Bonding method and apparatus for lithium niobate substrate and PDMS microchannel

Abstract

This invention provides a bonding method and apparatus based on a lithium niobate substrate and a PDMS microchannel. The bonding method includes: cleaning the lithium niobate substrate and the PDMS microchannel to remove impurities; bombarding the lithium niobate substrate and the PDMS microchannel with oxygen plasma; aligning the surfaces to be bonded on the lithium niobate substrate and the PDMS microchannel; bonding the surfaces to be bonded on the lithium niobate substrate and the PDMS microchannel; and baking the bonded lithium niobate substrate and the PDMS microchannel on a hot plate at 65°C to 95°C, applying pressure to the PDMS microchannel during baking to continue bonding. This invention can improve the bonding strength and stability between the lithium niobate substrate and the PDMS microchannel.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip technology, and in particular to a bonding method and apparatus based on lithium niobate substrate and PDMS microchannels. Background Technology

[0002] Currently, microfluidic chips for acoustically manipulated particles widely employ piezoelectric crystals such as lithium niobate to generate surface acoustic waves (SAWs), utilizing acoustic radiation forces to manipulate the particles. The microchannels are typically fabricated from PDMS (polydimethylsiloxane). A significant challenge in acoustically manipulated microfluidic chips is the bonding between the lithium niobate substrate with interdigitated electrodes and the PDMS microchannels. In other words, the bonding quality between the lithium niobate substrate and the PDMS microchannels directly affects the fluid movement within the microchannels, thus influencing the effectiveness of acoustic particle manipulation. In the field of microfluidic chip technology, the bonding process between the lithium niobate substrate and the PDMS microchannels is a crucial step in the fabrication of acoustically manipulated microfluidic chips; only with sufficiently high bonding strength can the assembled microfluidic chip withstand certain pressures.

[0003] Currently, the bonding methods used for lithium niobate substrates and PDMS microchannels mainly include direct bonding, intermediate layer-assisted bonding, and surface-modified bonding. Direct bonding is a reversible bonding method but cannot withstand high pressure. Intermediate layer-assisted bonding mainly uses silicon or silicon dioxide as an intermediate transition layer between the lithium niobate chip and the PDMS chip, utilizing the silicon in the silicon to form a strong chemical bond with the silicon-oxygen bonds in the PDMS chip. However, this method is complex, and the bonding strength between silicon or silicon dioxide and PDMS is higher than that with lithium niobate, easily leading to detachment of lithium niobate from silicon or silicon dioxide. Surface-modified bonding mainly uses oxygen plasma to bombard the surfaces of lithium niobate and PDMS to be bonded, activating both surfaces. However, the bonding strength obtained using current process parameters is low, failing to achieve high-strength bonding. In summary, existing bonding methods based on lithium niobate substrates and PDMS microchannels cannot meet the high bonding strength requirements of chips, and the bonding effect is unstable. Summary of the Invention

[0004] The technical problem solved by the present invention is: how to improve the bonding strength and stability between lithium niobate substrate and PDMS microchannel in microfluidic chip manufacturing process.

[0005] To address the aforementioned technical problems, the present invention provides a bonding method based on a lithium niobate substrate and a PDMS microchannel for use in microfluidic chips. The bonding method includes: The lithium niobate substrate and PDMS microchannels are cleaned to remove impurities; The lithium niobate substrate and PDMS microchannels were bombarded with oxygen plasma. Align the lithium niobate substrate with the bonding surface of the PDMS microchannel; The lithium niobate substrate is bonded to the bonding surface of the PDMS microchannel; The bonded lithium niobate substrate and PDMS microchannels are placed on a hot plate at 65°C to 95°C and baked. During baking, pressure is applied to the PDMS microchannels to continue bonding.

[0006] Optionally, the bonding method further includes: forming the lithium niobate substrate; the formation of the lithium niobate substrate includes: The lithium niobate substrate was cleaned and irradiated to make it hydrophilic. A first photoresist is disposed on the lithium niobate substrate and exposed to form the desired pattern; The residual adhesive on the patterned lithium niobate substrate is removed, and magnetron sputtering is performed to prepare the desired electrode.

