A Superhydrophobic Surface Electrohydrodynamic Inkjet Printing MLA Process and Its Structure

Abstract

The present invention relates to the technical field of optical microlenses, and in particular to a superhydrophobic surface electrohydrodynamic inkjet printing MLA process and its structure, which includes a moving platform, an electro-inkjet printing device, a heavy release film, a PDMS layer, a zinc oxide layer, and a perfluorocyclobutane layer. The heavy release film is installed on the moving platform, the PDMS layer is disposed on the upper surface of the heavy release film, the zinc oxide layer is evaporated on the upper surface of the PDMS layer, and a plurality of cylindrical grooves are provided on the upper surface of the zinc oxide. The plurality of grooves are arranged in an array, and the perfluorocyclobutane layer is evaporated on the upper surface of the zinc oxide layer. In the present invention, a superhydrophobic surface can be obtained by modifying a low surface energy substance on the surface of zinc oxide. Relying on the surface tension of the polymer, droplets are avoided from remaining in the non-MLA formation area; the MLA has high appearance consistency and good quality, and is suitable for AR / VR glasses or related AR / VR devices.

Description

Technical Field

[0001] The present invention relates to the technical field of optical microlenses, and in particular to a superhydrophobic surface electrohydrodynamic jet printing MLA process and its structure. Background Art

[0002] The existing self-assembly process flow of Micro lens array (MLA) is as follows: i) cleaning the PDMS surface carried by the heavy release film with deionized water; ii) performing hydrophilic treatment on the PDMS surface by SF6&O2 plasma (plasma cleaning); iii) coating photoresist and then exposing it, leaving the area where MLA needs to self-assemble; iv) performing hydrophobic treatment on the non-MLA self-assembly area with perfluorooctanoic acid & titanium dioxide & polystyrene nano-solution to obtain a hydrophobic surface layer; v) removing the photoresist in the MLA self-assembly area to obtain a hydrophilic area; vi) spraying NOA65 solution on the surface and using a water-repellent rod to drain the solution to the self-assembly area, thereby obtaining MLA (Micro lens array); as Figure 1 shown, the micro-lens array produced by this process flow has poor appearance consistency, and its etching accuracy is limited. It is difficult to produce products with high appearance consistency and good quality of micro-lens arrays. Due to the limited etching accuracy of this process, the micro-lens arrays produced by it cannot be applied to AR / VR glasses or related AR / VR devices. Summary of the Invention

[0003] In view of the problems of the prior art, the present invention provides a superhydrophobic surface electrohydrodynamic jet printing MLA process and its structure. Modifying the zinc oxide surface with a low surface energy substance can obtain a superhydrophobic surface. Relying on the surface tension of the polymer, the residual droplets are avoided in the non-MLA formation area; the MLA has high appearance consistency and good quality, and is suitable for AR / VR glasses or related AR / VR devices.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a superhydrophobic surface electrohydrodynamic jet printing MLA process, which includes the following steps:

[0006] S1. Cleaning the PDMS surface carried by the heavy release film with deionized water;

[0007] S2. Evaporating zinc oxide onto the PDMS surface by physical vapor deposition;

[0008] S3. Spin-coating photoresist on the zinc oxide surface and exposing the area where MLA is formed;

[0009] S4. Removing the photoresist in the exposed area with a developer and cleaning with deionized water;

[0010] S5. Use dry etching with sulfur hexafluoride and argon to etch the zinc oxide in the exposed area and form an array of cylindrical grooves.

[0011] S6. Use a stripping solution to remove the unexposed photoresist and wash with deionized water.

[0012] S7. Use chemical vapor deposition to deposit octafluorocyclobutane onto the surface of the zinc oxide for low surface energy modification.

[0013] S8. Wash the surface of the octafluorocyclobutane with deionized water.

[0014] S9. Connect the electrospray printing device and the substrate coated with octafluorocyclobutane to an electric circuit, and move the platform to position the substrate under the electrospray printing device. Gradually increase the circuit voltage to 600 V to form a Taylor cone of the polymer at the nozzle in the electrospray printing device. Then gradually increase the voltage to 800 V so that the polymer drops onto the surface of the cylindrical grooves. Since the groove surface is a hydrophobic surface, the polymer forms a hemisphere, i.e., a microlens, above the grooves due to surface tension. Move the platform to the next position where microlenses need to be fabricated, and the nozzle drops the polymer to form microlenses until the entire microlens array is fabricated.

[0015] S10. Cure the dropped polymer.

[0016] Among them, a plurality of nozzles are provided on the nozzle of the electrospray printing device, and the plurality of nozzles are arranged in an array.

[0017] Among them, the developer is tetramethylammonium hydroxide.

[0018] Among them, the stripping solution is dimethyl sulfoxide.

[0019] Among them, between step S6 and step S7, there is also included: step S6.1. Measure whether the aperture of the etched cylindrical grooves is within the specified dimensional range.

