Electrowetting chip for controlling directional movement of droplets

Abstract

The present invention discloses an electrowetting chip for controlling the directional movement of droplets. The electrowetting chip comprises a hydrophobic layer (2), a dielectric layer (3), an electrode layer (4) and a substrate (5); the hydrophobic layer, dielectric layer, electrode layer and substrate are stacked together in sequence; a driving electrode (41) and two grounding electrodes (42) are provided in the electrode layer, the two grounding electrodes are located on both sides of the driving electrode, one end of the driving electrode serves as a starting end, and the other end of the driving electrode serves as a terminating end, and the radial width of the driving electrode gradually increases from the starting end to the terminating end. In the electrowetting chip of the present invention, a driving electrode and two grounding electrodes are provided in the electrode layer to achieve long-distance directional transfer and transportation of droplets (1). The structure is very simple and easy to implement. No complex control unit and a large number of wiring are required, thereby improving the integration and portability of the device and greatly improving the chip area utilization rate.

Description

Technical Field

[0001] The present invention relates to a microfluid control device, in particular to an electrowetting chip for controlling the directional movement of liquid droplets. Background Art

[0002] The long-distance, directional transport of droplets has important applications in biomedicine, chemical analysis, environmental monitoring, and other fields. Existing technologies have employed 3D structures inspired by the legs of fruit flies and other insects to achieve long-distance, directional transport of droplets. However, these structures face challenges such as difficulty collecting droplets, sample loss, slow droplet movement, and complex manufacturing, significantly limiting their practical applications.

[0003] At present, electrowetting technology is a common digital microfluidic technology that changes the wettability of the material surface through electric potential, thereby realizing the movement, merging and splitting of droplets.

[0004] The current problem is that existing electrowetting technology relies on pixelated electrodes to achieve long-distance movement of droplets, which requires a large number of electrode arrays, cumbersome processes, and complex wiring, limiting its application. Summary of the Invention

[0005] The object of the present invention is to provide an electrowetting chip for controlling the directional movement of droplets. The electrowetting chip can realize the long-distance directional transfer and transportation of droplets, and has a very simple structure and is very easy to implement.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] An electrowetting chip for controlling the directional movement of droplets, the electrowetting chip comprising a hydrophobic layer, a dielectric layer, an electrode layer, and a substrate; the hydrophobic layer, dielectric layer, electrode layer, and substrate are stacked together in sequence; a driving electrode and two grounding electrodes are provided in the electrode layer, the two grounding electrodes are located on either side of the driving electrode, one end of the driving electrode serves as a starting end, and the other end of the driving electrode serves as a terminating end, and the radial width of the driving electrode gradually increases from the starting end to the terminating end.

[0008] Furthermore, the electrowetting chip has a starting end and an ending end; the starting end of the driving electrode is located at the starting end of the electrowetting chip, and the ending end of the driving electrode is located at the ending end of the electrowetting chip.

[0009] Furthermore, the driving electrodes are in a straight line type, a spiral line type or an S-line type.

[0010] Furthermore, the hydrophobic layer is made of Teflon.

[0011] Furthermore, on the electrode layer, several outer extensions are provided on both sides of the driving electrode.

[0012] Furthermore, the plurality of outer extension portions are staggeredly arranged on both sides of the driving electrode.

[0013] Compared with the prior art, the electrowetting chip of the present invention has the following advantages:

[0014] In the electrowetting chip of the present invention, a driving electrode and two ground electrodes are provided in the electrode layer to realize long-distance directional transfer and transportation of droplets. The structure is very simple and easy to implement. There is no need for a complex control unit and a large number of wiring, thereby improving the integration and portability of the device and greatly improving the chip area utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of the electrowetting chip for controlling the directional movement of droplets according to the present invention, which is a side view;

[0016] Figure 2 Schematic diagram of the electrode layer in the electrowetting chip of the present invention, which is a top view;

[0017] Figure 3 Schematic diagram of using the electrowetting chip of the present invention to achieve directional movement of droplets. DETAILED DESCRIPTION

[0018] The present invention will be further described below with specific embodiments:

[0019] This embodiment provides an electrowetting chip for controlling the directional movement of droplets. The electrowetting chip is used to achieve "controlling the long-distance directional movement of droplets on a droplet operation surface."

[0020] The electrowetting chip of this embodiment has a surface facing upwards referred to as a droplet manipulation surface.

