PCB-based high-throughput digital microfluidic chip, driving system and preparation method

Abstract

The application belongs to the technical field of digital microfluidics, and discloses a high-throughput digital microfluidic chip based on a PCB, a driving system and a preparation method.The chip comprises a driving electrode substrate and a lower substrate.The driving electrode substrate provides a flat contact surface for micro-droplet movement, reduces micro-droplet movement resistance and residue and adhesion on the chip surface, the gap between adjacent driving electrodes is less than or equal to 100 microns, and the driving voltage for micro-droplet control is reduced.The lower substrate controls vertical addressing of the electrodes on the bonded driving electrode substrate, and on the basis of ensuring the electrode contact gap and flatness, a portable digital microfluidic chip with any large throughput can be manufactured at low cost.Based on the high scalability of active circuits and PCB chips, tens of thousands of discrete droplets can be driven in parallel on the same chip.By changing the chemical and biological components in the micro-droplets, the application can perform high-throughput analysis and synthesis tasks in chemical, biological and medical engineering applications.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of digital microfluidics, and particularly relates to a high-throughput digital microfluidic chip based on a PCB, a driving system and a preparation method. BACKGROUND

[0002] Digital microfluidics (DMF) technology is a new droplet manipulation technology for independent manipulation of discrete droplets, and can automatically realize droplet distribution, movement, merging and splitting, etc. It is one of the mainstream fluid driving forms. Digital microfluidics technology has great application prospects in biology, chemistry and medical engineering due to its automation, miniaturization and integration. However, with the development of DMF, the demand for parallel manipulation of microdroplets is increasing, and high-throughput digital microfluidic devices are expected to appear to complete parallel processing and reactions of multiple samples.

[0003] It is a simple task to manufacture a digital microfluidic chip with an electrode array of less than 100 levels, which can be realized by "single-plane" silk screen printing or two-dimensional pattern etching technology to achieve low-cost rapid manufacturing. However, when the size of the electrode array is large, the wiring and external driving system of the digital microfluidic chip will be extremely complex. At present, the number of droplets that can be driven in parallel by a digital microfluidic chip based on thin film transistor technology (TFT chip) is as high as thousands, but the high processing cost and complex manufacturing process have hindered the market promotion of TFT chips. In theory, a digital microfluidic chip based on low-cost printed circuit board technology (PCB) can also achieve parallel driving of thousands or even higher number of discrete droplets. However, the digital microfluidic chip directly using a standard PCB has a driving electrode gap of usually >100 μm, and its surface topography is not ideal for smooth and reliable droplet movement. In addition, with the increase of throughput, the one-to-one passive switch control scheme of the driving chip will lead to a complex and large driving system, which limits the high-throughput development of the digital microfluidic chip.

[0004] Please refer to Figure 1As shown, the flatness of the contact surface between the digital microfluidic chip electrode plate and the droplet 11 directly affects the control performance of the digital microfluidic chip on the microdroplet. In the prior art, after the electrode array 101 is made on the substrate 100, the dielectric layer 102 is deposited on the electrode array 101, and then the hydrophobic layer 103 is deposited on the dielectric layer 102. Due to the thickness of the electrode array 101 and the wire of the electrode plate, the thickness of the deposited dielectric layer 102 is uniform, and the thickness of the hydrophobic layer 103 is uniform, which leads to the uneven surface of the hydrophobic layer 103. The uneven surface of the chip not only increases the resistance of the droplet 11 moving, but also affects the smoothness of the droplet control. The uneven surface of the electrode plate makes it difficult to obtain a uniform hydrophobic layer 103, and the non-uniform hydrophobic layer 103 directly affects the consistency and reliability of the droplet 11 moving on different areas of the chip. In addition, the uneven surface of the chip increases the possibility of adhesion of the precipitated liquid, especially in the application scenario of enrichment, the process hole and groove on the surface of the chip will leave the detected substance, which seriously affects the detection accuracy.

[0005] Therefore, how to develop a low-cost, flat-surface high-throughput digital microfluidic chip and its miniaturized driving system is an urgent problem to be solved for the development of digital microfluidic chips as disposable and efficient biochemical detection tools. SUMMARY

[0006] The purpose of the present application is to provide a high-throughput digital microfluidic chip based on PCB, a driving system and a preparation method, to solve one of the problems of the uneven surface of the electrode plate of the existing digital microfluidic chip based on PCB, the limited throughput and the complexity and largeness of the high-throughput driving system.

[0007] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a high-throughput digital microfluidic chip based on PCB, comprising: a lower substrate and a driving electrode substrate.

[0009] The lower substrate comprises a lower substrate dielectric layer and a contact connection pad layer and an electrode connection pad layer arranged on the lower substrate dielectric layer.

