Quartz glass micro-channel structure of PDMS inner wall and preparation method thereof

Abstract

The invention provides a quartz glass microchannel structure with a PDMS inner wall and a preparation method of the quartz glass microchannel structure, and aims to solve the problems that the microchannel inner wall of existing quartz glass is rough, the volatilization process of a solution in a microchannel is uncontrollable when an organic matter film is prepared on the microchannel inner wall by adopting a solvent volatilization film forming method, the thickness uniformity of the film is poor, and the service life of the film is prolonged. When the concentration of the solution is low, a continuous film is difficult to form along the longitudinal direction of the micro-channel, or when the concentration of the solution is high, organic matters are easy to block the micro-channel after the solvent is volatilized. According to the preparation method of the quartz glass micro-channel structure with the PDMS inner wall, the PDMS thin film is prepared on the micro-channel inner wall of the quartz glass by adopting a method of low-temperature treatment, gradient thermocuring and constant-pressure blowing, the obtained PDMS thin film is good in continuity and uniformity, and the roughness of the micro-channel inner wall of the quartz glass can be remarkably improved.

Description

Technical Field

[0001] The invention relates to a quartz glass microchannel structure and a processing technology thereof, and in particular to a quartz glass microchannel structure with a PDMS inner wall and a preparation method thereof. Background Art

[0002] Microfluidic chips cleverly integrate complex experimental processes on a chip platform, achieving miniaturization, integration, and automation of experimental operations. They are widely used in detection in biology, chemistry, and other fields.

[0003] At present, quartz glass is a commonly used microchannel structure in microfluidic chips, and femtosecond laser wet etching is usually used to prepare microchannels inside quartz glass. However, due to the pulsed light characteristics of femtosecond laser, the femtosecond laser is modified point by point when it is focused inside the material, so the modified area is not uniform, resulting in a rough inner wall of the microchannel prepared by femtosecond laser wet etching, which limits the application scope of quartz glass in microfluidic chips to a certain extent.

[0004] In order to improve the roughness of the inner wall of the quartz glass microchannel, a smooth surface film can be covered on the inner wall of the microchannel as a modification layer. At present, the solvent evaporation film-forming method is mainly used to prepare organic thin films on the inner wall of the microchannel, but the solvent evaporation film-forming method has many disadvantages: the evaporation process of the solution in the microchannel is uncontrollable, resulting in poor uniformity of the film thickness; when the solution concentration is low, it is difficult to form a continuous film along the longitudinal direction of the microchannel; when the solution concentration is high, organic matter is prone to block the microchannel after the solvent evaporates. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems that the inner wall of the existing quartz glass microchannel is relatively rough, and the volatilization process of the solution in the microchannel when the organic film is prepared on the inner wall of the microchannel by the solvent volatilization film-forming method is uncontrollable, resulting in poor uniformity of film thickness, or when the solution concentration is low, it is difficult to form a continuous film along the longitudinal direction of the microchannel, or when the solution concentration is high, the organic matter is easy to block the microchannel after the solvent evaporates, and to provide a quartz glass microchannel structure with a PDMS inner wall and a preparation method thereof.

[0006] In order to achieve the above object, the technical solution provided by the present invention is:

[0007] A quartz glass microchannel structure with a PDMS inner wall, wherein a plurality of microchannels are arranged in the quartz glass; the special feature of the structure is that a PDMS film is arranged on the inner wall of the microchannel.

[0008] Furthermore, the PDMS film is formed by mixing and curing polydimethylsiloxane and a curing agent in a weight ratio of 20:1 to 5:1.

[0009] In addition, the present invention also provides a method for preparing the quartz glass microchannel structure of the PDMS inner wall, which is special in that it comprises the following steps:

[0010] Step 1, using a femtosecond laser to scan a modified area inside the selected quartz glass according to a preset path;

[0011] Step 2, immersing the quartz glass with the modified area scanned out in an etching solution, so that the modified area of ​​the quartz glass is etched into a microchannel;

[0012] Step 3, filling the PDMS solution into the microchannel of the quartz glass; the PDMS solution contains polydimethylsiloxane and a curing agent in a weight ratio of 20:1 to 5:1;

[0013] Step 4, heating the quartz glass, and when the PDMS solution near the inner wall of the quartz glass microchannel is in a solidified state and the PDMS solution near the center is in a semi-solidified state, blowing away the semi-solidified PDMS solution in the center of the microchannel by blowing;

[0014] Step 5, further heating and curing the PDMS film initially formed on the inner wall of the microchannel to form a continuous and smooth PDMS film, thereby completing the preparation of the quartz glass microchannel structure.

[0015] Furthermore, the method further comprises step 6:

[0016] The gas flow through the uncoated microchannel and the coated microchannel is detected by a flow meter to obtain a corresponding curve of gas flow and pore size, and the inner wall diameter of the microchannel with the PDMS film can be converted.

[0017] Furthermore, in step 4, when the quartz glass is heated, the heating temperature and time can be obtained by experiment.