[0007] Optionally, the bonding method further includes: forming the PDMS microchannel; the formation of the PDMS microchannel includes: Place the prepared PDMS prepolymer into a vacuum chamber and evacuate it. The PDMS prepolymer is cast onto a flow channel template and then cured to form the PDMS microchannel.

[0008] Optionally, the bonding method further includes: forming the flow channel template; the forming of the flow channel template includes: The silicon substrate is cleaned and irradiated to make it hydrophilic; The second photoresist is spin-coated onto the silicon substrate, and the silicon substrate is then baked for the first time. The baked silicon substrate is cooled to room temperature for exposure and then baked a second time. Cool the exposed silicon substrate and perform cyclic development; The developed silicon substrate is placed in a vacuum drying oven and left to stand for evaporation of the remaining second photoresist.

[0009] Optionally, aligning the lithium niobate substrate with the bonding surface of the PDMS microchannel includes: Align and bond the lithium niobate substrate with the bonding surface of the PDMS microchannel; Use a roller brush to press the bonded lithium niobate substrate and PDMS microchannels to remove air bubbles between the surfaces to be bonded.

[0010] Optionally, aligning the lithium niobate substrate with the bonding surface of the PDMS microchannel includes: Lubricant is dropped onto the bonding surfaces of the lithium niobate substrate and the PDMS microchannel to align and bond them. The lithium niobate substrate and PDMS microchannels are pressed together with a roller brush to squeeze out air bubbles and the lubricant between the surfaces to be bonded. The lithium niobate substrate and PDMS microchannel were placed in a vacuum drying oven and evacuated to remove the lubricant.

[0011] Optionally, the lubricant is anhydrous ethanol.

[0012] Optionally, the bombardment of the lithium niobate substrate and PDMS microchannel with oxygen plasma includes: The cleaned lithium niobate substrate and PDMS microchannels are placed in the cavity of an oxygen plasma cleaner and bombarded with preset gas pressure, preset power and preset duration.

[0013] Optionally, the step of cleaning the lithium niobate substrate and PDMS microchannels to remove impurities includes: The lithium niobate substrate and PDMS microchannel were sequentially placed in acetone, anhydrous ethanol and deionized water, and each was cleaned in an ultrasonic cleaner for a preset cleaning time.

[0014] To address the aforementioned technical problems, the present invention also provides a device containing a microfluidic chip, wherein the microfluidic chip comprises a lithium niobate substrate and a PDMS microchannel, and the lithium niobate substrate and the PDMS microchannel are bonded by the bonding method described above.

[0015] The beneficial effects of the technical solution of the present invention include at least the following: The bonding method based on lithium niobate substrate and PDMS microchannels of the present invention can bond PDMS microchannels on lithium niobate substrate with high strength through cleaning, oxygen plasma bombardment, bonding and heating and pressurization. The bonding method is simple and quick to operate, has a stable bonding effect, and can be mass-produced, thereby realizing high-strength encapsulation of lithium niobate and PDMS.

[0016] The bonding method of the present invention has a fast bonding speed and simple process operation. It only requires bombarding the surface with oxygen plasma and heating with a hot plate, which reduces the complexity of the process and is conducive to the low-cost and mass production of microfluidic chips.

[0017] The technical solution of this invention activates the surfaces of lithium niobate substrate and PDMS microchannel by bombarding them with oxygen ions in a plasma cleaner, thereby improving the tightness of the bond. Compared with existing bonding technologies, this bonding method has higher bonding strength and more stable bonding effect. Attached Figure Description

[0018] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the microfluidic chip involved in the technical solution of the present invention.

[0019] Figure 2 This is a schematic diagram of the specific structure of the microfluidic chip involved in the technical solution of this invention.

[0020] Figure 3 This is a schematic diagram of a method for preparing a lithium niobate substrate provided by the technical solution of the present invention.

[0021] Figure 4 This is a schematic diagram of a method for preparing PDMS microchannels provided by the technical solution of the present invention.

[0022] Figure 5 This is a schematic flowchart of a method for preparing a flow channel template, which is provided by the technical solution of the present invention.

