Method for manufacturing acoustic microfluidic chip, and acoustic microfluidic device

Abstract

A method for manufacturing an acoustic microfluidic chip, and an acoustic microfluidic device. A phononic crystal plate and a microfluidic cavity are cleaned and then dried, and the phononic crystal plate and the microfluidic cavity are connected by means of a thin film layer to form an acoustic microfluidic chip. The present invention has strong binding force and flexible design, avoids liquid leakage, and facilitates installation.

Description

Acoustic microfluidic chip preparation method and acoustic microfluidic device Technical Field

[0001] The present application belongs to the field of microfluidics technology, and in particular relates to a method for preparing an acoustic microfluidic chip and an acoustic microfluidic device. Background Art

[0002] In recent years, thanks to advances in micro- and nanofabrication technologies such as soft lithography, the fabrication of multifunctional microfluidic devices has made significant progress, enabling lab-on-a-chip integration. Acoustofluidics is an emerging interdisciplinary field involving acoustics, chemistry, fluid physics, microelectronics, and new materials. It combines acoustics with microfluidics, utilizing sound waves as a driving force to manipulate fluids or particles within microchannels.

[0003] Acoustofluidic devices primarily consist of a microfluidic network and a substrate that supports this network and propagates acoustic waves. These substrates can be made of various materials, such as PDMS (polydimethylsiloxane), plastic, glass, and metal, depending on the application. PDMS, a silicone-based elastomer, is a commonly used material for microfluidic networks due to its many desirable properties (e.g., elasticity, optical transparency, biocompatibility, low autofluorescence, and excellent thermal and chemical stability). A crucial aspect of acoustofluidic device fabrication is the sealing of microfluidic components. Tight sealing is required to ensure proper injection and delivery of fluids without leakage, prevent external and cross-contamination, and protect sensitive areas during device operation. Currently, microchannels are typically created in PDMS and then sealed with solid or flexible substrates to form chips. Silicon-based substrates (e.g., glass or silicon) can bond relatively easily to PDMS through simple surface activation methods, such as oxygen plasma treatment, making these the most widely used methods for sealing microchannels. Because irreversible chemical bonds are formed between the activated or functionalized PDMS and the substrate surface, these sealing methods are known as bonding techniques. However, these methods are applicable only to select materials.

[0004] Phononic crystal plates are man-made structures or materials that can control the reflection, transmission, absorption, and transmission of sound waves. Phononic crystal plates are periodic acoustic structures composed of a thin plate with a periodic grid patterned on the surface. Because they are typically made of metal, direct bonding to PDMS cavities via oxygen plasma bonding is difficult.

[0005] Existing packaging methods primarily involve simple bonding or embedded fixation. A microcavity is constructed by bonding a PDMS cavity wall to a glass substrate. The phononic crystal plate is then placed within the cavity, and a cover glass is attached to the PDMS cavity wall on top. This does not directly bond the phononic crystal plate to the microfluidic channel; the bonding strength is weak, making it prone to leakage. Embedded fixation methods are inflexible and difficult to install and miniaturize.

[0006] Summary of the Invention

[0007] 1. Technical problems to be solved

[0008] Based on the packaging problem between the existing microfluidic cavity and the phononic crystal plate, the present application provides a method for preparing an acoustic microfluidic chip and an acoustic microfluidic device.

[0009] 2 Technical Solutions

[0010] In order to achieve the above-mentioned purpose, the present application provides a method for preparing an acoustic microfluidic chip, which includes cleaning and drying a phononic crystal plate and a microfluidic cavity, and connecting the phononic crystal plate and the microfluidic cavity through a thin film layer.

[0011] Another embodiment provided by the present application is: the connection includes depositing a thin film layer that is easily bonded to the microfluidic channel on the surface of the phononic crystal plate by a physical vapor deposition method, and then performing oxygen plasma treatment on the surfaces of the phononic crystal plate and the microfluidic channel to be joined, and then laminating the phononic crystal plate and the microfluidic channel to form an irreversible bond.