[0021] More specifically,

[0022] See also Figure 1 The electrowetting chip is composed of four layers: a hydrophobic layer 2, a dielectric layer 3, an electrode layer 4, and a substrate 5. These four layers are stacked together from top to bottom to form the electrowetting chip. The upper surface of the topmost hydrophobic layer 2 serves as the droplet manipulation surface for the entire electrowetting chip.

[0023] For the convenience of description, one end of the entire electrowetting chip in the longitudinal direction is called the starting end ( Figure 1 or Figure 2 The other end in the length direction is called the terminal end ( Figure 1 or Figure 2 the right end of the ).

[0024] For the convenience of description, two horizontal directions are defined for the electrowetting chip, namely X direction and Y direction (eg Figure 2 ). The X direction corresponds to the length direction of the electrowetting chip, specifically, the direction from the starting end to the ending end; the Y direction corresponds to the width direction of the electrowetting chip; the X and Y directions are perpendicular to each other on the horizontal plane.

[0025] The hydrophobic layer 2 is made of a hydrophobic material, and in this embodiment, Teflon material is used. The hydrophobic layer 2 made of this material has the property of repelling water, that is, the contact angle is large, greater than 90 degrees, which makes it difficult for water to spread on its surface and easily form droplets.

[0026] The dielectric layer 3 is made of insulating material;

[0027] The substrate 5 is made of quartz glass. In other embodiments, silicon wafers or various plastics may also be used.

[0028] The main innovation of the electrowetting chip of this embodiment lies in the structure of the electrode layer 4 .

[0029] Specifically, the electrode layer 4 is mainly composed of three electrodes combined together, wherein one electrode serves as a driving electrode 41 and the other two electrodes serve as grounding electrodes 42 .

[0030] The driving electrode 41 is in a long strip shape as a whole. For the convenience of description, one end of the driving electrode 41 is referred to as a starting end, and the other end of the driving electrode 41 is referred to as a terminating end.

[0031] The driving electrode 41 is disposed at the longitudinal center axis of the entire electrode layer 4 (i.e., the X-axis). The starting end of the driving electrode 41 is located at the starting end of the entire electrowetting chip, and the terminating end of the driving electrode 41 is located at the ending end of the entire electrowetting chip. In other words, the driving electrode 41 penetrates the entire electrode layer 4 in the X-direction.

[0032] Another important feature of the drive electrode 41 is that its radial width gradually increases from its starting end to its ending end. Specifically, it increases linearly, or in other words, the drive electrode 41 gradually diverges from its starting end to its ending end. It is precisely because of this configuration that the electrowetting chip of this embodiment can achieve the specific "directional droplet movement" function (described later in detail).

[0033] For the convenience of description, the area of ​​the hydrophobic layer 2 (ie, the droplet operation surface) perpendicular to the driving electrode 41 is referred to as an “effective driving area”.

[0034] The two ground electrodes 42 are disposed on both sides of the driving electrode 41 . The driving electrode 41 and the ground electrode 42 are adjacent to each other without contacting each other, thereby forming an electric field region therebetween.

[0035] The specific working principle of the electrowetting chip of this embodiment is as follows:

[0036] A droplet 1 (the droplet is the object of the experiment) is dropped on the droplet operation surface of the electrowetting chip. The droplet 1 falls on the position corresponding to the driving electrode 41 on the droplet operation surface (usually falls on the starting end of the driving electrode 41). A bias voltage is applied between the driving electrode 41 and the ground electrode 42. In this way, a planar electric field will be formed on the driving electrode 41 and the ground electrode 42.

[0037] See also Figure 3 , “edge of droplet 1” and effective driving area ( Figure 3 There are two intersection lines in the gray area indicated by the arrow C, one of which ( Figure 3 Indicated by arrow A) compared to the other intersecting line ( Figure 3 Indicated by the arrow B in the middle) is closer to the starting end of the driving electrode 41; for the convenience of description, the intersection line relatively close to the starting end of the driving electrode 41 is called a near-intersection line ( Figure 3 The intersection line relatively far from the starting end of the driving electrode 41 is called the far intersection line ( Figure 3 (indicated by arrow B in the figure).

[0038] The planar electric field can change the wettability of the effective driving area on the surface of the hydrophobic layer 2 (droplet operation surface). According to the Lippman-Young equation, the contact angle in the effective driving area on the surface of the hydrophobic layer 2 (droplet operation surface) is smaller than that in other areas.

