A solvent-resistant, oxidation-resistant and corrosion-resistant microfluidic chip and a simple preparation method and application thereof

Abstract

The application relates to the field of materials, and discloses a solvent-resistant, oxidation-resistant and corrosion-resistant micro-fluidic chip and a simple preparation method and application thereof. The chip comprises a hydrophilic substrate and a hydrophobic pattern on the surface of the hydrophilic substrate, and the hydrophobic pattern is composed of a cross-linked and solidified product of a hydrophobic precursor. Compared with a micro-fluidic chip prepared from a traditional hydrophilic and hydrophobic patterned surface, the application can more effectively confine a liquid, can resist most organic and inorganic solvents, and can not be dissolved or have any swelling behavior when the chip is soaked in a solvent for a long time. Therefore, the application can greatly widen the application of the micro-fluidic chip in liquid drop microarray and extreme environment, the processing process of the application is relatively simple, the preparation efficiency is relatively high, and the application is very convenient for large-area preparation and industrial production of the solvent-resistant micro-fluidic chip.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chips, and particularly relates to a chip resistant to solvents, oxidation and corrosion and having excellent liquid confining capability as well as a simple preparation method and application thereof. BACKGROUND

[0002] Surface hydrophilic-hydrophobic patterning is an important method for controlling the shape of microdroplets on chip surfaces, and has been rapidly developed and widely applied in recent years. Due to the difference in chemical wettability, a hydrophilic-hydrophobic patterned chip can confine liquid droplets in the hydrophilic region to form a regular microdroplet array, which has important applications in regulating liquid behavior, self-assembly, high-precision printing, microfluidics, cell culture, virus detection, DNA synthesis and the like.

[0003] Currently reported hydrophilic-hydrophobic patterned chips mainly include two types. The first type is a planar hydrophilic-hydrophobic patterned chip, which is prepared by selectively grafting hydrophobic molecules on the surface of a hydrophilic substrate to form a planar hydrophilic-hydrophobic patterned chip without height difference. However, this planar hydrophilic-hydrophobic chip has weak liquid confining capability. The second type is a hydrophilic-hydrophobic patterned chip with physical height difference, which is prepared by selectively depositing polytetrafluoroethylene, high molecular resin and other hydrophobic chemical materials on the surface of a hydrophilic substrate by micro-nano processing to form a hydrophilic-hydrophobic patterned chip with both physical topographic difference and chemical wettability difference. This hydrophilic-hydrophobic patterned chip with physical topographic difference has more excellent liquid confining capability and can more effectively regulate liquid behavior due to the simultaneous physical confining effect of geometric topography and chemical confining effect of hydrophilic-hydrophobic. However, since the hydrophobic material with physical structure is usually an organic high molecular material, these materials generally have poor resistance to organic solvents, and often swell, deform or even dissolve when soaked in organic solvents for a long time. Moreover, with the extension of service life, the microfluidic chip is also very easy to be oxidized and corroded by reaction reagents, which not only makes the chip lose the confining effect of physical topography, but also pollutes the reaction reagents, thus greatly limiting the application of the hydrophilic-hydrophobic patterned chip in chemical experiments and industrial production. Therefore, it is of great significance and application value to explore a hydrophilic-hydrophobic microfluidic chip resistant to solvents, oxidation and corrosion and having physical height difference as well as a simple preparation method thereof. SUMMARY

[0004] The purpose of the present application is to provide a hydrophilic-hydrophobic microfluidic chip resistant to solvents, oxidation and corrosion, which is simple, universal, low in cost and suitable for large-scale production.

[0005] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0006] A microfluidic chip, comprising a hydrophilic substrate and a hydrophobic pattern on the surface of the hydrophilic substrate, the hydrophobic pattern being composed of a cross-linked and cured product of a hydrophobic precursor.

[0007] The hydrophobic pattern is higher than the surface of the hydrophilic substrate.

[0008] The height of the hydrophobic pattern ranges from 10 nm to 100 μm.

[0009] The area of the hydrophobic pattern can account for 1% to 99% of the hydrophilic substrate.

