A method for generating liquid droplets on a dual-plane light-controlled electrowetting device

Abstract

The application relates to a kind of double-plane light-controlled electrowetting device liquid drop generation methods, method includes the following steps: obtaining double-plane light-controlled electrowetting device, bias voltage is applied on the electrode of device, transverse electric field is generated at this time, then the profile and position of liquid drop are captured, according to profile and position, two parallel dark stripes are projected on the liquid drop using projector, the rest part is illuminated, so that liquid drop is split, the dark stripes do not coincide and penetrate liquid drop, the direction of dark stripe is perpendicular to the direction of electric field of lower plate of device, the direction of the transverse electric field is X axis, then;The double-plane light-controlled electrowetting device includes upper plate and lower plate, two ends on the lower plate are provided with electrode, the electrode includes first electrode and second electrode, gage is arranged between the upper plate and the lower plate.Compared with prior art, the application has the advantages of realizing uniform splitting of liquid drop and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light-controlled electrowetting technology, in particular to a method for generating droplets on a double-plane light-controlled electrowetting device. BACKGROUND

[0002] Chip laboratories have a wide application prospect in the fields of biological medicine, chemical detection, etc., and therefore have been widely discussed by researchers. Electrowetting on dielectric (EWOD) technology is the most common discrete flow digital microfluidic technology in chip laboratories, because EWOD technology has the advantages of non-intervention, high throughput, high operation precision, etc. At present, EWOD technology successfully realizes the movement, merging and splitting of droplets by means of pixelated electrodes, and is successfully applied. However, in the face of high-throughput and small-volume droplet application scenarios, EWOD faces the problem of wiring. Opto-electrowetting (OEW) technology is expected to solve this problem. This technology uses light guide materials to realize a reconfigurable virtual electrode with light, and the virtual electrode can realize two-dimensional movement of droplets on a single-plane OEW. However, it is challenging to realize controllable splitting of droplets on a single plane to produce droplets, which makes it difficult for OEW to quickly generate droplets, which greatly limits the practical application of OEW. SUMMARY

[0003] The purpose of the present application is to provide a method for generating droplets on a double-plane light-controlled electrowetting device to realize uniform and controllable splitting of droplets.

[0004] The purpose of the present application can be achieved by the following technical solutions:

[0005] A method for generating droplets on a double-plane light-controlled electrowetting device, the method comprising the following steps:

[0006] A double-plane light-controlled electrowetting device is obtained, a bias voltage is applied to the electrodes of the device, a transverse electric field is generated at this time, then the profile and position of the droplet are captured, two parallel dark stripes are projected above the droplet using a projector according to the profile and position, the rest is illuminated, the droplet is split, the dark stripes do not coincide and penetrate the droplet, the direction of the dark stripes is perpendicular to the direction of the electric field of the lower plate of the device, and the direction of the transverse electric field is the X-axis.

[0007] The double-plane light-controlled electrowetting device comprises an upper plate and a lower plate, two ends of the lower plate are provided with electrodes, the electrodes comprise a first electrode and a second electrode, and a plug gauge is arranged between the upper plate and the lower plate.

[0008] Furthermore, the projecting of two parallel dark stripes above the droplet using a projector according to the contour and position is specifically as follows: the width of the dark stripes is controlled to be between 1 / 2 and 1.5 times the radius of the droplet, the width of the two dark stripes is controlled to be the same, the width of the gap between the two dark stripes is controlled to be between 1 / 50 and 1 times the radius of the droplet, the midline of the gap between the two dark stripes coincides with the midline of the droplet in the Y-axis direction, and the Y-axis is perpendicular to the X-axis.

[0009] Furthermore, the upper electrode plate includes a first hydrophobic layer and a first glass substrate.

[0010] Furthermore, the lower electrode plate includes a second glass substrate, a second hydrophobic layer, a photoconductive layer and a dielectric layer.

[0011] Furthermore, the second glass substrate, the photoconductive layer, the dielectric layer and the second hydrophobic layer are arranged in sequence from bottom to top, and the droplet is located on the second hydrophobic layer.

[0012] Furthermore, a first hydrophobic layer and a first glass substrate are sequentially arranged on the second hydrophobic layer.

[0013] Furthermore, a first electrode and a second electrode are etched on the photoconductive layer.

[0014] Furthermore, the plug gauge includes a first plug gauge and a second plug gauge.

[0015] Furthermore, after projecting two parallel dark stripes, the potential gradient on the lower plate changes.

