A controllable patterned wetting microfluidic chip and a preparation method thereof

Abstract

This invention discloses a controllable patterned wetting microfluidic chip and its preparation method. The preparation method includes the following steps: injecting an alkaline solution into a glass chip channel and allowing it to stand to hydroxylate the surface of the glass chip channel; after standing, cleaning and drying the glass chip channel; then preparing a hydrophobic film on the surface of the glass chip channel; subsequently treating the hydrophobic film to adjust the hydrophobicity of a preset area of ​​the hydrophobic film, thereby obtaining the controllable patterned wetting microfluidic chip. This invention, by preparing a hydrophobic film on the surface of the glass chip channel and then treating it to adjust the hydrophobicity of a preset area, enables the glass chip channel to have different surface properties, fully replicating the complex wetting properties of oil reservoirs. Furthermore, the contact angle can be freely adjusted according to the formation properties, achieving controllable patterned wetting. The fabrication process is simple, low-cost, and does not require expensive equipment.

Description

Technical Field

[0001] This invention belongs to the field of microfluidics technology, and in particular to an adjustable patterned wetting microfluidic chip and its preparation method. Background Technology

[0002] In recent years, microfluidic chip technology has been widely applied in fields such as chemistry, analysis, biology, and medicine, and it also has significant applications in oilfield development. Microfluidic technology can reproduce the micron- and nanon-scale pore structures of oil reservoirs and observe the flow and phase transition processes of reservoir fluids and displacing phase fluids within these structures in situ. Compared with traditional core displacement experiments, microfluidic technology offers advantages such as real-time visualization, small confined scale, low sample consumption, and short measurement time. A crucial characteristic in oil reservoir development engineering is the wettability of core pore surfaces, which influences fluid flow patterns, oil displacement efficiency, residual oil saturation, and bound water saturation in porous media. The wettability of rock pore surfaces in formations can be oil-wet, water-wet, or mixed-wet, with mixed-wetting being the most common. However, current microfluidic technologies lack the ability to continuously adjust wettability, making it difficult to reproduce the complex wetting properties of reservoirs with locally different or multiple surface properties. Summary of the Invention

[0003] To address the current limitations of microfluidics in continuously adjusting wettability and in representing the complex wettability of reservoirs with varying surface properties, this invention provides an adjustable patterned wettability microfluidic chip and its fabrication method. The chip channel obtained by this invention can exhibit two or more surface properties, fully reproducing the complex wettability of reservoirs. Furthermore, the contact angle can be freely adjusted according to formation properties. The fabrication process is simple, low-cost, and requires no expensive equipment.

[0004] The present invention adopts the following technical solution:

[0005] A method for fabricating an adjustable patterned wetting microfluidic chip includes the following steps:

[0006] An alkaline solution is injected into the glass chip channel and allowed to stand to hydroxylate the surface of the glass chip channel, which makes it easier for subsequent hydrophobic groups to be grafted. After standing, the glass chip channel is cleaned and dried.

[0007] A hydrophobic film is then prepared on the surface of the glass chip channel. The hydrophobic film is then treated to adjust the hydrophobicity of the hydrophobic film in a preset area, thereby obtaining the adjustable patterned wetting microfluidic chip.

[0008] Preferably, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the concentration of the strong alkaline solution is 1-1.2 mol / L, and the standing time is 10-15 min.

[0009] Preferably, after the glass chip channel has been left to stand, it is cleaned and dried by alternately injecting deionized water and anhydrous ethanol into the glass chip channel several times to clean it. Then, air is injected to dry the glass chip channel.

[0010] Preferably, when preparing a hydrophobic film on the surface of the glass chip channel, a dichlorodimethylsilane solution is injected into the glass chip channel, and then heated to form a hydrophobic film on the surface of the glass chip channel. Then, deionized water and anhydrous ethanol are alternately injected into the glass chip channel several times to clean the glass chip channel. Finally, air is injected to dry the glass chip channel.