[0023] Figure 6 This is a schematic flowchart illustrating a bonding method between a lithium niobate substrate and a PDMS microchannel, which is provided for the technical solution of this invention. Detailed Implementation

[0024] To better illustrate the technical solution of the present invention, the present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of a microfluidic chip in the prior art, including a lithium niobate substrate 1 and PDMS microchannels 2. The PDMS microchannels 2 are disposed on the lithium niobate substrate 1 and bonded to the lithium niobate substrate 1 by a bonding method. Figure 2 An interdigitated electrode 4 and a deflection electrode 7 are disposed on a lithium niobate substrate 1. The PDMS microchannel 2 may include a channel inlet 3, a channel inlet 6, a microchannel 8 and a channel outlet 9. A charging electrode grounding wire 5 is also disposed at the intersection of the microchannel 8.

[0026] To Figure 1 To bond the lithium niobate substrate 1 and PDMS microchannel 2 of the microfluidic chip, it is first necessary to prepare the lithium niobate substrate 1 and PDMS microchannel 2.

[0027] Figure 3 A method for preparing a lithium niobate substrate 1 is illustrated, comprising the following steps: S100, Clean and irradiate the lithium niobate substrate to make the lithium niobate substrate hydrophilic.

[0028] Specifically, the lithium niobate substrate used in the experiment can be cleaned with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, and then irradiated with a UV cleaner for 25 minutes to make its surface hydrophilic.

[0029] Step S101: A layer of photoresist is deposited on the lithium niobate substrate and exposed to form the desired pattern.

[0030] Specifically, a layer of photoresist can be evenly coated onto a lithium niobate substrate using a spin coater, and then pre-baked on a hot plate to evaporate the photoresist solvent, thus arranging the photoresist on the lithium niobate substrate. A pre-prepared photomask with electrode patterns is placed on the photoresist-coated lithium niobate substrate, exposed under a photolithography machine, and then post-baked. The desired pattern is then formed on the lithium niobate substrate through development.

[0031] In step S102, the residual adhesive on the patterned lithium niobate substrate is removed, and magnetron sputtering is performed to prepare the desired electrode.

[0032] Specifically, the patterned lithium niobate substrate can be placed in oxygen plasma to remove residual photoresist and then magnetron sputtered. The substrate is sputtered twice with a power of 200W DC for 5 minutes each time, with a 30-minute interval between the two sputterings. After sputtering, excess photoresist is removed with acetone to prepare the required electrode on the lithium niobate substrate.

[0033] Based on Figure 4 The process steps shown are for preparing PDMS microchannels 2. The method for preparing PDMS microchannels 2 may include: Step S200: Place the prepared PDMS prepolymer into a vacuum chamber and evacuate it.

[0034] Specifically, the PDMS prepolymer can be prepared as follows: Use two droppers to draw 10 ml of PDMS adhesive and 1 ml of curing agent respectively, and place them in a clean glass petri dish. Mix the PDMS adhesive and curing agent, and stir with a glass rod for 20 minutes until a large number of uniform small bubbles appear on the surface of the mixture. Place the prepared PDMS prepolymer in a vacuum chamber and evacuate until no bubbles appear on the surface or inside the mixture, thus completing step S200.

[0035] Step S201: The PDMS prepolymer is poured onto the flow channel template and the PDMS prepolymer is cured to form the PDMS microchannel.

[0036] Specifically, PDMS prepolymer can be cast onto a flow channel template and baked in an oven at 80°C for 2 hours to cure the PDMS, thus obtaining a PDMS chip with microchannels.

[0037] More specifically, in step S201, the flow channel template can be adopted as follows: Figure 5 The process steps shown are as follows: Step S300: Clean and irradiate the silicon substrate to make it hydrophilic.

[0038] Specifically, the silicon substrate used in the experiment was cleaned with acetone, anhydrous ethanol and deionized water for 15 minutes each, and then irradiated with a UV cleaner for 25 minutes to make its surface hydrophilic.

[0039] Step S301: Spin-coat the photoresist onto the silicon substrate and bake the silicon substrate for the first time.

[0040] Specifically, SU-8 photoresist can be spin-coated onto a silicon substrate. The coated silicon substrate is then placed on a hot plate at 65°C and held for 5 minutes. Next, the hot plate temperature is set to 95°C and held for 10 minutes. Then, the hot plate temperature is lowered to 65°C and held for 5 minutes to complete the first baking of the silicon substrate.