[0010] The hydrophobic pattern can be any regular or irregular pattern.

[0011] The hydrophobic precursor is a hydrophobic organosilicon precursor; preferably, at least one selected from the group consisting of organopolysilazane, perhydropolysilazane, cyclopentadimethylsiloxane, fluorinated polysiloxane, and a mixture of organopolysilazane or perhydropolysilazane and an epoxy photocuring resin.

[0012] The cross-linked and cured product of the hydrophobic precursor is a ceramicized product or an ultraviolet light cured product, which is obtained by curing the hydrophobic organosilicon precursor under ultraviolet light irradiation or high temperature heating.

[0013] The present application further provides a preparation method of the microfluidic chip, comprising the following steps:

[0014] 1) constructing a soluble raised microstructure pattern in an organic solvent on the hydrophilic substrate by photolithography or printing to obtain a patterned substrate;

[0015] 2) coating a hydrophobic precursor or a monomer forming the hydrophobic precursor on the surface of the patterned substrate;

[0016] 3) high-temperature heating the coated substrate or using an ultraviolet exposure system to perform ultraviolet light irradiation on the coated substrate to cross-link and cure the hydrophobic precursor;

[0017] 4) placing the converted substrate into a solvent soluble to the raised microstructure pattern and performing ultrasonic treatment to obtain the microfluidic chip.

[0018] In step 1), the microstructure pattern is constructed on the hydrophilic substrate by micro-nano processing technology.

[0019] In step 2), the coating process is spin coating.

[0020] In step 3), the central wavelength of the ultraviolet light used can range from 180 nm to 405 nm, the irradiation power can range from 20 W to 1 KW, and the exposure time can range from 20 minutes to 120 minutes.

[0021] In step 3), the heating temperature in the high-temperature heating can range from 80 to 500 DEG C.

[0022] In step 4), the ultrasonic treatment refers to a method of using solvent ultrasonic to dissolve or separate the raised microstructure pattern on the patterned substrate.

[0023] In step 3) and step 4), the raised microstructure pattern can be dissolved in the organic solvent or separated from the substrate.

[0024] 3) using an ultraviolet exposure system to irradiate the substrate coated with the hydrophobic precursor with ultraviolet light, so that the hydrophobic precursor is subjected to ceramic conversion;

[0025] 4) then soaking it in acetone for ultrasonic treatment, and when the raised microstructure pattern on the patterned substrate is completely dissolved in the acetone or separated from the substrate, the substrate is taken out, and then the substrate is cleaned with water, so that the microfluidic chip is obtained.

[0026] The method specifically comprises the following steps:

[0027] 1) using photolithography or inkjet printing and other micro-nano processing means to construct a raised microstructure pattern that can be dissolved in an organic solvent on a hydrophilic substrate, so as to obtain a patterned substrate;

[0028] 2) coating a hydrophobic silicone precursor on the surface of the patterned substrate to obtain a substrate uniformly coated with the hydrophobic silicone precursor;

[0029] 3) using an ultraviolet exposure system to irradiate the substrate coated with the hydrophobic silicone precursor with ultraviolet light, so that the hydrophobic silicone precursor is subjected to ceramic conversion;

[0030] 4) soaking the substrate subjected to ceramic conversion in acetone for ultrasonic treatment, and when the raised microstructure on the initial patterned substrate and the upper hydrophobic ceramic are completely dissolved in the acetone or separated from the substrate, the substrate is taken out, and then the substrate is cleaned with water, so that the microfluidic chip is obtained.

[0031] The application further provides the use of the microfluidic chip, and the chip is used in the fields of DNA synthesis (specifically, inkjet printing DNA synthesis), droplet behavior regulation, self-assembly, microfluidics, high-precision printing, cell culture, and virus detection.

[0032] Advantages

[0033] Compared with the prior art, the application has the following advantages:

[0034] 1) The present application provides a chip, which is a microfluidic chip, having the advantages of solvent resistance, oxidation resistance, corrosion resistance, large-area preparation, simple and fast preparation method, and the like.

