Microfluidic Substrate, Microfluidic Device, and Driving Method of Microfluidic Device

Abstract

The present invention relates to a microfluidic substrate, a microfluidic device, and a driving method for a microfluidic device. The microfluidic substrate includes: a substrate; a driving circuit layer located on one side of the substrate, the driving circuit layer including a plurality of driving units, each driving unit including a driving transistor and a variable capacitor; the variable capacitor includes a first electrode plate, a conductive layer, a semiconductor layer, and a second electrode plate, the conductive layer and the semiconductor layer are located between the first electrode plate and the second electrode plate, the conductive layer and the semiconductor layer are electrically connected, the conductive layer is connected to a reference voltage, the semiconductor layer is located on the side of the first electrode plate away from the substrate, the first electrode plate is electrically connected to the gate of the driving transistor; an electrode array layer located on the side of the driving transistor away from the substrate, the electrode array layer including driving electrodes corresponding one-to-one to the driving units, and the second electrode plate is part of the driving electrode. Embodiments of the present invention can increase the driving voltage applied to the driving electrode to meet the droplet driving requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of microfluidics, and particularly relates to a microfluidic substrate, a microfluidic device, and a driving method for the microfluidic device. Background Art

[0002] Microfluidics is an emerging interdisciplinary field involving chemistry, fluid physics, microelectronics, new materials, biology, and biomedical engineering. It can precisely control the movement of droplets, realize operations such as droplet fusion and separation, and complete various biochemical reactions. It is a technology mainly characterized by manipulating fluids in a micron-scale space. In recent years, microfluidic chips have been widely used in the fields of biology, chemistry, medicine, etc. due to their advantages of small size, low power consumption, low cost, small amounts of required samples and reagents, the ability to achieve individual and precise manipulation of droplets, short detection time, high sensitivity, and easy integration with other devices.

[0003] In the prior art, the principle of electrowetting is usually utilized to drive the movement of droplets by applying a driving voltage to a driving electrode. However, the driving voltage required to effectively drive the movement of droplets is relatively high, generally dozens of volts or even hundreds of volts. However, the driving voltage output by the current active driving circuit or active driving chip is quite different from the driving voltage required to effectively drive the movement of droplets, and thus cannot meet the droplet driving requirements. Summary of the Invention

[0004] The present invention provides a microfluidic substrate, a microfluidic device, and a driving method for the microfluidic device to increase the driving voltage applied to the driving electrode and meet the droplet driving requirements.

[0005] In a first aspect, an embodiment of the present invention provides a microfluidic substrate, including:

[0006] A substrate;

[0007] A driving circuit layer located on one side of the substrate. The driving circuit layer includes a plurality of driving units, and each driving unit includes a driving transistor and a variable capacitor. The driving transistor includes a gate, an active layer, a first electrode, and a second electrode. The gate receives a scanning signal, and the first electrode receives a driving signal. The variable capacitor includes a first plate, a conductive layer, a semiconductor layer, and a second plate. The conductive layer and the semiconductor layer are located between the first plate and the second plate, and the conductive layer and the semiconductor layer are electrically connected. The conductive layer is connected to a reference voltage, and the semiconductor layer is located on the side of the first plate away from the substrate. The first plate is electrically connected to the gate;

[0008] The electrode array layer is located on a side of the driving transistor away from the substrate. The electrode array layer includes driving electrodes corresponding one by one to the driving units. The driving electrodes are electrically connected to the second electrodes of the corresponding driving transistors. The second electrode plate is a part of the driving electrode. In a direction perpendicular to the plane of the substrate, both the second electrode plate and the first electrode plate cover a first part of the semiconductor layer. The second electrode plate and the conductive layer overlap, and the conductive layer and the first part of the semiconductor layer do not overlap.

[0009] In a second aspect, an embodiment of the present invention provides a microfluidic device, including the microfluidic substrate provided in the first aspect, and a counter substrate disposed opposite to the microfluidic substrate. A channel for the droplet to move is formed between the counter substrate and the microfluidic substrate.

[0010] In a third aspect, an embodiment of the present invention further provides a driving method for the microfluidic device provided in the second aspect, including:

[0011] In a first stage, a first scan signal and a driving signal are provided to the driving transistor of the target driving unit to turn on the driving transistor. The conductive layer and the semiconductor layer together form a first capacitor with the second electrode plate.

