Nanoparticle microcolumn array and preparation method thereof

Abstract

The invention discloses a preparation method of a nano-particle micro-column array. The preparation method comprises the following steps: S1, bonding a silica gel template with a micro-column array on a substrate to form a net-shaped micro-channel; s2, a silica gel template with the micro-column array is bonded on a substrate to form a net-shaped micro-channel, the net-shaped micro-channel is filled with model wax, after the model wax is solidified, the silica gel template is uncovered, and a wax film with a micropore array is left on the substrate; s3, coating the nano-particle dispersion liquid on the wax film with the micropore array, and repeating for multiple times until the micropores are filled with the nano-particles; and S4, removing redundant nano-particles on the surface of the wax film, and after high-temperature calcination, removing the wax film and sintering the nano-particles at the same time to obtain the nano-particle microcolumn array on the substrate. The preparation method disclosed by the invention can be suitable for various substrates and various sinterable nanoparticles; meanwhile, the prepared nano-particle microcolumn array does not contain resin, the property of nano-particles is not influenced by resin coating, and the application scene is wide.

Description

Technical Field

[0001] The present invention belongs to the technical field of microfabrication, and particularly relates to a nanoparticle microcolumn array and a preparation method thereof. Background Art

[0002] A microcolumn array is a material with regularly arranged micron-scale columnar structures and has wide applications in the fields of microfluidics, biomimetic surfaces, optical devices, biological detection, etc. Currently, there are many microfabrication techniques for preparing microcolumn arrays, such as subtractive microfabrication techniques like laser etching, wet etching, focused ion beam etching, additive microfabrication techniques like photolithography, 3D printing, or soft lithography techniques like casting PDMS molds. Among them, the microcolumn arrays prepared by subtraction and molding are limited in their application scenarios because the substrate and the microcolumn array are made of the same material. Additive microfabrication techniques like photolithography and 3D printing can prepare microcolumn arrays on different substrates, but photosensitive resins or hot-melt resins are often used in the preparation process. This restricts their application scenarios to the properties of the resins. In addition, these microfabrication techniques usually require a complete set of instruments and equipment, with high costs, complex process flows, and long time consumption. Therefore, there is an urgent need for a microfabrication technique for preparing microcolumn arrays with a simple process, low cost, and wide application scenarios. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the main object of the present invention is to provide a nanoparticle microcolumn array and a preparation method thereof with a simple process, low cost, and wide application scenarios.

[0004] The object of the present invention is achieved by the following technical solutions:

[0005] A preparation method of a nanoparticle microcolumn array includes the following steps:

[0006] S1. Bond a silica gel template with a microcolumn array to a substrate to form a reticular microchannel;

[0007] S2. Fill the reticular microchannel formed by bonding the silica gel template with the microcolumn array to the substrate with modeling wax. After the modeling wax is cured, remove the silica gel template, and a wax film with a micropore array remains on the substrate;

[0008] S3. Coat a nanoparticle dispersion liquid on the wax film with the micropore array, and repeat multiple times until the micropores are filled with nanoparticles;

[0009] S4. Remove the excess nanoparticles on the surface of the wax film, and after high-temperature calcination, remove the wax film and sinter the nanoparticles simultaneously to obtain a nanoparticle microcolumn array on the substrate.

[0010] In some specific embodiments, it further includes: The method for preparing the silica gel template with a microcolumn array includes, but is not limited to: using liquid silica gel to mold a silicon wafer template to obtain a silica gel template with a microcolumn array.

[0011] Further, using liquid silica gel to mold a silicon wafer template specifically includes: removing air bubbles under vacuum conditions, curing the liquid silica gel on a 70°C heating plate, peeling off the silica gel, and further curing it on a 90°C heating plate to obtain a silica gel template with a microcolumn array;

[0012] In some specific embodiments, the silicon wafer template includes, but is not limited to, being prepared by the following method: preparing a photoresist film with a microhole array to obtain a silicon wafer template.