[0035] 2) The present application provides a preparation method of the above chip, which realizes the construction of a hydrophobic ceramic pattern on the surface of a hydrophilic substrate by coating a hydrophobic organosilicon precursor on a patterned physical template, and utilizing ultraviolet exposure or high-temperature heating to make the organosilicon precursor undergo ceramic conversion, and through the steps of immersion and ultrasonic cleaning, simple, fast, controllable, good uniformity, and convenient for large-scale production.

[0036] 3) The method of the present application can realize large-area preparation of a hydrophobic pattern on the surface of a hydrophilic substrate resistant to various organic solvents, oxidation, and corrosion. The prepared chip surface not only has physical morphology differences, but also has different chemical wettability, has strong liquid confinement ability, and can control a variety of liquid droplets, thus having great application prospects in many fields.

[0037] 4) The chip prepared by the method of the present application has a physical height of the hydrophobic region that can be accurately controlled, and can accurately prepare a chip with a physical height of less than 500 nm. The chip not only has strong liquid confinement ability, but also does not affect the kinetic behavior of continuous fluid due to the barrier of physical morphology, thus having important application prospects in the field of inkjet printing synthetic DNA. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A process flow chart for making a hydrophilic-hydrophobic microfluidic chip resistant to solvents, oxidation, and corrosion in the embodiments of the present application;

[0039] Figure 2 An optical micrograph of a patterned substrate for photolithography in the embodiments of the present application;

[0040] Figure 3 An optical micrograph of a hydrophilic-hydrophobic chip after ceramic conversion in the embodiments of the present application;

[0041] Figure 4 A height distribution graph of a hydrophilic-hydrophobic chip after ceramic conversion in the embodiments of the present application tested by a step profiler;

[0042] Figure 5 A contact angle of a hydrophobic region of a hydrophilic-hydrophobic chip in the embodiments of the present application;

[0043] Figure 6 A contact angle of a hydrophilic region of a hydrophilic-hydrophobic chip in the embodiments of the present application. DETAILED DESCRIPTION

[0044] The present application is based on ceramic conversion of hydrophobic organic silicon precursor, and a solvent-resistant, oxidation-resistant and corrosion-resistant microfluidic chip is prepared by spin-coating organic silicon precursor on a patterned substrate, and using ultraviolet irradiation (or heating) for ceramic conversion and ultrasonic cleaning.

[0045] The present application discloses a microfluidic chip, which comprises a hydrophilic substrate and a hydrophobic pattern on the surface of the hydrophilic substrate, and the hydrophobic pattern is composed of a cross-linked and cured product of a hydrophobic precursor.

[0046] The microfluidic chip has many advantages such as solvent resistance, oxidation resistance and corrosion resistance.

[0047] According to an embodiment of the present application, the hydrophobicity refers to a contact angle with water greater than 90°.

[0048] According to an embodiment of the present application, the hydrophobic pattern is higher than the surface of the hydrophilic substrate.

[0049] According to an embodiment of the present application, the height of the hydrophobic pattern ranges from 10 nm to 100 μm.

[0050] According to an embodiment of the present application, the area of the hydrophobic pattern can account for 1% to 99% of the hydrophilic substrate.

[0051] According to an embodiment of the present application, the hydrophobic pattern can be any regular pattern or irregular pattern; for example, it can be a single circle, square, rectangle, triangle, diamond, straight line, curve, and an array composed of these patterns.

[0052] According to an embodiment of the present application, the hydrophobic precursor is, for example, a hydrophobic organic silicon precursor, and specifically, it can be at least one selected from the group consisting of organic polysilazane, perhydrous polysilazane, cyclopenta polydimethylsiloxane, fluorinated polysiloxane, and a mixture of organic polysilazane or perhydrous polysilazane and epoxy photocuring resin.

[0053] According to an embodiment of the present application, the cross-linked and cured product of the hydrophobic precursor is a ceramic product or a UV-cured product, which is obtained by curing the hydrophobic organic silicon precursor under UV irradiation or high temperature. Taking organic polysilazane as an example, its ceramic product is a mixture of silicon dioxide and polysiloxane.

