Digital microfluidic system and method based on static electrode array

Abstract

The invention discloses a digital microfluidics system and method based on a static electrode array, and relates to the technical field of digital microfluidics, and a metal electrode array is fixed on a mobile support and suspended above a super-hydrophobic platform. Each electrode is separated by an insulating polymer material, each electrode is connected to the electrostatic generator through a control circuit, and the controller can independently control the on / off of each electrode. Different potentials can be applied to the metal electrode, and operations such as movement, combination and mixing of liquid drops can be realized by accurately regulating and controlling electric field distribution. By constructing a high-precision electrostatic controller, adopting non-contact electrostatic driving, using a super-hydrophobic surface and adopting a high-density integrated electrostatic electrode array structure, non-contact and accurate control on micro-droplets is realized, so that the defects of the existing digital microfluidic technology in the aspects of stability, biological compatibility and high-throughput operation are overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of digital microfluidics, and specifically relates to a digital microfluidic system and method based on an electrostatic electrode array. Background Art

[0002] Digital Microfluidics (DMF), as an emerging droplet manipulation technology, has received extensive attention in recent years in the fields of biomedical analysis, chemical synthesis, environmental monitoring, and high-throughput screening. This technology mainly uses methods such as electrowetting, electrostatic force, or magnetic field to achieve precise manipulation of microdroplets, including operations such as droplet generation, movement, merging, and mixing. Compared with traditional continuous flow microfluidics, DMF has significant advantages such as no pipelines, programmability, high automation, and low sample consumption, making it an important development direction for the next generation of portable and integrated laboratory technologies. Currently, DMF technology is developing towards intelligence, high throughput, and portability. However, DMF technology still faces challenges such as biocompatibility, droplet manipulation stability, and large-scale integration.

[0003] Firstly, the droplet manipulation stability of existing DMF technology is relatively low and is easily affected by dielectric layer aging, surface contamination, and electric field non-uniformity, resulting in inaccurate droplet movement, and even droplet retention or unpredictable deviation. This instability limits the application of DMF in high-precision analysis and automated experiments. Secondly, the biocompatibility issue remains a major challenge for DMF technology. The commonly used hydrophobic coatings and dielectric layers may undergo non-specific adsorption with biological samples, affecting cell viability, protein stability, or the accuracy of nucleic acid detection. In addition, there are still technical bottlenecks in the high-throughput and large-scale integration of existing DMF systems. The control complexity of high-density electrode arrays is high, and the electric field coupling effect may cause cross-interference between multiple droplets, affecting the accuracy of manipulation. At the same time, the manufacturing cost of DMF chips is relatively high and the durability is low. The chips are prone to failure due to electrode aging or dielectric layer breakdown during long-term use, increasing the experimental cost.

[0004] In summary, there are still many deficiencies in existing DMF technology in terms of droplet manipulation stability, biocompatibility, high-throughput operation, and manufacturing cost. It is urgent to further optimize materials, improve the control method, and enhance the system integration to meet wider application requirements. This patent proposes an improved solution for the above problems. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, so as to improve the stability, applicability and scalability of the digital microfluidic system; for this purpose, the present invention provides a digital microfluidic system and method based on an electrostatic electrode array.

[0006] As the first aspect provided by the present invention, the present invention provides a digital microfluidic system based on an electrostatic electrode array, comprising:

[0007] A superhydrophobic platform, the surface of which has a superhydrophobic structure formed by staggered porous and protruding microstructures, and the sizes of these protrusions range from several hundred nanometers to several micrometers.

[0008] An electrostatic electrode array, which is fixed on a moving bracket and suspended above the superhydrophobic platform;

[0009] Each electrode in the electrostatic electrode array is respectively connected to an electrostatic generator through a control circuit, and the movement, merging and mixing of droplets on the superhydrophobic platform are controlled by controlling the on / off of each electrode and applying different magnitudes of electric potentials. The surface of the superhydrophobic platform serves as an operating platform, and droplets are pre-placed. Once an electrostatic charge is applied to the metal electrode, the droplet deviating from the electrode axis will quickly move to the position below the metal electrode. After a short damped oscillation (due to the inertia of the droplet), the droplet finally stops directly below the metal electrode, and the metal electrode manipulates the droplet through electrostatic force.

[0010] Further, the electrode is a metal rod.

[0011] Further, each of the electrodes is separated by an insulating polymer material and arranged at equal intervals.

[0012] Further, a controller is connected to the control circuit through a control signal line.

[0013] Further, the controller controls the generation of digital signals for connecting and disconnecting each electrode.