[0013] In some specific embodiments, the preparation of the photoresist film with a microhole array includes, but is not limited to, using at least one of optical lithography technology, electron beam lithography, two-photon polymerization lithography, and 3D printing technology.

[0014] Further, preparing a photoresist film with a microhole array by lithography technology, adjusting the photoresist film thickness, microhole size, and microhole array pattern to obtain a silica gel template;

[0015] In some specific embodiments, in step S1, an inlet and an outlet are provided on the silica gel template, the inlet of the silica gel template is connected to model wax, and the outlet of the silica gel template is connected to a micropump.

[0016] In some specific embodiments, placing the network microchannel composed of the silica gel template and the substrate on a heating plate, placing model wax at the inlet of the microchannel, connecting the outlet of the microchannel to a micropump, and slowly pumping the melted model wax into the microchannel through the micropump after the model wax melts; after the melted model wax fills the microchannel, removing the microchannel from the heating plate, cooling and curing the model wax, peeling off the silica gel template, and leaving a wax film with a microhole array on the substrate;

[0017] In some specific embodiments, in step S3, the nanoparticle dispersion is an ethanol solution of nanoparticles.

[0018] Further, the nanoparticles include, but are not limited to, one or more of TiO2, SiO2, CuO, WO3, BiVO4, and perovskite.

[0019] In some specific embodiments, it further includes pretreating the substrate in steps S1 and S3 with air plasma.

[0020] In some specific embodiments, the process parameters of the pretreatment are: treating in an air plasma environment with a pressure of 500 - 1800 mTorr for 1 - 20 minutes.

[0021] In some specific embodiments, the model wax described in step 2) includes but is not limited to at least one of Shanba super hard wax and TP-80 Tianshi wax.

[0022] In some specific embodiments, the process parameters of the high-temperature calcination in step 4) are that under air conditions, the calcination temperature is 500-600 °C.

[0023] As the same inventive concept, the present invention also provides a nanoparticle microcolumn array.

[0024] Compared with the prior art, the present invention has at least the following advantages:

[0025] 1) Parameters such as the shape, size, height, and pattern of the nanoparticle microcolumn array in the present application can be precisely regulated by using lithography technology when preparing the silicon wafer template.

[0026] 2) The preparation method of the nanoparticle microcolumn array provided by the present invention can repeat the preparation of the microcolumn array with only one lithography, with a simple process, convenient operation, and low preparation cost.

[0027] 3) The preparation method of the nanoparticle microcolumn array provided by the present invention is applicable to various substrates and various sinterable nanoparticles, with a wide range of application scenarios.

[0028] 4) The nanoparticle microcolumn array proposed by the present invention does not contain resin, the properties of the nanoparticles are not affected by resin coating, and the subsequent application scenarios of the microcolumn array are not limited by the properties of the resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below.

[0030] Figure 1 is the process flow chart of the preparation of the nanoparticle microcolumn array described in the present invention;

[0031] Figure 2 is the scanning electron microscope (SEM) image of the TiO2 microcolumn array photoanode embodiments with different sizes prepared by the present invention;

[0032] Figure 3 is the linear sweep voltammetry (LSV) curve of the TiO2 microcolumn array photoanode embodiments with different sizes prepared by the present invention;

[0033] Figure 4 is the schematic diagram of the working principle of the photodetector array. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are merely illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0035] When a quantity, concentration, or other value or parameter is expressed in the form of a range, a preferred range, or a preferred upper and lower limit of a value, it should be understood that any range formed by combining any pair of upper limits of the range or preferred values with any lower limit of the range or preferred values is specifically disclosed, regardless of whether the range is specifically disclosed. Unless otherwise indicated, the numerical range values listed herein include the endpoints of the range and all integers and fractions within the range.

[0036] Unless otherwise specified, all percentages, parts, ratios, etc. in this article are by weight.

[0037] The materials, methods, and embodiments in this article are all exemplary and should not be construed as restrictive unless otherwise specified.

