Micro-fluidic chip as well as preparation method and application thereof

Abstract

The invention relates to a micro-fluidic chip and a preparation method and application thereof, and the method comprises the following steps: respectively carrying out first ultraviolet radiation and second ultraviolet radiation on a to-be-bonded surface of a polydimethylsiloxane micro-fluidic chip and a to-be-bonded surface of a glass sheet, and finishing the first ultraviolet radiation and the second ultraviolet radiation at the same time, the to-be-bonded surface of the polydimethylsiloxane micro-fluidic chip after ultraviolet irradiation and the to-be-bonded surface of the glass sheet are oppositely arranged and pressed to form a first bonding assembly; the first bonding assembly is subjected to heating treatment, and the micro-fluidic chip is obtained. The micro-fluidic chip with high bonding strength prepared by the method does not need an additional surface modification instrument for pretreatment, is simple, convenient and efficient, remarkably improves the preparation success rate of the micro-fluidic chip, simplifies the bonding process, reduces the use of chemical reagents, and has wide application potential and commercial value in multiple fields.

Description

Technical Field

[0001] The present invention relates to the field of microfluidic technology, and particularly to a microfluidic chip, a preparation method thereof, and an application thereof. Background Art

[0002] A microfluidic chip is a miniaturized device integrating microfluidic channels and microreactors. As the core platform of microfluidic technology, it shows great application potential in multiple fields such as environment, biology, chemistry, and medicine. Polydimethylsiloxane (PDMS), as the most common microfluidic chip material, its bonding methods usually include adhesive bonding and surface modification bonding. Adhesive bonding uses an adhesive to achieve the sealing between chips or between a chip and a glass slide. Although the operation is simple, the adhesive may flow into the microfluidic channels and cause blockage, and at the same time, the introduced adhesive may also change the physicochemical properties of the microchannels. Therefore, adhesive bonding is not the commonly used bonding method currently. Surface modification bonding introduces active chemical groups on the PDMS bonding surface to form covalent bonds at the contact interface between the chip and the glass substrate to achieve bonding. This method has simple operation, short modification time, and the bonding reaction can proceed spontaneously, which is particularly suitable for the bonding of PDMS with other materials.

[0003] CN118788409A discloses a bonding method for a microfluidic chip with SiOxNy and PDMS as substrates. The main steps include: at room temperature, first cleaning the surfaces of the two chips, then performing at least two oxygen plasma treatments on the bonding surface of the chip with SiOxNy as the substrate, performing at least one oxygen plasma treatment on the bonding surface of the PDMS chip, and finally bonding the treated bonding surfaces of the two chips and completing subsequent treatments. This method enhances the bonding force between the chips through oxygen plasma treatment, but requires a plasma generator to perform a secondary plasma treatment, with complex operation processes and cumbersome procedures.

[0004] CN102093583A discloses an irreversible bonding method with PDMS as the substrate. The main steps include: successively ultrasonic cleaning the PDMS component in acetone and isopropyl alcohol, cleaning the substrate component in ethanol and deionized water to remove impurities and oil stains, then baking in an oven to further remove moisture and volatile substances, then treating the bonding surfaces of the components with a corona discharge device to increase the surface energy, and finally directly bonding the treated components and clamping them for 3 - 4 days to achieve bonding. This method has low cost and wide application range, but has problems such as complex operation process, long time consumption, and low yield.

[0005] CN1683443A discloses a simple irreversible bonding method for a chip with PDMS as the substrate. The main steps include: soaking the prepared polydimethylsiloxane chip assembly in ammonia water for 10 - 30 minutes, then repeatedly rinsing with deionized water, and bonding two processed PDMS chips together or bonding one PDMS chip to a clean glass slide. This method has a low operation cost, but a narrow application range, low bonding strength, and low stability and utilization rate of the chip.

[0006] In the preparation process of microfluidic chips, the bonding step is crucial as it ensures the smooth flow of fluids in the sealed channels and directly affects the performance of the chips. Therefore, a preparation method for microfluidic chips is needed to solve the problems of low bonding strength and complex bonding operation process. Summary of the Invention

[0007] To solve the above technical problems, the present invention proposes an innovative method that is simple in operation process, low in cost, and significantly improves the bonding strength of polydimethylsiloxane microfluidic chips. By combining ultraviolet irradiation and heat treatment, the present invention can effectively reduce the bonding time of microfluidic chips and the damage rate of the liquid storage chambers of microfluidic chips. This method not only improves the durability of microfluidic chips but also ensures the stability of the microfluidic system during long-term operation, which is of great significance for enhancing the reliability of microfluidic chips and expanding their application scope in scientific research and industrial fields.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a bonding method for a microfluidic chip, and the method includes the following steps:

[0010] Perform first ultraviolet irradiation and second ultraviolet irradiation on the bonding surface of the polydimethylsiloxane microfluidic chip and the bonding surface of the glass slide respectively. The first ultraviolet irradiation and the second ultraviolet irradiation end simultaneously, and then set the bonding surface of the ultraviolet-irradiated polydimethylsiloxane microfluidic chip opposite to the bonding surface of the glass slide and press them together to form a first bonding assembly;

[0011] The first bonding assembly is subjected to heat treatment to obtain a microfluidic chip.

