Digital micro-fluidic electrode array with row-column series-connection staggered structure

Abstract

The invention belongs to the technical field of digital microfluidics, and particularly relates to a digital microfluidics electrode array with a row-column series staggered structure. The array comprises a first driving layer and a second driving layer, the first driving layer is provided with a column series electrode array, the column series electrode array is composed of a plurality of parallel single-column series electrodes, each single-column series electrode comprises a plurality of first driving electrodes arranged longitudinally, the second driving layer is provided with a row series electrode array, and each row series electrode array comprises a plurality of second driving electrodes arranged longitudinally. The row series electrode array is composed of a plurality of parallel single-row series electrodes, each single-row series electrode comprises a plurality of second driving electrodes which are transversely arranged, the driving electrodes of the adjacent single-row series electrodes are staggered in arrangement, and the driving electrodes of the adjacent single-row series electrodes are also staggered in arrangement. And the single-row series electrodes and the single-row series electrodes are arranged in a staggered and embedded manner. By adopting the design of the electrodes which are connected in series in rows and columns and distributed in a staggered manner, the number of input electrodes required by a large-scale electrode array is remarkably reduced, a peripheral control circuit is simplified, and the cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of digital microfluidics, and in particular relates to a digital microfluidics electrode array with a row-column series staggered structure. Background Art

[0002] Digital microfluidics is a technology that uses electrical signals to manipulate droplets. The current mainstream method is based on the principle of electrowetting on dielectric (EWOD) and is mainly used to solve the automated processing process of microdroplet samples.

[0003] Traditional digital microfluidic arrays are typically fabricated using micro-nanofabrication processes, typically a single-layer process. Specifically, each droplet-driving electrode corresponds to a corresponding signal input electrode. These droplet-moving electrodes are then arranged in a regular pattern to form an electrode array, and the signal input electrodes are connected to external signal devices. The core structure of a traditional digital microfluidic chip revolves around the driving electrode array, and its manufacturing process involves multiple key layers. The chip is supported by a transparent insulating substrate, on which a conductive layer is formed using photolithography or sputtering, creating a regularly arranged array of driving electrodes. The electrode array is typically covered with a dielectric layer and a hydrophobic layer to optimize droplet manipulation. The dielectric layer acts as an insulator, while the hydrophobic layer assists droplet movement. Droplet movement is based on the electrowetting effect. When an external actuator selects and activates a target electrode, the local contact angle of the corresponding area decreases, causing the droplet to be attracted by the electric field and migrate toward the high-field region. This mechanism enables precise droplet movement. Furthermore, droplet splitting and merging operations rely on voltage gradient regulation. In the splitting operation, opposite voltage gradients are applied to adjacent electrodes, gradually stretching the droplet interface until it forms two parts and breaks apart. Merging operation: Activate the target electrodes simultaneously, so that adjacent droplets spontaneously merge after contact, achieving mixing.

[0004] Since traditional chips use a single-input-single-drive mode, that is, each driving electrode needs to be connected to an independent input electrode and connected to an external control device through a wire, when the electrode array is expanded to 3×3 or larger, the lead layout of the internal driving electrode becomes a design difficulty. The main problems include: Limited routing space: The gap between the electrode arrays is limited, and the wires of all driving electrodes need to be led out from the gaps, but the space is limited, which easily leads to crowded layout. Multi-layer process requirements: If the routing cannot be laid out in a single-layer electrode array, it is necessary to use a multi-layer wiring process (such as a multi-layer metal interconnect structure) to solve it, that is, to build different levels of wires inside the chip to avoid direct interference from the electrode array.

[0005] With the development of technology and the pursuit of efficiency, the demand for large-scale, multi-sample parallel processing is gradually increasing. This high-throughput demand means that digital microfluidic chips require large-scale electrode arrays. However, large-scale electrode arrays often require more input electrodes and complex control circuits, which further increases the difficulty and cost of manufacturing digital microfluidic chips.

[0006] In recent years, in order to reduce the number of input electrodes and simplify peripheral control circuits, people have begun to apply thin-film transistor technology (TFT) to the manufacture of digital microfluidic chip electrode arrays. However, this technology, which is widely used by panel manufacturers, has many limitations. First, the manufacturing process is complicated. Since it involves the manufacturing process of transistors, it usually requires at least five layers of thin-film structure manufacturing, which also results in a long process time and high cost. In addition, due to the high voltage required by this dielectric wetting principle, the life of the array controlled by this transistor switch is short, resulting in great waste and is not conducive to the promotion of digital microfluidic chips. And because this thin-film transistor technology has high requirements for equipment, it often leads to high technical barriers, forcing digital microfluidic chip manufacturers to cooperate with panel manufacturers to produce.

[0007] Therefore, the present invention proposes a digital microfluidic core having an array of electrodes connected in series and staggered in rows and columns. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a digital microfluidic electrode array with a row-column series staggered structure, which is used to solve the problems of the digital microfluidic chip electrode array in the prior art, such as too many input electrodes, complex peripheral control circuits, high manufacturing costs, high voltage requirements and short life.

[0009] To achieve the above-mentioned purpose and other related purposes, the present invention is achieved through the following technical solutions.