[0054] According to an embodiment of the present application, the hydrophilic substrate is obtained by hydrophilic treatment of a substrate. Specifically, the substrate is, for example, one of inorganic material substrates such as glass, silicon wafer, quartz, and metal substrates such as gold film, aluminum sheet, aluminum oxide and stainless steel.

[0055] According to one embodiment of the present application, the hydrophilic treatment of the substrate can be at least one of plasma treatment (such as air or oxygen plasma treatment), ultraviolet ozone irradiation, and oxidant solution oxidation (such as oxidation using a mixed solvent of one or both of concentrated sulfuric acid and hydrogen peroxide as an oxidant).

[0056] The present application also provides a method for preparing the microfluidic chip, comprising the following steps:

[0057] 1) using photolithography or printing to construct a soluble raised microstructure pattern in an organic solvent on a hydrophilic substrate to obtain a patterned substrate;

[0058] 2) coating a hydrophobic precursor or a monomer forming a hydrophobic precursor on the surface of the patterned substrate;

[0059] 3) heating the coated substrate at high temperature or using an ultraviolet exposure system to irradiate the coated substrate with ultraviolet light to cross-link and solidify the hydrophobic precursor;

[0060] 4) placing the converted substrate into a solvent that can dissolve the raised microstructure pattern and performing ultrasonic treatment to obtain the microfluidic chip.

[0061] According to one embodiment of the present application, in step 1), the hydrophilic substrate is defined as above.

[0062] According to one embodiment of the present application, in step 1), the raised microstructure pattern is constructed on the hydrophilic substrate using micro-nano processing technology. Specifically, the micro-nano processing technology can be one of photolithography, inkjet printing, micro-contact printing, etc.

[0063] According to one embodiment of the present application, in step 2), the hydrophobic precursor is defined as above.

[0064] According to one embodiment of the present application, in step 2), the coating process is spin coating, for example, the spin coating speed is 20-20000 rad / min.

[0065] According to one embodiment of the present application, in step 3), the central wavelength of the ultraviolet light used can be in the range of 180-405 nm, the irradiation power is 20-1 KW, and the exposure time is 20-120 minutes.

[0066] According to one embodiment of the present application, in step 3), the heating temperature in the high-temperature heating is 80-500℃.

[0067] According to one embodiment of the present application, in step 4), the ultrasonic treatment refers to a method of using solvent ultrasonic to dissolve or separate the raised microstructure pattern on the patterned substrate. Specifically, the solvent can be, but is not limited to, at least one of alkanes, alcohols, ethers, ketones or esters.

[0068] According to one specific embodiment, the steps 3) and 4) can be specifically:

[0069] 3) using a UV exposure system to irradiate the substrate coated with the hydrophobic precursor with ultraviolet light, so that the hydrophobic precursor is subjected to ceramic conversion;

[0070] 4) then immerse it in acetone for ultrasonic treatment, and when the raised microstructure pattern on the patterned substrate is completely dissolved in acetone or separated from the substrate, take out the substrate, then wash the substrate with water, and the microfluidic chip is obtained.

[0071] Exemplarily, the method specifically comprises:

[0072] 1) using photolithography or inkjet printing and other micro-nano processing means to construct a raised microstructure pattern that can be dissolved in an organic solvent on a hydrophilic substrate, to obtain a patterned substrate;

[0073] 2) coating a hydrophobic silicone precursor on the surface of the patterned substrate to obtain a substrate uniformly coated with the hydrophobic silicone precursor;

[0074] 3) using a UV exposure system to irradiate the substrate coated with the hydrophobic silicone precursor with ultraviolet light, so that the hydrophobic silicone precursor is subjected to ceramic conversion;

[0075] 4) immersing the substrate after ceramic conversion in acetone for ultrasonic treatment, and when the raised microstructure on the initial patterned substrate and the upper hydrophobic ceramic are completely dissolved in acetone or separated from the substrate, taking out the substrate, then washing the substrate with water, and the microfluidic chip of the present application is obtained.