[0012] The present invention proposes an innovative method with simple operation process, low cost and enhanced bonding strength of polydimethylsiloxane microfluidic chips. The bonding method first uses ultraviolet light to irradiate the bonding surfaces of the glass slide and the polydimethylsiloxane microfluidic chip, and then applies pressure to achieve preliminary bonding of the two, obtaining a first bonding assembly. Subsequently, the first bonding assembly is subjected to a heat treatment step, which aims to further strengthen the bonding interface through the heat treatment to ensure a firm bond between the polydimethylsiloxane microfluidic chip and the glass slide, and a microfluidic chip with high bonding strength is prepared. The bonding method provided by the present invention does not require additional surface modification instrument pretreatment, is simple and efficient, significantly improves the utilization rate of the microfluidic chip, simplifies the bonding process, reduces the use of chemical reagents, and has broad application potential and commercial value in multiple fields.

[0013] Among them, the glass slide is a sailing brand glass slide (model number 7101), and its main component is silicon dioxide.

[0014] As a preferred technical solution of the present invention, the intensity of the first ultraviolet irradiation is 5 - 20 W, for example, it can be 5 W, 8 W, 10 W, 13 W, 15 W, 17 W or 20 W, but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable, preferably 8 - 10 W.

[0015] Preferably, the intensity of the second ultraviolet irradiation is 8 - 25 W, for example, it can be 8 W, 12 W, 16 W, 20 W or 25 W, but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable, preferably 12 - 16 W.

[0016] The present invention uses ultraviolet light with different intensities to irradiate the bonding surfaces of the polydimethylsiloxane microfluidic chip and the glass slide. This is because the polydimethylsiloxane microfluidic chip has a certain sensitivity to ultraviolet light, and ultraviolet light irradiation of 5 - 20 W can trigger chemical reactions on its surface, thereby enhancing the adhesion force and improving the hydrophilicity. At the same time, too high ultraviolet intensity may lead to excessive aging or degradation of the surface of the polydimethylsiloxane microfluidic chip. Compared with the polydimethylsiloxane microfluidic chip, the glass slide has lower sensitivity to ultraviolet light, so a higher ultraviolet intensity (8 - 25 W) is required to modify its surface, causing chemical bond breakage or recombination on its surface, thereby increasing its surface activity. At the same time, high-intensity ultraviolet irradiation will cause tiny cracks or damages on the surface of the glass slide, and these damages will affect the flatness and sealing performance of the bonding interface.

[0017] As a preferred technical solution of the present invention, the wavelengths of the first ultraviolet irradiation and the second ultraviolet irradiation are independently 185-254nm, for example, 185nm, 200nm, 220nm, 240nm or 254nm, but are not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0018] Ultraviolet light with a wavelength of 185-254nm can effectively improve the hydrophilicity of the surface of the polydimethylsiloxane microfluidic chip, thereby enhancing its bonding effect with the glass sheet. Specifically, ultraviolet light with a wavelength of 185-254nm can break the Si-C chemical bonds on the surface of the polydimethylsiloxane microfluidic chip to generate silicon radicals (Si·) and methyl radicals (CH3·). These free radicals react with oxygen (O2) and water molecules (H2O) in the air to generate polar groups such as hydroxyl groups (-OH) and form a large number of Si-OH bonds on the surface, thereby improving the hydrophilicity of the polydimethylsiloxane microfluidic chip and enhancing its bonding effect with the glass sheet. If the ultraviolet wavelength is less than 185nm, its high energy may cause excessive oxidation or damage to the surface of the polydimethylsiloxane microfluidic chip, making the material brittle and causing cracks and peeling at the bonding interface, thereby affecting the bonding effect and stability; if the ultraviolet wavelength is greater than 254nm, its energy is relatively low and may not effectively break the Si-C bond, resulting in the inability to effectively generate enough active groups to form a strong chemical bond, thereby reducing the bonding strength and making it easy for the microfluidic chip channel to leak, which is very unfavorable for the sealing of the microfluidic system.

[0019] Preferably, the first ultraviolet irradiation time is 1-10 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, but is not limited to the listed values. Other unlisted values ​​within the above numerical range are also applicable, preferably 5-6 min.

