A method for making artificial compound eyes

Abstract

The present invention provides a method for making an artificial compound eye, comprising the following steps: Step 1: obtaining a curved substrate, wherein the first surface of the curved substrate is hydrophobic; Step 2: obtaining a soft mask having a through-hole array, and attaching the soft mask to the first surface of the curved substrate; Step 3: performing hydrophilic-hydrophobic patterning treatment on the first surface of the curved substrate, so that the first surface has a plurality of hydrophilic areas; Step 4: contacting the first surface with an optical liquid, wherein the optical liquid forms a microlens array on the first surface by self-assembly, thereby obtaining the artificial compound eye. The present invention is used to improve the problems existing in the existing method for making an artificial compound eye, such as high cost, low efficiency, poor precision, and many limiting factors.

Description

Technical Field

[0001] The invention relates to the field of bionic compound eyes, and in particular to a method for manufacturing an artificial compound eye. Background Art

[0002] In recent years, the compound eye structure of insects such as flies and moths has inspired researchers to design multi-scale microlenses. Each insect compound eye is composed of thousands to tens of thousands of small eyes, which are small in size, highly sensitive, can measure speed, have an almost 360° observation angle and high-precision resolution, and can be applied to cameras, military radar detectors, precision guidance, infrared detection and other visual systems and lighting systems, and has extremely broad application prospects in defense, medical and commercial fields.

[0003] The preparation methods of compound eye microlens array can be divided into direct processing method, template method and deformation method. Among them, the direct processing method can construct a microlens array on a curved substrate, effectively avoiding the deformation of the microlens structure during the conversion of a planar microlens array into a curved structure. For example, femtosecond laser precision processing technology combined with wet etching or dry etching technology can directly prepare microlens arrays on curved surfaces, and the filling rate can reach 100%, but its processing cost is high and efficiency is low; DMD maskless lithography technology uses digital masks to directly prepare curved photoresist compound eyes, but has the disadvantages of low precision and difficult processing; although ultra-precision diamond milling can prepare large-area curved microlens arrays with good uniformity, it is difficult to process smaller-scale structures, and the processing accuracy is restricted by the equipment; the template method uses nanoimprinting to make a polycarbonate flexible template with a subwavelength microstructure, and uses hot extrusion to form a polycarbonate compound eye microlens array through a micropore array silicon template. The resulting imitation compound eye microlens pattern has good uniformity, but the template is expensive to make and has poor flexibility; the deformation method uses electric fields, magnetic fields, air pressure, etc. to deform a planar microlens array into a curved compound eye microlens array, which requires the use of special materials or the preparation of special auxiliary structures. The process is complicated and the accuracy controllability is poor. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a method for producing an artificial compound eye to improve the problems existing in the existing method for producing an artificial compound eye, such as high cost, low efficiency, poor precision, and many limiting factors.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for making an artificial compound eye, comprising the following steps: Step 1: obtaining a curved substrate, wherein the first surface of the curved substrate is hydrophobic; Step 2: obtaining a soft mask having an array of through holes, and attaching the soft mask to the first surface of the curved substrate; Step 3: performing hydrophilic-hydrophobic patterning treatment on the first surface of the curved substrate, so that the first surface has a plurality of hydrophilic areas; Step 4: bringing the first surface into contact with an optical liquid, wherein the optical liquid forms a microlens array on the first surface through self-assembly, thereby obtaining the artificial compound eye.

[0006] After the first surface is subjected to hydrophilic-hydrophobic patterning treatment, the first surface can have a plurality of hydrophilic regions for the optical liquid to self-assemble to form a microlens array to obtain an artificial compound eye. The plurality of hydrophilic regions are orderly arranged on the surface of the substrate.

[0007] In one embodiment of the present invention, step 1 of obtaining a curved substrate comprises the steps of: setting the size and curvature of the curved substrate; injecting a monomer and a crosslinker / curing agent mixture of a polymer material into a first mold that meets the set requirements and curing it, and obtaining a curved substrate that meets the set requirements after peeling; wherein the polymer material is any one of silica gel, polymethyl methacrylate (PMMA), polycarbonate (PC), polydimethylsiloxane (PDMS), UV curable resin, and photoresist.