[0010] The first aspect of the present invention provides a digital microfluidic electrode array having a row-column series staggered structure, comprising a first drive layer and a second drive layer, wherein a column-series electrode array is provided on the first drive layer, and the column-series electrode array is composed of a plurality of parallel single-column series electrodes, and each of the single-column series electrodes includes a plurality of first drive electrodes arranged longitudinally; the second drive layer is provided with a row-series electrode array, and the row-series electrode array is composed of a plurality of parallel single-row series electrodes, and each of the single-row series electrodes includes a plurality of second drive electrodes arranged transversely; the drive electrodes of adjacent single-column series electrodes are staggered in arrangement, and the drive electrodes of adjacent single-row series electrodes are also staggered in arrangement, and the single-column series electrodes are staggered and arranged in an interlaced manner with the single-row series electrodes.

[0011] In some embodiments of the present invention, a plurality of first input electrodes and second input electrodes are further included, each of the first input electrodes is connected to a single column of series electrodes, and each of the second input electrodes is connected to a single row of series electrodes.

[0012] In some embodiments of the present invention, a dielectric layer is provided at the intersection of the conductors of the column series electrode array and the row series electrode array, wherein the dielectric layer is selected from one or more of a silicon nitride layer, a silicon dioxide layer, a silicon carbide layer, a zirconium oxide layer, a hafnium oxide layer, or a titanium oxide layer.

[0013] In some embodiments of the present invention, each of the first driving electrodes is made by depositing a conductive material on the first driving layer, and each of the second driving electrodes is made by depositing a conductive material on the second driving layer.

[0014] In some embodiments of the present invention, each of the first driving electrodes and each of the second driving electrodes includes a dielectric layer and a hydrophobic layer.

[0015] In some embodiments of the present invention, the thickness of the first driving layer and the second driving layer is 10-100 nm.

[0016] In some embodiments of the present invention, each of the first driving electrodes and each of the second driving electrodes has a length of 1-10 mm and a width of 1-10 mm.

[0017] In some embodiments of the present invention, after the column series electrode array and the row series electrode array are interlaced and interlocked, the spacing between adjacent first driving electrodes and second driving electrodes is 10-100 μm.

[0018] In some embodiments of the present invention, the thickness of the dielectric layer is 10-300 nm.

[0019] A second aspect of the present invention provides a micro-nanofabrication method for preparing a digital microfluidic electrode array having a row-column series staggered structure, comprising the following steps:

[0020] 1) Preparation of the first driving layer: a photoresist is applied to a silicon substrate, and after curing by baking, the pattern on the first mask is transferred to the photoresist surface by ultraviolet exposure. After development, a photoresist pattern is formed. A conductive material is deposited on the photoresist pattern, and the excess conductive material is stripped off to obtain the first driving layer;

[0021] 2) Preparation of dielectric layer: After depositing a dielectric material on the first driving layer obtained in step 1), a photoresist is applied to the surface of the dielectric material, and the pattern on the second mask is transferred to the surface of the dielectric material by ultraviolet exposure. After etching, the excess photoresist is removed to obtain a dielectric layer;

[0022] 3) Preparation of the second driving layer: Apply photoresist on the dielectric layer of step 2), bake and solidify it, transfer the pattern on the third mask to the photoresist surface by UV exposure, expose, develop, deposit conductive material and strip off excess conductive material,

[0023] Get the second driver layer.

[0024] The present invention also provides the digital microfluidic electrode array with a row-column series staggered structure as described above and / or the application of the digital microfluidic electrode array with a row-column series staggered structure prepared by the micro-nano processing method as described above in digital microfluidics.

[0025] The present invention also provides a digital microfluidic electrode array PCB with a row-column series staggered structure, including a driving electrode array, a first signal layer, a second signal layer and a bottom wiring layer; the driving electrode array includes a plurality of driving electrodes arranged in a rectangular array, the driving electrodes include a first driving electrode and a second driving electrode, the first driving electrode and the second driving electrode are staggered, the first signal layer includes a plurality of column series wires, the column series wires connect two first driving electrodes adjacent in the column direction; the second signal layer includes a plurality of row series wires, the row series wires connect two second driving electrodes adjacent in the column direction, the first driving electrodes connected by the column series wires form a column series electrode array, the second driving electrodes connected by the row series wires form a row series electrode array, the column series electrode array and the row series electrode array are staggered and arranged, the bottom wiring layer includes a plurality of bottom wires, each single column series electrode in the row series electrode array, and each single column series electrode in the column series electrode array is respectively connected to a bottom wire.

[0026] In some embodiments of the present invention, each of the driving electrodes includes a dielectric layer and a hydrophobic layer.

[0027] In some embodiments of the present invention, a through-hole pad is further included, and the through-hole pad is arranged in the middle of the driving electrode.

[0028] In some embodiments of the present invention, a plurality of input electrodes are further included, and each of the input electrodes is connected to a bottom conductor.

[0029] As described above, the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention has the following beneficial effects:

[0030] (1) Simplify peripheral circuits: The electrode design with staggered distribution in rows and columns significantly reduces the number of input electrodes required for large-scale electrode arrays, simplifies peripheral control circuits, and reduces costs.

[0031] (2) Simple process and low cost: The electrode array of the present invention only requires three layers of micro-nano process to prepare, avoiding the complex transistor switch structure, simplifying the manufacturing process and reducing production costs.

[0032] (3) Improve device life and stability: Since there is no transistor switch, the life reduction and leakage problems caused by transistor damage are avoided, ensuring the stability of the device during long-term operation.

[0033] (4) Strong scalability and wide range of applications: The three-layer electrode array structure can be extended to printed circuit boards (PCBs), further reducing costs and expanding its application range in low-cost, highly flexible substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It shows a schematic diagram of a column-series electrode array according to Example 1 of the present invention, wherein Figure a shows a single column-series electrode, and Figure b shows a column-series electrode array formed by combining multiple single column-series electrodes.