[0041] In step S302, the baked silicon substrate is cooled to room temperature for exposure and then baked a second time.

[0042] Specifically, after the first baking, the silicon substrate is cooled to room temperature and exposed on a lithography machine. The exposed substrate is then placed on a hot plate at 65°C and held for 2 minutes. Next, the temperature of the hot plate is adjusted to 95°C and held for 10 minutes to complete the second baking of the silicon substrate.

[0043] Step S303: Cool the exposed silicon substrate and perform cyclic development.

[0044] Specifically, after cooling the silicon substrate to room temperature, it was placed in propylene glycol methyl ether acetate and isopropanol solutions for 15 seconds each for cyclic development until no white precipitate appeared.

[0045] Step S304: Place the developed silicon substrate in a vacuum drying oven and let it stand to evaporate the remaining photoresist.

[0046] Specifically, the developed silicon substrate is placed in a vacuum drying oven at 150°C and left to stand for 10 minutes to evaporate the remaining SU-8 photoresist solvent and make the adhesion between the photoresist on the substrate and the silicon wafer stronger, thus completing the preparation of the flow channel template.

[0047] The lithium niobate substrate can be prepared through steps S100 to S102, and the PDMS microchannel can be prepared through steps S200 to S201.

[0048] The technical solution of this invention provides a way to... Figure 1 and Figure 2The method for bonding the lithium niobate substrate 1 and the PDMS microchannel 2 shown employs oxygen plasma treatment to activate the surfaces to be bonded. This bonding method can improve the strength and stability of the bonding between the lithium niobate substrate and the PDMS microchannel in the microfluidic chip manufacturing process. The lithium niobate substrate and the PDMS microchannel can be bonded via… Figures 3 to 5 The preparation is carried out according to the following methods and steps.

[0049] refer to Figure 6 A bonding method based on lithium niobate substrate and PDMS microchannels for fabricating microfluidic chips includes the following steps: Step S400: The lithium niobate substrate and PDMS microchannel are cleaned to remove impurities.

[0050] The lithium niobate substrate and PDMS microchannels can be sequentially immersed in acetone, anhydrous ethanol, and deionized water, and then cleaned in an ultrasonic cleaner for a preset cleaning time to complete the cleaning step of the lithium niobate substrate and PDMS microchannels. The preset cleaning time can be set according to the need for thorough cleaning of the bonding surfaces, generally 10 to 20 minutes. Specifically, the lithium niobate substrate and PDMS chip (microchannels) can be sequentially immersed in acetone, anhydrous ethanol, and deionized water, and cleaned in an ultrasonic cleaner for 15 minutes in each to remove impurities from the surfaces of the lithium niobate substrate and PDMS chip and maintain cleanliness.

[0051] Step S401: The lithium niobate substrate and PDMS microchannel are bombarded with oxygen plasma.

[0052] Step S401 can be completed through the following steps: The cleaned lithium niobate substrate and PDMS microchannels are placed into the cavity of an oxygen plasma cleaner, and bombarded with preset gas pressure, preset power, and preset duration. Specifically, the cleaned lithium niobate substrate and PDMS chip are placed into the cavity of the oxygen plasma cleaner, the oxygen plasma flow rate is adjusted to 50 ml / min, and bombardment of the lithium niobate substrate and PDMS chip begins when the gas pressure is around 100 Pa. Bombardment is performed at 150 W power for 2 minutes, after which they are removed.