[0008] In one embodiment of the present invention, step 1 of obtaining a curved substrate includes obtaining a curved substrate, wherein the material of the curved substrate is hydrophilic or hydrophobic; when the material of the curved substrate is hydrophilic, the step of obtaining the curved substrate also includes: spin coating a hydrophobic material on the curved substrate to form a hydrophobic layer; the hydrophobic material includes: polytetrafluoroethylene (PTFE or Teflon), fluorinated polyethylene, fluorocarbon wax, CYTOP, octadecyltrichlorosilane (OTS) and its derivatives or other fluorine-containing polymers; or any one of polydimethylsiloxane (PDMS), polystyrene (PS), and polyimide (PI).

[0009] In one embodiment of the present invention, obtaining a soft mask having a through-hole array in step 2 includes the steps of: preparing the soft mask by a photolithography mask method using a UV-curable resin or a photoresist, dissolving unexposed areas of the soft mask by an organic solvent that meets the requirements to obtain a soft mask having a through-hole array.

[0010] In one embodiment of the present invention, the step 2 of obtaining a soft mask having a through-hole array includes the steps of: injecting polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA) or gel into the second mold, and then curing it by ultraviolet light or heating to obtain a soft mask having a through-hole array. The soft mask can be completely fitted to the surface of the substrate to facilitate etching and obtain a relatively ideal hydrophilic area.

[0011] In one embodiment of the present invention, step three of performing hydrophilic-hydrophobic patterning treatment on the first surface of the curved substrate so that the first surface has a plurality of hydrophilic areas includes: etching the curved substrate with a soft mask attached to the first surface so that the first surface exposed outside the through-hole array of the soft mask becomes a plurality of hydrophilic areas, and the area protected by the soft mask remains a hydrophobic area.

[0012] In one embodiment of the present invention, the etching treatment is any one of reactive ion etching, inductively coupled plasma etching, focused ion beam etching, ultraviolet ozone treatment, and atmospheric pressure plasma surface modification; the reactive ion etching gas is any one of SF6, CF4, CHF3, Ar, and O2, and the RF power of the reactive ion etching is between 0-600w.

[0013] In one embodiment of the present invention, the step of bringing the first surface into contact with the optical liquid in step 4 comprises: immersing the curved substrate in the optical liquid so that the first surface is completely immersed in the optical liquid; the optical liquid is any one of UV curable resin, colorless transparent photoresist (such as SU-series), glycerol, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), silicone oil, SL-5267, and transparent gel.

[0014] In one embodiment of the present invention, the step of forming a microlens array on the first surface by self-assembly of the optical liquid in step four comprises: allowing the optical liquid to flow through the first surface for self-assembly by a pulling method or a scraping method, and the optical liquid adheres to the hydrophilic area and forms a microlens array under the action of surface tension.

[0015] In one embodiment of the present invention, the step of immersing the curved substrate in the optical liquid includes: placing the curved substrate flatly in the optical liquid so that the first surface is completely immersed in the optical liquid. The flat placement is a position state of the curved substrate, in which the plane where the edge of the first surface is located is parallel to the liquid surface of the optical liquid in a static state.

[0016] In one embodiment of the present invention, after forming the microlens array and before obtaining the artificial compound eye, the method further includes the step of curing the microlens array.

[0017] The method for making an artificial compound eye of the present invention can obtain the required substrate according to the needs of the production purpose, and form a microlens array by performing hydrophilic and hydrophobic patterning treatment on the substrate and self-assembly of optical liquid to obtain a bionic compound eye. The method avoids the damage to the microlens caused by the transformation process from a planar microlens array to a curved microlens array, thereby obtaining a smooth lens surface, and has low preparation cost and flexible operation. It can be prepared on substrates of different materials to achieve bionic compound eyes with different curvatures and different aperture eye arrangements.