[0012] Another embodiment provided by the present application is: the connection includes subjecting the thin film layer and the surface to be joined of the microfluidic cavity to oxygen plasma treatment, and then laminating the two to form an irreversible bond to obtain an encapsulated microfluidic cavity, and then laminating the encapsulated microfluidic cavity to the phononic crystal plate.

[0013] Another embodiment provided by the present application is that the thin film layer is a SiO2 thin film layer.

[0014] Another embodiment provided by the present application is that the physical vapor deposition method includes vacuum evaporation coating, vacuum sputtering coating and vacuum ion plating.

[0015] Another embodiment provided by the present application is: the connection includes respectively coating the thin film layer on the phononic crystal plate and the microfluidic channel, then performing oxygen plasma treatment on the surfaces of the coated phononic crystal plate and the coated microfluidic channel to be joined, and then bonding the coated phononic crystal plate and the coated microfluidic channel.

[0016] The present application also provides an acoustic microfluidic device, characterized by being an acoustic microfluidic chip prepared by the acoustic microfluidic chip preparation method according to any one of claims 1 to 6.

[0017] Another embodiment provided by the present application is: comprising a sample delivery and collection module, the acoustic microfluidic chip and an ultrasonic excitation module connected in sequence.

[0018] Another embodiment provided by the present application is that the sample delivery and collection module includes a syringe pump and a collection component connected to each other, the syringe pump is connected to the microfluidic channel, and the collection component is connected to the microfluidic channel.

[0019] Another embodiment provided by the present application is that the ultrasonic excitation module includes a signal generator, a power amplifier and an ultrasonic transducer connected in sequence, and the sound waves generated by the ultrasonic transducer excite the phononic crystal plate to generate a resonant sound field.

[0020] 3. Beneficial effects

[0021] Compared with the prior art, the acoustic microfluidic chip preparation method and acoustic microfluidic device provided by this application have the following advantages:

[0022] The present application provides a method for preparing an acoustic microfluidic chip, which prepares a new acoustic microfluidic chip. The microfluidic cavity and the phononic crystal plate are connected together by an intermediate film layer. The bonding force is strong, the design is flexible, and the installation is simple, thereby achieving good packaging of the phononic crystal plate, thereby providing a new type of packaged acoustic microfluidic chip.

[0023] The acoustic microfluidic chip preparation method provided in this application can directly combine the phononic crystal plate with the microfluidic cavity to form a new acoustic microfluidic chip.

[0024] The acoustic microfluidic chip preparation method provided in this application has strong binding force and will not leak.

[0025] The acoustic microfluidic chip preparation method provided in this application is easy to install and can be assembled flexibly.

[0026] The acoustic microfluidic device provided in this application mainly utilizes the drag force of the incident flow in the cavity on the particles, the acoustic radiation force of the resonant sound field of the phononic crystal plate on the particles, and the drag force of the acoustic flow induced by the resonant sound field on the particles to achieve the manipulation of particles of different sizes and material parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic flow chart of the method for preparing an acoustic microfluidic chip of the present application;

[0028] FIG2 is a schematic diagram of the transmission spectrum of the phononic crystal plate of the present application;

[0029] FIG3 is a diagram of the resonance sound field of a phononic crystal plate without a PDMS cavity;

[0030] FIG4 is a diagram of the resonance sound field of a PDMS cavity phononic crystal plate;

[0031] FIG5 is a schematic diagram of the grid side of the phononic crystal plate of the present application;

[0032] FIG6 is a schematic diagram of the acoustic microfluidic chip of the present application;

[0033] FIG7 is a schematic diagram showing that particles of both sizes are captured under high input power of the present application;

[0034] FIG8 is a schematic diagram showing large particles being captured and small particles flowing out of the cavity under appropriate input power of the present application;

[0035] FIG9 is a schematic diagram of the acoustic field distribution when a 50 μm thick PDMS film is present between the cavity and the phononic crystal plate of the present invention;

[0036] FIG10 is a schematic diagram of an acoustic microfluidic device of the present application;

[0037] FIG11 is a schematic diagram of the principle of the acoustic microfluidic device of the present application. DETAILED DESCRIPTION

[0038] Hereinafter, specific embodiments of the present application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand the present application and implement the present application. Without violating the principles of the present application, the features of different embodiments may be combined to obtain new implementations, or certain features of certain embodiments may be substituted to obtain other preferred implementations.