[0038] A method for preparing a nanoparticle microcolumn array provided by the present invention has a process flow as Figure 1 shown, and specifically includes the following steps:

[0039] S1. Prepare a photoresist film with a micropore array to obtain a silicon wafer template

[0040] S2. Use liquid silicone to make a mold of the silicon wafer template to obtain a silicone template with a microcolumn array.

[0041] S3. Bond the silicone template with the microcolumn array to the substrate to form a network microchannel;

[0042] S4. Fill the network microchannel formed by bonding the silicone template with the microcolumn array to the substrate with model wax. After the model wax is cured, remove the silicone template, and a wax film with a micropore array remains on the substrate;

[0043] S5. Coat the wax film with the micropore array with a nanoparticle dispersion liquid, and repeat multiple times until the micropores are filled with nanoparticles;

[0044] S6. Remove the excess nanoparticles on the surface of the wax film, and after high-temperature calcination, remove the wax film and sinter the nanoparticles at the same time to obtain a nanoparticle microcolumn array on the substrate.

[0045] In the following embodiments, the TiO2 raw material has an index of 30 nm and anatase phase, and is specifically purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; the photoresist raw material has an index of SU-8 type and is specifically purchased from Suzhou Yancai Micro-Nano Technology Co., Ltd.; the liquid silicone raw material has an index of semi-transparent 40 degrees and is specifically purchased from Huanyao Materials Store; the conductive glass raw material has an index of FTO, a sheet resistance of 10 ohms, and dimensions of 25*25*2 mm, and is specifically purchased from Jingjiexin Glass; the model wax raw material has an index of TP-80 type and is specifically purchased from Nanjing Tianshi New Materials Technology Co., Ltd.

[0046] The test methods adopted in the following embodiments include:

[0047] By separately testing the main properties of each test sample, the performance of the TiO2 microcolumn array is reflected; the main properties tested in this application include surface microtopography, photoelectrochemical properties, etc.

[0048] 1) Surface microtopography test;

[0049] Use a scanning electron microscope to test the surface microtopography of the sample;

[0050] 2) Photoelectrochemical performance test

[0051] Use an electrochemical workstation to perform linear sweep voltammetry test on the sample under a three-electrode system;

[0052] Example 1:

[0053] This embodiment provides a method for preparing a TiO2 microcolumn array, which includes the following steps:

[0054] The photoanode is prepared from a photocatalyst. When irradiated with light, it will absorb light to generate photogenerated carriers, realizing the conversion of light energy to electrical energy, and is a key component in a photoelectrochemical cell. The mass transfer characteristics within the photoanode catalytic layer directly affect the photoelectrochemical reaction within the photoanode; in a microcolumn array photoanode, reactants can be transported into the microcolumns through the gaps between the microcolumn arrays, enhancing the photoelectrochemical reaction and improving the performance of the photoanode. Combining with the technical solution of the present invention, the preparation steps of the TiO2 microcolumn array photoanode are as follows:

[0055] S1. Prepare a photoresist film with a microporous array through lithography technology to obtain a silicon wafer template. The thickness of the photoresist film is 20 microns, the area of the film is 1.4*1.4 cm, the middle of the film is a microporous array, the area of the microporous array is 1*1 cm, the micropore size is 20*20 microns, and the micropore spacing is 20 microns;

[0056] S2. Use liquid silicone to make a mold of the silicon wafer template, remove air bubbles under vacuum conditions, cure the liquid silicone on a 70 °C hot plate, peel off the silicone, further cure it on a 90 °C hot plate, and cut the edges to obtain a silicone template with a microcolumn array;

[0057] S3. Ultrasonically clean the conductive glass with ethanol and water respectively, then place the conductive glass in an air plasma environment with a pressure of 1400 mTorr for 10 minutes. After that, punch holes at specific positions on the silicone template as inlets and outlets, and bond the silicone template to the conductive glass to form a network of microchannels;