[0018] The curved compound eye structure produced by the invention has the characteristics of controllable volume, controllable position, controllable focal length, low cost and simple production process. In the present invention, the hydrophilic and hydrophobic patterned array is generated on the curved surface by reactive ion etching technology, and the microlens array can be directly prepared on the curved surface. The soft mask can be closely attached to the curved surface to achieve selective etching of the curved surface, and the shape, size and position of the through hole in the soft mask can be flexibly changed to achieve the preparation of bionic compound eyes with different curvature radii and different field angles, achieving the advantages of simple operation and controllable structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a flow chart of the method for making an artificial compound eye of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of preparing a curved substrate using a hydrophobic material according to the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of preparing a curved substrate using a glass substrate in the present invention;

[0023] Figure 4It is a structural schematic diagram of the selective exposure of the present invention;

[0024] Figure 5 It is a structural schematic diagram of the soft mask of the present invention placed in anhydrous ethanol;

[0025] Figure 6 is a structural schematic diagram of the second mold of the present invention;

[0026] Figure 7 A schematic diagram of the structure of the soft mask prepared by the present invention;

[0027] Figure 8 This is a schematic diagram of the structure of the soft mask of the present invention, which is arranged in a regular hexagonal shape with hexagonal apertures;

[0028] Fig. 9 This is a schematic diagram of the structure of the soft mask of the present invention with a circular aperture and a square arrangement;

[0029] Fig.10 This is a schematic diagram of the structure of the soft mask of the present invention having a circular aperture and a circumferential arrangement;

[0030] Fig.11 It is a schematic diagram of the structure of reactive ion etching of the present invention;

[0031] Fig.12 This is a schematic diagram of the structure of the curved substrate of the present invention being placed flat into an optical liquid;

[0032] Fig.13 This is a schematic diagram of the structure of a microlens array made by the Czochralski method of the present invention;

[0033] Fig.14 It is a schematic diagram of the structure of the cured microlens array of the present invention.

[0034] Component number description

[0035] 1. First mold; 2. Curved substrate; 21. Glass substrate; 22. Hydrophobic layer; 23. Hydrophilic area; 3. Soft mask; 31. Through hole; 4. Optical liquid; 5. Microlens array; 6. Glass sheet; 7. UV-curable resin; 8. Anhydrous ethanol; 9. Second mold. DETAILED DESCRIPTION

[0036] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0037] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" etc. used in this specification are only for the convenience of description and are not intended to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be regarded as the scope of implementation of the present invention.

[0038] See also Figures 1 to 14 The present invention provides a method for making an artificial compound eye, comprising the following steps: Step 1: obtaining a curved substrate 2, wherein the first surface of the curved substrate 2 is hydrophobic; Step 2: obtaining a soft mask 3 having a through-hole array, and closely attaching the soft mask 3 to the first surface of the curved substrate 2; Step 3: performing hydrophilic-hydrophobic patterning treatment on the first surface of the curved substrate 2, so that the first surface has a plurality of hydrophilic areas; Step 4: contacting the first surface with an optical liquid 4, wherein the optical liquid 4 forms a microlens array 5 on the first surface by self-assembly, thereby obtaining the artificial compound eye. When obtaining the curved substrate 2, the curvature, diameter, and thickness of the curved substrate 2 can be selected appropriately according to actual needs.

[0039] The self-assembly described in the present invention means that when the optical liquid flows through the first surface having hydrophilic and hydrophobic regions, the optical liquid tends to adhere to the hydrophilic region, and the liquid originally in the hydrophilic region will also be "trapped" by the hydrophobic cofferdam and remain in the hydrophilic region, and shrink into a microdroplet array under the action of surface tension.

[0040] The first surface is the attachment surface of the artificial compound eye, that is, the face of the artificial compound eye needs to be made on it. After the first surface is treated with hydrophilic and hydrophobic patterns, the first surface can have several hydrophilic areas for the optical liquid to self-assemble to form a microlens array to obtain an artificial compound eye. Several hydrophilic areas are arranged on the surface of the substrate in a target order. The target order is the arrangement order determined according to the size, spacing and arrangement of the artificial compound eye.

[0041] In one embodiment of the present invention, the step of obtaining the curved substrate 2 includes: Step 1 Obtaining the curved substrate 2 includes the steps of: setting the size and curvature of the curved substrate 2; the size includes diameter and thickness, injecting a monomer of a polymer material and a crosslinker / curing agent mixture into a first mold that meets the set requirements and solidifying it, and obtaining a curved substrate 2 that meets the set requirements after peeling; wherein the polymer material is any one of silica gel, polymethylmethacrylate (PMMA), polycarbonate (PC), polydimethylsiloxane (PDMS), ultraviolet curing resin, and photoresist. The curved substrate material can also be quartz glass, silicon, etc. The set requirements include curvature, diameter, and thickness.