[0039] 1 to 11 , the present application provides a method for preparing an acoustic microfluidic chip, the method comprising cleaning and drying a phononic crystal plate and a microfluidic cavity, and connecting the phononic crystal plate and the microfluidic cavity via a thin film layer.

[0040] An intermediate film layer is introduced between the phononic crystal plate and the microfluidic cavity to achieve close integration of the phononic crystal and the microfluidic cavity, and to construct a new acoustic microfluidic chip based on the phononic crystal plate.

[0041] Furthermore, the connection includes depositing a thin film layer that is easily bonded to the microfluidic channel on the surface of the phononic crystal plate by a physical vapor deposition method, then subjecting the surfaces of the phononic crystal plate and the microfluidic channel to be bonded to oxygen plasma treatment, and then laminating the phononic crystal plate and the microfluidic channel to form an irreversible bond.

[0042] In this scheme, plasma bonding is achieved by depositing thin film layers and cavities on the surface of the phononic crystal plate, the materials of which are SiO2 and PDMS respectively.

[0043] Specifically, referring to FIG1 , (1) using an organic solvent such as isopropyl alcohol to clean the surface of the phononic crystal plate and the PDMS cavity to remove impurities such as grease and dust, and then drying;

[0044] (2) A 100 nm thick thin film layer, i.e., the intermediate film layer, is deposited on the surface of the phononic crystal plate by physical vapor deposition (PVD). The material of the intermediate film layer needs to be able to undergo oxygen plasma bonding with PDMS, such as SiO2. PVD technology refers to the technology of using physical methods to vaporize the surface of a material source (solid or liquid) into gaseous atoms or molecules, or partially ionize it into ions under vacuum conditions, and deposit a thin film with certain special functions on the surface of the substrate through a low-pressure gas (or plasma) process. Physical vapor deposition is one of the main surface treatment technologies. PVD coating technology is mainly divided into three categories: vacuum evaporation coating, vacuum sputtering coating, and vacuum ion coating. The corresponding vacuum coating equipment includes vacuum evaporation coating machines, vacuum sputtering coating machines, and vacuum ion coating machines. These vacuum coating equipment can deposit the required materials on the surface of the phononic crystal plate.

[0045] (3) Place the deposited phononic crystal plate, intermediate film layer, and PDMS into an oxygen plasma cleaner to plasma-treat the surfaces to be bonded. Then, place the two together and wait for several minutes to complete the irreversible bonding. The specific waiting time depends on the material, cleaning time, and other factors.

[0046] Another method that can be implemented in this application is: the connection includes oxygen plasma treatment of the thin film layer and the surface to be joined of the microfluidic cavity, and then laminating the two to form an irreversible bond to obtain an encapsulated microfluidic cavity, and then laminating the encapsulated microfluidic cavity on the phononic crystal plate (plasma treatment is not performed in this step. In fact, there is no bond between the cavity and the phononic crystal plate, and they are separable). Under this scheme, the thin film layer and the cavity are plasma bonded, and the materials are PDMS and PDMS respectively. This thin film layer is not obtained by the deposition method in scheme one (thickness 100 nanometers). In the experiment, I purchased it (PDMS film, made by other processes, thickness 50 microns).