[0020] Preferably, the second ultraviolet irradiation time is 5-15 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, but is not limited to the listed values. Other unlisted values ​​within the above numerical range are also applicable, preferably 10-11 min.

[0021] By defining the bonding method, the present invention uses ultraviolet light irradiation in combination with heat treatment to strengthen the bonding effect between the polydimethylsiloxane microfluidic chip and the glass slide, which can effectively reduce the bonding time between the two. Only 1 - 10 minutes of ultraviolet irradiation on the polydimethylsiloxane microfluidic chip and 5 - 15 minutes of ultraviolet irradiation on the glass slide are required to achieve the preliminary bonding of the two.

[0022] As a preferred technical solution of the present invention, the temperature of the heat treatment is 80 - 100 °C, for example, it can be 80 °C, 85 °C, 90 °C, 95 °C or 100 °C, but is not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0023] Preferably, the time of the heat treatment is 1 - 2 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.8 hours or 2 hours, but is not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0024] By defining the bonding method, the present invention uses ultraviolet light irradiation in combination with heat treatment to strengthen the bonding effect between the polydimethylsiloxane microfluidic chip and the glass slide, which can effectively reduce the bonding time between the two. Only 1 - 2 hours of heat treatment on the first bonding component is required to complete the strengthening of the bonding interface between the polydimethylsiloxane microfluidic chip and the glass slide, ensuring a firm bond between the polydimethylsiloxane microfluidic chip and the glass slide.

[0025] As a preferred technical solution of the present invention, the preparation method of the polydimethylsiloxane microfluidic chip includes:

[0026] (1) Mix and stir the polydimethylsiloxane main agent and the curing agent, and perform a vacuum operation to obtain a mixture;

[0027] (2) Pour the mixture into a mold and perform hot processing to obtain a polydimethylsiloxane chip;

[0028] (3) Successively perform cutting, punching, and cleaning on the polydimethylsiloxane chip to obtain the polydimethylsiloxane microfluidic chip.

[0029] As a preferred technical solution of the present invention, the mass ratio of the polydimethylsiloxane main agent to the curing agent is (8 - 12):1, for example, it can be 8:1, 9:1, 10:1, 11:1 or 12:1, but is not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0030] Preferably, the number-average molecular weight of the polydimethylsiloxane is 20,000 - 40,000. For example, it can be 20,000, 25,000, 30,000, 35,000 or 40,000, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0031] Preferably, the rotation speed of the stirring is 100 - 300 r / min. For example, it can be 100 r / min, 150 r / min, 200 r / min, 250 r / min or 300 r / min, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0032] Preferably, the stirring time is 10 - 20 min. For example, it can be 10 min, 12 min, 14 min, 16 min, 18 min or 20 min, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0033] Preferably, the vacuum degree of the vacuum pumping operation is 60 - 70 kPa. For example, it can be 60 kPa, 62 kPa, 64 kPa, 66 kPa, 68 kPa or 70 kPa, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0034] Preferably, the time of the vacuum pumping operation is 0.5 - 1 h. For example, it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0035] In the present invention, the main agent and curing agent of polydimethylsiloxane after stirring are subjected to vacuum treatment to make the obtained mixture bubble-free, so as to prepare a polydimethylsiloxane microfluidic chip with a uniform internal structure, so that it can be better bonded to the glass slide during bonding.

[0036] As a preferred technical solution of the present invention, the temperature of the thermal processing is 80 - 100 °C. For example, it can be 80 °C, 85 °C, 90 °C, 95 °C or 100 °C, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0037] Preferably, the time of the thermal processing is 1 - 2 h. For example, it can be 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, but is not limited to the listed values. Other unlisted values within the above numerical range are equally applicable.

[0038] Preferably, the length of the cut polydimethylsiloxane chip is less than the length of the glass slide.

[0039] Preferably, the width of the cut polydimethylsiloxane chip is less than the width of the glass sheet.

[0040] Preferably, the cleaning further includes cleaning the glass sheet.

[0041] Preferably, the specific operation of the cleaning is as follows: rinsing the polydimethylsiloxane chip and the glass sheet with deionized water at least 5 times, then performing ultrasonic treatment for 2 - 10 min, and drying. The number of times of rinsing with deionized water can be 5 times, 7 times, 9 times, 10 times, 12 times or 15 times, and the time of ultrasonic treatment can be 2 min, 4 min, 6 min, 8 min or 10 min, but is not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0042] Preferably, the atmosphere for drying includes any one or a combination of at least two of nitrogen, argon or helium. Typical but non - restrictive combinations include: a combination of nitrogen and argon, a combination of nitrogen and helium, a combination of argon and helium, and a combination of nitrogen, argon and helium.