[0014] As the second aspect provided by the present invention, the present invention provides a digital microfluidic method based on an electrostatic electrode array. The digital microfluidic method is used to control the digital microfluidic system described in the first aspect, and the microfluidic method comprises the following steps:

[0015] Step S1: Suspending an electrode array formed by a plurality of metal electrodes separated by an insulating polymer material above the superhydrophobic platform through a moving bracket;

[0016] Step S2: Connecting each metal electrode to an electrostatic generator through a control circuit respectively;

[0017] Step S3: Controlling the movement, merging and mixing of droplets on the superhydrophobic platform by controlling the on / off of each electrode and applying different magnitudes of electric potentials.

[0018] Further, an electrostatic potential is sequentially applied to the metal electrodes in the electrode array to achieve stepwise movement of the droplets.

[0019] Further, a controller is used to control the generation of digital signals for connecting and disconnecting each metal electrode.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention constructs a high-precision electrostatic control electrode array. By sequentially charging the static electrodes, the droplets will move forward step by step along the designed path; realizing contactless and precise manipulation of micro-droplets to overcome the defects of existing digital microfluidic technologies in terms of stability, biocompatibility, and high-throughput operation. Description of the Drawings

[0022] Figure 1 Schematic diagram of the DMF system based on the static electrode array of the present invention;

[0023] Figure 2 Schematic diagram of the process of the static electrode capturing the droplet deviating from the axis of the metal electrode of the present invention;

[0024] Figure 3 Schematic diagram of the charge distribution and force analysis of the droplet of the present invention;

[0025] Figure 4 Physical diagram of the realization of the digital microfluidic function based on the static electrode array of the present invention. Detailed Embodiments

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Embodiment 1:

[0028] As Figure 1 shown, as the first embodiment provided by the present invention, the present invention is a digital microfluidic system based on a static electrode array, including:

[0029] A superhydrophobic platform, the surface of which has a superhydrophobic structure formed by staggered porous and protruding microstructures, and the sizes of these protrusions range from several hundred nanometers to several micrometers;

[0030] A static electrode array, which is fixed on a moving bracket and suspended above the superhydrophobic platform;

[0031] Each electrode in the static electrode array is respectively connected to an electrostatic generator through a control circuit, and the movement, merging and mixing of droplets on the superhydrophobic platform are controlled by controlling the on / off of each electrode and applying different magnitudes of electric potential; the surface of the superhydrophobic platform serves as an operation platform, and droplets are pre-placed. Once an electrostatic force is applied to the metal electrode, the droplets deviating from the electrode axis will quickly move to the position below the metal electrode. After a short damped oscillation (due to the inertia of the droplets), the droplets finally stay directly below the metal electrode, and the metal electrode manipulates the droplets through electrostatic force.

[0032] As an embodiment provided by the present invention, preferably, electrostatic force is used for driving, without relying on the traditional electro-wetting (EWOD) effect, fundamentally avoiding problems such as dielectric layer aging, surface contamination, and contact angle hysteresis, making droplet manipulation more stable and reliable; improving the stability and repeatability of droplet transmission.

[0033] As an embodiment provided by the present invention, preferably, polytetrafluoroethylene (PTFE), as a typical electrical insulating material, has wide applications in industry and daily life. Femtosecond laser has the characteristics of ultra-short pulse duration and ultra-high peak power density, and can ablate almost any material; in this application, the superhydrophobic platform uses polytetrafluoroethylene as the substrate, and a superhydrophobic structure is ablated on the surface of the substrate by a femtosecond laser. Laser ablation will generate staggered porous and protruding microstructures on the PTFE surface, and the sizes of these protrusions range from several hundred nanometers to several micrometers. The synergistic effect of the surface microstructure and the inherent low surface energy chemical composition results in the superhydrophobicity of the PTFE surface. However, the superhydrophobic platform is not limited to PTFE materials, nor is it limited to achieving superhydrophobicity using femtosecond lasers, and it is applicable to superhydrophobic platforms obtained by other materials and other methods.

[0034] As an embodiment provided by the present invention, preferably, the present invention does not rely on hydrophobic coatings and dielectric layers, but instead uses a superhydrophobic surface processed by femtosecond laser or a superhydrophobic platform obtained by other methods to achieve a simpler chip manufacturing process, reduce production costs, and at the same time improve the durability and long-term stability of the system.

[0035] As an embodiment provided by the present invention, preferably, the electrode is a metal rod, the top of the metal electrode is connected to an electrostatic generator to generate high-voltage static electricity, and the electrode is fixed on a three-dimensional moving bracket. The superhydrophobic surface serves as an operation platform, and droplets are pre-placed. Once an electrostatic force is applied to the metal electrode, the droplets deviating from the electrode axis will quickly move to the position below the metal electrode. Figure 2 It is the process of the static electrode capturing the droplets deviating from the metal electrode axis. After a short damped oscillation (due to the inertia of the droplets), the droplets finally stay directly below the metal electrode. The metal electrode manipulates the droplets through electrostatic force.