[0010] A plurality of electrode connection pads are arranged in the electrode connection pad layer; the plurality of electrode connection pads are arranged in an array; the electrode connection pads in the electrode connection pad layer are filled with a dielectric material; the surface of the dielectric material in the electrode connection pad layer is flush with the surface of the electrode connection pad;

[0011] A plurality of contact connection pads are arranged in the contact connection pad layer; each contact connection pad in the contact connection pad layer is connected to one or more electrode connection pads.

[0012] The driving electrode substrate is located above the electrode connection pad layer; the driving electrode substrate comprises a lower hydrophobic layer, a driving electrode dielectric layer and a driving electrode layer arranged in sequence from top to bottom; a plurality of driving electrodes are arranged in the driving electrode layer; the driving electrodes are arranged in an array and correspond to the electrode connection pads; and the corresponding driving electrodes are in contact with the corresponding electrode connection pads.

[0013] The electrode connection pad layer is further improved in that the surface of the dielectric material is flush with the surface of the electrode connection pad, specifically, the surface roughness Ra of the electrode connection pad layer is less than or equal to 5 microns; the surface roughness Ra of the lower hydrophobic layer is less than or equal to 3 microns; and the gap between adjacent driving electrodes is less than or equal to 100 microns.

[0014] The electrode connection pad layer is further improved in that the contact connection pad is arranged at the bottom of the lower substrate and exposed on the bottom surface of the lower substrate; or the contact connection pad and the electrode connection pad are arranged on the same layer and located on the side of the electrode connection pad.

[0015] The electrode connection pad layer is further improved in that the upper electrode plate is further improved in that the upper electrode plate comprises an upper substrate, a conductive layer and an upper hydrophobic layer from top to bottom; a plurality of ground electrode connection pads are arranged in the electrode connection pad layer; a plurality of ground electrode contact pads are arranged in the contact connection pad layer; the ground electrode connection pad is connected to the corresponding ground electrode contact pad; the conductive layer is connected to the ground electrode connection pad in the lower substrate through a conductive gasket; and the ground electrode connection pad is electrically connected to the ground through the ground electrode contact pad.

[0016] The upper hydrophobic layer is arranged in parallel with the driving electrode substrate; and a space for liquid drop movement is formed between the upper hydrophobic layer and the driving electrode substrate.

[0017] The electrode connection pad layer is further improved in that the lower substrate further comprises a temperature control module; the temperature control module comprises a heater wire and a temperature sensor; the heater wire and the temperature sensor are connected to the contact pad and the contact connection pad respectively and connected to the host through a connector for controlling the temperature of different regions.

[0018] The electrode connection pad layer is further improved in that a through hole is punched on the electrode connection pad, conductive glue is filled in the through hole, so that the driving electrode substrate is fixed on the lower substrate, and the corresponding driving electrode and the electrode connection pad are electrically connected.

[0019] In the second aspect, the application provides a digital microfluidic driving system, comprising a PCB-based high-throughput digital microfluidic chip and an active matrix control circuit board.

[0020] The active matrix control circuit board is provided with a plurality of connectors corresponding to the positions of the contact connection pads for controlling the power-on or power-off of the corresponding contact connection pads.

[0021] The further improvement of the present application is that the plurality of connectors comprises M rows and N columns; the active matrix control circuit board is provided with M row conductors and N column conductors, and M and N are natural numbers greater than or equal to 2.

[0022] Each of the connectors is connected to an electrode driving module; the electrode driving module comprises a three-terminal bidirectional switch and a capacitor; the three-terminal bidirectional switch comprises a first main terminal, a gate and a second main terminal; in the electrode driving module located at the i-th row and the j-th column, the second main terminal of the three-terminal bidirectional switch is connected to one end of the capacitor and the connector, the other end of the capacitor is grounded, the gate of the three-terminal bidirectional switch is connected to the row conductor of the i-th row, and the first main terminal of the three-terminal bidirectional switch is connected to the column conductor of the j-th column.

[0023] The further improvement of the present application is that the plurality of connectors comprises M rows and N columns; the active matrix control circuit board is provided with M row conductors and N column conductors, and M and N are natural numbers greater than or equal to 2.