[0043] As a preferred technical solution of the present invention, the method includes the following steps:

[0044] (1) Mix the polydimethylsiloxane main agent and the curing agent in a mass ratio of (8 - 12):1, stir at a rotation speed of 100 - 300 r / min for 10 - 20 min, and perform a vacuum pumping operation for 0.5 - 1 h to obtain a mixture;

[0045] (2) Pour the mixture into a mold and perform hot processing at 80 - 100 °C for 1 - 2 h to obtain a polydimethylsiloxane chip;

[0046] (3) Perform cutting, punching and cleaning treatments on the polydimethylsiloxane chip in sequence, and perform cleaning treatment on the glass sheet to obtain a polydimethylsiloxane microfluidic chip and a cleaned glass sheet;

[0047] (4) Use ultraviolet light with an intensity of 5 - 20 W and a wavelength of 185 - 254 nm to irradiate the bonding surface of the polydimethylsiloxane microfluidic chip for 1 - 10 min, use ultraviolet light with an intensity of 8 - 25 W and a wavelength of 185 - 254 nm to irradiate the bonding surface of the cleaned glass sheet for 5 - 15 min. The ultraviolet irradiation of the polydimethylsiloxane microfluidic chip and the glass sheet ends simultaneously, and then immediately set the bonding surface of the ultraviolet - irradiated polydimethylsiloxane microfluidic chip opposite to the bonding surface of the glass sheet and press them together to form a first bonding assembly. The first bonding assembly is heated at 80 - 100 °C for 1 - 2 h to obtain a microfluidic chip.

[0048] In the present invention, "immediately" means that the polydimethylsiloxane microfluidic chip and the glass sheet are pressed together within 30 s after the ultraviolet irradiation ends.

[0049] In a second aspect, the present invention provides a microfluidic chip, which is prepared by using the bonding method of the microfluidic chip described in the first aspect.

[0050] The liquid storage chamber of the microfluidic chip provided by the present invention has a low damage rate, and the microfluidic chip has good durability, and has good stability and reliability during the long-term operation of the microfluidic system.

[0051] In a third aspect, the present invention provides an application of a microfluidic chip prepared by using the bonding method of the microfluidic chip described in the first aspect in environmental monitoring, drug screening or chemical analysis.

[0052] The microfluidic chip after strengthening bonding provided by the present invention can be used for micro control and analysis in various fields such as environment, biomedicine, and chemistry, and provides an ideal platform for basic research.

[0053] Compared with the prior art, the present invention has at least the following beneficial effects:

[0054] The present invention provides a simple and efficient bonding technology for a polydimethylsiloxane microfluidic chip and a glass sheet, which does not require expensive equipment such as a plasma generator, has a short bonding time, a low bonding cost and a high bonding strength, and the bonding strength can reach more than 0.36 MPa. The method provided by the present invention can not only effectively avoid the problems of introducing impurities such as adhesives and blocking microchannels existing in traditional adhesive bonding, but also significantly reduce the damage rate of the microfluidic chip during use and improve the utilization rate of the microfluidic chip. This method not only simplifies the bonding process, but also improves the reliability and service life of the microfluidic chip, and has significant significance for improving the performance and practicability of the microfluidic chip. Description of the Drawings

[0055] Figure 1 It is a schematic diagram of the bonding of the polydimethylsiloxane microfluidic chip and the glass sheet in Example 1 of the present invention.

[0056] Among them, 1 - polydimethylsiloxane microfluidic chip; 2 - glass sheet; 3 - first bonding component. Detailed Embodiments

[0057] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention, and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention is subject to the claims.

[0058] Example 1

[0059] This embodiment provides a bonding method for a microfluidic chip, and the method includes the following steps:

[0060] (1) Mix the polydimethylsiloxane main agent and the curing agent (Dow Corning, DC184) in a mass ratio of 10:1, stir at a rotation speed of 200 r / min for 15 min, and perform a vacuum pumping operation to keep the vacuum degree at 65 kPa for 0.7 h to obtain a mixture; wherein the number-average molecular weight of the polydimethylsiloxane is 25,000;

[0061] (2) Pour the mixture into a silicon wafer mold and perform hot processing at 90 °C for 1.5 h to obtain a polydimethylsiloxane chip;

[0062] (3) Cut the polydimethylsiloxane chip, with four pairs of chips as a group, and one pair of chips contains two liquid storage chambers. Then, punch holes in the polydimethylsiloxane chip, punch one hole in each chamber as a solution injection hole, rinse the polydimethylsiloxane chip 7 times with deionized water, then ultrasonicate for 5 min, rinse the glass slide 5 times with deionized water, then ultrasonicate for 5 min, and dry with nitrogen to obtain a polydimethylsiloxane microfluidic chip and a cleaned glass slide;

[0063] (4) Irradiate the bonding surface of the polydimethylsiloxane microfluidic chip with ultraviolet light of 10 W intensity and 200 nm wavelength for 5 min, irradiate the bonding surface of the cleaned glass slide with ultraviolet light of 15 W intensity and 220 nm wavelength for 10 min. The ultraviolet irradiation of the polydimethylsiloxane microfluidic chip and the glass slide ends simultaneously. Then, immediately place the bonding surface of the ultraviolet-irradiated polydimethylsiloxane microfluidic chip opposite to the bonding surface of the glass slide and press them together to form a first bonding assembly (as Figure 1 shown), and heat the first bonding assembly at 90 °C for 1.5 h to obtain a microfluidic chip.