[0058] S4. Place the microchannel composed of the silicone template and the conductive glass on an 87 °C hot plate. Place TP-80 type Tian Shi wax at the inlet of the microchannel. The melting point of this model wax is lower than 87 °C. Connect the outlet of the microchannel to a micropump. After the model wax melts, slowly pump it into the microchannel through the micropump;

[0059] S5. After the melted model wax fills the microchannel, remove the microchannel from the hot plate, let the model wax cool and solidify, peel off the silicone template, and a wax film with a micropore array remains on the conductive glass;

[0060] S6. Place the conductive glass with the wax film in an air plasma environment with a pressure of 1400 mTorr for 10 minutes to make the wax film hydrophilic. Disperse 1 gram of TiO2 nanoparticles in 30 ml of ethanol, and use a soft brush to apply the TiO2 nanoparticle dispersion on the wax film with a micropore array, so that the dispersion enters the micropores. After the ethanol evaporates, TiO2 nanoparticles are deposited in the micropores. Repeat several times until the micropores are filled with TiO2 nanoparticles;

[0061] S7. Wipe off the excess TiO2 nanoparticles on the surface of the wax film with a water-dampened dust-free paper, and calcine it at 550 °C for 2 hours under air conditions with a heating rate of 10 °C / min to remove the wax film and sinter the TiO2 nanoparticles simultaneously, obtaining a TiO2 microcolumn array photoanode with a size of 20 microns.

[0062] TiO2 microcolumn array photoanodes with sizes of 30, 40, and 50 microns were prepared by the same method by changing the micropore size and micropore spacing during photolithography.

[0063] Scanning electron microscope (SEM) images of TiO2 microcolumn array photoanodes with different sizes are as Figure 2 shown. It can be seen from the figure that the size of the prepared TiO2 microcolumn array and the spacing between the microcolumns are consistent with the design, which are 20, 30, 40, and 50 microns respectively. This shows that the method for preparing nanoparticle microcolumn arrays proposed in the present invention can accurately control parameters such as the size and pattern of the microcolumns.

[0064] The linear sweep voltammetry (LSV) curves of TiO2 microcolumn arrays with different sizes were tested, as Figure 3 shown. It can be seen from the figure that TiO2 microcolumn arrays with different sizes all have good photoelectrochemical properties. This indicates that the microcolumn arrays prepared by the method of the present invention can be applied to photoelectrochemical cells, and the photoelectrochemical properties of the TiO2 nanoparticles themselves are not affected.

[0065] Example 2: Microcolumn array of photodetector

[0066] Photodetectors have important applications in the fields of optical communication, high-density optical information technology, artificial eyes, etc. Photodetector arrays are important components in photodetectors and have photoelectric response characteristics. By designing the circuit, each individual module in the photodetector array forms an independent circuit; only when light irradiates this module will the circuit conduct and form an electrical signal. Thus, the optical signal is converted into an electrical signal through the photodetector array and transmitted to other devices for reading. Figure 4 is a schematic diagram of the working principle of the photodetector array. Combining the technical solution of the present invention, the preparation steps of the microcolumn array of the photodetector are as follows:

[0067] S1. Deposit the metal electrode (10nm Ti / 80nm Au) and the designed circuit on the substrate through UV lithography, electron beam evaporation, and lift-off processes

[0068] S2. Customize the mask for lithography according to the designed circuit, and prepare a photoresist film with a micropore array through lithography technology to obtain a silicon wafer template;

[0069] S3. Use liquid silicone to make a mold of the silicon wafer template, remove air bubbles under vacuum conditions, cure the liquid silicone on a 70°C hot plate, peel off the silicone, further cure it on a 90°C hot plate, and trim the edges to obtain a silicone template with a microcolumn array;

[0070] S4. Place the substrate with the electrode and circuit in an air plasma environment at a pressure of 1400 mTorr for 10 minutes. Then, punch holes at specific positions on the silicone template as inlets and outlets, and bond the silicone template to the substrate with the help of an alignment system for lithography to form a network microchannel;