[0024] In a third aspect, the present application provides a preparation method of a high-throughput digital microfluidic chip based on a PCB, comprising:

[0025] The lower substrate is processed based on a printed circuit board process; the lower substrate comprises a contact connection pad layer and an electrode connection pad layer; a plurality of electrode connection pads are arranged in the electrode connection pad layer; the plurality of electrode connection pads are arranged in an array; a plurality of contact connection pads are arranged in the contact connection pad layer; each of the contact connection pads in the contact connection pad layer is connected to one or more electrode connection pads; after the electrode connection pads in the electrode connection pad layer are processed, the surface of the electrode connection pad layer is washed, polished and processed after the electrode connection pads in the electrode connection pad layer are filled with a dielectric material and solidified, so that the surface roughness Ra of the electrode connection pad layer is less than or equal to 5 μm, and the preparation of the lower substrate is completed;

[0026] A driving electrode substrate is prepared; the driving electrode substrate comprises a driving electrode dielectric layer and a driving electrode layer arranged in sequence from top to bottom; the driving electrodes in the driving electrode layer are arranged in an array, and the number and position of the driving electrodes correspond to the electrode connection pads;

[0027] The lower substrate is inverted on the driving electrode layer, the electrode connecting pad is aligned and attached to the driving electrode through the positioning slot, conductive glue is filled in the through hole of the electrode connecting pad, so that the driving electrode substrate is fixed on the lower substrate, and the corresponding driving electrode and the electrode connecting pad are electrically connected, after the conductive glue solidifies, the conductive glue on the back of the lower substrate is washed and polished, so that the contact connecting pad of the lower substrate does not occur adhesion and short circuit, the lower hydrophobic layer is prepared on the driving electrode dielectric layer, a transparent upper hydrophobic layer is prepared on the conductive side surface of the upper substrate, and a plurality of injection holes penetrating through the upper substrate and the transparent upper hydrophobic layer are prepared, the upper substrate is an ITO conductive glass layer;

[0028] The upper plate is inverted on the driving electrode substrate, the conductive layer of the upper plate is connected to the ground electrode connecting pad in the lower substrate through the conductive pad, the ground electrode connecting pad is electrically connected to the ground through the ground electrode contact pad, and the space capable of supplying the liquid drop movement is formed between the upper plate and the lower substrate through the conductive pad support.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The present application provides a high-throughput digital microfluidic chip based on PCB, comprising: a driving electrode substrate and a lower substrate; the surface roughness Ra of the driving electrode substrate is less than or equal to 3 microns, which provides a flat contact surface for micro-droplet movement, reduces the resistance of micro-droplet movement and the residue and adhesion on the chip surface; the electrode contact gap of the driving electrode substrate is less than or equal to 100 microns, which reduces the driving voltage of the micro-droplet in operation; the lower substrate vertically addresses and controls the electrodes on the driving electrode substrate bonded thereto, and ensures the gap and flatness between adjacent electrodes, so that a portable digital microfluidic chip with any large throughput can be quickly and low-cost manufactured; the active control circuit based on the capacitor charge lock realizes the scanning control of the high-throughput digital microfluidic chip, the electrode driving module only generates current when the driving electrode is switched between on and off, which reduces the power consumption and heat generation of the driving system, the system has strong expandability and is easy to miniaturize and integrate; the present application has the characteristics of high throughput, and based on the high scalability of the active circuit and the PCB chip, tens of thousands of discrete droplets can be automatically and parallelly driven on the same chip without mutual interference; by changing the chemical and biological substances in the droplets, the present application can automatically perform high-throughput analysis and synthesis tasks in chemical engineering, biological engineering and biomedical engineering applications. BRIEF DESCRIPTION OF DRAWINGS

[0031] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application and the explanation thereof serve to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0032] Figure 1It is a sectional view of the existing digital microfluidic chip;

[0033] Figure 2 It is a sectional view of the high-throughput digital microfluidic chip based on PCB of the present application;

[0034] Figure 3 It is a sectional view of the lower substrate;

[0035] Figure 4 It is a top view of the lower substrate;

[0036] Figure 5 It is a sectional view of the driving electrode layer;

[0037] Figure 6 It is a bottom view of the driving electrode layer;

[0038] Figure 7 It is a structural schematic diagram of the electrode driving module arranged in an array;

[0039] Figure 8 It is a schematic diagram of the cooperation of the lower substrate and the active matrix control circuit board. DETAILED DESCRIPTION

[0040] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0041] The following detailed description is exemplary and is intended to provide further detailed description of the present application. Unless otherwise specified, all technical terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs. The terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the exemplary embodiments according to the present application.

[0042] Embodiment 1

[0043] The high-throughput digital microfluidic chip based on PCB provided by the present application mainly presents in the form of double-plate digital microfluidic chip, and can also present in the form of single-plate, hybrid plate digital microfluidic chip.

[0044] Please refer to Figures 2 to 6 As shown in the figure, the present application introduces a high-throughput digital microfluidic chip based on PCB in the form of double-plate digital microfluidic chip, which comprises an upper substrate 1, an upper hydrophobic layer 2, a conductive gasket 3, a ground electrode connection pad 10, a driving electrode substrate 4 and a lower substrate 5.