[0039] In particular, the near intersection line of droplet 1 ( Figure 3 The arrow A in the middle) is always larger than the far intersection line ( Figure 3 In this way, the wetting force on the droplet 1 in the X direction is always greater than the wetting force on the droplet 1 in the negative direction, thereby forming a driving force for "driving the droplet 1 to move along the X direction". Driven by this driving force, the droplet 1 will move in a directional manner toward the terminal end of the driving electrode 41 within the effective driving area until it reaches the position corresponding to the terminal end of the driving electrode 41.

[0040] It should be noted that in this embodiment, the longitudinal center axis of the driving electrode 41 is a straight line, while in other embodiments, the longitudinal center axis of the driving electrode 41 can also be various other line types, such as a spiral line type or an S line type, to meet various needs.

[0041] For the convenience of description, the "driving electrode 41 whose central axis in the longitudinal direction is straight" is called a "straight-type driving electrode", the "driving electrode 41 whose central axis in the longitudinal direction is spiral-shaped" is called a "spiral-type driving electrode", and the "driving electrode 41 whose central axis in the longitudinal direction is S-shaped" is called an "S-type driving electrode".

[0042] The main advantages of the electrowetting chip of this embodiment are:

[0043] In the electrowetting chip of this embodiment, only one driving electrode 41 and two ground electrodes 42 are provided in the electrode layer 4 to realize the long-distance directional transfer and transportation of the droplets 1. The structure is very simple and easy to implement. There is no need for a complex control unit and a large number of wiring, thereby improving the integration and portability of the device and greatly improving the chip area utilization.

[0044] In addition, the electrowetting chip of this embodiment has the following advantages:

[0045] 1) Bionic electrowetting electrodes: When a bias voltage is applied, the biomimetic electrowetting electrodes change the wettability of the electrodes, providing a continuous unbalanced wetting force and enabling long-distance directional movement of droplets.

[0046] 2) Reversible wettability: The wettability of the chip surface is reversible. When there is no electric field, the surface returns to hydrophobicity and the droplet 1 stops moving. This overcomes the limitations of difficult sample collection and uninterruptible operation in biomimetic structures.

[0047] 3) No control unit required: By utilizing the structure of bionic electrodes, there is no need for a complex control system, which improves the integration and portability of the device, breaks through the limitations of a large number of wiring, and greatly improves the area utilization on the chip.

[0048] In addition, in order to achieve the effect of bionic insect legs, several external extensions 43 are provided on both sides of the driving electrode 41 on the electrode layer 4. These external extensions 43 are staggered on both sides of the driving electrode 41. In this way, the droplets 1 on the electrowetting chip can more easily contact the driving electrode 41.

[0049] The above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electrowetting chip for controlling the directional movement of droplets, characterized by: The electrowetting chip comprises a hydrophobic layer (2), a dielectric layer (3), an electrode layer (4), and a substrate (5); the hydrophobic layer (2), the dielectric layer (3), the electrode layer (4), and the substrate (5) are stacked together in sequence; A driving electrode (41) and two grounding electrodes (42) are provided in the electrode layer (4), the two grounding electrodes (42) are located on both sides of the driving electrode (41), one end of the driving electrode (41) serves as a starting end, and the other end of the driving electrode (41) serves as a terminating end, and the radial width of the driving electrode (41) gradually increases from the starting end to the terminating end.

2. The electrowetting chip for controlling directional movement of droplets according to claim 1, characterized in that: The electrowetting chip has a starting end and an ending end; the starting end of the driving electrode (41) is located at the starting end of the electrowetting chip, and the ending end of the driving electrode (41) is located at the ending end of the electrowetting chip.

3. The electrowetting chip for controlling directional movement of droplets according to claim 1, characterized in that: The driving electrodes (41) are of a straight line type, a spiral line type or an S line type.

4. The electrowetting chip for controlling directional movement of droplets according to claim 1, characterized in that: The hydrophobic layer (2) is made of Teflon material.

5. The electrowetting chip for controlling directional movement of droplets according to claim 1, characterized in that: On the electrode layer (4), a plurality of outer extension portions (43) are provided on both sides of the driving electrode (41).

6. The electrowetting chip for controlling directional movement of droplets according to claim 5, characterized in that: The plurality of outer extensions (43) are arranged in a staggered manner on both sides of the driving electrode (41).

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