[0035] Figure 2 It shows a schematic diagram of a row-series electrode array according to Example 1 of the present invention, wherein FIG a shows a single row of series electrodes, and FIG b shows a row-series electrode array formed by combining multiple single row of series electrodes.

[0036] Figure 3 It is a schematic diagram of the dielectric layer according to Example 1 of the present invention.

[0037] Figure 4 Shown is a schematic diagram of a digital microfluidic electrode array having a row-column series staggered structure according to Example 1 of the present invention.

[0038] Figure 5 It shows a cross-sectional view of a digital microfluidic electrode array having a row-column series staggered structure according to Example 1 of the present invention.

[0039] Figure 6 Shown is a physical picture of a digital microfluidic electrode array having a row-column series staggered structure according to Example 1 of the present invention.

[0040] Figure 7 It shows a schematic diagram of a column-series electrode array according to Example 2 of the present invention, wherein Figure a shows a single column-series electrode, and Figure b shows a column-series electrode array formed by combining multiple single column-series electrodes.

[0041] Figure 8 It shows a schematic diagram of a row-series electrode array according to Example 2 of the present invention, wherein FIG a shows a single row of series electrodes, and FIG b shows a row-series electrode array formed by combining multiple single row of series electrodes.

[0042] Figure 9Shown is a schematic diagram of a digital microfluidic electrode array PCB with a row-column series staggered structure according to Example 2 of the present invention, wherein Figure a is a schematic diagram of the PCB array, and Figure b is a side view of the PCB array, showing only part of a single row of series-connected electrodes.

[0043] Component number description

[0044] 1 row of series electrode array

[0045] 11 Single row series electrodes

[0046] 111 first driving electrode

[0047] 111' series conductors

[0048] 112 first input electrode

[0049] 2 Dielectric layer

[0050] 3-row series electrode array

[0051] 31 Single row series electrodes

[0052] 311 second driving electrode

[0053] 311' row series conductor

[0054] 312 second input electrode DETAILED DESCRIPTION

[0055] The following describes in detail the implementation of the disclosed digital microfluidic electrode array having a row-column series staggered structure.

[0056] The applicant of the present invention was inspired by the memristor (a resistive electronic component that can memorize the history of charge passing through, and its resistance value changes with the charge accumulation state) and designed the present invention. The present invention is formed by cross-connecting the column series electrode array and the row series electrode array to form a digital microfluidic electrode array with a row-column series staggered structure, and the dielectric layer is used to isolate the electrical connection at the overlap between the two, which is similar to the sandwich structure characteristic of the memristor. Applying the present invention to digital microfluidic droplet drive can not only increase the flux, but also simplify the peripheral control circuit, reduce costs, and increase the life of the device. The three-layer structure can be completed by micro-nano processing, and specifically, the patterning of the thin film can be completed by lithography, etching and coating. In addition, the electrode array with staggered distribution after row and column series connection can also be extended to a printed circuit board (PCB), which can be realized with only a 4-layer board design. On this basis, the present invention was completed.

[0057] Digital microfluidic electrode array with row-column series staggered structure

[0058] See also Figure 1-6In a first aspect, the present invention provides a digital microfluidic electrode array having a row-column series staggered structure, comprising a first driving layer and a second driving layer, such as Figure 1 and 2 As shown, the first drive layer is provided with a column-series electrode array 1, which is composed of multiple parallel single-row series electrodes 11, each of which includes multiple first drive electrodes 111 arranged longitudinally. The second drive layer is provided with a row-series electrode array 3, which is composed of multiple parallel single-row series electrodes 31, each of which includes multiple second drive electrodes 311 arranged transversely. The drive electrodes of adjacent single-row series electrodes 11 are staggered in arrangement, and the drive electrodes of adjacent single-row series electrodes 31 are also staggered in arrangement. The single-row series electrodes 11 and the single-row series electrodes 31 are interlaced and arranged to form a checkerboard structure. Specifically, the drive electrodes adjacent to each first drive electrode 111 above, below, left, and right are all second drive electrodes 311, and the drive electrodes adjacent to each second drive electrode 311 above, below, left, and right are all first drive electrodes 111. This layout is highly regular, with the types of adjacent drive electrodes alternating in space, presenting an orderly staggered distribution.

[0059] The digital microfluidic electrode array of the present invention further includes a first input electrode 112 and a second input electrode 312 . Each single-column series electrode 11 is connected one-to-one with the first input electrode 112 , and each single-row series electrode 31 is connected one-to-one with the second input electrode 312 .

[0060] like Figure 5 As shown, at the intersection of the wires of the column series electrode array 1 and the row series electrode array 3, each wire maintains its own independence to ensure normal transmission of electrical signals in different directions. To avoid electrical interference and maintain system stability, a dielectric layer 2 is provided at the wire intersection to provide electrical isolation, ensuring that wires from different drive layers do not short-circuit or interfere with each other at the intersection. This also optimizes the wiring layout of the electrode array, enabling efficient signal transmission and drive control for the entire system.

[0061] Compared to existing thin-film transistor technology, the present invention employs a staggered electrode design with rows and columns connected in series. This significantly reduces the number of input electrodes required for large-scale electrode arrays. Only N+M input electrodes are needed to control an N×M array of drive electrodes, effectively simplifying the peripheral control circuitry and reducing costs. This design is also suitable for the high-throughput requirements of digital microfluidics. Furthermore, due to the frequent switching of transistors under high voltage, their service life is limited, and later, problems such as leakage often lead to unstable device operation. The present invention, with its simple structure and the only wire connection between the input and drive electrodes, ensures long-term stable operation.