[0045] In an embodiment, the lower substrate 5 comprises three layers, which are, from bottom to top, the contact pad layer 50, the lower substrate dielectric layer 52 and the electrode pad layer 51. The electrode pad layer 51 is provided with a plurality of electrode pads 511, which are arranged in an array. The electrode pads 511 in the electrode pad layer 51 are separated by dielectric material. The contact pad layer 50 is provided with a plurality of contact pads 510, which are arranged in an array. The contact pads 510 in the contact pad layer 50 are separated by dielectric material. One contact pad 510 is electrically connected to one or more electrode pads 511.

[0046] The two surfaces of the lower substrate 5 are polished flat by a milling machine or other equipment.

[0047] The driving electrode substrate 4 is a replaceable layer, which comprises, from top to bottom, the lower hydrophobic layer 43, the driving electrode dielectric layer 42 and the driving electrode layer. The driving electrode layer is provided with a plurality of driving electrodes 41, which are arranged in an array and correspond to the electrode pads 511 in number and position. The electrode gap of the array of driving electrodes 41 is not greater than 1000 μm.

[0048] The driving electrode substrate 4 is arranged on the electrode pad layer 51 of the lower substrate 5, and the corresponding driving electrode 41 is in contact with the corresponding electrode pad 511. Each electrode pad 511 is provided with a through hole 53, and the through hole 53 is filled with conductive glue, so that the driving electrode substrate 4 is firmly fixed on the lower substrate 5, and the corresponding driving electrode 41 and electrode pad 511 are electrically connected. After the conductive glue solidifies, the conductive glue on the back of the lower substrate 5 is washed and polished to ensure that the contact pads 510 do not stick together or short circuit.

[0049] The contact pads 510 are arranged at the bottom of the contact pad layer 50 and exposed on the bottom surface of the contact pad layer 50, so that the corresponding contact pads 510 can be contacted from the bottom by the connector 602 to control whether the corresponding driving electrode 41 is powered on or not.

[0050] The electrode connection pad layer 51 is further provided with a plurality of ground electrode connection pads 10; the contact pad layer 50 is provided with a plurality of ground electrode contact pads; the ground electrode connection pad 10 is connected to the corresponding ground electrode contact pad; the conductive layer is connected to the ground electrode connection pad 10 in the lower substrate 5 through the conductive gasket 3; the ground electrode connection pad 10 is electrically connected to the ground through the ground electrode contact pad; the upper electrode plate is supported on the conductive gasket 3; the bottom surface of the upper electrode plate is provided with a transparent upper hydrophobic layer 2 facing the driving electrode substrate 4 of the upper substrate. The temperature control module can be arranged in the lower substrate dielectric layer 52, and the heating wire and the temperature sensor included in the temperature control module are respectively connected with the host through the connector 602, so that the temperature of different regions can be controlled when part of the experiment is carried out, and the experimental requirements are met.

[0051] The conductive gasket 3 is located between the transparent upper hydrophobic layer 2 of the upper electrode plate and the driving electrode substrate 4 of the lower substrate, and the conductive gasket 3 is connected to the ground electrode connection pad 10; a plurality of injection holes 12 are provided through the upper substrate 1 and the transparent upper hydrophobic layer 2, and the liquid drops 11 injected through the injection holes 12 can flow between the upper and lower substrates.

[0052] The PCB-based high-throughput digital microfluidic chip has high integration, and the number of electrodes can be expanded.

[0053] The PCB-based high-throughput digital microfluidic chip has high flatness, small movement resistance of microdroplets, reduced voltage required for driving the chip, reduced chip breakdown, and improved service life of the chip.

[0054] The PCB-based high-throughput digital microfluidic chip can reduce residue and adhesion when driving droplets, and is more likely to obtain a uniform and flat hydrophobic layer, which is beneficial to improving the consistent stability of microdroplet manipulation in different regions of the chip.

[0055] Example 2

[0056] The PCB-based high-throughput digital microfluidic chip of the embodiment is based on the embodiment 1, in the electrode connection pad layer 51 of the embodiment, the electrode connection pad 511 array gap, the electrode and the wire gap, the wire and the wire gap and the process hole slot generated in the processing process are filled with dielectric material, so that the upper surface of the electrode connection pad layer 51 is flush with the upper surface of the two-dimensional electrode connection pad 511 array; the upper surface of the electrode connection pad layer 51 is further polished by using a numerical control milling machine, and the surface roughness Ra is less than or equal to 5 microns.