[0042] In one embodiment of the present invention, the step of obtaining a curved surface substrate in step 1 includes obtaining a curved surface substrate, wherein the material of the curved surface substrate is hydrophilic or hydrophobic; when the material of the curved surface substrate is hydrophilic, the step of obtaining a curved surface substrate also includes: spin coating a hydrophobic material on the curved surface substrate to form a hydrophobic layer 22; the hydrophobic material includes: polytetrafluoroethylene (PTFE or Teflon), fluorinated polyethylene, fluorocarbon wax, Teflon, CYTOP, octadecyltrichlorosilane (OTS) and its derivatives or other fluorine-containing polymers; or any one of polydimethylsiloxane (PDMS), polystyrene (PS), and polyimide (PI). Wherein, CYTOP is a mixed solution of fluororesin and perfluorotributylamine, and the mass ratio of fluororesin to perfluorotributylamine can be 1:20.

[0043] See also Figure 2In one embodiment of the present invention, the above-mentioned hydrophobic material can be used to prepare a curved substrate, and the specific steps include: obtaining a first mold 1 that meets the set requirements, preparing a liquid mixture using the hydrophobic material, injecting the liquid mixture into the first mold 1 and solidifying it to obtain a curved substrate 2 that meets the set requirements. The use of hydrophobic materials to prepare a liquid mixture can specifically include two ways: the first is to directly use the hydrophobic material to prepare the liquid mixture without adding other materials. The second is to use auxiliary materials, specifically: determine the hydrophobic material and auxiliary materials, and then weigh the hydrophobic material and the auxiliary materials according to the set ratio, fully mix, and eliminate bubbles in the mixture; then inject the mixture into the first mold and solidify it to obtain a curved substrate 2 that meets the set requirements. The auxiliary materials refer to other materials required in the process of preparing the curved substrate in addition to the hydrophobic material body. The set ratio can be any ratio that can achieve the target effect, for example, 10:1. The first mold 1 can be a plano-concave lens. Before injecting the mixture, it is necessary to confirm that the cleanliness of the concave surface of the plano-concave lens meets the set requirements. The set requirements are set by the staff based on the actual experimental standards in order to obtain a qualified curved surface substrate.

[0044] See also Figure 3 In one embodiment of the present invention, the step of obtaining the curved substrate 2 includes: obtaining a curved glass substrate 21 that meets the design requirements, and making a hydrophobic layer 22 on the surface of the curved glass substrate to obtain the curved substrate 2. The curved glass substrate 21 can be obtained by processing or purchasing by a third party, and the hydrophobic layer 22 can be made by coating a hydrophobic material on the curved glass substrate. The hydrophobic material for making the hydrophobic layer can be polytetrafluoroethylene (PTFE), fluorinated polyethylene, fluorocarbon wax, Teflon, CYTOP, octadecyltrichlorosilane (OTS) and its derivatives or other fluorine-containing polymers; or low surface energy polymers such as polydimethylsiloxane (PDMS), polystyrene (PS), and polyimide.

[0045] In one embodiment of the present invention, before the step of obtaining a soft mask having a through-hole array in step 2, the step includes: determining the size, spacing, and arrangement of the artificial compound eyes. The soft mask having a through-hole array is obtained based on the size, spacing, and arrangement of the artificial compound eyes.

[0046] See also Figure 4 and Figure 5In one embodiment of the present invention, the step 2 of obtaining a soft mask having a through-hole array includes the steps of: using a UV-curable resin 7 or a photoresist to prepare the soft mask 3 by a photolithography mask method, dissolving the unexposed area of ​​the soft mask 3 by an organic solvent (such as ethanol) that meets the requirements, and obtaining a soft mask 3 having a through-hole array. Specifically, firstly, the UV-curable resin is spin-coated on the substrate, and the substrate is subjected to UV exposure treatment through a mask having a circular spot array, so that the area not protected by the circular spots is cured, and the area protected by the circular spots can be removed by ethanol, thereby obtaining a soft mask having a through-hole array.