[0062] In the present invention, the first input electrode 112 and the second input electrode 312 refer to electrodes for receiving signals or currents from external input devices, such as computers, microcontrollers, sensors, etc. The input signals are usually voltage signals, including DC voltage signals and AC voltage signals.

[0063] like Figure 4 As shown, the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention is mainly used to manipulate droplets. Manipulating droplets means inputting a voltage signal to a specific drive electrode to control the directional movement of the droplet. Its working principle relies on the electrowetting effect (EWOD) and row-column addressing control. Specifically: by programming the voltage signal, voltage can be applied to the target row or column drive electrode in sequence. According to the Yong-Lippmann equation, it can be seen that high voltage causes the surface tension to change, the contact angle of the droplet to decrease, and then the droplet is driven to move toward the high voltage electrode. Due to the characteristics of the present invention having a row or column series staggered distribution, when the droplet is on a specific row drive electrode, i.e., the second drive electrode 311, by activating a column drive electrode, i.e., the first drive electrode 111, on both sides of the electrode, the droplet moves toward the high voltage direction, that is, achieving left and right movement; when the droplet is on a specific column drive electrode, i.e., the first drive electrode 111, by activating the row drive electrodes, i.e., the second drive electrode 311, on both sides of the electrode, the droplet moves toward the high voltage, that is, achieving up and down movement. During the splitting operation, the droplets can be moved to both sides by applying voltage signals simultaneously on both sides of a specific driving electrode at the splitting point until the droplet interface is stretched to break. During the merging operation, the droplets can be caused to spontaneously fuse after contact by synchronously activating the target driving electrodes. It should be noted that in the above-mentioned process of manipulating droplets, the droplet movement has only 2 degrees of freedom, that is, when the droplet is on a certain column of driving electrodes, the droplet can only be controlled to move to the left or right; similarly, when the droplet is on a certain row of driving electrodes, the droplet can only be controlled to move upward or downward, otherwise it may cause the droplet to split or the droplet movement direction to be uncontrolled. The present invention reduces the number of electrode leads from N to 1 through row-column cross addressing. 2 The level is reduced to 2N level, and combined with the electric field focusing characteristics of the dielectric layer, it can achieve submillimeter positioning error of micro-liter droplets <50μm, dynamic splitting or merging, and parallel control of multiple reactions. It can support automation scenarios such as high-throughput biochemical detection and dynamic droplet network construction, and is suitable for mass production of photolithography processes.

[0064] In the digital microfluidic chip of the present invention, the size of the driving electrode array can be reasonably estimated based on the volume, number and range of motion of the droplets that actually need to be manipulated, so as to ensure that there are enough electrodes to support the precise movement of the droplets. Specifically: Assume that the size of a single droplet roughly matches the size of a single electrode, that is, the droplet just covers one driving electrode. The droplet needs to move within the 4×4 electrode range during the manipulation process, which means that the activity space of each droplet is composed of a 4-row × 4-column electrode array. If 4 droplets are to be manipulated at the same time, and each droplet has an independent 4×4 electrode activity range, in order to ensure that all droplets can move normally, the overall scale of the electrode array needs to be at least 8×8, that is, 8 rows × 8 columns, so that enough space can be provided for the 4 droplets to operate undisturbed in their respective areas.

[0065] In the digital microfluidic electrode array with a staggered row-column structure provided by the present invention, each first drive electrode 111 is made by depositing a conductive material on a first drive layer, and each second drive electrode 311 is made by depositing a conductive material on a second drive layer. The conductive material is selected from one or more of gold, silver, titanium, copper, aluminum, chromium, or indium tin oxide.

[0066] In the digital microfluidic electrode array having a row-column series staggered structure provided by the present invention, each of the first drive electrodes 111 and each of the second drive electrodes 311 includes a dielectric layer and a hydrophobic layer. The dielectric layer can be, for example, one or more of a silicon nitride layer, a silicon dioxide layer, a silicon carbide layer, a zirconium oxide layer, a hafnium oxide layer, or a titanium oxide layer, and the hydrophobic layer can be, for example, a silane coating or a fluorinated polymer layer.

[0067] In the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention, the thickness of the first driving layer and the second driving layer is 10-100nm, which can be 10-25nm, 25-55nm, 55-75nm, 75-100nm, 10-55nm or 55-100nm, etc., preferably 55nm.

[0068] In the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention, the length of each first driving electrode 111 and each second driving electrode 311 is 1-10 mm, which can be 1-3 mm, 3-5 mm, 5-7 mm or 7-10 mm, etc.; the width is 1-10 mm, which can be 1-3 mm, 3-5 mm, 5-7 mm or 7-10 mm, etc.

[0069] In the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention, after the column series electrode array 1 and the row series electrode array 3 are cross-engaged, the spacing between adjacent first drive electrodes 111 and second drive electrodes 311 is 10-100μm, which can be optionally 10-30μm, 30-50μm, 50-70μm or 70-100μm, etc.

[0070] In the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention, the thickness of the dielectric layer is 10-300nm, which can be 10-50nm, 50-100nm, 100-150nm, 150-200nm, 200-250nm or 250-300nm, etc., and is preferably 300nm.

[0071] In the digital microfluidic electrode array with a row-column series staggered structure provided by the present invention, the dielectric layer 2 is selected from one or more of silicon nitride layer, silicon dioxide layer, silicon carbide layer, zirconium oxide layer, hafnium oxide layer or titanium oxide layer, preferably silicon nitride layer.