[0057] The upper substrate is reversely buckled on the microdroplet 11 to be controlled, the upper hydrophobic layer 2 faces downward to the microdroplet to be controlled, and the lower substrate 1 is ITO conductive glass; the conductive layer of the ITO conductive glass is connected to the ground electrode connection pad 10 through the conductive pad 3; the droplet to be controlled can flow between the driving electrode substrate 4 and the upper hydrophobic layer 2.

[0058] Embodiment 3

[0059] The embodiment provides a PCB-based high-throughput digital microfluidic chip, the electrode connection pad layer 51 and the contact connection pad layer 50 of the embodiment 1 are arranged on the same layer; the electrode connection pad (511) is arranged at a center position, and the contact connection pad (510) is located at a side of the electrode connection pad (511).

[0060] Embodiment 4

[0061] Referring to Figures 2 to 8 The embodiment provides a digital microfluidic driving system, which comprises the PCB-based high-throughput digital microfluidic chip and the active matrix control circuit board 6.

[0062] The embodiment further reduces the manufacturing cost of the high-throughput digital microfluidic chip, and makes the cost of single detection lower; the electrode driving module for driving the electrode 41 to work is manufactured on the active matrix control circuit board 6; in order to further reduce the pin usage quantity of the controller in the driving system of the high-throughput digital microfluidic chip, the driving electrode 510 is controlled to be on or off through the row-column scanning mode.

[0063] The electrode driving module arranged on the active matrix control circuit board 6 includes M rows and N columns; M row leads 61 and N column leads 62, M and N are natural numbers greater than or equal to 2, each electrode driving module includes a three-wire bidirectional switch 600, a capacitor 601 and a connector 602 connected with the contact connection pad 510, the three-wire bidirectional switch 600 includes a first main terminal 6001, a gate 6002 and a second main terminal 6003; in the electrode driving module of the ith row and the jth column, 1≤i≤M, 1≤j≤N, the second main terminal 6003 of the three-wire bidirectional switch 600 is connected to one end of the capacitor 601 and the connector 602, the other end of the capacitor 601 is grounded, the gate 6002 of the three-wire bidirectional switch 600 is connected to the row lead 61 of the ith row, the first main terminal 6001 of the three-wire bidirectional switch 600 is connected to the column lead 62 of the jth column, the M row leads 61 and the N column leads 62 are respectively connected to a row-column address controller, when the column lead 62 of the jth column and the row lead 61 of the ith row are electrified at the same time, the connector 602 located on the ith row and the jth column is electrified, the corresponding contact connection pad 510 is electrified, the column lead 62 of the jth column is de-energized at the same time, the driving electrode located above the ith row and the jth column is de-energized, so as to control the on-off of the corresponding contact connection pad 510; in order to avoid signal crosstalk of multiple column parallel control and improve scanning efficiency, the two-dimensional driving electrode array is driven in a column-by-column scanning manner to realize on-off control: the column lead 62 of the jth column is de-energized at the same time, and the row lead of the driving electrode in the jth column which needs to be switched from the energized state to the de-energized state is electrified, to realize the de-energized control of the driving electrode in the jth column which needs to be switched from the energized state to the de-energized state, then the column lead 62 of the jth column is electrified at the same time, and the row lead of the driving electrode in the jth column which needs to be switched from the de-energized state to the energized state is electrified, to realize the energized control of the driving electrode in the jth column which needs to be switched from the de-energized state to the energized state, the row lead of the driving electrode in the jth column which does not need to switch the on-off state is always de-energized, so as to control the on-off state refresh of the driving electrode in the jth column, and through column-by-column scanning, the on-off control of the two-dimensional driving electrode array is realized.

[0064] Embodiment 5

[0065] The embodiment provides a digital microfluidic driving system, on the basis of the embodiment 3, a plurality of connectors 602 are arranged in an array on the upper surface of the active matrix control circuit board 6; the position of the connector 602 corresponds to the position of the corresponding contact connection pad 510 on the lower substrate 5; the lower substrate 5 and the active matrix control circuit board 6 are provided with a positioning structure, which is used for aligning and contacting the connector 602 and the corresponding contact connection pad 510 on the lower substrate 5 when the lower substrate 5 is installed on the active matrix control circuit board 6, so as to realize electrical connection.

[0066] In a specific embodiment, the positioning structure can be a plurality of protrusions arranged on the upper surface of the active matrix control circuit board 6, and the lower substrate 5 can be just clamped between the plurality of protrusions to achieve accurate and rapid positioning.

[0067] In a specific embodiment, the positioning structure can include a plurality of positioning columns arranged on the upper surface of the active matrix control circuit board 6, and a plurality of positioning holes arranged on the lower surface of the lower substrate 5. The positioning columns are clamped into the corresponding positioning holes to achieve accurate and rapid positioning between the lower substrate 5 and the active matrix control circuit board 6.