[0011] Preferably, when forming a hydrophobic film on the surface of the glass chip channel, the heating temperature is 70-75℃ and the holding time is 1-1.5h.

[0012] Preferably, the mass concentration of the solute in the dichlorodimethylsilane solution is 8%-12%, and the solvent is n-hexane or toluene.

[0013] Preferably, when treating the hydrophobic membrane and adjusting the hydrophobicity of the hydrophobic membrane in the preset area, the hydrophobicity of the hydrophobic membrane in the preset area is adjusted by covering the membrane with a mask and irradiating the membrane with ultraviolet light.

[0014] Preferably, the ultraviolet light wavelength is 185 nm and 254 nm, and the ultraviolet light intensity is 200-220 mW / cm². 2 .

[0015] Preferably, the glass chip is made of soda-lime glass.

[0016] The present invention also provides an adjustable patterned wetting microfluidic chip, which is prepared by the preparation method described above.

[0017] The present invention has the following beneficial effects:

[0018] This invention prepares a hydrophobic film on the surface of a glass chip channel, and then treats the hydrophobic film to adjust the hydrophobicity of the film in a preset area. This allows the glass chip channel to have different surface properties, which can fully reproduce the complex wettability of the reservoir. Furthermore, the contact angle can be freely adjusted according to the formation properties, enabling controllable patterned wetting. The manufacturing process is simple, low-cost, and can be prepared without expensive equipment. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the ultraviolet irradiation device used in an embodiment of the present invention;

[0020] Figure 2 These are contact angle test diagrams of the hydrophobic modified chip under different irradiation times in embodiments of the present invention;

[0021] Figure 3 This is a schematic diagram of the experimental process of adjustable patterning of hydrophobic glass under ultraviolet irradiation in Embodiment 5 of the present invention.

[0022] In the diagram, 1-ultraviolet light source, 2-mask, 3-glass chip, 4-adjustable bracket, 5-hydrophobic channel glass chip, 6-first mask, 7-second mask, 3-third mask. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] The adjustable patterned wetting microfluidic chip of this invention is formed by irradiating ultraviolet light with a hydrophobically modified glass chip under different masks; the hydrophobic modifier is derived from dichlorodimethylsilane, and the ultraviolet light wavelengths are 185 and 254 nm.

[0025] The principle of this invention is as follows:

[0026] Due to the properties of glass, the glass channel of a microfluidic chip exhibits hydrophilic wettability. After dichlorodimethylsilane combines with the silanol groups on the glass chip, a hydrophobic film is formed inside the glass channel, changing the glass channel from hydrophilic to hydrophobic. The dichlorodimethylsilane hydrophobic coating on the glass channel gradually decomposes under irradiation with ultraviolet light at a wavelength of 254nm, thus gradually restoring the glass channel to its hydrophilicity. In the preparation process of this invention, a mask is made based on this principle to prepare a patterned microfluidic chip by irradiating different parts of the glass chip with different times.

[0027] Compared to conventional microfluidic chips, this invention uses dichlorodimethylsilane as a hydrophobic modifier for the microfluidic chip, allowing dichlorodimethylsilane to form a hydrophobic film in the microfluidic glass chip channel. Then, a mask is placed on top and irradiated directly from above with ultraviolet light. Compared to conventional microfluidic chips, the chip channel in this invention can have two or more surface properties, which can fully reproduce the complex wettability of oil reservoirs. Furthermore, the contact angle can be freely adjusted according to the formation properties, enabling controllable patterned wetting. The manufacturing process is simple, low-cost, and can be prepared without expensive equipment.