[0053] In other embodiments, step S401 can also be completed through the following steps: First, the lithium niobate substrate is placed in an oxygen plasma cleaner and bombarded with a first preset pressure, a first preset power, and a first preset duration; then, after the lithium niobate substrate has been bombarded, the chamber pressure of the oxygen plasma cleaner is allowed to rise to a second preset pressure, and the PDMS microchannel is placed into the chamber of the oxygen plasma cleaner, bombarding the lithium niobate substrate and the PDMS microchannel with the second preset pressure, a second preset power, and a second preset duration. Specifically, the lithium niobate substrate can be placed in the oxygen plasma cleaner and bombarded at 120W power for 2 minutes; after the lithium niobate substrate has been bombarded, the chamber pressure is allowed to rise to atmospheric pressure, and without removing the lithium niobate substrate, the PDMS is placed into the chamber of the oxygen plasma cleaner and bombarded together with the lithium niobate substrate at 120W power for 32 seconds, and then removed. The surface activity of lithium niobate decreases rapidly after bombardment. Therefore, the surface of lithium niobate can be bombarded once in advance as needed. Using this method of bombarding lithium niobate with oxygen plasma first can improve the activity of the lithium niobate surface to be bonded.

[0054] Step S402: Align the lithium niobate substrate with the bonding surface of the PDMS microchannel, and bond the lithium niobate substrate with the bonding surface of the PDMS microchannel.

[0055] The following steps can be used to align the lithium niobate substrate and the bonding surfaces of the PDMS microchannel: Align and bond the lithium niobate substrate and the bonding surfaces of the PDMS microchannel; press the bonded lithium niobate substrate and PDMS microchannel with a roller brush to remove air bubbles between the bonding surfaces. Specifically, immediately after removing the lithium niobate substrate and PDMS chip, align and bond their bonding surfaces, and press the aligned chip with a roller brush until all air bubbles between the lithium niobate substrate and PDMS are squeezed out, thus completing the alignment of the bonding surfaces of the lithium niobate substrate and PDMS microchannel.

[0056] In other embodiments, the following steps are also used to align the lithium niobate substrate and the PDMS microchannel surfaces to be bonded: Lubricant is applied to the bonding surfaces of the lithium niobate substrate and the PDMS microchannel to align and bond; a roller brush is used to press the bonded lithium niobate substrate and PDMS microchannel to squeeze out air bubbles and the lubricant between the bonding surfaces; the lithium niobate substrate and PDMS microchannel are placed in a vacuum drying oven for degassing to remove the lubricant. The lubricant involved in this process can be anhydrous ethanol, deionized water, isopropanol, etc. Specifically, after step S401, the lithium niobate substrate and PDMS chip can be removed, and a few drops of anhydrous ethanol can be applied to the bonding surfaces as a lubricant to allow the PDMS to slide on the lithium niobate substrate until it is correctly aligned. A roller brush is used to press the aligned and bonded chip until air bubbles and a large amount of ethanol between the lithium niobate substrate and the PDMS chip are squeezed out, thus completing the alignment of the bonding surfaces of the lithium niobate substrate and the PDMS microchannel. If the lubricant used can be a drier preparation such as anhydrous ethanol, in a variation of this embodiment, after the surfaces to be bonded are aligned and bonded, the partially bonded lithium niobate substrate and PDMS chip can be placed in a vacuum drying oven for degassing to remove residual anhydrous ethanol and enhance the bonding strength.

[0057] In step S402, the lithium niobate substrate and the PDMS microchannel can be bonded using existing technology.

[0058] Step S403: Place the bonded lithium niobate substrate and PDMS microchannel on a hot plate at 65°C to 95°C for baking. During baking, pressure is applied to the PDMS microchannel to continue bonding.

[0059] Specifically, after the lithium niobate substrate is bonded to the PDMS chip, it is baked on a hot plate at 65°C to 95°C for 8 hours, during which a force of approximately 8N is applied above the PDMS to enhance the bonding strength between the two. In other embodiments, the baking temperature can be set to around 85°C, and the baking time can be longer than 8 hours, during which a force of approximately 10N is applied above the PDMS.

[0060] Based on the process steps S400 to S404 above, the lithium niobate substrate required for the microfluidic chip can be bonded to the PDMS microchannel using the bonding method of the first application example: The lithium niobate substrate and PDMS were placed in acetone, anhydrous ethanol and deionized water in sequence, and each was cleaned in an ultrasonic cleaner for 15 minutes to remove impurities from the surface of the lithium niobate substrate and PDMS and keep them clean. The cleaned lithium niobate substrate and PDMS were placed in the cavity of the oxygen plasma cleaner. The flow rate of the oxygen plasma was adjusted to 50 ml / min. When the pressure was around 100 Pa, the lithium niobate substrate and PDMS were bombarded for 2 minutes at a power of 150 W, and then removed. Immediately after removing the lithium niobate substrate and PDMS, align and bond the surfaces of the two substrates to be bonded. Use a roller brush to press and align the bonded chip until all air bubbles between the lithium niobate substrate and PDMS are squeezed out. After the lithium niobate substrate is bonded to PDMS, it is baked on a hot plate at 65℃-95℃ for 8 hours, and during this period, a force of about 8N is applied above the PDMS to enhance the bonding strength between the two.