[0012] In a second stage, a second scan signal is provided to the driving transistor of the target driving unit to turn off the driving transistor. The second electrode plate forms a second capacitor with the conductive layer, and the second electrode plate forms a third capacitor with the first electrode plate.

[0013] The technical solutions provided by the embodiments of the present invention have the following advantages compared with the prior art:

[0014] The microfluidic substrate provided by the embodiment of the present invention increases a variable capacitor. The first electrode of the variable capacitor is electrically connected to the gate of the driving transistor. A part of the driving electrode is used as the second electrode of the variable capacitor, and a conductive layer and a semiconductor layer which are electrically connected are arranged between the first electrode and the second electrode. In this way, when a first scanning signal (i.e., gate voltage) is provided to the gate of the driving transistor, the semiconductor layer is turned on to form a conductive channel. At this time, the semiconductor layer is equivalent to a conductor, and the conductive layer and the semiconductor layer together form a reference electrode. At the same time, the driving transistor is turned on. By providing a driving signal to the first electrode of the driving transistor, a driving voltage can be applied to the driving electrode through the second electrode. Thus, a first capacitor is formed between the reference electrode and the second plate. After that, a second scanning signal is provided to the gate of the driving transistor, and the semiconductor layer is turned off to form an insulating channel. At this time, the semiconductor layer is equivalent to an insulating medium and constitutes a dielectric layer between the first plate and the second plate. At this time, a second capacitor is formed between the second plate and the conductive layer, and a third capacitor is formed between the second plate and the first plate. Since the semiconductor layer is turned off, the facing area of the upper and lower plates of the second capacitor is significantly smaller than that of the upper and lower plates of the first capacitor, and the distance between the upper and lower plates of the third capacitor is greater than that of the upper and lower plates of the first capacitor. Therefore, the first capacitor is greater than the sum of the second capacitor and the third capacitor. Based on the fact that the electric charge amount of the second electrode remains unchanged, the driving voltage applied to the driving electrode can be increased. Therefore, the microfluidic substrate provided by the embodiment of the present invention increases a variable capacitor, and the semiconductor layer in the variable capacitor can change the capacitance value of the variable capacitor, thereby increasing the driving voltage to meet the droplet driving requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0017] Figure 1 is a partial cross-sectional schematic diagram of a microfluidic substrate provided by the related art;

[0018] Figure 2 is a partial cross-sectional schematic diagram of a microfluidic substrate provided by the embodiment of the present invention;

[0019] Figure 3 is an equivalent circuit diagram of the driving unit provided by the embodiment of the present invention;

[0020] Figure 4 It is a top view of a conductive layer and a semiconductor layer of a variable capacitor provided by an embodiment of the present invention;

[0021] Figure 5 It is a partial cross-sectional schematic diagram of another microfluidic substrate provided by an embodiment of the present invention;

[0022] Figure 6 It is a structural schematic diagram of a microfluidic substrate provided by an embodiment of the present invention;

[0023] Figure 7 It is a partial cross-sectional schematic diagram of another microfluidic substrate provided by an embodiment of the present invention;

[0024] Figure 8 It is a cross-sectional schematic diagram of a microfluidic device provided by an embodiment of the present invention;

[0025] Figure 9 It is a flowchart of a driving method for a microfluidic device provided by an embodiment of the present invention;

[0026] Figure 10 It is a timing diagram of a driving method for a microfluidic device provided by an embodiment of the present invention. Detailed implementation manners

[0027] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0028] Figure 1 It is a partial cross-sectional schematic diagram of a microfluidic substrate provided by the related art (only one driving unit is schematically shown in the figure). The related art adopts an active driving method. As Figure 1 shown, a microfluidic substrate in the related art includes a driving transistor 10 and a driving electrode 20, and the driving transistor 10 applies a driving voltage to the driving electrode 20. Generally, the voltage capable of effectively driving the droplet to move needs to be about 50V. For some chemical solutions or biological reagents with higher viscosities, a higher voltage is required. However, according to the driving voltage of the active driving in the prior art, even high-voltage driving generally can only provide a driving voltage of about 30V. Therefore, the related art has the problem of insufficient driving voltage, which cannot meet the droplet driving requirement and affects the driving effect of the droplet.

