Quartz glass microchannel structure of inner wall of PDMS and preparation method thereof

Abstract

The application provides a quartz glass microchannel structure with a PDMS inner wall and a preparation method thereof, and is used for solving the technical problems that the inner wall of the existing quartz glass microchannel is rough, the volatilization process of a solution in the microchannel is uncontrollable when an organic film is prepared on the inner wall of the microchannel by using a solvent volatilization film forming method, the thickness uniformity of the film is poor, 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 microchannel is easily blocked by the organic matter after the solvent volatilization. The preparation method of the quartz glass microchannel structure with the PDMS inner wall provided by the application adopts a method of low-temperature treatment + gradient heat curing + constant-pressure gas blowing to prepare a PDMS film on the inner wall of the quartz glass microchannel, and the obtained PDMS film has good continuity and uniformity, and can significantly improve the roughness of the inner wall of the quartz glass microchannel.

Description

TECHNICAL FIELD

[0001] The present application relates to a quartz glass micro-channel structure and its processing technology, in particular to a quartz glass micro-channel structure with PDMS inner wall and its preparation method. BACKGROUND

[0002] Microfluidic chip ingeniously integrates complex experimental processes on the chip platform, realizes the miniaturization, integration and automation of experimental operation, and has a wide application in the detection of biological and chemical fields.

[0003] At present, quartz glass is commonly used as a micro-channel structure in a microfluidic chip, and a micro-channel is usually prepared in the quartz glass by using a femtosecond laser wet etching method. However, due to the pulse light characteristics of the femtosecond laser, the modification area generated by the femtosecond laser is not uniform when the femtosecond laser is focused in the material, which leads to a rough inner wall of the micro-channel prepared by the femtosecond laser wet etching method, and this limits the application range of quartz glass in the microfluidic chip to some extent.

[0004] In order to improve the roughness of the inner wall of the quartz glass micro-channel, a thin film with a smooth surface can be covered on the inner wall of the micro-channel as a modification layer. At present, an organic thin film is mainly prepared on the inner wall of the micro-channel by using a solvent evaporation film forming method. However, the solvent evaporation film forming method has many shortcomings: the evaporation process of the solution in the micro-channel is uncontrollable, which leads to poor uniformity of the thickness of the thin film; when the solution concentration is low, it is difficult to form a continuous thin film along the longitudinal direction of the micro-channel; when the solution concentration is high, the organic matter is easy to block the micro-channel after the solvent is evaporated. SUMMARY

[0005] The present application aims to solve the technical problems that the inner wall of the existing quartz glass micro-channel is rough, and when an organic thin film is prepared on the inner wall of the micro-channel by using a solvent evaporation film forming method, the evaporation process of the solution in the micro-channel is uncontrollable, which leads to poor uniformity of the thickness of the thin film, or when the solution concentration is low, it is difficult to form a continuous thin film along the longitudinal direction of the micro-channel, or when the solution concentration is high, the organic matter is easy to block the micro-channel after the solvent is evaporated, and to provide a quartz glass micro-channel structure with PDMS inner wall and its preparation method.

[0006] In order to achieve the above-mentioned purpose, the technical scheme provided by the present application is as follows:

[0007] A quartz glass micro-channel structure with PDMS inner wall, a plurality of micro-channels are arranged in the quartz glass; the special feature is that a PDMS thin film is arranged on the inner wall of the micro-channel.

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

[0009] In addition, the application further provides a preparation method of the quartz glass micro-channel structure with the PDMS inner wall, and the method is characterized by comprising the following steps:

[0010] Step 1, scanning a modified region in a preset path in the selected quartz glass by using a femtosecond laser;

[0011] Step 2, soaking the quartz glass with the scanned modified region in an etching solution, so that the modified region of the quartz glass is etched into a micro-channel;

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

[0013] Step 4, heating the quartz glass, and when the PDMS solution close to the inner wall of the quartz glass micro-channel is in a cured state and the PDMS solution close to the center is in a semi-cured state, blowing the PDMS solution in the semi-cured state in the center of the micro-channel by using a blowing method;

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

[0015] Further, the method further comprises the following step 6:

[0016] detecting the gas flow through the uncoated micro-channel and the coated micro-channel by using a flow meter, obtaining a corresponding curve of the gas flow and the pore size, and converting the diameter of the inner wall of the micro-channel with the PDMS film.

[0017] Further, in step 4, the heating temperature and time of the quartz glass can be obtained by experiments.

[0018] Further, in step 4, the PDMS solution is a PDMS solution after low-temperature treatment in a low-temperature environment of-10-5 ℃.