[0047] In the original design, once the phononic crystal plate and cavity are bonded, they cannot be separated. If the cavity becomes clogged, the entire chip must be replaced. This alternative design eliminates the need to bond the phononic crystal plate and cavity. Instead, a thin layer of material, such as a PDMS film or glass sheet, is bonded to the microfluidic cavity to encapsulate the cavity. This encapsulated cavity is then adhered to the phononic crystal plate by intermolecular forces. Since the cavity is now sealed, separation and leakage cannot occur. If the cavity becomes clogged, the cavity can be replaced and re-encapsulated without replacing the phononic crystal plate. Furthermore, since the encapsulated cavity is separated from the phononic crystal plate, the channel's position can be adjusted during use, providing greater flexibility. As shown in Figure 8, with the film in place, the acoustic field within the cavity retains the same shape as without the cavity, making it suitable for particle manipulation.

[0048] Another method that can be implemented in this application is: the bonding includes coating the thin film layer on the phononic crystal plate and the microfluidic channel, respectively, then subjecting the coated phononic crystal plate and the coated microfluidic channel to oxygen plasma treatment on the surfaces to be bonded, and then laminating the coated phononic crystal plate and the coated microfluidic channel. In this solution, plasma bonding is achieved between the thin film layer deposited on the phononic crystal plate and the PDMS surface. The materials are SiO2 and SiO2, respectively.

[0049] This application also provides an acoustic microfluidic device, an acoustic microfluidic chip fabricated using the acoustic microfluidic chip fabrication method. The material, size, shape, and placement of the microfluidic channel can be adjusted based on the field morphology of the phononic crystal plate and the particle manipulation requirements. The material of the intermediate film layer must be selected to be both deposited on the surface of the phononic crystal plate and capable of oxygen plasma bonding with PDMS.

[0050] Furthermore, it includes a sample delivery and collection module, the acoustic microfluidic chip and an ultrasonic excitation module which are connected in sequence.

[0051] Furthermore, the sample delivery and collection module includes a syringe pump and a collection component that are connected to each other, the syringe pump is connected to the microfluidic channel, and the collection component is connected to the microfluidic channel.

[0052] A flexible tube connects the syringe pump to the microfluidic channel and collection device. After the syringe pump injects the sample into the microfluidic channel, the particles can be manipulated by the acoustic field within the channel. The acoustic microfluidic chip module consists of three parts: a phononic crystal plate, an intermediate film layer, and a microfluidic channel.

[0053] Furthermore, the ultrasonic excitation module includes a signal generator, a power amplifier and an ultrasonic transducer connected in sequence, and the sound waves generated by the ultrasonic transducer excite the phononic crystal plate to generate a resonant sound field.

[0054] The phononic crystal plate can be curved, and its grid can be curved and non-uniformly spaced. The ultrasonic transducer can be a Gaussian beam sound source.

[0055] Ultrasound is used to excite a phononic crystal plate into resonance. The resulting periodic, spatially distributed, localized, intense sound field generates acoustic radiation forces to manipulate particles in a microfluidic cavity, capturing and arranging them while they are stationary or flowing. Alternatively, the particles can be manipulated using the acoustic flow induced by the phononic crystal plate. The control effect can be adjusted based on the input flow velocity and incident sound pressure.

[0056] For a stainless steel phononic crystal plate with a plate thickness of t = 50 μm, a grid thickness of h = 50 μm, a grid width of w = 50 μm, and a grid spacing of a = 300 μm, the calculated transmission spectrum is shown in Figure 3. Under normal incidence of a 4 MHz plane wave, the phononic crystal plate, completely submerged in water, resonates, generating non-leaky Lamb waves in the A0 mode within the plate. The acoustic field is shown in Figure 3. Horizontally, the acoustic field resembles a standing wave distribution, and radiation forces can trap particles at pressure nodes. Vertically, radiation forces can trap particles on the surface of the phononic crystal plate. When the phononic crystal plate contains a PDMS cavity, the acoustic field within the cavity remains unchanged, maintaining the shape of the cavity-free field, as shown in Figure 4. Therefore, particle manipulation is possible. Furthermore, Figure 4 shows the adjustable cavity width, allowing for narrower microfluidic channels than those in Figure 3.