[0047] See also Figure 6 In one embodiment of the present invention, the step 2 of obtaining a soft mask 3 having a through-hole array includes the steps of: injecting polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA) or gel into the second mold 9, and then curing it by ultraviolet light or heating to obtain a soft mask 3 having a through-hole array. The second mold 9 is provided with a plurality of micro-columns, and a polymer material is injected into the second mold 9 for curing. When the polymer material is injected, the liquid level cannot exceed the upper edge of the micro-column. When the polymer material is completely cured, it is peeled off from the second mold 9 to form a soft mask.

[0048] The second mold 9 is determined based on the size, spacing, and arrangement of the artificial compound eye. The shape and size of the columns inside it correspond to the shape and size of the artificial compound eye, the spacing between two adjacent columns corresponds to the spacing of the artificial compound eye, and the arrangement of multiple columns corresponds to the arrangement of the artificial compound eye.

[0049] The shape and size of the through holes on the soft mask 3 correspond to the size of the artificial compound eye, the spacing between two adjacent through holes corresponds to the spacing of the artificial compound eye, and the arrangement of the through holes corresponds to the arrangement of the artificial compound eye.

[0050] See also Figures 4 to 10In one embodiment of the present invention, step 3 of performing hydrophilic-hydrophobic patterning on the first surface of the curved substrate 2 so that the first surface has a plurality of hydrophilic areas 23 includes: performing etching on the curved substrate with a soft mask attached to the first surface so that the first surface exposed outside the through-hole array of the soft mask becomes a plurality of hydrophilic areas 23, and the area protected by the soft mask 3 is still a hydrophobic area, and then removing the soft mask. The soft mask 3 can be completely fitted on the first surface of the curved substrate 2 to facilitate etching and obtain a relatively ideal hydrophilic area 23. The etching treatment is any one of reactive ion etching, inductively coupled plasma etching, focused ion beam etching, ultraviolet ozone treatment, and atmospheric pressure plasma surface modification; the reactive ion etching gas is any one of SF6, CF4, CHF3, Ar, and O2, and the RF power of the reactive ion etching is between 0-600w.

[0051] See also Fig. 9 , the arrows in the figure represent charged particles (such as oxygen ions). In one embodiment of the present invention, the etching process is reactive ion etching. The reactive gas used in the present invention is oxygen, which reacts and ionizes into oxygen plasma in the instrument chamber and reacts with the substrate. The surface energy of the area of ​​the curved substrate not protected by the soft mask is regulated by adjusting the oxygen flow rate, radio frequency power, and etching time. The surface energy of the area protected by the soft mask remains unchanged. After removing the soft mask, a hydrophilic area corresponding to the size, shape and position of the through hole of the soft mask is obtained on the curved substrate. Because the plasma is diffusely distributed in the gas, it can etch the surface of a three-dimensional structure.

[0052] See also Figures 7 to 10 The soft mask 3 is provided with a plurality of through holes 31, and the shape of the through holes 31 is the same as the shape of the sub-eye, for example, a circle, a hexagon or an octagon. The arrangement of the through holes 31 is a regular hexagonal arrangement, a square arrangement or a circular arrangement, wherein the hexagonal arrangement is as follows: Figure 7 and 8 As shown, Figure 7 is a schematic diagram of the regular hexagonal arrangement. Fig. 9 The aperture sizes of the plurality of through holes 31 may be consistent or inconsistent.

[0053] In one embodiment of the present invention, the step of removing the soft mask 3 includes: peeling the soft mask 3 off the first surface of the curved substrate 2 using tweezers.

[0054] In one embodiment of the present invention, the step of bringing the first surface into contact with the optical liquid includes: immersing the curved substrate 2 in the optical liquid 4 .

[0055] See also Fig.12 , the arrow in the figure indicates the direction of movement of the curved substrate 2. The curved substrate 2 can be immersed in the optical liquid 4 in any posture. In one embodiment of the present invention, the curved substrate is placed flat in the optical liquid so that the first surface is completely immersed in the optical liquid. The flat placement is a posture or position state of the curved substrate 2, in which the plane where the edge of the first surface is located is parallel to the liquid surface of the optical liquid in a static state.