[0020] Among them, between step S8 and step S9, there is also included: step S8.1. Measure whether the water contact angle of the polymer is within the specified range.

[0021] The present invention also provides a superhydrophobic surface electrohydrodynamic jet printing MLA structure, which includes a moving platform, an electrospray printing device, a heavy release film, a PDMS layer, a zinc oxide layer, and a perfluorocyclobutane layer. The heavy release film is installed on the moving platform. The PDMS layer is disposed on the upper surface of the heavy release film. The zinc oxide layer is evaporated on the upper surface of the PDMS layer. Multiple cylindrical grooves are provided on the upper surface of the zinc oxide. The multiple grooves are arranged in an array. The perfluorocyclobutane layer is evaporated on the upper surface of the zinc oxide layer. The electrospray printing device is provided with a nozzle, and the nozzle is used to drip a polymer onto the groove to form a microlens.

[0022] Preferably, the electrospray printing device is provided with multiple nozzles, and the multiple nozzles are arranged in an array.

[0023] Advantages of the present invention:

[0024] The present invention is ingeniously designed. Zinc oxide is used as the material for the rough structure for etching, and the etching accuracy is more precise. Coupled with a moving platform with a micron-level moving error (<3 μm), the finally obtained MLA appearance has the advantage of consistency. Modifying a low surface energy substance on the surface of zinc oxide can obtain a superhydrophobic surface, and relying on the surface tension of the polymer, it is possible to avoid the residue of droplets in the non-MLA formation area. Since the etching accuracy and the aperture of the electrospray printing nozzle reach the micron level, the finally obtained MLA size is 5-10 μm, which is suitable for AR / VR glasses or related AR / VR devices. The MLA produced by the present invention has high appearance consistency and good quality. Description of the drawings

[0025] Figure 1 It is a schematic diagram of fabricating MLA by the self-assembly method in the prior art.

[0026] Figure 2 It is a flowchart of a superhydrophobic surface electrohydrodynamic jet printing MLA process of the present invention.

[0027] Figure 3 It is a superhydrophobic surface electrohydrodynamic jet printing MLA process of the present invention.

[0028] In Figures 1 to 3 The reference numerals include:

[0029] 1. Heavy release film; 2. PDMS layer; 3. Zinc oxide layer; 4. Perfluorocyclobutane layer; 5. Microlens; 6. Electrospray printing device; 7. Moving platform. Detailed implementation manners

[0030] For the convenience of those skilled in the art, the present invention will be further described below in conjunction with embodiments and the accompanying drawings. The content mentioned in the embodiments does not limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0031] Embodiment 1

[0032] A superhydrophobic surface electrohydrodynamic jet printing MLA process, which includes the following steps: S1. Clean the PDMS surface carried by the heavy release film with deionized water;

[0033] S2. Evaporate zinc oxide onto the PDMS surface by physical vapor deposition;

[0034] S3. Spin-coat photoresist on the zinc oxide surface and expose the area where the MLA is formed;

[0035] S4. Remove the photoresist in the exposed area with a developer and wash it with deionized water. The developer is tetramethylammonium hydroxide;

[0036] S5. Etch the zinc oxide in the exposed area with sulfur hexafluoride and argon by dry etching to form a cylindrical groove array;

[0037] S6. Remove the unexposed photoresist with a stripping solution and wash it with deionized water. The stripping solution is dimethyl sulfoxide;

[0038] S7. Evaporate octafluorocyclobutane onto the surface of zinc oxide by chemical vapor deposition for low surface energy modification;

[0039] S8. Wash the surface of octafluorocyclobutane with deionized water;

[0040] S9. Connect the electrospray printing device and the substrate coated with octafluorocyclobutane to an electric circuit, and the moving platform moves the substrate under the electrospray printing device; gradually raise the circuit voltage to 600V to form a Taylor cone of the polymer at the nozzle in the electrospray printing device; then gradually raise the voltage to 800V to make the polymer droplets fall onto the surface of the cylindrical groove. Since the groove surface is a hydrophobic surface, the polymer forms a hemisphere, i.e., a microlens, above the groove due to surface tension; the moving platform moves the substrate to the next position where a microlens needs to be fabricated, and the nozzle drops the polymer to form a microlens; until the entire microlens array is fabricated; the electrospray printing device is provided with multiple nozzles, and the multiple nozzles are arranged in an array;

[0041] S10. Cure the dropped polymer.

[0042] Specifically, the present invention is ingeniously designed. Zinc oxide is used as the material for the rough structure for etching, and the etching accuracy is more precise. Coupled with a moving platform with a micrometer-level movement error (<3 μm), the finally obtained MLA appearance has the advantage of consistency. Modifying the surface of zinc oxide with low surface energy substances can obtain a superhydrophobic surface. Relying on the surface tension of the polymer, the residual droplets are avoided in the non-MLA formation area. Due to the etching accuracy and the aperture of the electrospray nozzle reaching the micrometer level, the finally obtained MLA size is 5-10 μm, which is suitable for AR / VR glasses or related AR / VR devices. The MLA produced by the present invention has high appearance consistency and good quality.