[0028] The specific operation of the preparation method of the present invention is as follows:

[0029] Prepare a strong alkali solution, using potassium hydroxide or sodium hydroxide as the strong alkali, with a concentration of 1-1.2 mol / L; prepare a dichlorodimethylsilane solution, with a solute concentration of 8 wt%-12 wt%, using n-hexane or toluene as the solvent;

[0030] A prepared strong alkaline solution was injected into the glass chip channel and allowed to stand for 10-15 minutes. The glass chip thickness was 6 mm, and the material was soda-lime glass. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, a prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 70-75℃ for 1-1.5 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 nm and 254 nm and an intensity of 200-220 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip. By irradiating with different masks multiple times, different wetting environments can be created as required.

[0031] As can be seen from the above scheme, the present invention uses dichlorodimethylsilane as a hydrophobic modifier for microfluidic chips, so that dichlorodimethylsilane forms a hydrophobic film in the microfluidic glass chip channel. Then, a mask is placed on it and ultraviolet light is irradiated from directly above. Two or more surface properties can exist, which can completely reproduce the complex wettability of oil reservoirs. Moreover, the contact angle can be freely adjusted according to the formation properties, and controllable patterned wetting can be achieved. The manufacturing process is simple, low cost, and can be prepared without expensive equipment.

[0032] See Figures 1-3 The distance of the embodiments of the present invention is explained as follows.

[0033] Example 1

[0034] A strong alkali solution was prepared, with potassium hydroxide as the strong alkali and a concentration of 1.0 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 8 wt% and hexane as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 10 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 70°C and held at that temperature for 1 hour. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 200 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0035] Figure 1 This is a schematic diagram of an ultraviolet irradiation device. As you can see, the chip is covered by a mask and is directly below the ultraviolet lamp. The contact angle of the part irradiated by ultraviolet light will gradually decrease, and the hydrophilicity of the glass will gradually be restored. The part not irradiated by ultraviolet light will remain hydrophilic, so that the wettability of the chip can be controlled and patterned.

[0036] Example 2

[0037] A strong alkali solution was prepared, with sodium hydroxide as the strong alkali and a concentration of 1.2 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 12 wt% and toluene as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 15 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 75°C and held at that temperature for 1.5 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 220 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0038] Example 3

[0039] A strong alkali solution was prepared, with potassium hydroxide or sodium hydroxide as the strong alkali and a concentration of 1.1 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 10 wt% and hexane as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 12 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 72°C and held at that temperature for 1.2 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 nm and 254 nm and an intensity of 210 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0040] Example 4

[0041] A strong alkali solution was prepared, with sodium hydroxide as the strong alkali and a concentration of 1.2 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 9 wt% and hexane as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 13 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 70°C and held at that temperature for 1 hour. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 200 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0042] Example 5

[0043] A strong alkali solution was prepared, with sodium hydroxide as the strong alkali and a concentration of 1.1 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 8 wt% and hexane as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 14 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 75°C and held at that temperature for 1 hour. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 220 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0044] Figure 2 The image shows the contact angle test results of the hydrophobic modified chip under different irradiation times. It tests the change of the contact angle of the hydrophobic modified chip with the duration of ultraviolet irradiation when oil and water are present at the same time. It can be seen that the contact angle of the hydrophobic modified chip gradually decreases with the increase of ultraviolet irradiation time, which is consistent with the expected results.

[0045] Figure 3 This is a schematic diagram of the experimental process of adjustable patterning of hydrophobic glass under ultraviolet irradiation in Example 5. It can be seen that after three irradiations with different masks, the microfluidic chip has more than two surface properties, which can completely reproduce the complex wettability of the reservoir. The contact angle is 113° after 5 hours of irradiation, 95° after 10 hours of irradiation, and 51° after 45 hours of irradiation, realizing the adjustable patterning of the wettability of the microfluidic chip.