[0029] Based on the above technical problems, the inventors propose the technical solutions of the embodiments of the present invention. Specifically, the embodiments of the present invention provide a microfluidic substrate, comprising: a substrate; a driving circuit layer located on one side of the substrate, the driving circuit layer including a plurality of driving units, each driving unit including a driving transistor and a variable capacitor; the driving transistor including a gate, an active layer, a first electrode and a second electrode, the gate receiving a scanning signal and the first electrode receiving a driving signal; the variable capacitor including a first plate, a conductive layer, a semiconductor layer and a second plate, the conductive layer and the semiconductor layer being located between the first plate and the second plate, the conductive layer and the semiconductor layer being electrically connected, the conductive layer being connected to a reference voltage, the semiconductor layer being located on the side of the first plate away from the substrate, the first plate being electrically connected to the gate; an electrode array layer located on the side of the driving transistor away from the substrate, the electrode array layer including driving electrodes corresponding one-to-one to the driving units, the driving electrodes being electrically connected to the second electrodes of the corresponding driving transistors, the second plate being a part of the driving electrode, in a direction perpendicular to the plane where the substrate is located, both the second plate and the first plate cover a first part of the semiconductor layer, the second plate and the conductive layer overlap, and the conductive layer and the first part of the semiconductor layer do not overlap.

[0030] Through the above technical solutions, the semiconductor layer in the variable capacitor cooperates with the on / off state of the driving transistor to be able to change its own conductivity, enabling the semiconductor layer to switch between a conductor and an insulator, thereby being able to change the capacitance value of the variable capacitor. Using the principle of constant charge quantity, the driving voltage applied to the driving electrode can be increased.

[0031] The above is the core idea of the present invention. Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0032] Figure 2 It is a partial cross-sectional schematic diagram of a microfluidic substrate provided by an embodiment of the present invention.

[0033] As Figure 2 shown, a microfluidic substrate provided by an embodiment of the present invention includes:

[0034] A substrate 01;

[0035] The driving circuit layer 02 is located on one side of the substrate 01. The driving circuit layer 02 includes a plurality of driving units, and each driving unit includes a driving transistor 10 and a variable capacitor 30. The driving transistor 10 includes a gate 11, an active layer 12, a first electrode 13, and a second electrode 14. The gate 11 receives a scanning signal, and the first electrode 13 receives a driving signal. The variable capacitor 30 includes a first plate 31, a conductive layer 33, a semiconductor layer 34, and a second plate 32. The conductive layer 33 and the semiconductor layer 34 are located between the first plate 31 and the second plate 32, and the conductive layer 33 and the semiconductor layer 34 are electrically connected. The conductive layer 33 is connected to a reference voltage. The semiconductor layer 34 is located on the side of the first plate 31 away from the substrate 01, and the first plate 31 is electrically connected to the gate 11.

[0036] The electrode array layer 03 is located on the side of the driving transistor 10 away from the substrate 01. The electrode array layer 03 includes driving electrodes 20 corresponding to the driving units one by one. The driving electrodes 20 are electrically connected to the second electrodes 14 of the corresponding driving transistors 10. The second plate 32 is a part of the driving electrode 20. In the direction perpendicular to the plane where the substrate 01 is located, both the second plate 32 and the first plate 31 cover a first part 341 of the semiconductor layer 34. The second plate 32 and the conductive layer 33 overlap, and the conductive layer 33 and the first part 341 of the semiconductor layer 34 do not overlap.