[0068] Embodiment 6

[0069] The application provides a preparation method of a high-throughput digital microfluidic chip based on a PCB, comprising:

[0070] 1) Preparation of the lower substrate 5:

[0071] The printed circuit board is used as the substrate of the lower substrate 5. The PCB design software (such as Altium Designer, protel, PADS, CAM350) is used to form the pattern of the two-dimensional electrode array (electrode connection pad 511 and contact connection pad 510) in the contact connection pad layer 50 and the electrode connection pad layer 51 of the lower substrate 5.

[0072] When the lower substrate 5 is processed based on the standard process of the printed circuit board, the through holes and blind holes connected with the electrode array need to be filled to be flush with the upper surface of the electrode array. The application is processed by the PCB via hole filling process (filling the solder resist ink into the via hole, or filling the resin into the via hole and grinding) and the numerical control milling machine to process the lower substrate 5 of the chip.

[0073] First, the gaps between the two-dimensional electrode array, the gaps between the electrodes and the wires, and the gaps between the wires are filled with the solder resist (acrylic oligomer) with the same thickness as the electrode connection pad 511 array. Then, the PCB pad windowing process or polishing / polishing operation is used to remove the residual solder resist on the upper surface of the electrode connection pad 511 array and the unintended protrusions in the manufacturing process. Finally, the grinder is used to further grind the resin or solder resist ink overflowing on the upper surface of the lower substrate 5, and the grinding depth is about 2 μm. The flat lower substrate 5 with the electrode connection pad 511 array and the filling layer is obtained, and the surface roughness Ra is less than or equal to 5 μm.

[0074] 2) Preparation of the driving electrode substrate 4

[0075] 2.1) Spin 3wt% polyvinyl alcohol (PVA) solution on the top surface of the silicon wafer at 1000 rpm for 60 seconds to form a PVA film as a release layer. The PVA film is baked on a hot plate at 95°C for 15 minutes. A 6μm thick parylene-C film is deposited on the wafer as a driving electrode dielectric layer 42 using a low pressure chemical vapor deposition (CVD) apparatus; a 200nm chromium layer is sputtered on the top surface of the driving electrode dielectric layer 42 by magnetron sputtering;

[0076] 2.2) Driving electrode etching

[0077] Spin photoresist S1811 on each piece of unprotected chromium layer (2000 rpm, 30s), then soft bake on a hot plate at 95°C for 60s. Expose through a photomask in a mask aligner for 6s, then develop in Microposit MF-312 (diluted 1:1) for 45 seconds, rinse in deionized water and dry under nitrogen. Then immerse in a chromium etchant until the driving electrode 41 pattern is observed; the gap between adjacent driving electrodes 41 is ≤100μm; in a particular embodiment, the gap between adjacent driving electrodes 41 can be less than 1μm, as required by the application. After that, rinse in deionized water, strip the photoresist using AZ 300T stripper, and remove persistent photoresist residues by brief exposure to acetone and isopropyl alcohol; finally, rinse with deionized water and dry with nitrogen; the array of driving electrodes 41 is formed on the driving electrode dielectric layer 42.

[0078] 2.3) Assembly

[0079] Flip the lower substrate 5 on the driving electrode substrate 4, align and attach the electrode connection pads 511 to the driving electrodes 41 by positioning the clamping slots; fill the through holes 53 of the lower substrate 5 with conductive glue, and after the conductive glue solidifies, wash and polish the conductive glue on the back of the lower substrate 5 to ensure that the contact connection pads 510 of the lower substrate 5 do not stick together or short circuit. Soak the lower substrate 5 attached to the silicon wafer in deionized water for 8 hours to dissolve the water-soluble PVA film, then peel off the lower substrate 5 from the silicon wafer and dry it in a high-temperature oven at 165°C for 20 minutes. Finally, spin the hydrophobic material Teflon-AF solution on the driving electrode dielectric layer 42 (1500 rpm, 30s), and bake the lower substrate 5 in a forced air drying oven at 100°C for 20 minutes to obtain the lower hydrophobic layer 43.