[0036] As an embodiment provided by the present invention, preferably, non-contact electrostatic driving is adopted, which avoids the direct contact between the droplet and the electrode, effectively reduces the non-specific adsorption of biomolecules such as cells and proteins, reduces sample loss, improves the accuracy and repeatability of the experiment; enhances biocompatibility and reduces non-specific adsorption.

[0037] Embodiment Two:

[0038] As an embodiment provided by the present invention, preferably, when a positive potential is applied to the metal electrode, negative charges tend to migrate to the surface of the droplet closer to the metal electrode, while positive charges tend to accumulate on the surface of the droplet farther from the metal electrode. As Figure 3 shown, it is a diagram of the charge distribution and force analysis of the droplet. In the spatial electric field generated by the metal electrode, the local electric field strength gradually decreases with the increase of the distance from the electrode. Since the accumulated negative charges are closer to the electrode, the attractive electrostatic force (Fe = Eq, where q is the charge quantity) acting on the negative charges is greater than the repulsive force acting on the positive charges. Therefore, the droplet as a whole is electrostatically attracted. If a negative potential is applied to the metal electrode, a similar electrostatic attraction effect can also be obtained for the droplet, and the charges mainly accumulate on the surface of the droplet.

[0039] Embodiment Three:

[0040] Based on Embodiment Two, as an embodiment provided by the present invention, preferably, multiple metal electrodes are arranged at equal intervals and electrostatic potentials are applied to them in sequence, which can realize the step-by-step movement of the droplet. By adopting a high-density integrated static electrode array structure, the system integration degree is improved, enabling the system to have the ability of large-scale parallel manipulation, meeting the requirements of high-throughput screening and automated experiments, and improving the experimental efficiency.

[0041] As an embodiment provided by the present invention, preferably, each of the electrodes is separated by an insulating polymer material and arranged at equal intervals. The metal electrode array is fixed on a moving bracket and suspended above a super-hydrophobic platform. Each electrode is separated by an insulating polymer material, and the distance is far enough to minimize the interference between them.

[0042] As an embodiment provided by the present invention, preferably, a controller is connected to the control circuit through a control signal line. The droplet is always located below the charged metal electrode. Since the connection (marked as "on") and disconnection (marked as "off") of the metal electrode and the electrostatic generator respectively correspond to the "1" and "0" of the digital signal, controlling the static electrode array through the controller can be used to realize the digital microfluidics (DMF) function.

[0043] Embodiment Four:

[0044] Based on Embodiment 3, as an embodiment provided by the present invention, preferably, the digital microfluidic system uses a controller to control the generation of digital signals for connecting and disconnecting each electrode.

[0045] Specifically, a controller is used to control the generation of digital signals for connecting and disconnecting each electrode. When the controller issues a power-on control signal, the corresponding metal electrode is connected to the electrostatic generator, and the droplet will move to the corresponding position under the action of electrostatic force. When the static electrode above the droplet is powered off and connected to the next static electrode, the droplet quickly moves under the newly charged static electrode. By sequentially charging the static electrodes, the droplet will gradually advance along the designed path, and the movement path of the droplet is controlled by digital signals to achieve the digital droplet microfluidic function.

[0046] Embodiment 5:

[0047] As an embodiment provided by the present invention, the present invention is a digital microfluidic method based on a static electrode array. The digital microfluidic method is used to control the digital microfluidic system provided in the above embodiment. The microfluidic method includes the following steps:

[0048] Step S1: An electrode array formed by a plurality of metal electrodes separated by an insulating polymer material is suspended above the superhydrophobic platform through a moving bracket; Step S2: Each metal electrode is respectively connected to an electrostatic generator through a control circuit; Step S3: By controlling the on / off of each electrode and applying different magnitudes of electric potential, the movement, merging, and mixing of droplets on the superhydrophobic platform are controlled. Each metal electrode is respectively connected to an electrostatic generator through a control circuit. We can apply different magnitudes of electric potential to the metal electrodes. By precisely regulating the electric field distribution, operations such as the movement, merging, and mixing of droplets are realized, as Figure 4 shown. Based on the realization of the digital microfluidic function of droplet manipulation based on a static electrode array, by controlling the on / off of each electrode and applying different magnitudes of electric potential to control the programmable movement of droplets on the superhydrophobic platform, the digital microfluidic function is realized.

[0049] As an embodiment provided by the present invention, preferably, due to its high stability, biocompatibility, and large-scale manipulation ability, this technology is applicable to application scenarios such as biological analysis, medical detection, drug screening, and high-throughput screening, expanding the application scope of digital microfluidic technology.