[0016] Furthermore, the droplets are droplets of deionized water.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention breaks through the uncontrollable limitations of existing single-plane OEW devices (only the lower plate) in droplet splitting by constructing a dual-plane OEW device between the upper and lower plates. The dual-plane structure can increase the droplet wetting area, increase the wetting force, and provide more stable and controllable droplet splitting conditions. At the same time, the present invention sets parallel dark stripes as optical virtual electrodes. These optical virtual electrodes are projected onto the dual-plane OEW device by a projector, which can achieve unlimited reconstruction, thereby achieving repeated droplet splitting. The two parallel dark stripes remain non-overlapping, the stripes run through the droplets, and the direction of the stripes is perpendicular to the electric field direction on the lower plate. The use of optical virtual electrodes instead of physical electrodes breaks through the limitations of the number, size and position of droplet operations in the prior art. The design of the parallel double dark stripes can provide two wetting forces of equal size and opposite direction. Under the combined action of the above two designs, uniform droplet splitting can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A schematic diagram of the structure of the device of the present application;

[0020] Figure 2 An upper plate structure;

[0021] Figure 3 A lower plate structure;

[0022] In the figure, dark stripes 1, upper plate 2, plug gauge 3, droplet 4, lower plate 5, electrode 6, bias power supply 7, first hydrophobic layer 201, first glass substrate 202, first electrode 601, second electrode 602, second glass substrate 501, second hydrophobic layer 504, photoconductive layer 502, dielectric layer 503, first plug gauge 301, second plug gauge 302. DETAILED DESCRIPTION

[0023] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation methods and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0024] The present application proposes a method for generating droplets on a double-plane light-controlled electrowetting device, and a structural diagram of the device is shown in Figure 1 The upper plate structure is shown in Figure 2 The lower plate structure is shown in Figure 3 The method comprises the following steps:

[0025] A double-plane light-controlled electrowetting device is obtained, a bias voltage is applied to the electrode 6 of the device, a transverse electric field is generated at this time, then the profile and position of the droplet are captured, two parallel dark stripes 1 are projected above the droplet using a projector according to the profile and position, the rest is illuminated, so that the droplet 4 is split, the dark stripes 1 do not coincide and penetrate the droplet 4, the direction of the dark stripes 1 is perpendicular to the electric field direction of the lower plate 5 of the device, and the direction of the transverse electric field is set as the X axis, then;

[0026] The double-plane light-controlled electrowetting device comprises an upper plate 2 and a lower plate 5, two ends of the lower plate 5 are provided with electrodes 6, the electrodes 6 comprise first electrodes 601 and second electrodes 602, and a plug gauge 3 is arranged between the upper plate 2 and the lower plate 5.

[0027] The device comprises an upper plate 2 and a lower plate 5, and a plug gauge 3 with a certain thickness is arranged between the upper plate and the lower plate to ensure the height.

[0028] A bias voltage is applied to the electrodes 601 and 602 at both ends of the lower plate 5 of the double-plane light-controlled electrowetting chip.

[0029] Two parallel dark stripes 1 are projected on the double-plane light-controlled electrowetting chip, and the potential gradient on the lower plate 5 of the chip is changed.

[0030] The direction of the two parallel stripes should be perpendicular to the direction of the electric field, that is, coincide with the Y-axis direction.

[0031] The width of the two parallel dark stripes should be between 1 / 2 and 1.5 times the droplet radius, and they should be the same width. The width of the gap between the two dark stripes should be between 1 / 50 and 1 times the droplet radius. The midline of the gap between the two dark stripes should coincide with the midline of the droplet in the Y-axis direction.

[0032] Parallel dark stripes are generated by artificial intelligence algorithms; the image of the droplets on the chip is captured in real time, including the outline of the droplets and the coordinates of the droplets on the chip, and is automatically generated based on the outline and position of the droplets.

[0033] The present invention designs a device with a dual-plane structure based on the principle of light-controlled electrowetting, and designs a method for droplet generation. The basic principle of the device is: the bias voltage applied to electrodes 601 and 602 generates a transverse electric field along the X-axis between electrodes 601 and 602. When light is irradiated on the photoconductive layer, the resistivity of the photoconductive layer decreases, and conversely, the resistivity of the unilluminated area increases. By projecting two parallel dark stripes to simulate the unilluminated area, two areas with larger resistivity are generated, and a larger voltage drop is generated on the dielectric layer 503 above the areas with larger resistivity. According to the Lippman-Young equation, the contact angles of these two areas become smaller, generating two wetting forces of equal magnitude and opposite directions. The upper plate 2 increases the contact area between the droplet and the lower plate, that is, increases the wetting force, making the droplet split more uniformly.

[0034] The dual-plane light-controlled electrowetting device proposed in this invention can increase the wetting area of ​​a droplet and enhance the wetting force. The design of two parallel dark stripes provides two wetting forces of equal magnitude and opposite direction. The combined effect of these two designs can achieve uniform droplet splitting.

[0035] The process of device preparation and droplet generation of the present invention is as follows:

[0036] 1. Ultrasonic clean the purchased quartz glass substrates 501 and 202 in acetone for 3 minutes, then in isopropyl alcohol for 5 minutes, and finally in deionized water for 5 minutes. Dry the substrate surfaces with a nitrogen gun and dry them on a hot plate at 100°C for 5 minutes.

