention is arranged in a symmetrical or asymmetrical distribution along the separation path of the droplet 2. The symmetrical distribution is suitable for generating sub-droplets 2 of equal volume, which meets the requirements of most PCR reactions for the consistency of the reaction system. The asymmetrical distribution can be used to generate sub-droplets 2 of unequal volume, for example, one for PCR amplification and the other for subsequent detection or archiving, thus expanding the application functions of the chip.

[0022] The spacer 4 of this invention is designed to be square, circular, or trapezoidal. Different shapes of spacers 4 can generate different flow fields and capillary force effects. Square shapes are easy to manufacture, circular shapes can provide more uniform force, and trapezoidal shapes may be more conducive to guiding liquid flow in a specific direction. The spacer 4 can be optimized according to the specific properties of the droplets 2 and separation requirements to achieve the best separation effect.

[0023] The radius of curvature of electrode 3 in this invention is 1:1.5 to the diameter of droplet 2. This specific ratio is the result of simulation and experimental optimization, ensuring that the curvature of the crescent-shaped electrode 3 matches the size of the target droplet 2 optimally. At this ratio, the spread and stretching efficiency of droplet 2 on electrode 3 is highest, maximizing the length of the three-phase contact line, thereby obtaining the strongest driving force with minimal energy consumption. This is a key parameter guarantee for achieving high-performance separation.

[0024] The thickness of the spacer 4 in this invention is 0.5μm to 2μm. If the thickness is too thin, it may not provide an effective physical restraint; if the thickness is too thick, it may excessively impede the movement of the droplet 2 and increase the overall thickness of the chip. A thickness of 0.5μm to 2μm can effectively define the separation gap, ensuring that the droplet 2 breaks at the neck, without significantly affecting the normal transport of the droplet 2, and is suitable for standard microfabrication processes.

[0025] The hydrophobic coating 41 of this invention is made of Teflon or CYTOP material. Teflon and CYTOP are recognized in the industry as high-performance hydrophobic materials, characterized by stability, inertness, large hydrophobic angle, and durability. Using these materials ensures that the surface of the spacer 4 has a lasting and strong hydrophobicity, effectively preventing droplets 2 from spreading or adhering to the spacer 4, and ensuring that droplets 2 can be cleanly "pulled off" rather than "torn apart," thereby obtaining sub-droplets 2 with clear outlines and accurate volume.

[0026] The substrate 1 of this invention includes an upper substrate 11 and a lower substrate 12, which are arranged in parallel. An electrode 3 is disposed on the surface of the lower substrate 12 facing the upper substrate 11. The upper substrate 11 typically serves as a ground electrode 3, which together with the driving electrode 3 on the lower substrate 12 forms an electric field. This structure facilitates the uniform distribution of the electric field, providing a stable and reliable environment for driving the droplet 2, and also facilitates the integration of spacers 4 and hydrophobic layers.

[0027] This invention also includes a heating element 5 and a temperature sensor 6 for performing PCR reactions. Both the heating element 5 and the temperature sensor 6 are disposed on the substrate 1. The heating element 5 and the temperature sensor 6 enable the chip to form and precisely maintain three specific temperature regions required for the PCR process: denaturation, annealing, and extension. As a preferred embodiment, the heating element 5 is a platinum metal film deposited on the substrate 1, and the temperature sensor 6 is a platinum resistance temperature detector integrated with or adjacent to the heating element 5. The chip is powered by an external power supply through electrodes 3 and leads to achieve heating and temperature control detection. The droplet 2 of the heating element 5 can circulate within these temperature regions under the drive of the electrodes 3 to achieve automated nucleic acid amplification.

[0028] Of course, the above are only preferred embodiments of this utility model. Therefore, all equivalent changes or modifications made in accordance with the structure, features and principles of this utility model patent application are included in the scope of this utility model patent application.

Claims

1. A digital microfluidic PCR chip, comprising a substrate (1), droplets (2), a plurality of electrodes (3) disposed on the substrate (1), characterized in that: At least a portion of the electrodes (3) are crescent-shaped electrodes (3), the arc-shaped profile of the electrodes (3) matching the contact circle profile of the droplet (2) on the substrate (1); it also includes a spacer (4) disposed between the substrate (1) and the electrodes (3), the spacer (4) being coated with a hydrophobic coating (41) on one side of the substrate (1).

2. The digital microfluidic PCR chip according to claim 1, wherein: The spacers (4) are provided in a plurality of units, and the plurality of spacers (4) are respectively provided between two adjacent electrodes (3).

3. The digital microfluidic PCR chip according to claim 2, characterized in that: The spacers (4) are arranged symmetrically or asymmetrically along the separation path of the droplets (2).

4. The digital microfluidic PCR chip of claim 1, wherein: The spacer (4) is configured to be square, circular, or trapezoidal in shape.

5. The digital microfluidic PCR chip of claim 1, wherein: The ratio of the radius of curvature of the electrode (3) to the diameter of the droplet (2) is 1:1.

5.

6. The digital microfluidic PCR chip of claim 1, wherein: The thickness of the spacer (4) is 0.5 μm to 2 μm.

7. The digital microfluidic PCR chip of claim 1, wherein: The hydrophobic coating (41) is made of Teflon or CYTOP material.

8. The digital microfluidic PCR chip of claim 1, wherein: The substrate (1) includes an upper substrate (11) and a lower substrate (12). The upper substrate (11) and the lower substrate (12) are arranged in parallel. The electrode (3) is disposed on the surface of the lower substrate (12) facing the upper substrate (11).

9. The digital microfluidic PCR chip of claim 1, wherein: It also includes a heating element (5) and a temperature sensor (6) for performing PCR reactions, both of which are disposed on the substrate (1).

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