[0018] Furthermore, in step 4, the PDMS solution is a PDMS solution that has been subjected to a low-temperature treatment in a low-temperature environment of -10 to 5°C.

[0019] Furthermore, in step 4, a constant pressure air source of 0.5 to 0.8 MPa is used for blowing.

[0020] Furthermore, in step 5, the heating temperature for further heating and curing the remaining PDMS film in the microchannel is 60 to 80° C., and the heating time is 20 to 50 minutes.

[0021] Furthermore, in step 4, when the quartz glass is heated, the heating temperature is 60 to 85° C. and the heating time is 1 to 25 minutes.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention provides a quartz glass microchannel structure with a PDMS inner wall, wherein a PDMS film is arranged on the inner wall of the microchannel, and the PDMS film has good thickness uniformity, which effectively improves the roughness of the inner wall of the quartz glass microchannel and can be widely used in various fields such as microfluidic chips.

[0024] 2. The present invention provides a method for preparing a quartz glass microchannel structure with a PDMS inner wall, which adopts a method of low-temperature treatment + gradient thermal curing + constant pressure blowing to prepare a continuous and smooth PDMS film on the inner wall of the microchannel. The PDMS film prepared by this method has good continuity and uniformity, and can significantly improve the roughness of the inner wall of the microchannel.

[0025] 3. The method for preparing a quartz glass microchannel structure with a PDMS inner wall provided by the present invention has a strong controllability and many adjustable parameters in the process of preparing a thin film on the inner wall of a microchannel compared to the existing solvent volatilization film-forming method, and there will be no phenomenon such as film discontinuity or channel clogging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flow chart of an embodiment of a method for preparing a quartz glass microchannel structure with a PDMS inner wall, wherein (a) is a schematic diagram of laser modification in step 1, (b) is a schematic diagram of wet etching of a microchannel in step 2, (c) is a schematic diagram of preparing a PDMS solution in step 3, (d) is a schematic diagram of low temperature treatment of a PDMS solution in step 3, (e) is a schematic diagram of filling a PDMS solution in step 3, (f) is a schematic diagram of heating pre-curing in step 4, (g) is a schematic diagram of blowing off a semi-cured PDMS solution in the center of a microchannel in step 4, and (h) is a schematic diagram of further curing of a PDMS film in step 5. DETAILED DESCRIPTION

[0027] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The present invention provides a quartz glass microchannel structure with a PDMS inner wall, which adopts a mixture of polydimethylsiloxane (PDMS) and a curing agent in a weight ratio of 20:1 to 5:1, and solidifies the PDMS film on the inner wall of the microchannel to effectively improve the roughness of the inner wall of the quartz glass microchannel.

[0029] like Figure 1 As shown, a method for preparing a quartz glass microchannel structure with a PDMS inner wall specifically comprises the following steps:

[0030] Step 1, laser modification.

[0031] In this embodiment, fused quartz is selected as the substrate, the selected fused quartz is placed on a three-dimensional processing platform, and a femtosecond laser generated by a fiber laser is focused inside the fused quartz using an objective lens with a magnification of 100x. The laser power is set to 400mW, the scanning speed is set to 200μm / s, and the modified area is scanned according to the preset path, such as Figure 1 In other embodiments of the present invention, the femtosecond laser can also be generated by titanium sapphire laser, light conversion laser and other lasers.

[0032] Step 2, wet etching of microchannels.

[0033] A 2 mol / L KOH solution was placed in a constant temperature oil bath at 95°C, and the fused quartz scanned for the modified area was immersed in the KOH solution for etching for 30 hours. The modified area was etched away to form a microchannel, such as Figure 1 (b) as shown.

[0034] Then, the fused quartz with the microchannel etched was immersed in an alcohol solution with a volume concentration of 85% and ultrasonically cleaned for 25 minutes, and then ultrasonically cleaned with deionized water for 8 minutes, and then taken out and dried.

[0035] Step 3, filling with PDMS solution.

[0036] First, you need to prepare a PDMS solution. Specifically, mix polydimethylsiloxane and curing agent in a weight ratio of 20:1 to 5:1, and stir them manually or magnetically for 2 to 5 minutes to fully mix them to obtain a uniformly mixed PDMS solution. Place the uniformly mixed PDMS solution in a vacuum bucket and evacuate it for 20 to 30 minutes to remove bubbles in the PDMS solution. Figure 1 (c) as shown.

[0037] Then the prepared PDMS solution was taken out from the vacuum chamber and placed in a low temperature environment of 0°C for 30 min. Figure 1 Finally, the PDMS solution after low temperature treatment is filled into the microchannel of the quartz glass until it is full, as shown in Figure 1 (e) as shown.

[0038] Step 4: pre-curing by heating to blow off the semi-cured PDMS solution in the center of the microchannel.