[0072] [Micro-nanofabrication method for digital microfluidic electrode arrays with row-column series staggered structures]

[0073] A second aspect of the present invention provides a micro-nanofabrication method for preparing a digital microfluidic electrode array having a row-column series staggered structure, comprising the following steps:

[0074] 1) Preparation of the first driving layer: a photoresist is applied to a silicon substrate, and after curing by baking, the pattern on the first mask is transferred to the photoresist surface by ultraviolet exposure. After development, a photoresist pattern is formed. A conductive material is deposited on the photoresist pattern, and the excess conductive material is stripped off to obtain the first driving layer;

[0075] 2) Preparation of dielectric layer: After depositing a dielectric material on the first driving layer obtained in step 1), a photoresist is applied to the surface of the dielectric material, and the pattern on the second mask is transferred to the surface of the dielectric material by ultraviolet exposure. After etching, the excess photoresist is removed to obtain a dielectric layer;

[0076] 3) Preparation of the second driving layer: Apply photoresist on the dielectric layer of step 2), bake and cure, transfer the pattern on the third mask to the photoresist surface by ultraviolet exposure, expose, develop, deposit conductive material and strip off excess conductive material to obtain the second driving layer.

[0077] The present invention provides a method for preparing a digital microfluidic electrode array having a row-column series staggered structure, wherein step 1) is the preparation of a first driving layer: applying photoresist on a silicon substrate, baking and curing the substrate, transferring the pattern on a first mask to the photoresist surface by ultraviolet exposure, developing the substrate to form a photoresist pattern, depositing a conductive material on the photoresist pattern, and stripping off excess conductive material to complete the preparation of the first driving layer. Specifically: Use AutoCAD software to design the first drive layer electrode pattern and make the first mask; use a coater to spin-coat photoresist on the silicon substrate, and then bake it on a hot plate; use a photolithography machine model: MJB4 to perform UV exposure with the first mask, and then develop it to transfer the first mask pattern to the photoresist; use an electron beam E-beam instrument PROLine PVD75 (manufactured by Kurt J. Lesker Company) to evaporate and deposit conductive material, and then use a liftoff process instrument liftoff and KOHbench (model Wafab Front Access Web Bench Stations; manufacturer wafab international) to remove unnecessary conductive material to complete the preparation of the first drive layer.

[0078] In step 1) of the present invention, the conductive material is selected from one or more of gold, silver, titanium, copper, chromium or indium tin oxide, preferably titanium and gold.

[0079] In step 1) of the present invention, the conductive material is deposited to a thickness of 5-100 nm, which may be 5-20 nm, 20-40 nm, 40-60 nm, 60-80 nm or 80-100 nm, etc.

[0080] In a preferred embodiment, the photoresist in step 1) is a Lor5A+S1805 double-layer photoresist.

[0081] The present invention provides a method for preparing a digital microfluidic electrode array having a row-column series staggered structure, wherein step 2) is the preparation of a dielectric layer: after depositing a dielectric material on the first drive layer pattern obtained in step 1), a photoresist is applied to the surface of the dielectric material, and the pattern on the second mask is transferred to the surface of the dielectric material by ultraviolet exposure. After etching, the dielectric layer preparation is completed. Specifically: after depositing the dielectric material on the first drive layer pattern obtained in step 1 using a plasma enhanced chemical vapor deposition instrument: a plasma chemical vapor deposition instrument, manufacturer: Oxford Instruments, model: plasmapro80PECVD; spin coating photoresist, and using a photolithography machine with a second mask using AutoCAD software to design the pattern for ultraviolet exposure; the photoresist after ultraviolet exposure is baked for the first time, followed by flood exposure without blocking and baking for the second time to convert the photoresist from positive photoresist to negative photoresist. At this time, the blocked portion of the mask will be washed away in the development step; a reactive ion beam etching instrument: reactive ion beam etching system, manufacturer: Advance Vacuum Scandinavia AB, model: Vission322 is used to etch silicon nitride to form a dielectric layer pattern.

[0082] In step 2) of the present invention, the dielectric material is selected from one or more of silicon nitride, silicon dioxide, silicon carbide, zirconium oxide, hafnium oxide or titanium oxide, preferably silicon nitride.

[0083] In step 2) of the present invention, the deposition thickness of the dielectric material is 10-300 nm, which can be 10-50 nm, 50-100 nm, 100-150 nm, 150-200 nm, 200-250 nm or 250-300 nm, etc., and is preferably 300 nm.

[0084] In a preferred embodiment, the photoresist in step 2) is photoresist AZ5214.

[0085] The present invention provides a method for preparing a digital microfluidic electrode array having a staggered row-column structure. Step 3) is to prepare a second drive layer: photoresist is applied to the dielectric layer of step 2), baked and cured, and then the pattern on the third mask is transferred to the photoresist surface by ultraviolet exposure. After exposure, development, deposition of conductive material, and stripping of excess conductive material, the second drive layer is obtained. The conductive material, conductive material deposition thickness, and photoresist are the same as those in step 1).

[0086]

application

[0087] The present invention also provides the above digital microfluidic electrode array with a row-column series staggered structure and / or the application of the digital microfluidic electrode array with a row-column series staggered structure prepared by the above micro-nano processing method in digital microfluidics.