[0076] Another object of the present application is to provide a use of the above-mentioned microfluidic chip, which can be used in the fields of DNA synthesis (specifically, inkjet printing DNA synthesis), droplet behavior regulation, self-assembly, microfluidics, high-precision printing, cell culture, virus detection, etc.

[0077] For example, in inkjet printing DNA synthesis, when ink droplets containing base pairs are printed on a hydrophilic-hydrophobic patterned chip, the hydrophobic region of the chip can directly separate and confine the ink droplets in the hydrophilic point region, realizing in-situ synthesis of DNA, and the height of the hydrophobic region of the chip is controllable and does not affect the fluid cleaning process during DNA synthesis, which can simplify the process of DNA synthesis and improve the synthesis efficiency.

[0078] For example, in the field of high-precision printing, when droplets are printed on a hydrophilic-hydrophobic patterned substrate, the hydrophobic regions of the substrate can divide and confine the droplets in the hydrophilic point regions, thereby inhibiting the spreading of the droplets on the substrate or non-printing regions and improving the printing precision.

[0079] For example, in the field of cell culture, since cells are hydrophilic, the hydrophilic-hydrophobic microfluidic chip of the present application can utilize the confinement of water to regulate the growth and culture area of the cells.

[0080] Similarly, in the field of virus detection, when droplets containing viruses are dropped on the hydrophilic-hydrophobic microfluidic chip of the present application, since the liquid is confined to the hydrophilic regions of the chip, the viruses will also preferentially accumulate in the hydrophilic regions of the chip, thereby improving the detection limit of the viruses and achieving high-sensitivity virus detection.

[0081] The technical solutions of the present application will be further described in detail below in conjunction with specific examples. It should be understood that the following examples are only illustratively described and explained, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is encompassed within the scope intended to be protected by the present application.

[0082] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0083] The preparation method of the hydrophilic-hydrophobic chip is as follows: Figure 1 As shown in the schematic diagram, the present application will be further described in detail below in conjunction with examples.

[0084] Example 1

[0085] A single-side polished silicon wafer was selected, and the size of the silicon wafer could be determined as needed. The surface of the silicon wafer was made super-hydrophilic by oxygen plasma treatment at a power of 200 w and a time of 200 s.

[0086] An automatic spin coater was used to spin coat photoresist AZ5214 on the silicon wafer substrate, and a photolithography system was used to construct a circular protrusion array with a height of about 1 μm and a diameter of about 200 μm, thereby preparing a patterned substrate.

[0087] An automatic spin coater was used to spin coat a hydrophobic organosilicon precursor, polysilazane (IOTA9108), on the patterned substrate. First, the precursor was spin coated at 500 rad / min for 10 seconds, and then spin coated at 5000 rad / min for 30 seconds, so that the precursor uniformly covered the surface of the patterned substrate.

[0088] An ultraviolet exposure system was used to irradiate and expose the precursor, so that the precursor was converted into ceramic. The exposure intensity of the ultraviolet light used was about 40 mW / cm 2, and the exposure time was 50 minutes.

[0089] The exposed patterned substrate was immersed in acetone using tweezers and was ultrasonically treated for 2 hours. After the ultrasonic treatment, the substrate was placed in deionized water and was repeatedly washed. Finally, the silicon wafer was pulled out of the water and was dried using nitrogen. A silicon wafer having a patterned surface of hydrophilic and hydrophobic regions was obtained, i.e., a chip of the present application. The height of the hydrophobic region of the chip was about 2-2.5 μm, and the contact angle was about 95-115°. The contact angle of the hydrophilic region of the chip was about 10-25°.

[0090] The chip was pulled out of the water and was found to have good liquid droplet confining properties, and could be directly used to prepare patterned microdroplets. The stability of the chip was tested by immersing the chip in acetone for 24 hours. After drying with nitrogen, the chip was tested for the patterned hydrophilic and hydrophobic regions, and the liquid droplet confining properties were found to remain unchanged. Subsequently, the chip was used to separate and prepare patterned microdroplets of various liquids.