[0064] Example 2

[0065] This embodiment provides a bonding method for a microfluidic chip, and the method includes the following steps:

[0066] (1) Mix the polydimethylsiloxane main agent and the curing agent (Dow Corning, DC184) in a mass ratio of 8:1, stir at a rotation speed of 300 r / min for 10 min, and perform a vacuum pumping operation to keep the vacuum degree at 60 kPa for 1 h to obtain a mixture; wherein the number-average molecular weight of the polydimethylsiloxane is 40,000;

[0067] (2) Pour the mixture into a silicon wafer mold and perform hot processing at 100 °C for 1 h to obtain a polydimethylsiloxane chip;

[0068] (3) Cut the polydimethylsiloxane chip. Take four pairs of chips as a group. One pair of chips contains two liquid storage chambers. Then, punch holes in the polydimethylsiloxane chip, make one hole for each chamber as the solution injection hole, rinse the polydimethylsiloxane chip with deionized water 5 times, then ultrasonicate for 10 min, rinse the glass slide with deionized water 6 times, then ultrasonicate for 8 min, and dry with argon gas to obtain the polydimethylsiloxane microfluidic chip and the cleaned glass slide;

[0069] (4) Use ultraviolet light with an intensity of 5 W and a wavelength of 185 nm to irradiate the bonding surface of the polydimethylsiloxane microfluidic chip for 10 min, and use ultraviolet light with an intensity of 25 W and a wavelength of 254 nm to irradiate the bonding surface of the cleaned glass slide for 5 min. The ultraviolet irradiation of the polydimethylsiloxane microfluidic chip and the glass slide ends simultaneously. Then, immediately place the bonding surface of the ultraviolet-irradiated polydimethylsiloxane microfluidic chip opposite to the bonding surface of the glass slide and press them together to form the first bonding assembly. Heat the first bonding assembly at 80 °C for 2 h to obtain the microfluidic chip.

[0070] Example 3

[0071] This example provides a bonding method for a microfluidic chip. The method includes the following steps:

[0072] (1) Mix the polydimethylsiloxane main agent and the curing agent (Dow Corning, DC184) according to a mass ratio of 12:1, stir at a rotation speed of 100 r / min for 20 min, and perform a vacuum pumping operation to keep the vacuum degree at 70 kPa for 0.5 h to obtain a mixture; the number average molecular weight of the polydimethylsiloxane is 20000;

[0073] (2) Pour the mixture into a silicon wafer mold and perform hot processing at 80 °C for 2 h to obtain the polydimethylsiloxane chip;

[0074] (3) Cut the polydimethylsiloxane chip. Take four pairs of chips as a group. One pair of chips contains two liquid storage chambers. Then, punch holes in the polydimethylsiloxane chip, make one hole for each chamber as the solution injection hole, rinse the polydimethylsiloxane chip with deionized water 10 times, then ultrasonicate for 2 min, rinse the glass slide with deionized water 12 times, then ultrasonicate for 4 min, and dry with helium gas to obtain the polydimethylsiloxane microfluidic chip and the cleaned glass slide;

[0075] (4) Irradiate the bonding surface of the polydimethylsiloxane microfluidic chip with ultraviolet light at an intensity of 20 W and a wavelength of 254 nm for 10 min, and irradiate the bonding surface of the cleaned glass slide with ultraviolet light at an intensity of 8 W and a wavelength of 185 nm for 15 min. The ultraviolet irradiation of the polydimethylsiloxane microfluidic chip and the glass slide ends simultaneously. Then, immediately place the bonding surface of the ultraviolet-irradiated polydimethylsiloxane microfluidic chip opposite to the bonding surface of the glass slide and press them together to form a first bonding assembly. The first bonding assembly is heated at 100 °C for 1 h to obtain a microfluidic chip.

[0076] Example 4

[0077] This example provides a bonding method for a microfluidic chip. The difference from Example 1 is only that, except that the ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip is 5 W, the rest are the same as in Example 1.

[0078] Example 5

[0079] This example provides a bonding method for a microfluidic chip. The difference from Example 1 is only that, except that the ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip is 20 W, the rest are the same as in Example 1.