[0061] Compared with existing bonding methods, the bonding method in this application example can significantly enhance the bonding strength between the lithium niobate substrate and PDMS.

[0062] Based on the process steps S400 to S403 above, the lithium niobate substrate required for the microfluidic chip can also be bonded to the PDMS microchannel using the bonding method of the second application example below: The lithium niobate substrate and PDMS were placed in acetone, anhydrous ethanol and deionized water in sequence, and each was cleaned in an ultrasonic cleaner for 15 minutes to remove impurities from the surface of the lithium niobate substrate and PDMS and keep them clean. The cleaned lithium niobate substrate and PDMS were placed in the cavity of the oxygen plasma cleaner. The flow rate of the oxygen plasma was adjusted to 50 ml / min. When the pressure was around 100 Pa, the lithium niobate substrate and PDMS were bombarded for 2 minutes at a power of 120 W, and then removed. After removing the lithium niobate substrate and PDMS, drop a few drops of anhydrous ethanol on the surfaces to be bonded as a lubricant so that the PDMS can slide on the lithium niobate substrate until it is correctly aligned. Use a roller brush to press and align the chip after bonding until the air bubbles and a large amount of ethanol between the lithium niobate substrate and PDMS are squeezed out. Next, the partially bonded lithium niobate substrate and PDMS were placed in a vacuum drying oven for degassing to remove residual anhydrous ethanol and enhance the adhesion. After the lithium niobate substrate is bonded to PDMS, it is baked on a hot plate at 65℃-95℃ for 8 hours, and during this period, a force of about 8N is applied above the PDMS to enhance the bonding strength between the two.

[0063] The lithium niobate substrate bonded to PDMS using this second application example differs from the first application example in that anhydrous ethanol is used as a lubricant. The lubricant assists in the sliding of PDMS on the lithium niobate substrate until it is correctly aligned, further increasing the bond strength and stability.

[0064] Based on the process steps S400 to S403 above, the lithium niobate substrate required for the microfluidic chip can also be bonded to the PDMS microchannel using the following third application example bonding method: The lithium niobate substrate and PDMS were placed in acetone, anhydrous ethanol and deionized water in sequence, and each was cleaned in an ultrasonic cleaner for 15 minutes to remove impurities from the surface of the lithium niobate substrate and PDMS and keep them clean. The lithium niobate substrate was placed in an oxygen plasma cleaner and bombarded for 2 minutes at a power of 120W. After the lithium niobate substrate is bombarded, wait for the pressure inside the chamber to rise to atmospheric pressure. Without removing the lithium niobate substrate, place the PDMS into the chamber of the oxygen plasma cleaner and bombard it together with the lithium niobate substrate at a power of 120W for 32 seconds, and then remove it. After removing the lithium niobate substrate and PDMS, drop a few drops of anhydrous ethanol on the surfaces to be bonded as a lubricant so that the PDMS can slide on the lithium niobate substrate until it is correctly aligned. Use a roller brush to press and align the chip after bonding until all the air bubbles between the lithium niobate substrate and PDMS are squeezed out. Next, the partially bonded lithium niobate substrate and PDMS were placed in a vacuum drying oven for degassing to remove anhydrous ethanol and enhance the adhesion.

[0065] The lithium niobate substrate and PDMS bonded through this third application example differ from the second application example in that a different oxygen plasma bombardment method is used to bombard the lithium niobate substrate and PDMS microchannel. Specifically, the lithium niobate substrate is first bombarded with oxygen plasma, and then PDMS is added to continue bombarding the lithium niobate substrate and PDMS. This bombardment scheme can further increase the bonding strength and stability.