[0088] Digital microfluidic electrode array PCB with row-column series staggered structure

[0089] See also Figure 7-9 The digital microfluidic electrode array PCB provided by the present invention has a row-column series staggered structure, including a driving electrode array, a first signal layer, a second signal layer and a bottom wiring layer; the driving electrode array includes a plurality of driving electrodes arranged in a rectangular array, the driving electrodes include a first driving electrode 111 and a second driving electrode 311, and the first driving electrode 111 and the second driving electrode 311 are staggered. Figure 7 As shown, the first signal layer includes a plurality of column series conductors 111', and the column series conductors 111' connect two adjacent first driving electrodes 111 in the column direction; Figure 8 As shown, the second signal layer includes a plurality of row series wires 311', the row series wires 311' connect two second driving electrodes 311 adjacent to each other in the column direction, the first driving electrodes 111 connected by the column series wires 111' form a column series electrode array 1, and the second driving electrodes 311 connected by the row series wires 311' form a row series electrode array 3, as shown in FIG. Figure 9 As shown, the column-series electrode array 1 and the row-series electrode array 3 are interlaced and interwoven. The bottom wiring layer includes several bottom-layer conductors 4. Each single-column series electrode 31 in the row-series electrode array 3 and each single-column series electrode 11 in the column-series electrode array 1 are connected to a bottom-layer conductor 4. This layout is similar to the aforementioned digital microfluidic electrode array, with a high degree of regularity and an orderly, interlaced distribution.

[0090] Specifically, the staggered arrangement of the first drive electrodes 111 and the second drive electrodes 311 means that the drive electrodes adjacent to each first drive electrode 111 above, below, or left and right are all second drive electrodes 311, and the drive electrodes adjacent to each second drive electrode 311 above, below, or left and right are all first drive electrodes 111. This arrangement forms the basis for the staggered interlocking arrangement of the row series electrode array 3 and the column series electrode array 1.

[0091] In the digital microfluidic electrode array PCB with a row-column series staggered structure provided by the present invention, Figure 9 As shown in Figure 2b, a through-hole pad is placed between the drive electrodes. The drive electrodes can be fixed to the through-hole pad by welding, for example. The column series conductors 111' connect adjacent first drive electrodes 111 through the through-hole pad 5, and the row series conductors 311' connect adjacent second drive electrodes 311 through the through-hole pad 5.

[0092] In the digital microfluidic electrode array PCB with a row-column series staggered structure provided by the present invention, each driving electrode generally includes a dielectric layer and a hydrophobic layer. In a preferred embodiment, a dielectric layer is first deposited on the surface of the driving electrode by a chemical vapor deposition method, and the dielectric layer is selected from one or more of a silicon nitride layer, a silicon dioxide layer, a silicon carbide layer, a zirconium oxide layer, a hafnium oxide layer or a titanium oxide layer, and then the surface of the driving electrode array is covered with a hydrophobic layer by dip coating or spraying. The hydrophobic layer can be, for example, a silane coating or a fluorinated polymer layer. In another preferred embodiment, before the dielectric layer and the hydrophobic layer are set, a nickel layer can be first deposited on the surface of the driving electrode, and then gold is deposited on the nickel layer, and the conductivity and corrosion resistance of the driving electrode are improved by the gold deposition process. The first driving electrode 111 and the second driving electrode 311 are essentially the same electrodes, and are distinguished only by whether they belong to the row series electrode array 3 or the column series electrode array 1.

[0093] In the digital microfluidic electrode array PCB with a row-column series staggered structure provided by the present invention, the row series wiring is as follows Figure 8 As shown: the row series conductor 311' connects the adjacent second driving electrodes 311 through the through-hole pad 5, realizing the series connection of the electrodes along the row direction, so that the signal is distributed longitudinally in the driving electrode array, that is, each single row series electrode can independently control the signal. Figure 7 As shown: the column series conductors 111' are connected to adjacent first driving electrodes 111 through the through-hole pads 5, so that the electrode array forms a series connection in the horizontal arrangement, that is, each single column series electrode can independently control the signal. The row series wiring and the column series wiring cooperate to form a network, ensuring the integrity of signal transmission. Figure 9 As shown, the bottom wiring layer includes several bottom wires 4 for the final integration of signals, wherein each single-column series electrode 31 and each single-column series electrode 11 are respectively connected to a bottom wire 4. Through the coordination of the first signal layer, the second signal layer and the bottom wiring layer, optimized wiring is achieved, signal loss is reduced, and stable signal propagation in each layer is ensured, thereby improving the overall stability of the system; the bottom wire 4 is finally led out through the through-hole pad 5 and connected to the input electrode, and is connected one-to-one with the input electrode. The input electrode is further electrically connected to the external signal equipment to complete the signal input and control of the entire system.

[0094] The working principle of the digital microfluidic electrode array PCB with a row-column series staggered structure provided by the present invention relies on the electrowetting effect EWOD and row-column addressing control, that is, when a droplet is at a specific driving electrode, the driving electrode adjacent to the droplet can be activated on demand by programming the voltage signal in advance. The surface tension of the activated driving electrode changes, the contact angle of the droplet decreases, and the droplet is driven to move toward that location, thereby realizing droplet manipulation. Droplet splitting refers to the simultaneous activation of the driving electrodes on the adjacent left and right sides or upper and lower sides of the droplet, pulling the droplet to the left and right or up and down at the same time until the droplet surface splits. Droplet merging refers to driving two droplets to move to the same position and merge naturally.

[0095] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is described in detail below with reference to embodiments and drawings.

[0096] In the following examples, unless otherwise specified, all reaction raw materials are commercially available products.

[0097] Unless otherwise specified, the purity of each product in each embodiment of the present invention exceeds 98%.