[0043] In this embodiment, between step S6 and step S7, there is also included: step S6.1, measuring whether the aperture of the grooved cylinder to be etched is within the specified dimension range.

[0044] In this embodiment, between step S8 and step S9, there is also included: step S8.1, measuring whether the water contact angle of the polymer is within the specified range.

[0045] Embodiment 2

[0046] The present invention also provides a superhydrophobic surface electrohydrodynamic printing MLA structure, which includes a moving platform 7, an electrospray printing device 6, a heavy release film 1, a PDMS layer 2, a zinc oxide layer 3, and a perfluorocyclobutane layer 4. The heavy release film is installed on the moving platform, the PDMS layer is arranged on the upper surface of the heavy release film, the zinc oxide layer 3 is vapor-deposited on the upper surface of the PDMS layer 2, there are a plurality of grooved cylinders on the upper surface of the zinc oxide layer 3, and the plurality of grooves are arranged in an array. The perfluorocyclobutane layer is vapor-deposited on the upper surface of the zinc oxide layer. The electrospray printing device 6 is provided with a nozzle, and the nozzle is used to drip the polymer to the groove to form a microlens 5. Preferably, the electrospray printing device is provided with a plurality of nozzles, and the plurality of nozzles are arranged in an array.

[0047] The above are only the preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention is disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, when making some changes or modifications using the above-disclosed technical content as equivalent changed equivalent embodiments, but as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical means of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A superhydrophobic surface electrohydrodynamic jet printing MLA process, characterized in that, Including the following steps: S1. Clean the PDMS surface carried by the heavy release film with deionized water; S2. Evaporate zinc oxide onto the PDMS surface using physical vapor deposition; S3. Spin-coat photoresist on the zinc oxide surface and expose the area formed by the MLA; S4. Remove the photoresist in the exposed area using a developer solution and clean with deionized water; S5. Etch the zinc oxide in the exposed area using dry etching with sulfur hexafluoride and argon to form a cylindrical groove array; S6. Remove the unexposed photoresist using a stripping solution and clean with deionized water; S7. Evaporate octafluorocyclobutane onto the surface of the zinc oxide using chemical vapor deposition for low surface energy modification; S8. Clean the surface of the octafluorocyclobutane with deionized water; S9. Connect the electrospray printing device and the substrate coated with octafluorocyclobutane to an electric circuit, and move the platform to move the substrate under the electrospray printing device; gradually increase the circuit voltage to 600V to form a Taylor cone of the polymer at the nozzle in the electrospray printing device; then gradually increase the voltage to 800V to make the polymer drop onto the surface of the cylindrical groove. Since the groove surface is a hydrophobic surface, the polymer forms a hemisphere, i.e., a microlens, above the groove due to surface tension; move the platform to move the substrate to the next position where microlenses need to be fabricated, and the nozzle drops the polymer to form microlenses; until the fabrication of the entire microlens array is completed; S10. Cure the dropped polymer; The developer solution is tetramethylammonium hydroxide; the stripping solution is dimethyl sulfoxide.

2. The electrohydrodynamic jet printing MLA process for a superhydrophobic surface according to claim 1, wherein: The electrospray printing device is provided with a plurality of nozzles, and the plurality of nozzles are arranged in an array.

3. The electrohydrodynamic jet printing MLA process for a superhydrophobic surface according to claim 1, characterized in that, Between step S6 and step S7, there is also included: step S6.

1. Measure whether the aperture of the etched cylindrical groove is within the specified dimensional range.

4. The electrohydrodynamic inkjet printing MLA process for a superhydrophobic surface according to claim 1, wherein Between step S8 and step S9, there is also included: step S8.

1. Measure whether the water contact angle of the polymer is within the specified range.

5. A superhydrophobic surface electrohydrodynamic jet printing MLA structure formed by the superhydrophobic surface electrohydrodynamic jet printing MLA process according to any one of claims 1-4, characterized in that: Including a moving platform, an electrospray printing device, a heavy release film, a PDMS layer, a zinc oxide layer, and an octafluorocyclobutane layer. The heavy release film is installed on the moving platform, the PDMS layer is disposed on the upper surface of the heavy release film, the zinc oxide layer is evaporated on the upper surface of the PDMS layer, a plurality of cylindrical grooves are provided on the upper surface of the zinc oxide layer, and the plurality of grooves are distributed in an array. The octafluorocyclobutane layer is evaporated on the upper surface of the zinc oxide layer. The electrospray printing device is provided with nozzles for dropping the polymer to the grooves to form microlenses.

6. The electrohydrodynamic jet printing MLA structure with a superhydrophobic surface according to claim 5, characterized in that: The electrospray printing device is provided with a plurality of nozzles, and the plurality of nozzles are arranged in an array.

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