[0019] Further, in step 4, a constant-pressure gas source with a pressure of 0.5-0.8 MPa is used for blowing.

[0020] Further, in step 5, the heating temperature of the remaining PDMS film in the micro-channel is 60-80 ℃, and the heating time is 20-50 min.

[0021] Further, in step 4, the heating temperature of the quartz glass is 60-85 ℃, and the heating time is 1-25 min.

[0022] The beneficial effects of the present application compared with the prior art are as follows:

[0023] 1、The quartz glass microchannel structure of the present application has a PDMS thin film arranged on the inner wall of the microchannel, the thickness of the PDMS thin film is uniform, the roughness of the inner wall of the quartz glass microchannel is effectively improved, and the quartz glass microchannel structure can be widely applied in various fields such as microfluidic chips.

[0024] 2、The preparation method of the quartz glass microchannel structure of the present application has the advantages that the PDMS thin film prepared by the method is continuous and uniform, and the roughness of the inner wall of the microchannel can be significantly improved.

[0025] 3、The preparation method of the quartz glass microchannel structure of the present application has the advantages that compared with the existing solvent evaporation film forming method, the process of preparing the thin film on the inner wall of the microchannel is controllable and has more adjustable parameters, and the thin film is not discontinuous or blocked in the channel. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the preparation method of the quartz glass microchannel structure of the present application is shown in the figure, wherein (a) is a schematic diagram of step 1 of laser modification, (b) is a schematic diagram of step 2 of wet etching of the microchannel, (c) is a schematic diagram of step 3 of preparation of the PDMS solution, (d) is a schematic diagram of step 3 of low-temperature treatment of the PDMS solution, (e) is a schematic diagram of step 3 of filling of the PDMS solution, (f) is a schematic diagram of step 4 of heating and pre-curing, (g) is a schematic diagram of step 4 of blowing away of the PDMS solution in the center of the microchannel in a semi-cured state, and (h) is a schematic diagram of step 5 of further curing of the PDMS thin film. DETAILED DESCRIPTION

[0027] In order to make the advantages and characteristics of the present application clearer, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0028] The quartz glass microchannel structure of the present application has a PDMS thin film arranged on the inner wall of the microchannel, the thickness of the PDMS thin film is uniform, the roughness of the inner wall of the quartz glass microchannel is effectively improved, and the quartz glass microchannel structure can be widely applied in various fields such as microfluidic chips.

[0029] As shown in the figure, the preparation method of the quartz glass microchannel structure of the present application specifically includes the following steps: Figure 1

[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. A 100x objective is used to focus the femtosecond laser generated by the fiber laser inside the fused quartz. The laser power is set to 400 mW, and the scanning speed is 200 μm / s. The modified region is scanned according to the preset path, as shown in (a). In other embodiments of the present application, the femtosecond laser can also be generated by a titanium sapphire laser, a Light Conversion laser, or the like. Figure 1 (a). In other embodiments of the present application, the femtosecond laser can also be generated by a titanium sapphire laser, a Light Conversion laser, or the like.

[0032] Step 2, wet etching the microchannel.

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

[0034] Then the fused quartz with the etched microchannel is immersed in an alcohol solution with a volume concentration of 85% for ultrasonic cleaning for 25 min, and then in deionized water for ultrasonic cleaning for 8 min. After being taken out, it is dried.

[0035] Step 3, filling the PDMS solution.

[0036] First, the PDMS solution needs to be prepared. Specifically, polydimethylsiloxane and a curing agent are mixed in a weight ratio of 20:1 to 5:1, and stirred for 2-5 min by hand stirring or magnetic stirring to fully mix them, obtaining a uniformly mixed PDMS solution. The uniformly mixed PDMS solution is placed in a vacuum chamber for 20-30 min to remove air bubbles in the PDMS solution, as shown in (c). Figure 1 (c).

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

[0038] Step 4, heating and pre-curing, and blowing away the semi-cured PDMS solution in the center of the microchannel.

[0039] The quartz glass is placed in a constant temperature heater at 80°C for 3 min for pre-curing, so that the PDMS solution close to the inner wall of the microchannel is in a cured state, and the PDMS solution close to the center of the microchannel is in a semi-cured state, i.e., the PDMS solution in the microchannel forms a curing gradient, as shown in (f). Figure 1(f) shown. The heating time during pre-curing is related to the heating temperature and the weight ratio of polydimethylsiloxane and curing agent, the heating temperature ranges from 60 to 85℃, the heating time during pre-curing is inversely proportional to the heating temperature and proportional to the weight ratio of polydimethylsiloxane and curing agent.