[0098] Example 1

[0099] A micro-nano fabrication method for a digital microfluidic electrode array having a row-column series staggered structure, such as Figure 1-3 shown.

[0100] The specific preparation steps are as follows:

[0101] (1) Preparation of the first driving layer:

[0102] Mask design: Use AutoCAD software to design the first driving layer electrode pattern and hand it over to the company to make the mask.

[0103] Substrate pretreatment: Spin-coat Lor5A+S1805 double-layer photoresist on the silicon substrate using a spin coater, and then bake on a hot plate.

[0104] Pattern transfer: Use the photolithography machine MJB4 with the first layer of mask for UV exposure, followed by development to transfer the mask pattern to the photoresist.

[0105] Metal deposition and lift-off: Electron beam (E-beam) evaporation is used to deposit 5nm Ti and 50nm Au, and then the unnecessary metal is removed by lift-off process to complete the preparation of the first driving layer. Figure 1 shown.

[0106] (2) Preparation of dielectric layer

[0107] Dielectric layer deposition: Plasma enhanced chemical vapor deposition (PECVD) was used to deposit a 300 nm silicon nitride film on the first electrode pattern.

[0108] Photoresist coating and exposure: Spin-coat photoresist AZ5214 and use the photolithography machine MJB4 with the second layer mask for UV exposure.

[0109] Positive-resist reversal process: The UV-exposed photoresist undergoes a first bake, followed by a flood exposure (unblocked exposure) and a second bake, converting the photoresist from positive to negative. At this point, the blocked areas of the mask will be washed away during the development step.

[0110] Dielectric layer etching: Reactive ion beam etching (RIE) is used to etch silicon nitride. After the etching is completed, the dielectric layer preparation is completed. Figure 3 shown.

[0111] (3) Preparation of the second driving layer:

[0112] Apply photoresist on the dielectric layer of step 2), bake and solidify it, transfer the pattern on the third mask to the photoresist surface by ultraviolet exposure, expose, develop, deposit conductive material and remove excess conductive material to obtain the second driving layer. The conductive material, conductive material deposition thickness and photoresist are the same as those in step 1). The row series electrode array on the second driving layer is as follows: Figure 2 shown.

[0113] Example 2

[0114] A digital microfluidic electrode array PCB with a row-column series staggered structure, such as Figure 7-9 shown.

[0115] (1) Design and manufacturing: Use Jiali Chuang EDA software to design PCB, adopting a 4-layer board structure.

[0116] (2) A silicon nitride layer (dielectric layer) is first deposited on the surface of the driving electrode by chemical vapor deposition, and then a silane coating (hydrophobic layer) is covered on the surface of the driving electrode by dip coating. Figure 9 As shown, a through hole pad 5 is provided at the center of the driving electrode.

[0117] (3) Row series routing Figure 8 As shown: the row series conductor 311' connects the adjacent second driving electrodes 311 through the through-hole pad 5, realizing the series connection of the electrodes along the row direction, so that the signal is distributed longitudinally in the driving electrode array, that is, each single row series electrode can independently control the signal. Figure 7As shown, column series conductors 111' connect adjacent first drive electrodes 111 via through-hole pads 5, forming a series connection in the horizontal arrangement of the electrode array. This means that each column of series electrodes can independently control signals. The row and column series traces form a network, ensuring the integrity of signal transmission.

[0118] (3) The bottom conductor 4 is led out from the through-hole pad 5 and connected to the input electrode, which is then connected to the external signal device.

[0119] The main benefit of the digital microfluidic electrode array chip manufactured by PCB in this embodiment is low cost. Depending on the size of the driving electrode array and the manufacturing process, the cost usually ranges from several to tens of RMB per chip.

[0120] The current technology for high-throughput digital microfluidics relies on an active matrix approach based on thin-film transistors (TFTs). This technology, widely used by panel manufacturers, typically requires at least five layers of photolithography and etching. Its core principle is to use transistors as switches to control the on / off voltage of each drive electrode. This results in a high manufacturing threshold, a long manufacturing process, and high costs. Furthermore, due to the electrowetting on dielectric (EWOD) principle commonly employed by these digital microfluidic chips, the high-frequency, high-voltage signals required, and the humid environment caused by fluid movement often limit the service life of transistors in such environments, further reducing the operational stability of these digital microfluidic chips. In contrast, the digital microfluidic electrode array and PCB board proposed in this invention, with an interlaced row-column structure, does not rely on transistors; the row / column series connection is only connected by wires, which undoubtedly makes its operation more stable. Furthermore, manufacturing this digital microfluidic chip requires only three layers of micro-nanofabrication, significantly reducing its cost and manufacturing threshold. Furthermore, this structure can be extended to PCB manufacturing, eliminating the need for micro-nanofabrication, further reducing its manufacturing cost and making it more accessible.

[0121] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A digital microfluidic electrode array having a row-column series staggered structure, characterized in that: The invention comprises a first driving layer and a second driving layer, wherein a column series electrode array (1) is provided on the first driving layer, wherein the column series electrode array (1) is composed of a plurality of parallel single-row series electrodes (11), and each of the single-row series electrodes (11) includes a plurality of first driving electrodes (111) arranged longitudinally; and a row series electrode array (3) is provided on the second driving layer, wherein the row series electrode array (3) is composed of a plurality of parallel single-row series electrodes (31), and each of the single-row series electrodes (31) includes a plurality of second driving electrodes (311) arranged transversely; the driving electrodes of adjacent single-row series electrodes (11) are staggered in arrangement, and the driving electrodes of adjacent single-row series electrodes (31) are also staggered in arrangement, and the single-row series electrodes (11) and the single-row series electrodes (31) are arranged in an interlaced and interlocking manner.