[0050] As an embodiment provided by the present invention, preferably, an electrostatic potential is sequentially applied to the metal electrodes in the electrode array to realize the step-by-step movement of droplets. By optimizing the control method of the static electrodes and the structure of the electrode array, the energy consumption is reduced, and at the same time, the accuracy and response speed of droplet manipulation are improved, making the system more efficient and energy-saving.

[0051] As an embodiment provided by the present invention, preferably, a controller is used to control the generation of digital signals for connecting and disconnecting each electrode. When the controller issues a control signal for power-on, the corresponding metal electrode is connected to the electrostatic generator, and the droplet will move to the corresponding position under the action of electrostatic force. When the electrostatic electrode above the droplet is powered off and then connected to the next electrostatic electrode, the droplet quickly moves under the newly charged electrostatic electrode. By charging the electrostatic electrodes in sequence, the droplet will gradually advance along the designed path.

[0052] The present invention uses electrostatic force to drive the movement of droplets, without relying on the traditional electro-wetting (EWOD) effect, thus avoiding problems such as dielectric layer aging, surface contamination, and contact angle hysteresis, and improving the stability and repeatability of droplet transmission.

[0053] In the aspect of biological sample processing, this patent adopts a non-contact electrostatic driving method, effectively reducing the non-specific adsorption of biological molecules such as cells and proteins, improving biocompatibility, and being applicable to applications such as biological analysis, medical detection, and drug screening.

[0054] In addition, this technology does not rely on hydrophobic coatings and dielectric layers, but instead uses a superhydrophobic surface processed by femtosecond laser or a superhydrophobic platform obtained by other methods. In this way, the chip manufacturing is more convenient, the production cost is reduced, and the system durability is improved.

[0055] Moreover, the electrostatic electrode array structure proposed in this application can achieve high-density integration, enabling the system to have the ability of large-scale parallel manipulation, and being applicable to the requirements of high-throughput screening and automated experiments. By optimizing the electrostatic electrode control method, improving the electrode array structure, and enhancing the system integration, a more stable, efficient, biocompatible and large-scale operation applicable digital microfluidic method is realized, providing a new solution for the further development of microfluidic technology in scientific research and industrial applications.

[0056] The digital microfluidic system and method based on an electrostatic electrode array provide an innovative solution for the stability, repeatability, biocompatibility, manufacturing simplicity, and large-scale operation ability of the digital microfluidic system, laying an important foundation for the research and industrial application in fields such as biological analysis, medical detection, and drug screening.

[0057] The above embodiments are only used to illustrate the technical method of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical method of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A digital microfluidic system based on an electrostatic electrode array, characterized in that, Comprising: A superhydrophobic platform, the surface of which has a superhydrophobic structure formed by staggered porous and protruding microstructures; A static electrode array, which is fixed on a moving bracket and suspended above the superhydrophobic platform; Each electrode in the static electrode array is respectively connected to an electrostatic generator through a control circuit, and the movement, merging and mixing of droplets on the superhydrophobic platform are controlled by controlling the on / off of each electrode and applying different magnitudes of electric potential.

2. The digital microfluidic system based on a static electrode array according to claim 1, characterized in that The electrode is a metal rod.

3. The digital microfluidic system based on an electrostatic electrode array according to claim 1, characterized in that, Each of the electrodes is separated by an insulating polymer material and arranged at equal intervals.

4. The digital microfluidic system based on an electrostatic electrode array according to claim 1, characterized in that A controller is connected to the control circuit through a control signal line.

5. The digital microfluidic system based on an electrostatic electrode array according to claim 4, wherein The digital microfluidic system uses the controller to control the generation of digital signals for connecting and disconnecting each electrode.

6. A digital microfluidic method based on an electrostatic electrode array, characterized in that, The digital microfluidic method is used to control the digital microfluidic system according to any one of claims 1-5, and the microfluidic method includes the following steps: Step S1: An electrode array formed by a plurality of metal electrodes separated by an insulating polymer material is suspended above the superhydrophobic platform through a moving bracket; Step S2: Each metal electrode is respectively connected to an electrostatic generator through a control circuit; Step S3: The movement, merging and mixing of droplets on the superhydrophobic platform are controlled by controlling the on / off of each electrode and applying different magnitudes of electric potential.

7. The digital microfluidic method based on an electrostatic electrode array according to claim 6, wherein An electrostatic potential is sequentially applied to the metal electrodes in the electrode array to realize the step-by-step movement of the droplets.

8. The digital microfluidic method based on an electrostatic electrode array according to claim 6, characterized in that The generation of digital signals for connecting and disconnecting each metal electrode is controlled by the controller.

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