[0080] 3) Upper plate preparation

[0081] The upper substrate 1 is a layer of ITO conductive glass, and a transparent upper hydrophobic layer 2 is coated on the upper substrate 1; a plurality of injection holes 12 are made through the upper substrate 1 and the transparent upper hydrophobic layer 2;

[0082] 4) Assembly

[0083] High flatness double flat plate digital microfluidic chip is a sandwich structure, the upper plate is inverted on the microdroplet 11 to be controlled, and the transparent upper hydrophobic layer 2 faces downward to the microdroplet 11 to be controlled; a plurality of injection holes 12 are arranged on the upper plate, which are used for sample loading, unloading, detection and exhaust; the edge of the upper plate and the lower substrate 5 is sealed by a sealing ring or sealing glue, and the area between the upper and lower substrates is filled with one or more of gas, liquid or solid; the upper substrate 1 is ITO conductive glass; the conductive layer of the ITO conductive glass is connected to the ground electrode connection pad 10 through the conductive pad 3; the support for controlling the distance between the plates is arranged between the upper and lower substrates, and the support and the conductive pad 3 can be the same object; the droplet 11 to be controlled can flow between the driving electrode substrate 4 and the upper hydrophobic layer 2; the active matrix control circuit board 6 is connected to the contact connection pad 510 of the lower substrate 5 through the connector 602, and the power array provides voltage for the electrode connection pad 511 through the connector 602, and the working state of the electrode connection pad 511 is controlled.

[0084] From the common general knowledge, the present application can be implemented by other embodiments without departing from the spirit or essential characteristics thereof. Therefore, the above disclosed embodiments are merely illustrative in all aspects and are not the only ones. All changes within the scope of the present application or within the scope equivalent to the present application are included in the present application.

Claims

1. A PCB-based high-throughput digital microfluidic chip, characterized in that, The application relates to a liquid drop actuator, which comprises a lower substrate (5) and a driving electrode substrate (4). The lower substrate (5) comprises a lower substrate dielectric layer (52) and a contact connecting pad layer (50) and an electrode connecting pad layer (51) arranged on the lower substrate dielectric layer (52). A plurality of electrode connecting pads (511) are arranged in the electrode connecting pad layer (51) in a matrix manner; the electrode connecting pads (511) in the electrode connecting pad layer (51) are filled with dielectric materials; the surface of the dielectric materials in the electrode connecting pad layer (51) is flush with the surface of the electrode connecting pads (511). A plurality of contact connecting pads (510) are arranged in the contact connecting pad layer (50) in a matrix manner; one or more electrode connecting pads (511) are connected to each contact connecting pad (510) in the contact connecting pad layer (50). The driving electrode substrate (4) is arranged above the electrode connecting pad layer (51); the driving electrode substrate (4) comprises a lower hydrophobic layer (43), a driving electrode dielectric layer (42) and a driving electrode layer arranged in sequence from top to bottom; a plurality of driving electrodes (41) are arranged in the driving electrode layer in a matrix manner; the driving electrodes (41) are arranged in a matrix manner and correspond to the electrode connecting pads (511); the corresponding driving electrodes (41) are in contact with the corresponding electrode connecting pads (511). A through hole (53) is punched on the electrode connecting pad (511); the through hole (53) is filled with conductive glue, so that the driving electrode substrate (4) is fixed on the lower substrate (5) and the corresponding driving electrodes (41) and electrode connecting pads (511) are electrically connected. The surface roughness Ra of the electrode connecting pad layer (51) is less than or equal to 5 microns; the surface roughness Ra of the lower hydrophobic layer (43) is less than or equal to 3 microns; and the gap between adjacent driving electrodes (41) is less than or equal to 100 microns.

2. The PCB-based high-throughput digital microfluidic chip of claim 1, wherein, The contact connecting pads (510) are arranged at the bottom of the lower substrate (5) and exposed on the bottom surface of the lower substrate (5); or the contact connecting pads (510) and the electrode connecting pads (511) are arranged on the same layer and located on the side of the electrode connecting pads (511).

3. The PCB-based high-throughput digital microfluidic chip of claim 1, wherein, The upper electrode plate comprises an upper substrate (1), a conductive layer and an upper hydrophobic layer (2) arranged in sequence from top to bottom; a plurality of ground electrode connecting pads (10) are arranged in the electrode connecting pad layer (51); a plurality of ground electrode contact pads are arranged in the contact connecting pad layer (50); the ground electrode connecting pads (10) are connected to the corresponding ground electrode contact pads; the conductive layer is connected to the ground electrode connecting pads (10) in the lower substrate (5) through a conductive gasket (3); and the ground electrode connecting pads (10) are electrically connected to the ground through the ground electrode contact pads.

4. The PCB-based high-throughput digital microfluidic chip of claim 1, wherein, The upper hydrophobic layer (2) is arranged in parallel with the driving electrode substrate (4) in a spaced manner; and a space capable of allowing liquid drops to move is formed between the upper hydrophobic layer (2) and the driving electrode substrate (4). ​ 5. The PCB-based high-throughput digital microfluidic chip of claim 4, wherein, The lower substrate (5) is also arranged with a temperature control module; the temperature control module comprises a heater wire and a temperature sensor; the heater wire and the temperature sensor are respectively connected to the contact pad contact pad (510) and connected to the host through the connector (602), and are used for controlling the temperature of different areas.