[0071] S4. Place the microchannel composed of the silicone template and the substrate on an 87°C hot plate. Place TP-80 type Tian Shi wax at the inlet of the microchannel. The melting point of this model wax is lower than 87°C. Connect the outlet of the microchannel to a micropump. After the model wax melts, slowly pump it into the microchannel through the micropump;

[0072] S5. After the melted model wax fills the microchannel, remove the microchannel from the hot plate, let the model wax cool and solidify, peel off the silicone template, and a wax film with a micropore array remains on the substrate;

[0073] S6. Place the substrate with the wax film in an air plasma environment at a pressure of 1400 mTorr for 10 minutes to make the wax film hydrophilic. Disperse the photo-responsive nanoparticles (such as TiO2, BiVO4, perovskite, etc.) in ethanol, and use a soft brush to apply the nanoparticle dispersion on the wax film with a microporous array, so that the dispersion enters the micropores. After the ethanol evaporates, the nanoparticles are deposited in the micropores. Repeat this process multiple times until the micropores are filled with nanoparticles;

[0074] S7. Wipe off the excess nanoparticles on the surface of the wax film with a water-dampened dust-free paper, and calcine at 550 °C for 2 hours under air conditions with a heating rate of 10 °C / min to remove the wax film and sinter the nanoparticles simultaneously, obtaining a microcolumn array of photodetectors.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and the specification of the present invention.

Claims

1. A method for preparing a nanoparticle microcolumn array, characterized in that: The steps include: S1. Bonding a silica template with a micropillar array onto a substrate to form a mesh microchannel; S2. Filling the model wax in the mesh microchannel formed by bonding the silicone template with the micropillar array on the substrate, and after the model wax solidifies, peeling off the silicone template, leaving a wax film with a micropore array on the substrate; S3. coating the nanoparticle dispersion on the wax film with the micropore array, repeating the process several times until the nanoparticles fill the micropores; S4. Remove excess nanoparticles from the wax film surface, and after high-temperature calcination, remove the wax film and sinter the nanoparticles at the same time to obtain a nanoparticle microcolumn array on the substrate.

2. The method for preparing the nanoparticle microcolumn array according to claim 1, characterized in that: Also includes: The method for preparing the silica gel template with the micro-pillar array includes but is not limited to: using liquid silica gel to mold the silicon wafer template to obtain the silica gel template with the micro-pillar array.

3. The method for preparing the nanoparticle microcolumn array according to claim 2, characterized in that: The silicon wafer template includes but is not limited to being prepared by the following method: preparing a photoresist film with a micropore array to obtain a silicon wafer template.

4. The method for preparing the nanoparticle microcolumn array according to claim 3, characterized in that: The preparation of the photoresist film with the micropore array includes but is not limited to at least one of optical lithography, electron beam lithography, two-photon polymerization lithography and 3D printing technology.

5. The method for preparing the nanoparticle microcolumn array according to claim 1, characterized in that: In step S1, the silicone template is provided with an inlet and an outlet, the inlet of the silicone template is connected to the model wax, and the outlet of the silicone template is connected to a micro pump.

6. The method for preparing the nanoparticle microcolumn array according to claim 5, characterized in that: The nanoparticle dispersion in step S3 is an ethanol solution of nanoparticles.

7. The method for preparing the nanoparticle microcolumn array according to claim 6, characterized in that: The nanoparticles include, but are not limited to, one or more of TiO2, SiO2, CuO, WO3, BiVO4, and perovskite.

8. The method for preparing the nanoparticle microcolumn array according to claim 5, characterized in that: The method further includes pre-treating the substrate in step S1 and step S3 by using air plasma.

9. The method for preparing the nanoparticle microcolumn array according to claim 8, characterized in that: The process parameters of the pretreatment are: treating in an air plasma environment with a pressure of 500-1800 mTorr for 1-20 minutes.

10. A nanoparticle microcolumn array prepared by the preparation method according to any one of claims 1 to 9.

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