[0039] The quartz glass was placed in a constant temperature heater at 80 °C and heated for 3 min for pre-curing, so that the PDMS solution near the inner wall of the microchannel was in a solidified state, and the PDMS solution near the center of the microchannel was in a semi-solidified state, that is, the PDMS solution in the microchannel formed a solidification gradient, such as Figure 1(f) The heating time during pre-curing is related to the heating temperature and the weight ratio of polydimethylsiloxane to the curing agent. The heating temperature range is 60-85°C. The heating time during pre-curing is inversely proportional to the heating temperature and directly proportional to the weight ratio of polydimethylsiloxane to the curing agent.

[0040] Take the pre-cured quartz glass out of the constant temperature heater, connect the 0.7MPa constant pressure nitrogen source to the microchannel of the quartz glass with a clamp, and use constant pressure nitrogen to blow into the microchannel. The uncured PDMS solution in the center of the microchannel will be blown away. Figure 1 (g) as shown.

[0041] Step 5, placing the quartz glass treated in step 4 in a constant temperature heater at 80° C. and heating for 30 minutes to further solidify the PDMS film initially formed on the inner wall of the microchannel. After the PDMS film is completely solidified, a continuous and smooth PDMS film is formed on the inner wall of the microchannel, completing the preparation of the quartz glass microchannel structure. Figure 1 (h) shown.

[0042] Step 6, using a flow meter to detect the gas flow through the uncoated microchannel and the coated microchannel, obtain a corresponding curve of gas flow and pore size, and calculate the inner wall diameter of the microchannel with the PDMS film to complete the thickness detection of the PDMS film in the quartz glass microchannel.

[0043] The principle of the present invention is as follows: by selecting appropriate curing temperature and time, the PDMS solution forms a semi-cured state near the center of the inner wall of the microchannel, and forms a cured state near the inner wall, and then the semi-cured PDMS solution is blown away by constant pressure gas, and the fully cured PDMS film remaining on the inner wall of the microchannel is cured again, so that a continuous and smooth PDMS film with an inner wall can be obtained. The heating temperature and time of the first curing and the heating temperature and time of the second curing can be obtained through appropriate test data. When the ratio of polydimethylsiloxane to the curing agent is changed or the diameter of the microchannel is changed, it is necessary to test again to obtain the appropriate temperature and time values.

[0044] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A quartz glass microchannel structure with a PDMS inner wall, wherein a plurality of microchannels are arranged in the quartz glass; characterized in that: A PDMS film is arranged on the inner wall of the microchannel.

2. The quartz glass microchannel structure of the PDMS inner wall according to claim 1, characterized in that: The PDMS film is formed by mixing and curing polydimethylsiloxane and a curing agent in a weight ratio of 20:1 to 5:

1.

3. A method for preparing a quartz glass microchannel structure with a PDMS inner wall as claimed in claim 1 or 2, characterized in that: The following steps are involved: Step 1, using a femtosecond laser to scan a modified area inside the selected quartz glass according to a preset path; Step 2, immersing the quartz glass with the modified area scanned out in an etching solution, so that the modified area of ​​the quartz glass is etched into a microchannel; Step 3, filling the PDMS solution into the microchannel of the quartz glass; the PDMS solution contains polydimethylsiloxane and a curing agent in a weight ratio of 20:1 to 5:1; Step 4, heating the quartz glass, and when the PDMS solution near the inner wall of the quartz glass microchannel is in a solidified state and the PDMS solution near the center is in a semi-solidified state, blowing away the semi-solidified PDMS solution in the center of the microchannel by blowing; Step 5, further heating and curing the PDMS film initially formed on the inner wall of the microchannel to form a continuous and smooth PDMS film, thereby completing the preparation of the quartz glass microchannel structure.

4. The method for preparing the quartz glass microchannel structure with the PDMS inner wall according to claim 3, characterized in that: Also includes step 6: The gas flow through the uncoated microchannel and the coated microchannel is detected by a flow meter to obtain a corresponding curve of gas flow and pore size, and the inner wall diameter of the microchannel with the PDMS film can be converted.

5. The method for preparing the quartz glass microchannel structure with PDMS inner wall according to claim 3 or 4, characterized in that: In step 4, when the quartz glass is heated, the heating temperature and time can be obtained by experiment.

6. The method for preparing the quartz glass microchannel structure with PDMS inner wall according to claim 5, characterized in that: In step 4, the PDMS solution is a PDMS solution that has been subjected to a low temperature treatment in a low temperature environment of -10 to 5°C.

7. The method for preparing the quartz glass microchannel structure with PDMS inner wall according to claim 6, characterized in that: In step 4, a constant pressure gas source of 0.5 to 0.8 MPa is used for blowing.

8. The method for preparing the quartz glass microchannel structure with PDMS inner wall according to claim 7, characterized in that: In step 5, the remaining PDMS film in the microchannel is further heated and cured at a temperature of 60 to 80° C. and a heating time of 20 to 50 min.

9. The method for preparing the quartz glass microchannel structure with PDMS inner wall according to claim 3 or 4, characterized in that: In step 4, when the quartz glass is heated, the heating temperature is 60 to 85° C. and the heating time is 1 to 25 minutes.

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