[0037] In the above technical solution, the substrate 01 can be a glass substrate. The driving units can be arranged in an array. Each driving unit includes a driving transistor 10 and a variable capacitor 30. The variable capacitor 30 is a storage capacitor with a variable capacitance value. After the driving transistor 10 is turned off, the capacitance value is changed to increase the driving voltage and maintain the increased driving voltage to drive the droplet to move. Among them, the driving transistor 10 can be a thin film transistor. The active layer 12 can be made of amorphous silicon material, polycrystalline silicon material, metal oxide material, etc. The first electrode 13 and the second electrode 14 form the source and drain of the thin film transistor. Exemplarily, the first electrode 13 is the source, and the second electrode 14 is the drain. The thin film transistor can be a bottom gate structure, that is Figure 2The shown gate 11 is located on the side of the active layer 12 close to the substrate 01. This thin-film transistor can also be a top-gate structure, that is, the gate 11 is located on the side of the active layer 12 away from the substrate 01. The embodiments of the present invention do not limit this. The conductive layer 33 can adopt single-layer or multi-layer conductive metal materials such as molybdenum, aluminum or copper. The semiconductor layer 34 can adopt semiconductor materials such as amorphous silicon, polycrystalline silicon or metal oxide materials. Exemplarily, the material of the semiconductor layer 34 is the same as that of the active layer 12, so that when the driving transistor 10 is turned on, the semiconductor layer 34 exhibits conductive characteristics, that is, the semiconductor layer 34 is turned on, and when the driving transistor 10 is turned off, the semiconductor layer 34 exhibits insulating characteristics, that is, the semiconductor layer 34 is turned off. Since the conductive layer 33 is connected to the reference voltage and the conductive layer 33 and the semiconductor layer 34 are electrically connected, when the semiconductor layer 34 is turned on, the conductive layer 33 and the semiconductor layer 34 can jointly form a plate of the variable capacitor 30, that is, the reference plate. At this time, since the second plate 32 overlaps with the first part 341 of the semiconductor layer 34 and the second plate 32 and the conductive layer 33 overlap, the second plate 32 forms a first capacitor C1 with the above reference plate, and the facing area of the upper and lower plates of the first capacitor is equal to the area of the overlapping region of the two plates. When the semiconductor layer 34 is turned off, the conductive layer 33 can form a plate of the variable capacitor 30, called the middle plate, and the semiconductor layer 34 becomes a dielectric layer. At this time, since the second plate 32 and the conductive layer 33 overlap, the second plate 32 forms a second capacitor C2 with the conductive layer 33, and the facing area of the upper and lower plates of the second capacitor is equal to the area of the overlapping region of the two plates. At the same time, since the second plate 32 and the first plate 31 both cover the first part 341 of the semiconductor layer 34 and the conductive layer 33 and the first part 341 of the semiconductor layer 34 do not overlap, the second plate 32 forms a third capacitor C3 with the first plate 31, and the facing area of the third capacitor is equal to the area of the first part 341 of the semiconductor layer 34. In addition, the first plate 31 is electrically connected to the gate 11 to realize synchronous control of the on-off of the driving transistor 10 and the semiconductor layer 34 by the scanning signal; at the same time, the driving electrode 20 is multiplexed as the second plate 32, so that the driving voltage on the driving electrode 20 and the voltage on the second plate 32 are kept consistent, so that after applying the driving voltage to the driving electrode 20 through the driving transistor 10, the voltage on the second plate 32 is increased by changing the capacitance value of the variable capacitor 30, thereby further increasing the driving voltage. It should be noted that the two shown conductive layers 33 are actually an integral structure or electrically connected; in addition, Figure 2 It is only a schematic structural diagram of a microfluidic substrate. The sizes and shapes of the conductive layer 33 and the semiconductor layer 34, the positional relationship between the conductive layer 33 and the semiconductor layer 34, and the overlapping situations of the first plate 31 and the second plate 32 with the conductive layer 33 and the semiconductor layer 34 respectively depend on the actual situation.

[0038] Specifically, the gate 11 of the driving transistor 10 is electrically connected to the scanning signal line, and the first electrode 13 is connected to the data signal line. When the driving unit needs to provide a driving voltage for driving the droplet to move, first, a first scanning signal is simultaneously provided to the gate 11 of the driving transistor 10 and the first plate 31 of the variable capacitor 30 via the scanning signal line, so that the semiconductor layers of the driving transistor 10 and the variable capacitor 30 are simultaneously turned on. At this time, the variable capacitor 30 is composed of the above-mentioned first capacitor C1; at the same time, a driving signal is provided to the first electrode 13 of the driving transistor 10 via the data signal line. Since the driving electrode 20 is electrically connected to the second electrode 14 of the driving transistor 10, therefore, the driving voltage V1 corresponding to the driving signal is applied to the driving electrode 20 via the driving transistor 10, and a part of the driving electrode 20 serves as the second plate 32 of the variable capacitor 30. Thus, the above process is essentially a charging process of the first capacitor C1. After that, a second scanning signal is provided to the gate 11 of the driving transistor 10 and the first plate 31 of the variable capacitor 30, so that the semiconductor layers of the driving transistor 10 and the variable capacitor 30 are simultaneously turned off. At this time, the variable capacitor 30 is composed of the above-mentioned second capacitor C2 and the third capacitor C3 connected in series. When no voltage is applied to the variable capacitor 30, the charge amount on the second plate 32 remains unchanged at the moment when the capacitance value of the variable capacitor 30 changes. Therefore, the following equation can be obtained:

[0039] C1(V1 - Vcom) = C2(V2 - Vcom) + C3(V2 - VGL);

[0040] Furthermore, it can be obtained that:

[0041] V2 = C1V1 / (C2 + C3) + (C2 - C1)Vcom / (C2 + C3) + C3VGL / (C2 + C3); (1)

[0042] Wherein, V2 is the voltage on the second plate 32 after the variable capacitor 30 changes from the first capacitor C1 to the second capacitor C2 and the third capacitor C3, that is, the driving voltage on the driving electrode 20 at this time; Vcom is the reference voltage; VGL is the voltage on the first plate 31 when the semiconductor layer 34 is turned off, which is provided by the second scanning signal.

[0043] Combined with Figure 2 and Figure 3 , since the conductive layer 33 is connected to the reference voltage Vcom, the capacitance formed by the second plate 32 and the conductive layer 33, that is, the second capacitor C2, is a fixed capacitor. When the semiconductor layer 34 is turned on, a capacitor Ct1 is formed between the second plate 32 and the semiconductor layer 34, and the effective area of the capacitor Ct1 is equal to the area of the first part 341 of the semiconductor layer 34. When the semiconductor layer 34 is turned off, a capacitor Ct2 is formed between the second plate 32 and the first plate 31, that is, the third capacitor C3. Therefore, referring to Figure 3, the capacitor Ct is Ct1 when the semiconductor layer 34 is turned on and Ct2 when the semiconductor layer 34 is turned off, so that the partial capacitance Ct is adjustable, thereby forming a variable capacitance as a whole. Also, since the distance between the upper and lower plates of Ct1 is smaller than the distance between the upper and lower plates of C3, and the facing area of the upper and lower plates of the two is the same, so Ct1 > C3; and C1 = C2 + Ct1, therefore C1 > C2 + C3, and thus C1 / (C2 + C3) > 1. Thus, based on the above formula (1), when Vcom and VGL are set to about 0V, V2 > V1, thereby achieving the increase of V1, that is, the driving voltage applied by the active driving circuit (this embodiment includes the driving transistor 10) on the driving electrode 20 is increased. In addition, it can be seen from formula (1) that by changing C1 / (C2 + C3), the magnitude of the increased driving voltage can be changed, and the magnitude of C1 / (C2 + C3) is related to the first facing area between the conductive layer of the variable capacitance and the second electrode, and the second facing area between the semiconductor layer of the variable capacitance and the second electrode. And the smaller the ratio of the first facing area to the second facing area, the larger C1 / (C2 + C3) is (it can be obtained from the previous text that C1 = C2 + Ct1. Assuming that the ratio of the first facing area to the second facing area decreases, both the numerator and denominator have C2, so only the increase amounts of Ct1 and C3 need to be considered; and the increased areas of Ct1 and C3 are both equal to the decreased area of C2, and the plate distance of Ct1 is smaller than that of C3, so the increase amount of Ct1 is greater than that of C3, and thus C1 / (C2 + C3) increases). Therefore, according to the actual requirements of driving the droplet to move, the corresponding ratio of the first facing area and the second facing area can be set, and the design is relatively flexible. In particular, when the driving electrode completely covers the conductive layer and the semiconductor layer of the variable capacitance, only the ratio of the area occupied by the first part of the conductive layer and the semiconductor layer needs to be set.