[0057] Example

[0058] First, according to the process shown in Figure 1, a 100nm thick SiO2 intermediate film layer was deposited on the surface of a phononic crystal plate made of stainless steel with a plate thickness of t = 50μm, a grid thickness of h = 50μm, a grid width of w = 50μm, and a grid spacing of a = 300μm using a vacuum sputtering coater. It was then bonded to a linear PDMS cavity with a width of 2mm and a length of 3cm to form a new acoustic microfluidic chip, as shown in Figures 5 and 6.

[0059] Next, the chip was placed in a water tank, with a planar transducer positioned directly beneath it, as shown in Figure 10. The ultrasonic excitation module resonated the phononic crystal plate, generating an acoustic field within the cavity. A mixed suspension of polystyrene particles with diameters of 20 and 10 microns was delivered into the microfluidic cavity via a syringe pump at a flow rate of 20 μL / min. By adjusting the input power, the acoustic field capture force trapped the 20-micron diameter particles on the surface of the phononic crystal plate, while the 10-micron diameter particles flowed through the channel, achieving particle separation under flow conditions.

[0060] Although the present application has been described above with reference to specific embodiments, it should be understood by those skilled in the art that many modifications may be made to the configurations and details disclosed herein within the principles and scope of the present application. The scope of protection of the present application is determined by the appended claims, and the claims are intended to cover all modifications encompassed by the literal meaning or scope of equivalents of the technical features in the claims.

Claims

1. A method for preparing an acoustic microfluidic chip, characterized in that: The method comprises cleaning and drying the phononic crystal plate and the microfluidic cavity, and connecting the phononic crystal plate and the microfluidic cavity through a thin film layer.

2. The method for preparing an acoustic microfluidic chip according to claim 1, characterized in that: The connection includes depositing a thin film layer that is easily bonded to the microfluidic channel on the surface of the phononic crystal plate by a physical vapor deposition method, then subjecting the surfaces of the phononic crystal plate and the microfluidic channel to be bonded with oxygen plasma, and then laminating the phononic crystal plate and the microfluidic channel to form an irreversible bond.

3. The method for preparing an acoustic microfluidic chip according to claim 1, characterized in that: The connection includes subjecting the thin film layer and the surface to be joined of the microfluidic channel to oxygen plasma treatment, and then laminating the two to form an irreversible bond to obtain a packaged microfluidic channel, and then laminating the packaged microfluidic channel to the phononic crystal plate.

4. The method for preparing an acoustic microfluidic chip according to claim 1, characterized in that: The thin film layer is a SiO2 thin film layer.

5. The method for preparing an acoustic microfluidic chip according to claim 2, characterized in that: The physical vapor deposition method includes vacuum evaporation coating, vacuum sputtering coating and vacuum ion coating.

6. The method for preparing an acoustic microfluidic chip according to claim 1, characterized in that: The connection includes coating the thin film layer on the phononic crystal plate and the microfluidic channel respectively, and then performing oxygen plasma treatment on the surfaces of the coated phononic crystal plate and the coated microfluidic channel to be joined, and then bonding the coated phononic crystal plate and the coated microfluidic channel.

7. An acoustic microfluidic device, characterized in that: An acoustic microfluidic chip prepared by the method for preparing an acoustic microfluidic chip according to any one of claims 1 to 6.

8. The acoustic microfluidic device of claim 7, wherein: It includes a sample delivery and collection module, the acoustic microfluidic chip and an ultrasonic excitation module which are connected in sequence.

9. The acoustic microfluidic device of claim 8, wherein: The sample delivery and collection module comprises a syringe pump and a collection assembly connected to each other, wherein the syringe pump is connected to the microfluidic channel, and the collection assembly is connected to the microfluidic channel.

10. The acoustic microfluidic device of claim 8, wherein: The ultrasonic excitation module comprises a signal generator, a power amplifier and an ultrasonic transducer which are connected in sequence. The sound waves generated by the ultrasonic transducer excite the phononic crystal plate to generate a resonant sound field.

Images