[0080] Example 6

[0081] This example provides a bonding method for a microfluidic chip. The difference from Example 1 is only that, except that the ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip is 2 W, the rest are the same as in Example 1.

[0082] Example 7

[0083] This example provides a bonding method for a microfluidic chip. The difference from Example 1 is only that, except that the ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip is 30 W, the rest are the same as in Example 1.

[0084] Example 8

[0085] This example provides a bonding method for a microfluidic chip. The difference from Example 1 is only that, except that the ultraviolet irradiation time of the bonding surface of the polydimethylsiloxane microfluidic chip is adjusted to 0.5 min, the rest are the same as in Example 1.

[0086] Example 9

[0087] This example provides a bonding method for a microfluidic chip. The difference from Example 1 is only that, except that the ultraviolet irradiation time of the bonding surface of the polydimethylsiloxane microfluidic chip is adjusted to 15 min, the rest are the same as in Example 1.

[0088] Example 10

[0089] This embodiment provides a bonding method for a microfluidic chip. The difference from Embodiment 1 is only that, except that the temperature of the heat treatment is adjusted from 90 °C to 60 °C, the rest are the same as those in Embodiment 1.

[0090] Embodiment 11

[0091] This embodiment provides a bonding method for a microfluidic chip. The difference from Embodiment 1 is only that, except that the temperature of the heat treatment is adjusted from 90 °C to 120 °C, the rest are the same as those in Embodiment 1.

[0092] Comparative Example 1

[0093] This comparative example provides a bonding method for a microfluidic chip. The difference from Embodiment 1 is only that, except that the bonding surface to be bonded of the polydimethylsiloxane microfluidic chip after ultraviolet irradiation is oppositely arranged and pressed against the bonding surface to be bonded of the glass sheet to directly form a microfluidic chip, that is, no heat treatment is performed, the rest are the same as those in Embodiment 1.

[0094] Comparative Example 2

[0095] This comparative example provides a bonding method for a microfluidic chip. The difference from Embodiment 1 is only that, except that the washed glass sheet is directly pressed against the polydimethylsiloxane microfluidic chip after ultraviolet irradiation, that is, the bonding surface to be bonded of the glass sheet is not subjected to ultraviolet irradiation, the rest are the same as those in Embodiment 1.

[0096] Comparative Example 3

[0097] This comparative example provides a bonding method for a microfluidic chip. The difference from Embodiment 1 is only that, except that the bonding surface to be bonded of the polydimethylsiloxane microfluidic chip and the bonding surface to be bonded of the glass sheet are respectively subjected to plasma treatment and pressed to form a first bonding component, the rest are the same as those in Embodiment 1.

[0098] At room temperature, the maximum nitrogen pressure that the microfluidic chip prepared by the present invention can withstand is tested to evaluate its bonding quality. The test results are shown in Table 1.

[0099] Table 1

[0100] Bonding strength (MPa) Example 1 0.53 Example 2 0.46 Example 3 0.36 Example 4 0.28 Example 5 0.26 Example 6 0.13 Example 7 0.15 Example 8 0.15 Example 9 0.22 Example 10 0.24 Example 11 0.20 Comparative Example 1 0.12 Comparative Example 2 0.07 Comparative Example 3 0.22

[0101] It can be seen from the test results that:

[0102] (1) It can be seen from Examples 1 to 5 that the microfluidic chip prepared by the present invention through ultraviolet light irradiation in cooperation with heat treatment has a bonding strength of more than 0.26 MPa. The present invention does not require expensive equipment such as a plasma generator, has a short bonding time, low bonding cost and high bonding strength, and can effectively avoid the problems of introducing impurities such as adhesives and clogging microchannels existing in traditional adhesive bonding, significantly reducing the damage rate of the microfluidic chip during use and improving the utilization rate of the microfluidic chip, which has significant significance for improving the performance and practicality of the microfluidic chip.

[0103] (2) It can be seen from Example 1 and Examples 6 - 7 that the ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip in Example 1 is 10 W, and the bonding strength of the prepared microfluidic chip is 0.53 MPa. While the ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip in Example 6 is 2 W, and the bonding strength of the prepared microfluidic chip is 0.13 MPa. The ultraviolet irradiation intensity of the bonding surface of the polydimethylsiloxane microfluidic chip in Example 7 is 30 W, and the bonding strength of the prepared microfluidic chip is 0.15 MPa. This shows that the polydimethylsiloxane microfluidic chip of the present invention has a certain sensitivity to ultraviolet light. Ultraviolet light irradiation of 5 - 20 W can trigger chemical reactions on its surface, thereby enhancing adhesion and improving hydrophilicity. However, too high ultraviolet intensity will cause excessive aging or degradation of the surface of the polydimethylsiloxane microfluidic chip, thereby reducing the bonding strength of the prepared microfluidic chip.