6. A digital microfluidic drive system characterized by, The PCB-based high-throughput digital microfluidic chip and the active matrix control circuit board (6) according to any one of claims 1 to 5 are included. The active matrix control circuit board (6) is arranged with a plurality of connectors (602); the connectors (602) correspond to the positions of the contact pad contact pads (510), and are used for controlling the power-on or power-off of the corresponding contact pad contact pads (510).

7. The digital microfluidic driving system of claim 6, wherein, The plurality of connectors (602) comprises M rows and N columns; the active matrix control circuit board (6) is provided with M row leads (61) and N column leads (62), and M and N are natural numbers greater than or equal to 2. Each connector (602) is connected to an electrode driving module; the electrode driving module comprises a three-wire bidirectional switch (600) and a capacitor (601); the three-wire bidirectional switch (600) comprises a first main terminal (6001), a gate (6002) and a second main terminal (6003); in the electrode driving module located in the ith row and the jth column, the second main terminal (6003) of the three-wire bidirectional switch (600) is connected to one end of the capacitor (601) and the connector (602), the other end of the capacitor (601) is grounded, the gate (6002) of the three-wire bidirectional switch (600) is connected to the row lead (61) of the ith row, and the first main terminal (6001) of the three-wire bidirectional switch (600) is connected to the column lead (62) of the jth column.

8. The digital microfluidic driving system of claim 6, wherein, The plurality of connectors (602) are arranged in an array on the upper surface of the active matrix control circuit board (6); the positions of the connectors (602) correspond to the positions of the corresponding contact pad contact pads (510) on the lower substrate (5); the lower substrate (5) and the active matrix control circuit board (6) are provided with a positioning structure for aligning the connectors (602) with the corresponding contact pad contact pads (510) on the lower substrate (5) when the lower substrate (5) is mounted on the active matrix control circuit board (6); the number of the connectors (602) is greater than or equal to the number of the contact pad contact pads (510).

9. A method for fabricating a PCB-based high-throughput digital microfluidic chip, characterized in that, The PCB-based high-throughput digital microfluidic chip and the active matrix control circuit board (6) according to any one of claims 1 to 5 are included. A lower substrate (5) is processed based on a printed circuit board process; the lower substrate (5) comprises a contact connection pad layer (50) and an electrode connection pad layer (51); a plurality of electrode connection pads (511) are arranged in the electrode connection pad layer (51) in a middle interval; the plurality of electrode connection pads (511) are arranged in an array; a plurality of contact connection pads (510) are arranged in the contact connection pad layer (50) in a middle interval; one or more electrode connection pads (511) are connected to each contact connection pad (510) in the contact connection pad layer (50); after the electrode connection pads (511) are processed in the electrode connection pad layer (51), a dielectric material is filled between the electrode connection pads (511) in the electrode connection pad layer (51) after solidification, and the surface of the electrode connection pad layer (51) is processed by washing and polishing, so that the surface roughness Ra of the electrode connection pad layer (51) is less than or equal to 5 microns, and the preparation of the lower substrate (5) is completed; A driving electrode substrate (4) is prepared; the driving electrode substrate (4) comprises a driving electrode dielectric layer (42) and a driving electrode layer arranged in sequence from top to bottom; the driving electrodes (41) in the driving electrode layer are arranged in an array, and the number and position correspond to the electrode connection pads (511); The lower substrate (5) is inverted and buckled on the driving electrode layer, the electrode connection pads (511) are aligned and attached to the driving electrodes (41) through positioning clamping grooves; conductive glue is poured into the through holes (53) of the electrode connection pads (511), so that the driving electrode substrate (4) is fixed on the lower substrate (5), and the corresponding driving electrodes (41) and electrode connection pads (511) are electrically connected; after the conductive glue solidifies, the conductive glue on the back of the lower substrate (5) is washed and polished, so that the contact connection pads (510) of the lower substrate (5) do not adhere and short circuit; a lower hydrophobic layer (43) is prepared on the driving electrode dielectric layer (42); a transparent upper hydrophobic layer (2) is prepared on the conductive side surface of the upper substrate (1); a plurality of injection holes (12) are made through the upper substrate (1) and the transparent upper hydrophobic layer (2); the upper substrate (1) is an ITO conductive glass layer; The upper substrate is inverted and buckled on the driving electrode substrate (4), and the conductive layer of the upper substrate is connected to the ground electrode connection pad (10) in the lower substrate (5) through the conductive gasket (3); the ground electrode connection pad (10) is electrically connected to the ground through the ground electrode contact pad; the upper substrate and the lower substrate (5) are supported by the conductive gasket (3) to form a space for liquid drop movement; the preparation of the high-throughput digital microfluidic chip based on the PCB is completed.

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