2. The digital microfluidic electrode array having a row-column series staggered structure according to claim 1, characterized in that: It also includes a plurality of first input electrodes (112) and second input electrodes (312), each of the first input electrodes (112) is connected to a single column of series electrodes (11), and each of the second input electrodes (312) is connected to a single row of series electrodes (31).

3. The digital microfluidic electrode array having a row-column series staggered structure according to claim 1, characterized in that: A dielectric layer (2) is provided at the overlapping position of the conductive lines of the column series electrode array (1) and the row series electrode array (3).

4. The digital microfluidic electrode array having a row-column series staggered structure according to claim 3, characterized in that: The dielectric layer (2) is selected from one or more of a silicon nitride layer, a silicon dioxide layer, a silicon carbide layer, a zirconium oxide layer, a hafnium oxide layer or a titanium oxide layer.

5. The digital microfluidic electrode array having a row-column series staggered structure according to claim 1, characterized in that: Also includes any one or more of the following features: A1) each of the first driving electrodes (111) is made by depositing a conductive material on the first driving layer, and each of the second driving electrodes (311) is made by depositing a conductive material on the second driving layer; A2) each of the first driving electrodes (111) and each of the second driving electrodes (311) comprises a dielectric layer and a hydrophobic layer; A3) the thickness of the first driving layer and the second driving layer is 10-100 nm; A4) the length of each of the first driving electrodes (111) and each of the second driving electrodes (311) is 1-10 mm; Width: 1-10mm; A4) after the column series electrode array (1) and the row series electrode array (3) are interlaced and interlocked, the spacing between adjacent first driving electrodes (111) and second driving electrodes (311) is 10-100 μm; A5) The thickness of the dielectric layer (2) is 10-300 nm.

6. The micro-nano fabrication method for a digital microfluidic electrode array having a row-column series staggered structure according to any one of claims 1 to 5, characterized in that: The steps include: 1) Preparation of the first driving layer: a photoresist is applied to a silicon substrate, and after curing by baking, the pattern on the first mask is transferred to the photoresist surface by ultraviolet exposure. After development, a photoresist pattern is formed. A conductive material is deposited on the photoresist pattern, and the excess conductive material is stripped off to obtain the first driving layer; 2) Preparation of dielectric layer: After depositing a dielectric material on the first driving layer obtained in step 1), a photoresist is applied to the surface of the dielectric material, and the pattern on the second mask is transferred to the surface of the dielectric material by ultraviolet exposure. After etching, the excess photoresist is removed to obtain a dielectric layer; 3) Preparation of the second driving layer: Apply photoresist on the dielectric layer of step 2), bake and cure, transfer the pattern on the third mask to the photoresist surface by ultraviolet exposure, expose, develop, deposit conductive material and strip off excess conductive material to obtain the second driving layer.

7. The micro-nano fabrication method for a digital microfluidic electrode array having a row-column series staggered structure according to claim 6, characterized in that: Includes any of the following characteristics: B1) The conductive material in step 1) and step 3) is selected from one or more of gold, silver, titanium, copper, aluminum, chromium, and indium tin oxide; B2) The conductive material in step 1) and step 3) is deposited to a thickness of 5-100 nm; B3) the dielectric material in step 2) is selected from one or more of silicon nitride, silicon dioxide, silicon carbide, zirconium oxide, hafnium oxide or titanium oxide; B4) The deposition thickness of the dielectric material in step 2) is 10-300 nm.

8. Use of the digital microfluidic electrode array having a row-column series staggered structure as claimed in any one of claims 1 to 5 and / or the digital microfluidic electrode array having a row-column series staggered structure prepared by the micro-nano processing method as claimed in any one of claims 6 to 7 in digital microfluidics.

9. A digital microfluidic electrode array PCB with a row-column series staggered structure, characterized in that: The invention comprises a driving electrode array, a first signal layer, a second signal layer and a bottom wiring layer; the driving electrode array comprises a plurality of driving electrodes arranged in a rectangular array, the driving electrodes comprise a first driving electrode (111) and a second driving electrode (311), the first driving electrode (111) and the second driving electrode (311) are arranged in a staggered manner, the first signal layer comprises a plurality of column series wires (111'), the column series wires (111') connect two first driving electrodes (111) adjacent in the column direction; the second signal layer comprises a plurality of row series wires (311'), the row series wires (311') connect two first driving electrodes (111) adjacent in the column direction The invention relates to a device for manufacturing a plurality of second driving electrodes (311), wherein the first driving electrodes (111) connected via the column series wire (111') form a column series electrode array (1), and the second driving electrodes (311) connected via the row series wire (311') form a row series electrode array (3), wherein the column series electrode array (1) and the row series electrode array (3) are arranged in an interlaced manner, and the bottom wiring layer comprises a plurality of bottom wires (4), and each single column series electrode (31) in the row series electrode array (3) and each single column series electrode (11) in the column series electrode array (1) are respectively connected to a bottom wire (4).

10. The digital microfluidic electrode array PCB with a row-column series staggered structure according to claim 9, characterized in that: Also includes any one or more of the following features: C1) each of the driving electrodes comprises a dielectric layer and a hydrophobic layer; C2) further comprising a through-hole pad (5), wherein the through-hole pad (5) is arranged in the middle of the driving electrode; C3) also includes a plurality of input electrodes, each of which is connected to a bottom conductor (4).

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