[0091] Figure 1 Schematic diagram: preparation process of the chip having patterned hydrophilic and hydrophobic regions; Figure 2 Optical micrograph: patterned substrate after photolithography; Figure 3 Optical micrograph: chip having patterned hydrophilic and hydrophobic regions after ceramic conversion; Figure 4 Test photograph: height distribution of the chip tested by a step profiler; Figure 5 Test photograph: contact angle of the hydrophobic region of the chip; Figure 6 Test photograph: contact angle of the hydrophilic region of the chip.

[0092] Example 2

[0093] A single-side polished silicon wafer was selected, and the size of the silicon wafer could be determined according to requirements. The silicon wafer was treated by boiling in an eel solution (mass ratio of concentrated sulfuric acid 70% and hydrogen peroxide 30%) for 2 hours, so that the surface of the silicon wafer became super-hydrophilic.

[0094] The photoresist AZ5214 was used to form a raised square lattice having a height of about 500 nm and a side length of about 50 μm by microcontact printing, and a patterned substrate was prepared.

[0095] The hydrophobic organosilicon precursor polysilazane (IOTA9108) was spin-coated on the patterned substrate using an automatic spin coater. The precursor was uniformly coated on the surface of the patterned substrate by spin coating at 50 rad / min for 10 seconds and then at 7000 rad / min for 30 seconds.

[0096] The precursor was irradiated and exposed using a UV exposure system, so that the precursor was subjected to ceramic conversion. The exposure intensity of the UV light used was about 40 mW / cm2 The exposure time is 20 minutes.

[0097] The exposed patterned substrate is immersed into toluene with tweezers and treated with ultrasonic for 2 hours. After the ultrasonic treatment, the substrate is put into deionized water and cleaned repeatedly. Finally, the silicon wafer is pulled out of the water and dried with nitrogen. The silicon wafer with hydrophobic and hydrophilic patterned surface is obtained, which is composed of hydrophobic ceramic (convex microstructure) and hydrophilic silicon wafer (plane), namely the chip of the present application. The height of the chip hydrophobic region is 400-500 nm, and the contact angle is about 100-115°. The contact angle of the chip hydrophilic region is about 10-25°.

[0098] The chip is pulled out of the water, and it is found that the chip has good confined droplet performance and can directly realize the patterned preparation of water microdroplets. The stability of the chip is tested. The chip is immersed in acetone for 24 hours, dried with nitrogen, and then tested for hydrophobic and hydrophilic patterning. It is found that the performance of the confined droplet can still be maintained. Subsequently, the chip is applied to the printing synthesis of DNA. The hydrophilic region of the chip can well confine the multiple printing of base droplets, and the chip can tolerate any organic solvent in the synthesis process without affecting the cleaning process of the solvent in the DNA synthesis process. The steps of DNA synthesis can be simplified, and the rate of DNA synthesis can be improved.

[0099] Example 3

[0100] A suitable silica glass substrate is selected. The size of the glass can be cut according to the needs. The surface of the glass substrate is made super-hydrophilic by oxygen plasma treatment at a power of 200 w and for 200 s.

[0101] Inkjet printing is used to print liquid polydimethylsiloxane siloxane into convex circular dot matrix with a height of about 1 μm and a diameter of about 50 μm to prepare a patterned substrate.

[0102] A hydrophobic fluorinated polysiloxane is spin-coated on the patterned substrate using an automatic spin coater. The precursor is uniformly coated on the surface of the patterned substrate by spin coating at 100 rad / min for 10 seconds and then at 8000 rad / min for 30 seconds.

[0103] The patterned substrate is heated at a high temperature to perform ceramic conversion of the precursor. The heating temperature is 200°C, and the heating time is 60 minutes.

[0104] The patterned substrate converted by heating is immersed into acetone for ultrasonic treatment for 3 hours. After ultrasonic treatment, the substrate is placed into deionized water for repeated cleaning. Finally, the silicon wafer is pulled out of water and dried by nitrogen to obtain a silicon wafer with a patterned surface of hydrophobic ceramic (protruding microstructure) and hydrophilic silicon dioxide glass (plane), i.e. the chip of the application.

[0105] The height of the hydrophobic region of the chip is about 1.5-2 μm, and the contact angle is 100-106°. The contact angle of the hydrophilic region of the chip is about 10-20°.