[0056] In one embodiment of the present invention, the optical liquid 4 is any one of optical liquid materials with high transparency and appropriate viscosity, such as UV-curable resin, colorless transparent photoresist (such as SU-series), glycerol, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), silicone oil, SL-5267, gel, etc.

[0057] See also Fig.13 In one embodiment of the present invention, the step of forming the microlens array 5 on the first surface by self-assembly of the optical liquid 4 includes: self-assembling the optical liquid on the first surface by a Czochralski method or a scraping method to form a microlens array. When the curved substrate is taken out of the optical liquid by the Czochralski method, the curved substrate is separated from the optical liquid at a uniform speed.

[0058] See also Fig.14 In one embodiment of the present invention, after forming the microlens array 5 and before obtaining the artificial compound eye, the method further includes the step of curing the microlens array 5 .

[0059] In order to better understand the above technical solution, two specific embodiments are provided below for reference.

[0060] Embodiment 1

[0061] The curved surface substrate required in this embodiment is a PDMS convex lens, whose curvature diameter is 34 mm and thickness is 3.75 mm. The diameter of the target compound eye is 400 mm. μm , spacing 40 μm , arranged in a regular hexagon, with a filling rate of 75%.

[0062] The specific production steps are:

[0063] Step 1: Prepare PDMS convex lens.

[0064] See also Figure 2, use an electronic balance to weigh the PDMS body and curing agent at a mass ratio of 10:1, then stir for 10 minutes to fully mix them, and use a vacuum drying oven to evacuate and eliminate the bubbles in the PDMS. Inject the prepared PDMS into the clean first mold 1 (i.e., the concave surface of the plano-concave lens), and ensure that no bubbles are generated during the operation. Place it flat on a heating table at 130°C for 2 hours to cure, and take out the PDMS to obtain a convex lens with a hydrophobic surface.

[0065] Step 2: Spin-coat UV-curable resin and expose mask.

[0066] See also Figure 4 A layer of NOA65 UV curing resin 7 is spin-coated on the glass sheet 6 using a spin coater at a spin coating parameter of 900-1500 rpm for 30s-40s, and a parallel light source is used to irradiate from bottom to top for selective exposure.

[0067] Step 3: Remove the uncured UV-curable resin to obtain a soft mask 3.

[0068] See also Figure 5 , rinse the uncured part of NOA65 with anhydrous ethanol 8, and finally soak the glass sheet 6 in anhydrous ethanol for 3-5 minutes to peel the soft mask 3 from the glass sheet 6.

[0069] Step 4: Reactive ion etching of the PDMS lens covering the hole array soft film.

[0070] See also Fig.11 , attach the prepared NOA65 soft mask 3 to the curved surface of the PDMS lens, and then place it in the center of the reactive ion etcher, set the parameters of RF power 120-150W, working time 90-120s, pressure 2Pa, oxygen flow rate 20sccm (standard milliliters per minute), and etch it.

[0071] Step 5: The UV-curable resin liquid self-assembles on the surface of the curved substrate to form a microlens array.

[0072] See also Figure 12 to Figure 13 After etching, the PDMS convex lens is taken out, and the NOA65 soft mask 3 is peeled off with tweezers to obtain a PDMS curved substrate 2 with a hydrophilic and hydrophobic patterned surface. Then, the curved substrate 2 is placed in a container containing an optical liquid 4 (in this embodiment, NOA81 UV-curable resin liquid is used), and the NOA81 UV-curable resin liquid is self-assembled on the surface of the curved substrate 2 to form a microlens array 5 by using a Czochralski method.

[0073] Step 6: UV light curing to obtain the bionic compound eye.

[0074] See also Fig.14, fix the bionic compound eye flatly, irradiate the microlens array with an ultraviolet light source (50-100W), keep the distance between the light source and the bionic compound eye at 20-30cm, irradiate the liquid microlens array to solidify it for 10-15 minutes, and you can get the designed bionic compound eye structure.

[0075] Embodiment 2

[0076] The curved surface substrate in this embodiment is a glass substrate with a hydrophobic layer, the curvature diameter is 34 mm, the thickness is 3.75 mm, and the diameter of the target artificial compound eye is 400 mm. μm , spacing 150 μm .