[0044] The microfluidic substrate provided in this embodiment increases the variable capacitance. The first electrode of the variable capacitance is electrically connected to the gate of the driving transistor, a part of the driving electrode is used as the second electrode of the variable capacitance, and a conductive layer and a semiconductor layer are provided between the first electrode and the second electrode and are electrically connected. In this way, when a first scanning signal (i.e., gate voltage) is provided to the gate of the driving transistor, the semiconductor layer is turned on to form a conductive channel. At this time, the semiconductor layer is equivalent to a conductor, and the conductive layer and the semiconductor layer together form a reference electrode. At the same time, the driving transistor is turned on. By providing a driving signal to the first electrode of the driving transistor, a driving voltage can be applied to the driving electrode through the second electrode. Thus, a first capacitance is formed between the reference electrode and the second plate. After that, a second scanning signal is provided to the gate of the driving transistor, and the semiconductor layer is turned off to form an insulating channel. At this time, the semiconductor layer is equivalent to an insulating medium and constitutes a dielectric layer between the first plate and the second plate. At this time, a second capacitance is formed between the second plate and the conductive layer, and a third capacitance is formed between the second plate and the first plate. Since the semiconductor layer is turned off, the facing area of the upper and lower plates of the second capacitance is significantly smaller than that of the upper and lower plates of the first capacitance, and the distance between the upper and lower plates of the third capacitance is greater than that of the upper and lower plates of the first capacitance. Therefore, the first capacitance is greater than the sum of the second capacitance and the third capacitance. Based on the constant charge amount of the second electrode, the driving voltage applied to the driving electrode can be increased. Therefore, the microfluidic substrate provided in this embodiment increases the variable capacitance, and the semiconductor layer in the variable capacitance can change the capacitance value of the variable capacitance, thereby increasing the driving voltage to meet the droplet driving requirements.

[0045] In an alternative embodiment, in combination with Figure 2 and Figure 4 , the semiconductor layer 34 further includes a second part 342 adjacent to and surrounding the first part 341. The conductive layer 33 is provided with an opening, and in a direction perpendicular to the plane of the substrate 01, the opening overlaps with the first part 341. The conductive layer 33 is in electrical contact with the second part 342, or the conductive layer 33 is electrically connected to the second part 342 through a via. In this way, the first part 341 of the semiconductor layer 34 is defined by the opening of the conductive layer 33. By simply designing the size of the opening area of the conductive layer 33, the adjustment of the ratio of the above-mentioned first facing area to the second facing area can be achieved, making the design of the variable capacitance simpler. In this embodiment, the conductive layer 33 can be directly lapped on the second part 342 of the variable capacitance 30 to achieve electrical contact between the conductive layer 33 and the second part 342. It is also possible to design the conductive layer 33 and the semiconductor layer 34 to be on different layers, and the conductive layer 33 is electrically connected to the second part 342 through a via.

[0046] Generally, a microfluidic device can be designed with multiple channels. Different channels can be used to detect different solutions, and the viscosities of different solutions are generally different. Therefore, the driving voltages required for different channels will also be different. For this, in an alternative embodiment, the microfluidic substrate includes multiple channel regions. In the same channel region, the ratio of the first facing area between the conductive layer of each variable capacitor and the second electrode to the second facing area between the semiconductor layer of the variable capacitor and the second electrode is the same; in different channel regions, the ratio of the first facing area to the second facing area is different. In this embodiment, the channel region corresponds to the region where the channels of the microfluidic device are located. The relevant introduction to the setting of the ratio of the first facing area to the second facing area can be referred to in the previous text and will not be elaborated here. In this way, the driving voltages of each channel region can be set specifically, so that the driving voltages of each channel of the microfluidic device can all meet the driving requirements of their respective droplets.

[0047] In an alternative embodiment, referring to Figure 5 and Figure 6 , the first electrode plate 31 and the gate 11 are located on the same layer and are an integrally formed structure. In this way, the first electrode plate 31 and the gate 11 can be fabricated in the same process, and the fabrication process of the electrical connection structure between the first electrode plate 31 and the gate 11 is omitted, saving the process flow.

[0048] In an alternative embodiment, referring to Figure 5 and Figure 6 , the semiconductor layer 34 and the active layer 12 are located on the same layer and have the same preparation material. In this way, the semiconductor layer 34 and the active layer 12 can be fabricated in the same process, saving the process flow.

[0049] In an alternative embodiment, referring to Figure 5 and Figure 6 , the conductive layer 33, the first electrode 13 and the second electrode 14 are located on the same layer and have the same preparation material. In this way, the conductive layer 33, the first electrode 13 and the second electrode 14 can be fabricated in the same process, saving the process flow.