[0104] (3) It can be seen from Example 1 and Examples 8 - 9 that the ultraviolet irradiation time of the bonding surface of the polydimethylsiloxane microfluidic chip in Example 1 is 5 min, and the bonding strength of the prepared microfluidic chip is 0.53 MPa; while the ultraviolet irradiation time of the bonding surface of the polydimethylsiloxane microfluidic chip in Example 8 is 0.5 min, and the bonding strength of the prepared microfluidic chip is 0.15 MPa. The ultraviolet irradiation time of the bonding surface of the polydimethylsiloxane microfluidic chip in Example 9 is 15 min, and the bonding strength of the prepared microfluidic chip is 0.22 MPa. This shows that the present invention uses ultraviolet light irradiation in cooperation with heat treatment to strengthen the bonding effect between the polydimethylsiloxane microfluidic chip and the glass sheet, which can effectively reduce the bonding time of the two. Only by irradiating the polydimethylsiloxane microfluidic chip with ultraviolet light for 1 - 10 min can the preliminary bonding of the polydimethylsiloxane microfluidic chip and the glass sheet be achieved.

[0105] (4) It can be seen from Example 1 and Examples 10 - 11 that in Example 1, the temperature of the heat treatment in step (4) is 90 °C, and the bonding strength of the microfluidic chip prepared is 0.53 MPa; while in Example 10, the temperature of the heat treatment in step (4) is 60 °C, and the bonding strength of the microfluidic chip prepared is 0.24 MPa. In Example 11, the temperature of the heat treatment in step (4) is 120 °C, and the bonding strength of the microfluidic chip prepared is 0.20 MPa. This shows that by controlling the heating temperature during the heat treatment process of the present invention to be 80 - 100 °C, it can further strengthen the interface, ensure the firm bonding between the polydimethylsiloxane microfluidic chip and the glass sheet, and prepare a microfluidic chip with high bonding strength. If the temperature is lower than 80 °C, the bonding strength of the microfluidic chip will be reduced. At the same time, in order to achieve sufficient bonding strength, it will be necessary to extend the heating time, which will reduce the production efficiency. If the temperature is higher than 100 °C, due to the difference in the thermal expansion coefficients between the polydimethylsiloxane microfluidic chip and the glass sheet, microcracks or bubbles will be generated at the bonding interface, thereby reducing the bonding strength.

[0106] (5) It can be seen from Example 1 and Comparative Example 1 that in Comparative Example 1, only the bonding surfaces of the polydimethylsiloxane microfluidic chip and the glass sheet to be bonded were irradiated with ultraviolet light, and no heat treatment was performed. It only achieved the preliminary bonding of the two, and did not strengthen the bonding interface. The bonding strength of its microfluidic chip is 0.12 MPa. This shows that the present invention first irradiates the bonding surfaces of the glass sheet and the polydimethylsiloxane microfluidic chip with ultraviolet light, then realizes the preliminary bonding of the two by applying pressure, and then combines heat treatment to strengthen the bonding interface to ensure the firm bonding between the polydimethylsiloxane microfluidic chip and the glass sheet, and prepares a microfluidic chip with high bonding strength.

[0107] (6) It can be seen from Example 1 and Comparative Example 2 that in Comparative Example 2, the cleaned glass sheet was directly pressed with the ultraviolet-irradiated polydimethylsiloxane microfluidic chip, and then heat treatment was performed without ultraviolet light irradiation. The bonding strength of its microfluidic chip is 0.07 MPa. This shows that the present invention first irradiates the bonding surfaces of the glass sheet and the polydimethylsiloxane microfluidic chip with ultraviolet light, then realizes the preliminary bonding of the two by applying pressure, and then combines heat treatment to strengthen the bonding interface to ensure the firm bonding between the polydimethylsiloxane microfluidic chip and the glass sheet, and prepares a microfluidic chip with high bonding strength.

[0108] (7) It can be seen from Example 1 and Comparative Example 3 that in Comparative Example 3, the bonding surfaces of the polydimethylsiloxane microfluidic chip and the glass sheet were respectively treated with plasma and pressed to form the first bonding assembly, and then heat treatment was carried out. The bonding strength of the microfluidic chip was 0.22 MPa. This shows that the present invention uses ultraviolet light irradiation in combination with heat treatment to strengthen the bonding effect between the polydimethylsiloxane microfluidic chip and the glass sheet, which can not only avoid using expensive equipment such as plasma generators, reduce the bonding cost, but also increase the bonding strength.