[0077] The specific production steps are as follows:

[0078] Step 1: Design a curved glass substrate and perform hydrophobic treatment.

[0079] See also Figure 3 , design the size of the substrate according to the expected compound eye parameters, and then entrust a third party to process it into a glass convex lens, that is, a glass substrate 21, and spin-coat a layer of hydrophobic material, such as Teflon, CYTOP, octadecyltrichlorosilane and its derivatives, SU-glue, etc., on the curved surface of the clean glass substrate 21. CYTOP is used in this experiment. Then heat and cure to obtain a curved substrate 2 with a hydrophobic layer 22 on the surface.

[0080] Step 2: Prepare a PDMS soft mask 3 (NOA65 soft mask can also be used).

[0081] See also Figure 6 , the PDMS body and the curing agent were weighed with an electronic balance at a mass ratio of 10:1, and then stirred for 10 minutes to fully mix them, and the PDMS bubbles were eliminated by vacuum drying. The prepared PDMS was injected into the micro-pillar array mold 9, heated and cured at 130°C for 30 minutes, and then taken out to obtain a hole array soft film, i.e., a soft mask.

[0082] Step 3: Reactive ion etching of the glass lens covering the PDMS soft mask.

[0083] See also Fig.11 , the prepared soft mask 3 is closely attached to the surface of the glass lens. Then it is placed in the center of the reactive ion etcher, and the parameters are set to 120-150W of RF power, 90-120s of working time, 2Pa of pressure, and 20sccm of oxygen flow rate for etching.

[0084] Step 4: Glycerol self-assembles to obtain bionic compound eyes.

[0085] See also Figure 12 to Figure 13After etching, the glass convex lens is taken out, and the PDMS soft mask 3 is peeled off with tweezers to obtain a glass curved substrate 2 with a hydrophilic and hydrophobic patterned surface. Then the curved substrate is placed in a container containing glycerol (a variety of optical liquids can be selected), and the optical liquid is self-assembled on the surface of the curved substrate to form a microlens array 5 by using the Czochralski method, thereby obtaining a bionic compound eye.

[0086] The present invention first selects a polymer with low surface energy to prepare a curved substrate or coats a hydrophobic layer on the curved substrate. The soft mask is designed and prepared so that plasma can selectively etch the surface of the curved substrate to obtain a curved hydrophilic and hydrophobic patterned array. A soft mask with a micropore array is prepared by photolithography, which is tightly attached to the curved substrate and then placed in the chamber of a plasma etcher. A hydrophilic and hydrophobic patterned modification layer can be directly prepared on the curved substrate by plasma selective etching. Plasma selective etching can form selective protection for the curved substrate. Reactive ion etching makes the substrate surface hydrophilic by introducing hydrophilic groups on the substrate surface and changing the surface microstructure. The plasma can etch the surface of the three-dimensional structure because it is diffused and distributed in the gas. As a result, the area protected by the soft mask remains hydrophobic, while the area not protected by the soft mask becomes hydrophilic after etching, forming a hydrophilic and hydrophobic patterned array corresponding to the micropore array of the soft mask. The difference in surface energy between the hydrophilic and hydrophobic regions can enable liquid to self-assemble on a curved substrate to form a microdroplet array, thereby preparing a bionic compound eye. Using the hydrophilic and hydrophobic effect to drive liquid arrangement technology is a simple and flexible method for preparing artificial bionic compound eyes. By changing the microstructure or chemical composition of the substrate, the wettability of different positions to the droplets is different, thereby manipulating the distribution of droplets to form a curved microlens array. This method avoids the damage to the microlenses caused by the transition from a planar microlens array to a curved microlens array, and has a low preparation cost and flexible operation. It can be prepared on substrates of different materials to achieve bionic compound eyes with different curvatures and different aperture arrangements of small eyes.