[0066] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A bonding method based on lithium niobate substrate and PDMS microchannels for microfluidic chips, characterized in that, The bonding method includes: The lithium niobate substrate and PDMS microchannels are cleaned to remove impurities; The lithium niobate substrate and PDMS microchannels were bombarded with oxygen plasma. The method of bombarding the lithium niobate substrate and PDMS microchannel with oxygen plasma includes: first, placing the lithium niobate substrate in an oxygen plasma cleaner and bombarding the lithium niobate substrate with a first preset pressure, a first preset power, and a first preset duration; then, after the lithium niobate substrate has been bombarded, waiting for the chamber pressure of the oxygen plasma cleaner to rise to a second preset pressure, placing the PDMS microchannel in the chamber of the oxygen plasma cleaner, and bombarding the lithium niobate substrate and PDMS microchannel with the second preset pressure, a second preset power, and a second preset duration; Align the lithium niobate substrate with the bonding surface of the PDMS microchannel; bond the lithium niobate substrate with the bonding surface of the PDMS microchannel. The bonded lithium niobate substrate and PDMS microchannel are placed on a hot plate at 65°C to 95°C and baked for more than 8 hours. During baking, a force of approximately 8N to 10N is applied to the PDMS microchannel to enhance the bonding strength between the lithium niobate substrate and the PDMS microchannel, so as to continue bonding.

2. The bonding method as described in claim 1, characterized in that, It also includes: forming the lithium niobate substrate; the formation of the lithium niobate substrate includes: The lithium niobate substrate was cleaned and irradiated to make it hydrophilic. A first photoresist is disposed on the lithium niobate substrate and exposed to form the desired pattern; The residual adhesive on the patterned lithium niobate substrate is removed, and magnetron sputtering is performed to prepare the desired electrode.

3. The bonding method as described in claim 1, characterized in that, Also includes: Forming the PDMS microchannels; The formation of the PDMS microchannel includes: Place the prepared PDMS prepolymer into a vacuum chamber and evacuate it. The PDMS prepolymer is cast onto a flow channel template and then cured to form the PDMS microchannel.

4. The bonding method as described in claim 1, characterized in that, It also includes: forming a flow channel template; the forming flow channel template includes: The silicon substrate is cleaned and irradiated to make it hydrophilic; The second photoresist is spin-coated onto the silicon substrate, and the silicon substrate is then baked for the first time. The baked silicon substrate is cooled to room temperature for exposure and then baked a second time. Cool the exposed silicon substrate and perform cyclic development; The developed silicon substrate is placed in a vacuum drying oven and left to stand for evaporation of the remaining second photoresist.

5. The bonding method as described in claim 1, characterized in that, The step of aligning the lithium niobate substrate with the bonding surface of the PDMS microchannel includes: Align and bond the lithium niobate substrate with the bonding surface of the PDMS microchannel; Use a roller brush to press the bonded lithium niobate substrate and PDMS microchannels to remove air bubbles between the surfaces to be bonded.

6. The bonding method as described in claim 1, characterized in that, The step of aligning the lithium niobate substrate with the bonding surface of the PDMS microchannel includes: Lubricant is dropped onto the bonding surfaces of the lithium niobate substrate and the PDMS microchannel to align and bond them. The lithium niobate substrate and PDMS microchannels are pressed together with a roller brush to squeeze out air bubbles and the lubricant between the surfaces to be bonded. The lithium niobate substrate and PDMS microchannel were placed in a vacuum drying oven and evacuated to remove the lubricant.

7. The bonding method as described in claim 6, characterized in that, The lubricant is anhydrous ethanol.

8. The bonding method as described in claim 1, characterized in that, The step of cleaning the lithium niobate substrate and PDMS microchannels to remove impurities includes: The lithium niobate substrate and PDMS microchannel were sequentially placed in acetone, anhydrous ethanol and deionized water, and each was cleaned in an ultrasonic cleaner for a preset cleaning time.

9. A device comprising a microfluidic chip, the microfluidic chip comprising: A lithium niobate substrate and a PDMS microchannel, characterized in that the lithium niobate substrate and the PDMS microchannel are bonded by the bonding method as described in claim 1.

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