[0050] In an alternative embodiment, as Figure 7 shown, the microfluidic substrate further includes an insulating dielectric layer 04 located on the side of the electrode array layer 03 away from the substrate 01 and a first hydrophobic layer 05 located on the side of the insulating dielectric layer 04 away from the substrate 01. Among them, the insulating dielectric layer 04 can adopt the SiNx3 material, which can prevent the driving electrode from contacting the droplet and avoid the influence on the movement of the droplet caused by affecting the electric field formed between the driving electrodes. The first hydrophobic layer 05 can be a Teflon film layer to reduce the adhesion between the droplet and the microfluidic substrate, thereby reducing the driving voltage required to drive the droplet and lowering the power consumption of the microfluidic substrate.

[0051] Based on the above embodiments, an embodiment of the present invention further provides a microfluidic device, including the microfluidic substrate provided in any embodiment of the present invention, and a counter substrate disposed opposite to the microfluidic substrate, and a channel for droplet movement is formed between the counter substrate and the microfluidic substrate.

[0052] In an alternative embodiment, as Figure 8 shown, the microfluidic device includes a microfluidic substrate 100 and a counter substrate 200, and a channel 300 for droplet movement is formed between the counter substrate 200 and the microfluidic substrate 100. Among them, the counter substrate 200 is provided with an inlet for dripping the droplet into the channel, and the counter substrate 200 may include a second hydrophobic layer 06, a common electrode layer 07 and a cover plate 08 stacked in sequence, and the second hydrophobic layer 06 is located on the side of the cover plate 08 close to the microfluidic substrate 100. The common electrode layer 07 may be made of indium tin oxide (ITO) material, and the cover plate 08 may be a glass cover plate.

[0053] In addition, an embodiment of the present invention further provides a driving method for a microfluidic device, which is used to drive the microfluidic device provided in the embodiment of the present invention. As Figure 9 shown, a driving method for a microfluidic device provided in this embodiment includes the following steps:

[0054] S110. In the first stage, a first scan signal and a driving signal are provided to the driving transistor of the target driving unit to turn on the driving transistor, so that the conductive layer and the semiconductor layer jointly form a first capacitor with the second electrode plate.

[0055] S120. In the second stage, a second scan signal is provided to the driving transistor of the target driving unit to turn off the driving transistor, so that the second electrode plate forms a second capacitor with the conductive layer, and the second electrode plate forms a third capacitor with the first electrode plate.

[0056] Among them, the target driving unit is the driving unit to which the droplet will move, the first scan signal provides a turn-on voltage for the driving transistor, and the second scan signal provides a turn-off voltage for the driving transistor. Specifically, refer to Figure 10(In the figure, Gate is the scan signal, including the first scan signal and the second scan signal, Data is the drive signal, and Drive is the drive voltage, including drive voltage V1 and drive voltage V2). In the first stage T1, the first scan signal is provided to the gate of the driving transistor and the first electrode plate of the variable capacitor via the scan signal line simultaneously, so that the semiconductor layers of the driving transistor and the variable capacitor are turned on simultaneously. At this time, the variable capacitor is composed of the first capacitor. At the same time, the drive signal is provided to the first electrode of the driving transistor via the data signal line. Since the drive electrode is electrically connected to the second electrode of the driving transistor, the drive voltage V1 corresponding to the drive signal is applied to the drive electrode via the driving transistor. And a part of the drive electrode serves as the second electrode plate of the variable capacitor. Therefore, the above process is essentially a charging process of the first capacitor C1. After that, in the second stage T2, the second scan signal is provided to the gate of the driving transistor and the first electrode plate of the variable capacitor again, so that the semiconductor layers of the driving transistor and the variable capacitor are turned off simultaneously. At this time, the variable capacitor is composed of the second capacitor and the third capacitor connected in series. According to the relevant introduction above, the drive voltage can be increased from V1 to V2 at this time. It should be noted that in the second stage T2, to control the semiconductor layers of the driving transistor and the variable capacitor to be turned off simultaneously, only the second scan signal needs to be provided, and the presence or absence of the drive signal has no effect on the turn-off of the semiconductor layers of the driving transistor and the variable capacitor. Therefore, optionally, in the second stage T2, the drive signal provided to the driving transistor of the target driving unit is cancelled to reduce power consumption.

[0057] In addition, continue to refer to Figure 10 , after the second stage, it further includes: in the third stage T3, the first scan signal is provided to the driving transistor of the target driving unit.