[0087] The method for making an artificial compound eye of the present invention can obtain the required substrate according to the needs of the production purpose, and form a microlens array by performing hydrophilic and hydrophobic patterning treatment on the substrate and self-assembly of an optical liquid to obtain a bionic compound eye. The method avoids the damage to the microlens caused by the transformation process from a planar microlens array to a curved microlens array, and has low preparation cost and flexible operation. It can be prepared on substrates of different materials to achieve bionic compound eyes with different curvatures and different aperture eye arrangements. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0088] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for making an artificial compound eye, characterized in that The following steps are involved: Step 1: obtaining a curved substrate, wherein a first surface of the curved substrate is hydrophobic; Step 2: obtaining a soft mask having a through-hole array, and attaching the soft mask to the first surface of the curved substrate; Step 3: performing hydrophilic-hydrophobic patterning treatment on the first surface of the curved substrate so that the first surface has a plurality of hydrophilic areas; Step 4: contacting the first surface with an optical liquid, wherein the optical liquid forms a microlens array on the first surface by self-assembly to obtain the artificial compound eye; Step 1: Obtaining a curved substrate includes the following steps: setting the size and curvature of the curved substrate; injecting a monomer of a polymer material and a crosslinking agent / curing agent mixture into a first mold that meets the set requirements and curing the mixture, and then peeling the mixture to obtain a curved substrate that meets the set requirements; wherein the polymer material is any one of silica gel, polymethyl methacrylate, polycarbonate, polydimethylsiloxane, ultraviolet curing resin, and photoresist; The step of obtaining a soft mask having a through-hole array in step 2 includes: determining the size, spacing, and arrangement of the artificial compound eyes; obtaining a soft mask having a through-hole array based on the size, spacing, and arrangement of the artificial compound eyes; The step 2 of obtaining a soft mask having a through hole array includes the following steps: Using ultraviolet curing resin or photoresist to prepare a soft mask through a photolithography mask method; or, Injecting polydimethylsiloxane, polymethyl methacrylate or gel into the second mold, and then curing it by ultraviolet light or heating to obtain a soft mask with a through-hole array; Step 3: performing hydrophilic-hydrophobic patterning on the first surface of the curved substrate so that the first surface has a plurality of hydrophilic areas, including: performing etching on the curved substrate with a soft mask attached to the first surface so that the first surface exposed outside the through-hole array of the soft mask becomes a plurality of hydrophilic areas, and the area protected by the soft mask is still a hydrophobic area; Step 4: The step of self-assembling the optical liquid to form a microlens array on the first surface includes: allowing the optical liquid to flow through the first surface for self-assembly by a pulling method or a scraping method, and the optical liquid adheres to the hydrophilic area and forms a microlens array under the action of surface tension.

2. The method for making an artificial compound eye according to claim 1, characterized in that: Step 1: The step of obtaining a curved surface substrate includes obtaining a curved surface substrate, wherein the material of the curved surface substrate is hydrophilic or hydrophobic; when the material of the curved surface substrate is hydrophilic, the step of obtaining the curved surface substrate also includes: spin coating a hydrophobic material on the curved surface substrate to form a hydrophobic layer; the hydrophobic material includes: any one of polytetrafluoroethylene, fluorinated polyethylene, fluorocarbon wax, CYTOP, octadecyltrichlorosilane, polydimethylsiloxane, polystyrene or polyimide.

3. The method for making an artificial compound eye according to claim 1, characterized in that: The shape of the through holes in the through hole array described in step 2 is circular, hexagonal or octagonal; the arrangement of the through hole array is regular hexagonal arrangement, square arrangement or circular arrangement; the apertures of the through holes in the through hole array are the same or different; the shapes of the through holes in the through hole array are the same or different.

4. The method for making an artificial compound eye according to claim 1, characterized in that: The etching treatment is any one of reactive ion etching, inductively coupled plasma etching, focused ion beam etching, ultraviolet ozone treatment, and atmospheric pressure plasma surface modification; the reactive ion etching gas is any one of SF6, CF4, CHF3, Ar, and O2, and the RF power of the reactive ion etching is between 0-600w.

5. The method for making an artificial compound eye according to claim 1, characterized in that: The step of bringing the first surface into contact with the optical liquid in step 4 comprises: immersing the curved substrate in the optical liquid so that the first surface is completely immersed in the optical liquid; the optical liquid is any one of UV curable resin, colorless transparent photoresist, glycerin, polydimethylsiloxane, polymethyl methacrylate, silicone oil, and transparent gel.

6. The method for making an artificial compound eye according to claim 1, characterized in that: Step 4: Before the step of obtaining the artificial compound eye, the step also includes curing the microlens array.

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