[0040] The quartz glass after pre-curing is taken out from the constant temperature heater, a 0.7MPa constant pressure nitrogen source is connected to the micro-channel of the quartz glass by a clamp, and the micro-channel is blown by using constant pressure nitrogen, the PDMS solution not completely cured in the center of the micro-channel is blown away, and the micro-channel is filled with nitrogen, as shown in Figure 1 (g) shown.

[0041] Step 5, the quartz glass treated in step 4 is placed in a constant temperature heater at 80℃ for 30min to further cure the PDMS film preliminarily formed on the inner wall of the micro-channel, and after the PDMS film is completely cured, the inner wall of the micro-channel forms a continuous and smooth PDMS film, and the preparation of the quartz glass micro-channel structure is completed, as shown in Figure 1 (h) shown.

[0042] Step 6, the gas flow through the uncoated micro-channel and the coated micro-channel is detected by a flow meter, and the corresponding curve of the gas flow and the pore size is obtained, and the diameter of the micro-channel with the PDMS film can be calculated, and the thickness of the PDMS film in the quartz glass micro-channel is detected.

[0043] The principle of the present application is that by selecting appropriate curing temperature and time, the PDMS solution is formed in a semi-cured state near the center of the inner wall of the micro-channel, and in a cured state near the inner wall, and then the semi-cured PDMS solution is blown away by using constant pressure gas, and then the PDMS film left on the inner wall of the micro-channel is cured again, and a continuous and smooth PDMS film is obtained on the inner wall. The heating temperature and time of the first curing and the heating temperature and time of the second curing can be obtained by appropriate test data. When the ratio of polydimethylsiloxane to curing agent or the diameter of the micro-channel is changed, appropriate temperature and time values need to be obtained by further tests.

[0044] The above description is only to illustrate the technical solutions of the present application, and is not a limitation. For ordinary skilled persons in the art, the specific technical solutions described in the above embodiments can be modified, or some technical features can be replaced by equivalents, and these modifications or replacements do not change the essence of the corresponding technical solutions out of the scope of the technical solutions protected by the present application.

Claims

1. A method for producing a quartz glass microchannel structure of a PDMS inner wall, characterized by, The method comprises the following steps: Step 1, scanning a modification area in a quartz glass according to a preset path by using a femtosecond laser; Step 2, immersing the quartz glass with the scanned modification area in an etching solution, so that the modification area of the quartz glass is etched into a microchannel; Step 3, filling a PDMS solution into the microchannel of the quartz glass, wherein the PDMS solution comprises polydimethylsiloxane and a curing agent, and the weight ratio of the polydimethylsiloxane to the curing agent is 20:1-5:1; Step 4, heating the quartz glass, and when the PDMS solution close to the inner wall of the quartz glass microchannel is in a cured state and the PDMS solution close to the center is in a semi-cured state, blowing the PDMS solution in the semi-cured state in the center of the microchannel by using a blowing method; Step 5, further heating and curing the PDMS film preliminarily formed on the inner wall of the microchannel to form a continuous and smooth PDMS film, and completing the preparation of the quartz glass microchannel structure.

2. The method of claim 1, wherein the PDMS inner wall quartz glass microchannel structure is prepared by the steps of: The method further comprises the following step 6: Detecting the gas flow through the uncoated microchannel and the coated microchannel by using a flow meter, obtaining a corresponding curve of the gas flow and the pore diameter, and converting the diameter of the inner wall of the microchannel with the PDMS film.

3. The method for preparing the quartz glass microchannel structure with a PDMS inner wall according to claim 1 or 2, characterized in that: In step 4, the heating temperature and time of the quartz glass are obtained by experiments.

4. The method for preparing the quartz glass microchannel structure with a PDMS inner wall according to claim 3, characterized in that: In step 4, the PDMS solution is a PDMS solution after low-temperature treatment in a low-temperature environment of-10-5 ℃.

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

6. The method for preparing the quartz glass microchannel structure with a PDMS inner wall according to claim 5, characterized in that: In step 5, the heating temperature for further heating and curing the remaining PDMS film in the microchannel is 60-80 ℃, and the heating time is 20-50 min.

7. The method for preparing the quartz glass microchannel structure with a PDMS inner wall according to claim 1 or 2, characterized in that: In step 4, the heating temperature of the quartz glass is 60-85 ℃, and the heating time is 1-25 min.

8. 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; and the microchannel and the PDMS film on the inner wall of the microchannel are prepared by using the preparation method according to any one of claims 1-7.

9. The quartz glass microchannel structure with a PDMS inner wall according to claim 8, characterized in that: The PDMS film is formed by mixing and curing polydimethylsiloxane and a curing agent at a weight ratio of 20:1-5:1.

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