[0106] The chip is pulled out of water, and it is found that the chip has good liquid droplet confining performance and can directly realize the patterned preparation of water microdroplets. The stability of the chip is tested. The chip is immersed in toluene for 24 hours, dried by nitrogen, and then tested for hydrophobic and hydrophilic patterns. It is found that the liquid droplet confining performance of the chip can still be maintained. Subsequently, the chip is applied to high-precision inkjet printing. The chip can effectively suppress the coffee ring effect of ink droplets, reduce the printing radius of ink droplets, and the minimum diameter of a single point can reach 2 μm, which can effectively improve the precision of inkjet printing.

[0107] Example 4

[0108] A suitable aluminum plate substrate is selected. The size of the aluminum plate can be cut according to needs. The surface of the aluminum plate substrate is made super-hydrophilic by oxygen plasma treatment at a power of 250 W for 250 s.

[0109] An automatic spin coater is used to spin coat photoresist AZ1500 on the aluminum plate substrate. A photoetching process is used to construct a protruding circular dot array with a height of about 1 μm and a diameter of about 50 μm to prepare a patterned substrate.

[0110] An automatic spin coater is used to spin coat perfluoropolydimethylsiloxane on the patterned substrate. The precursor is uniformly coated on the surface of the patterned substrate by spin coating at 100 rad / min for 10 seconds and then at 8000 rad / min for 30 seconds.

[0111] The patterned substrate is heated at a high temperature to convert the precursor into ceramic. The heating temperature is 200°C, and the heating time is 60 minutes.

[0112] The patterned substrate converted by heating is immersed into acetone for ultrasonic treatment for 3 hours. After ultrasonic treatment, the substrate is placed into deionized water for repeated cleaning. Finally, the silicon wafer is pulled out of the water and dried by nitrogen to obtain a silicon wafer with a patterned surface of hydrophobic ceramic (protruding microstructure) and hydrophilic aluminum plate (plane), i.e. the chip of the application. The height of the hydrophobic region of the chip is about 300-500 nm, and the contact angle is about 95-102°. The contact angle of the hydrophilic region of the chip is about 10-30°.

[0113] The chip is pulled out of the water to directly realize the patterned preparation of microdroplets. The stability of the chip is tested by immersing the chip in toluene for 48 hours. After drying by nitrogen, the chip is tested for hydrophobic and hydrophilic patterns. It is found that the performance of the confined droplets can still be maintained. Subsequently, the chip is applied to virus detection. First, the chip is soaked in an antibody solution. The antibody is grafted to the hydrophilic region of the chip by base pairing. When a droplet containing a virus is added to the chip, the droplet can automatically enrich from the hydrophobic region to the hydrophilic region and react with the antibody on the hydrophilic region, thereby greatly improving the detection sensitivity of the virus.

[0114] Example 5

[0115] A gold film substrate with a suitable thickness is prepared on a silicon wafer. The size of the substrate can be cut according to needs. The gold film substrate is treated by boiling piranha solution (mass ratio of concentrated sulfuric acid 70% and hydrogen peroxide 30%) for 2 hours to make the surface of the gold film super-hydrophilic.

[0116] An automatic spin coater is used to spin coat photoresist AZ1500 on the patterned gold film substrate. Photolithography is used to construct a protruding circular lattice with a height of about 3 μm and a diameter of about 100 μm to prepare a patterned substrate.

[0117] An automatic spin coater is used to spin coat organosilicon precursor polysilazane (IOTA 9108) on the gold film substrate. The precursor is uniformly coated on the surface of the patterned substrate by first spin coating at 50 rad / min for 10 seconds and then spin coating at 7000 rad / min for 30 seconds.

[0118] The precursor is irradiated and exposed by a UV exposure system to convert the precursor into ceramic. The exposure intensity of the UV light used is about 10 mW / cm 2 , and the exposure time is 70 minutes.