[0037] 2. A photoconductive α-Si layer was deposited on the glass substrate obtained in step 1 above using PECVD. The deposition temperature was 300°C, the chamber pressure was 50-100 Pa, the SiH₄ flow rate was 20 sccm, the H₂ flow rate was 40 sccm, and the deposition power was 50 W. Under these process conditions, the deposition rate was 5-10 nm / min, and after 100 minutes, a 500-1000 nm thick α-Si photoconductive layer was obtained.

[0038] 3. A layer of metal is deposited on the photoconductive layer 502 using PVD, and then etched to leave conductive electrodes 601 and 602.

[0039] 4. Spin coat the SU8 dielectric layer 503 using a spin coater at 3000 rpm for 1 minute. Dry on a hot plate at 100°C, then heat to 150°C and dry for 30 minutes before allowing to cool naturally.

[0040] 5. Spin coat Teflon hydrophobic layers 504 and 201 using a spin coater at 3000 rpm for 1 minute. Dry on a hot plate at 100°C and allow to cool naturally.

[0041] 6. Place 300 μm thick gauges 301 and 302 on the surface of the lower plate, then drop a drop of deionized water 4 on the chip, and finally cover the upper plate.

[0042] 7. A 400V bias voltage is applied to electrodes 601 and 602. Using an intelligent algorithm, the droplet's outline and position are captured. A projector is used to project two parallel dark stripes above the droplet, illuminating the rest of the droplet to cause it to split.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1. Double-plane structure OEW device:

[0045] By constructing a dual-plane OEW device between upper and lower plates, the present invention overcomes the uncontrollable droplet splitting limitations of existing single-plane OEW devices (which only have a lower plate). The dual-plane structure provides more stable and controllable droplet splitting conditions.

[0046] 2. AI-generated optical virtual electrodes:

[0047] The present invention uses artificial intelligence (AI) to generate parallel dark stripes as optical virtual electrodes based on the position and volume of the droplet. These optical virtual electrodes are projected onto a dual-plane OEW device via a projector, enabling unlimited reconstruction and repeated droplet splitting. The two parallel dark stripes remain non-overlapping, running through the droplet and perpendicular to the electric field on the lower plate. Using optical virtual electrodes instead of physical electrodes overcomes the limitations of existing technologies in terms of the number, size, and location of droplet manipulation.

[0048] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for generating droplets on a dual-plane optically controlled electrowetting device, characterized in that: The method comprises the following steps: A dual-plane light-controlled electrowetting device is obtained, and a bias voltage (7) is applied to the electrode (6) of the device to generate a transverse electric field. Then, after capturing the outline and position of the droplet, two parallel dark stripes (1) are projected above the droplet using a projector according to the outline and position, and the remaining part is illuminated to split the droplet (4). The dark stripes (1) do not overlap and pass through the droplet (4). The direction of the dark stripes (1) is perpendicular to the electric field direction of the lower plate (5) of the device. Assuming the direction of the transverse electric field is the X-axis, then; The dual-plane light-controlled electrowetting device comprises an upper plate (2) and a lower plate (5), electrodes (6) are provided at both ends of the lower plate (5), the electrodes (6) comprise a first electrode (601) and a second electrode (602), and a plug gauge (3) is provided between the upper plate (2) and the lower plate (5).

2. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 1, wherein: The method of projecting two parallel dark stripes (1) on the droplet using a projector according to the contour and position is as follows: the width of the dark stripes (1) is controlled to be between 1 / 2 and 1.5 times the radius of the droplet (4); the width of the two dark stripes (1) is controlled to be the same; the width of the gap between the two dark stripes (1) is controlled to be between 1 / 50 and 1 times the radius of the droplet (4); the midline of the gap between the two dark stripes (1) coincides with the midline of the droplet in the Y-axis direction, and the Y-axis is perpendicular to the X-axis.

3. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 1, wherein: The upper electrode plate (2) comprises a first hydrophobic layer (201) and a first glass substrate (202).

4. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 3, wherein: The lower electrode plate (5) comprises a second glass substrate (501), a second hydrophobic layer (504), a photoconductive layer (502) and a dielectric layer (503).

5. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 4, characterized in that: The second glass substrate (501), the photoconductive layer (502), the dielectric layer (503) and the second hydrophobic layer (504) are arranged in sequence from bottom to top, and the droplet (4) is located on the second hydrophobic layer (504).

6. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 5, wherein: A first hydrophobic layer (201) and a first glass substrate (202) are sequentially arranged on the second hydrophobic layer (504).

7. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 4, wherein: A first electrode (601) and a second electrode (602) are etched on the photoconductive layer (502).

8. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 1, wherein: The plug gauge (3) includes a first plug gauge (301) and a second plug gauge (302).

9. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 1, wherein: After projecting two parallel dark stripes (1), the potential gradient on the lower plate (5) changes.

10. The method for generating droplets on a dual-plane optically controlled electrowetting device according to claim 1, wherein: The droplets (4) are droplets of deionized water.

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