[0046] Example 6

[0047] A strong alkali solution was prepared, with potassium hydroxide as the strong alkali and a concentration of 1.2 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 11 wt% and toluene as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 15 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 73°C and held at that temperature for 1.4 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 215 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0048] Example 7

[0049] A strong alkali solution was prepared, with sodium hydroxide as the strong alkali and a concentration of 1.2 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 11 wt% and hexane as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 10 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 71°C and held at that temperature for 1.1 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 205 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0050] Example 8

[0051] A strong alkali solution was prepared, with potassium hydroxide as the strong alkali and a concentration of 1.1 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 12 wt% and toluene as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 13 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 74°C and held at that temperature for 1.4 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 213 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0052] Example 9

[0053] A strong alkali solution was prepared, with sodium hydroxide as the strong alkali and a concentration of 1.0 mol / L. A dichlorodimethylsilane solution was also prepared, with a solute concentration of 11 wt% and hexane as the solvent. The prepared strong alkali solution was injected into the glass chip channel and allowed to stand for 12 minutes. Then, deionized water and anhydrous ethanol were alternately injected into the glass chip channel three times. Air was then injected to dry the chip channel. Next, the prepared dichlorodimethylsilane solution was injected into the glass chip channel, and the chip was placed in an oven at 70°C and held at that temperature for 1.4 hours. Again, deionized water and anhydrous ethanol were alternately injected three times. Air was then injected to dry the chip channel, resulting in a hydrophobically modified glass microfluidic chip. A mask was then placed over the hydrophobically modified glass microfluidic chip, and the chip was irradiated under a UV lamp with wavelengths of 185 nm and 254 nm and an intensity of 208 mW / cm². 2 After irradiation for 5 hours, the mask was replaced and irradiation continued for another 5 hours. Then, the mask was replaced and irradiation continued for another 35 hours to obtain an adjustable patterned wetting microfluidic chip.

[0054] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A method for fabricating a tunable patterned wetting microfluidic chip, characterized in that, The process includes the following: An alkaline solution is injected into the glass chip channel and allowed to stand to hydroxylate the surface of the glass chip channel. After standing, the glass chip channel is cleaned and dried. Then, a hydrophobic film is prepared on the surface of the glass chip channel, and then the hydrophobic film is treated to adjust the hydrophobicity of the hydrophobic film in a preset area to obtain the adjustable patterned wetting microfluidic chip. To prepare a hydrophobic film on the surface of a glass chip channel, a dichlorodimethylsilane solution is injected into the glass chip channel, followed by heating to form a hydrophobic film on the surface of the glass chip channel. Then, deionized water and anhydrous ethanol are alternately injected into the glass chip channel several times to clean it. Air is then injected to dry the glass chip channel, resulting in a hydrophobically modified glass microfluidic chip. The mass concentration of the solute in the dichlorodimethylsilane solution is 8%-12%, and the solvent used is n-hexane or toluene. Next, a mask was applied to the hydrophobically modified glass microfluidic chip, and then it was irradiated under a UV lamp with wavelengths of 185 and 254 nm and an intensity of 200-220 mW / cm². 2 After irradiation for a certain period of time, the mask is replaced and irradiation continues for a certain period of time. After that, the mask is replaced and irradiation continues for a certain period of time to obtain an adjustable patterned wetting microfluidic chip.

2. The method for fabricating a tunable patterned wetting microfluidic chip according to claim 1, characterized in that, The alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the concentration of which is 1-1.2 mol / L, and the standing time is 10-15 min.

3. The method for fabricating an adjustable patterned wetting microfluidic chip according to claim 1, characterized in that, After the settling period, clean the glass chip channel and dry it. Then, alternately inject deionized water and anhydrous ethanol into the glass chip channel several times to clean it. Finally, inject air to dry the glass chip channel.

4. The method for fabricating a tunable patterned wetting microfluidic chip according to claim 1, characterized in that, When forming a hydrophobic film on the surface of the glass chip channel, the heating temperature is 70-75℃ and the holding time is 1-1.5h.

5. The method for fabricating a tunable patterned wetting microfluidic chip according to claim 1, characterized in that, The glass chip is made of soda-lime glass.

6. A patterned wetting microfluidic chip with adjustable properties, characterized in that, The adjustable patterned wetting microfluidic chip is prepared by the method described in any one of claims 1-5.

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