[0119] The patterned substrate after ceramic conversion is immersed in acetone for ultrasonic treatment for 3h, and after ultrasonic treatment, the substrate is put into deionized water for repeated cleaning, and finally the chip is pulled out of the water and dried with nitrogen, to obtain a silicon wafer with a hydrophobic and hydrophilic patterned surface composed of hydrophobic ceramic (convex microstructure) and hydrophilic gold film (plane), i.e. the chip of the application. The height of the chip hydrophobic region is about 200-300nm, and the contact angle is about 95-107°, and the contact angle of the chip hydrophilic region is about 5-15°.

[0120] The chip is pulled out of the water, which can directly realize the patterned preparation of microdroplets; the stability of the chip is tested by immersing the chip in toluene for 48h, and after nitrogen blowing, the hydrophobic and hydrophilic patterned test is carried out, and it is found that the performance of the confined droplets can still be maintained. Subsequently, we applied the chip to the printing synthesis of DNA, and the hydrophilic region of the chip can well confine the multiple printing of base droplets, and the chip can tolerate any organic solvent in the synthesis process, and will not affect the cleaning process of the solvent in the DNA synthesis, and is very suitable for DNA synthesis.

[0121] The anti-oxidation and anti-corrosion performance of the chip in Examples 1-5 is further determined, and the specific test results are as follows: the chip is long-term exposed to ultraviolet ozone and salt solution environment, and its structure and performance will not be damaged.

[0122] As can be seen from the above examples, the chip prepared by the application has excellent droplet confinement performance, can realize the patterning of various liquids, and will not be affected by organic solvents, is corrosion resistant and oxidation resistant, and has important practical application value.

[0123] The above illustrates the exemplary embodiments of the application. However, the protection scope of the present application is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fabricating a microfluidic chip, the chip comprising a hydrophilic substrate and a hydrophobic pattern on the surface of the hydrophilic substrate, characterized in that, The hydrophobic pattern is composed of a cross-linked cured product of a hydrophobic precursor; The method comprises the following steps: 1) constructing a soluble-in-organic-solvent raised microstructure pattern on a hydrophilic substrate using photolithography or printing to obtain a patterned substrate; 2) coating a hydrophobic silicone precursor on the surface of the patterned substrate to obtain a substrate uniformly coated with the hydrophobic silicone precursor; 3) using a UV exposure system to irradiate the substrate coated with the hydrophobic silicone precursor with ultraviolet light to cause ceramic conversion of the hydrophobic silicone precursor; 4) immersing the substrate after ceramic conversion in a solvent that can dissolve the raised microstructure pattern, performing ultrasonic treatment, and when the raised microstructure on the initial patterned substrate and the upper hydrophobic ceramic are completely dissolved in the solvent that can dissolve the raised microstructure pattern or separated from the substrate, taking out the substrate, and then washing the substrate with water to obtain the microfluidic chip.

2. The production method according to claim 1, characterized by, The hydrophobic pattern is higher than the surface of the hydrophilic substrate; And / or, the height of the hydrophobic pattern ranges from 10 nm to 100 μm; And / or, the area of the hydrophobic pattern accounts for 1% to 99% of the hydrophilic substrate; And / or, the hydrophobic pattern is an arbitrary regular pattern or an irregular pattern.

3. The method of claim 1, wherein, The hydrophobic silicone precursor is selected from at least one of organic polysilazane, perhydropolysilazane, cyclopenta polydimethylsiloxane, fluorinated polysiloxane, and a mixture of organic polysilazane or perhydropolysilazane and epoxy photocuring resin.

4. The method of claim 1, wherein, In step 1), the raised microstructure pattern is constructed on the hydrophilic substrate using micro-nano processing technology; And / or, in step 2), the coating process is spin coating.

5. The preparation method according to claim 1, characterized in that, In step 3), the central wavelength of the ultraviolet light used ranges from 180 nm to 405 nm, the irradiation power is 20 W to 1 KW, and the exposure time is 20 minutes to 120 minutes.

6. Use of the microfluidic chip prepared by the method according to any one of claims 1-5, characterized in that, The chip is used in the fields of inkjet printing DNA synthesis, droplet behavior control, self-assembly, microfluidics, high-precision printing, cell culture, and virus detection.

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