[0058] Specifically, under the drive of the drive voltage V2, the droplet moves to the target driving unit. This target driving unit is used as the current target driving unit. To make the droplet continue to move to the next target driving unit, it is necessary to reduce the drive voltage of the current target driving unit and increase the drive voltage of the next target driving unit to V2. Therefore, the first scan signal is provided to the driving transistor of the target driving unit, so that the driving transistor is turned on again, and the voltage on the drive electrode is forced to be pulled down to the drive voltage corresponding to the drive signal or 0. For this purpose, in the third stage T3, the drive signal can continue to be provided to the driving transistor of the target driving unit, or the drive signal provided to the driving transistor of the target driving unit can be cancelled. Optionally, refer to Figure 10 , in the third stage T3, the drive signal provided to the driving transistor of the target driving unit is cancelled to reduce power consumption.

[0059] It should be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0060] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments described herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A microfluidic substrate, characterized in that, Comprising: A substrate; A driving circuit layer located on one side of the substrate, the driving circuit layer comprising a plurality of driving units, each driving unit comprising a driving transistor and a variable capacitor; the driving transistor comprises a gate, an active layer, a first electrode and a second electrode, the gate receives a scanning signal, and the first electrode receives a driving signal; The variable capacitor comprises a first plate, a conductive layer, a semiconductor layer and a second plate, the conductive layer and the semiconductor layer are located between the first plate and the second plate, the conductive layer and the semiconductor layer are electrically connected, the conductive layer is connected to a reference voltage, the semiconductor layer is located on the side of the first plate away from the substrate, and the first plate is electrically connected to the gate; An electrode array layer located on the side of the driving transistor away from the substrate, the electrode array layer comprising driving electrodes corresponding one by one to the driving units, the driving electrodes being electrically connected to the second electrodes of the corresponding driving transistors, the second plate being a part of the driving electrodes, in a direction perpendicular to the plane of the substrate, both the second plate and the first plate cover a first part of the semiconductor layer, the second plate and the conductive layer overlap, and the conductive layer and the first part of the semiconductor layer do not overlap.

2. The microfluidic substrate according to claim 1, characterized in that, The semiconductor layer further comprises a second part adjacent to and surrounding the first part, the conductive layer is provided with an opening, in a direction perpendicular to the plane of the substrate, the opening overlaps with the first part; the conductive layer is in electrical contact with the second part, or the conductive layer is electrically connected to the second part through a via.

3. The microfluidic substrate according to claim 1, wherein Comprising a plurality of channel regions, in the same channel region, the ratio of the first facing area of the conductive layer of each variable capacitor to the second electrode to the second facing area of the semiconductor layer of the variable capacitor to the second electrode is the same; in different channel regions, the ratio of the first facing area to the second facing area is different.

4. The microfluidic substrate according to claim 1, characterized in that The first plate and the gate are located on the same layer and are of an integrally formed structure.

5. The microfluidic substrate according to claim 1, wherein The semiconductor layer and the active layer are located on the same layer and have the same preparation material.

6. The microfluidic substrate according to claim 1, wherein The conductive layer, the first electrode and the second electrode are located on the same layer and have the same preparation material.

7. The microfluidic substrate according to claim 1, characterized in that, Further comprising an insulating dielectric layer located on the side of the electrode array layer away from the substrate and a first hydrophobic layer located on the side of the insulating dielectric layer away from the substrate.

8. A microfluidic device, characterized in that, Comprising a microfluidic substrate as described in any one of claims 1 to 7, and a counter substrate disposed opposite to the microfluidic substrate, a channel for droplet movement being formed between the counter substrate and the microfluidic substrate.

9. A driving method for the microfluidic device according to claim 8, characterized in that, Comprising: In a first stage, a first scanning signal and a driving signal are provided to the driving transistor of a target driving unit to turn on the driving transistor, and the conductive layer and the semiconductor layer together form a first capacitor with the second plate; In the second stage, a second scan signal is provided to the driving transistor of the target driving unit to turn off the driving transistor, a second capacitor is formed between the second electrode plate and the conductive layer, and a third capacitor is formed between the second electrode plate and the first electrode plate.

10. The driving method according to claim 9, wherein After the second stage, it further includes: In the third stage, the first scan signal is provided to the driving transistor of the target driving unit.

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