[0109] In summary, the present invention first irradiates the bonding surfaces of the glass sheet and the polydimethylsiloxane microfluidic chip with ultraviolet light, and then realizes the preliminary bonding of the two by applying pressure to obtain the first bonding assembly. Then, the first bonding assembly is heat-treated to further strengthen the bonding interface and ensure a firm bond between the polydimethylsiloxane microfluidic chip and the glass sheet. The present invention prepares a microfluidic chip with high bonding strength by a simple and time-saving operation. The bonding method provided by the present invention does not require additional surface modification instrument pretreatment, is simple and efficient, significantly improves the utilization rate of the microfluidic chip, simplifies the bonding process, reduces the use of chemical reagents, and has broad application potential and commercial value in multiple fields.

[0110] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A bonding method for a microfluidic chip, characterized in that: The method comprises the following steps: The surface to be bonded of the polydimethylsiloxane microfluidic chip and the surface to be bonded of the glass sheet are subjected to a first ultraviolet irradiation and a second ultraviolet irradiation respectively, the first ultraviolet irradiation and the second ultraviolet irradiation are terminated at the same time, and then the surface to be bonded of the polydimethylsiloxane microfluidic chip and the surface to be bonded of the glass sheet after ultraviolet irradiation are arranged opposite to each other and pressed to form a first bonding assembly; The first bonding component is subjected to heating treatment to obtain a microfluidic chip.

2. The bonding method according to claim 1, characterized in that: The intensity of the first ultraviolet radiation is 5-20W, preferably 8-10W; Preferably, the intensity of the second ultraviolet radiation is 8-25W, preferably 12-16W.

3. The bonding method according to claim 2, characterized in that: The wavelengths of the first ultraviolet radiation and the second ultraviolet radiation are independently 185-254 nm; Preferably, the first ultraviolet irradiation time is 1-10 min, preferably 5-6 min; Preferably, the second ultraviolet irradiation time is 5-15 min, preferably 10-11 min.

4. The bonding method according to any one of claims 1 to 3, characterized in that: The temperature of the heating treatment is 80-100°C; Preferably, the heating treatment time is 1-2 hours.

5. The bonding method according to any one of claims 1 to 4, characterized in that: The preparation method of the polydimethylsiloxane microfluidic chip comprises: (1) mixing and stirring a polydimethylsiloxane main agent and a curing agent, and performing a vacuum operation to obtain a mixture; (2) pouring the mixture into a mold and performing thermal processing to obtain a polydimethylsiloxane chip; (3) Cutting, punching and cleaning the polydimethylsiloxane chip in sequence to obtain the polydimethylsiloxane microfluidic chip.

6. The bonding method according to claim 5, characterized in that: The mass ratio of the polydimethylsiloxane main agent and the curing agent is (8-12):1; Preferably, the number average molecular weight of the polydimethylsiloxane is 20000-40000; Preferably, the stirring speed is 100-300r / min; Preferably, the stirring time is 10-20 min; Preferably, the vacuum degree of the vacuum operation is 60-70 kPa; Preferably, the vacuuming operation time is 0.5-1h.

7. The bonding method according to claim 5 or 6, characterized in that: The temperature of the thermal processing is 80-100°C; Preferably, the thermal processing time is 1-2 hours.

8. The bonding method according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) mixing a polydimethylsiloxane main agent and a curing agent in a mass ratio of (8-12):1, stirring at a speed of 100-300 r / min for 10-20 min, and performing a vacuum operation for 0.5-1 h to obtain a mixture; (2) pouring the mixture into a mold and heat-processing it at 80-100° C. for 1-2 hours to obtain a polydimethylsiloxane chip; (3) cutting, punching and cleaning the polydimethylsiloxane chip in sequence, and cleaning the glass sheet to obtain a polydimethylsiloxane microfluidic chip and a cleaned glass sheet; (4) Using ultraviolet light with an intensity of 5-20W and a wavelength of 185-254nm to irradiate the surface to be bonded of the polydimethylsiloxane microfluidic chip for 1-10min, and using ultraviolet light with an intensity of 8-25W and a wavelength of 185-254nm to irradiate the surface to be bonded of the cleaned glass sheet for 5-15min. The ultraviolet irradiation of the polydimethylsiloxane microfluidic chip and the glass sheet is terminated at the same time. Then, the surface to be bonded of the polydimethylsiloxane microfluidic chip after ultraviolet irradiation and the surface to be bonded of the glass sheet are immediately arranged opposite to each other and pressed to form a first bonding assembly. The first bonding assembly is heat-treated at 80-100°C for 1-2h to obtain a microfluidic chip.

9. A microfluidic chip, characterized in that: The microfluidic chip is prepared by the bonding method of any one of claims 1 to 8.

10. Use of the microfluidic chip according to claim 9 in environmental monitoring, drug screening or chemical analysis.

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