Acoustic micro-fluidic chip preparation method and acoustic micro-fluidic device

Abstract

The invention belongs to the technical field of microfluid, and particularly relates to an acoustic micro-fluidic chip preparation method and an acoustic micro-fluidic device. At present, the existing packaging method mainly comprises simple attachment or embedded fixation. A microcavity formed by bonding a PDMS cavity wall and a glass substrate is constructed, a photonic crystal plate is placed in the microcavity, and the top of the microcavity is attached to the PDMS cavity wall through a cover glass. The photonic crystal plate is not directly combined with the micro-flow cavity channel; the adhesive force is weak, and liquid leakage is easy; an embedded fixing method is not flexible enough, and installation and microminiaturization are difficult. The invention provides a preparation method of an acoustic micro-fluidic chip, which comprises the following steps: cleaning and drying a photonic crystal plate and a micro-fluid cavity channel, and connecting the photonic crystal plate and the micro-fluid cavity channel through a thin film layer. The phononic crystal plate can be directly combined with the microfluid cavity channel to form a novel acoustic micro-fluidic chip.

Description

Technical Field

[0001] The present application belongs to the field of microfluidic 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 the development of micro-nano processing technologies such as soft lithography, the manufacturing of microfluidic devices with multiple functions has made great progress to achieve chip lab integration. Acoustofluidics is an emerging interdisciplinary science involving acoustics, chemistry, fluid physics, microelectronics and new materials, which combines acoustics with microfluidics technology and uses sound waves as a driving force to manipulate fluids or particles in microchannels.

[0003] Acoustofluidic devices mainly include a microfluidic network and a substrate that carries the network and propagates sound waves, which is made of different materials as needed, such as PDMS (polydimethylsiloxane), plastic, glass, metal, etc. PDMS is a silicon-based elastomer that is one of the commonly used materials for microfluidic networks due to its many ideal material properties (e.g., elasticity, optical transparency, biocompatibility, low autofluorescence, excellent thermal stability and chemical stability, etc.). An important aspect of the fabrication of acoustic fluidic devices is the sealing of microfluidic components. Tight sealing is required to properly inject and transport liquids without leakage, avoid external and cross contamination, and protect sensitive areas during device operation. Today, microchannels are usually created in PDMS and then formed into chips by closing them with solid or flexible substrates. Silicon-based substrates (e.g., glass or silicon) can be bonded to PDMS relatively easily by simple surface activation, such as oxygen plasma, so these are the most widely used methods for sealing microchannels. Because irreversible chemical bonds are formed between the activated or functionalized PDMS and the substrate surface, this closure method is called bonding technology. However, this method can only be applied to some materials.

[0004] Acoustic artificial structure refers to an artificial structure or material that can control the reflection, transmission, absorption and transmission of sound waves. Phononic crystal plate is a periodic acoustic artificial structure, which consists of a thin plate and a periodic grid engraved on the surface. Because it is usually made of metal, it is difficult to bond directly to the PDMS cavity by oxygen plasma.

[0005] The existing packaging methods mainly include simple bonding or embedded fixation. A microcavity is constructed by bonding the PDMS cavity wall to the glass substrate, and then the phononic crystal plate is placed in the microcavity. The top of the microcavity is then bonded to the PDMS cavity wall with a cover glass. It is not a direct bond between the phononic crystal plate and the microfluidic cavity; the bonding force is weak and it is easy to leak; the embedded fixation method is not flexible enough, and it is difficult to install and miniaturize. Summary of the invention

[0006] 1. Technical problems to be solved

[0007] 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.

[0008] 2 Technical Solution

[0009] 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.

[0010] 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 subjecting the surfaces of the phononic crystal plate and the microfluidic channel to be bonded with oxygen plasma, and then bonding the phononic crystal plate and the microfluidic channel to form an irreversible bond.

[0011] 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 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.

[0012] Another implementation manner provided by the present application is that the thin film layer is a SiO2 thin film layer.

[0013] Another embodiment provided by the present application is that the physical vapor deposition method includes vacuum evaporation coating, vacuum sputtering coating and vacuum ion coating.

[0014] Another embodiment provided by the present application is: 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 to be joined of the coated phononic crystal plate and the coated microfluidic channel, and then bonding the coated phononic crystal plate and the coated microfluidic channel.

[0015] The present application also provides an acoustic microfluidic device, characterized by: an acoustic microfluidic chip prepared by the acoustic microfluidic chip preparation method according to any one of claims 1 to 6.

[0016] 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.

[0017] Another embodiment provided by the present application is: 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.

[0018] Another implementation manner provided by the present application is: 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.

[0019] 3. Beneficial effects

[0020] Compared with the prior art, the acoustic microfluidic chip preparation method and the acoustic microfluidic device provided by the present application have the following beneficial effects:

[0021] The acoustic microfluidic chip preparation method provided in the present application prepares a new acoustic microfluidic chip, in which the microfluidic cavity and the phononic crystal plate are connected together by an intermediate film layer, and the bonding force is strong, the design is flexible, and the installation is simple, thereby achieving good packaging of the phononic crystal plate, and providing a new type of packaged acoustic microfluidic chip.

[0022] The acoustic microfluidic chip preparation method provided in the present application can directly combine the phononic crystal plate with the microfluidic cavity to form a new acoustic microfluidic chip.

[0023] The acoustic microfluidic chip preparation method provided in the present application has strong binding force and will not leak.

[0024] The acoustic microfluidic chip preparation method provided in the present application is easy to install and can be assembled flexibly.

[0025] The acoustic microfluidic device provided in the present 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

[0026] Figure 1 It is a schematic diagram of the process of preparing the acoustic microfluidic chip of the present application;

[0027] Figure 2 is a schematic diagram of the transmission spectrum of the phononic crystal plate of the present application;

[0028] Figure 3 This is the resonance acoustic field diagram of the phononic crystal plate without PDMS cavity;

[0029] Figure 4 This is the resonance sound field diagram of the PDMS cavity phononic crystal plate;

[0030] Figure 5It is a schematic diagram of the grid side of the phononic crystal plate of the present application;

[0031] Figure 6 is a schematic diagram of the acoustic microfluidic chip of the present application;

[0032] Figure 7 It is a schematic diagram of capturing particles of both sizes under high input power of the present application;

[0033] Figure 8 It is a schematic diagram of large particles being captured and small particles flowing out of the cavity under the appropriate input power of the present application;

[0034] Fig. 9 This is a schematic diagram of the acoustic field distribution when a 50-micron-thick PDMS film is present between the cavity and the phononic crystal plate of the present application;

[0035] Fig.10 is a schematic diagram of an acoustic microfluidic device of the present application;

[0036] Fig.11 It is a schematic diagram of the principle of the acoustic microfluidic device of the present application. DETAILED DESCRIPTION

[0037] Hereinafter, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in the various embodiments can be combined to obtain new implementations, or certain features in certain embodiments can be replaced to obtain other preferred implementations.

[0038] See also Figures 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 through a thin film layer.

[0039] An intermediate film layer is introduced between the phononic crystal plate and the microfluidic channel to achieve close integration of the phononic crystal and the microfluidic channel, and to construct a new acoustic microfluidic chip based on the phononic crystal plate.

[0040] 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, and then subjecting the surfaces of the phononic crystal plate and the microfluidic channel to be bonded with oxygen plasma, and then bonding the phononic crystal plate and the microfluidic channel to form an irreversible bond.

[0041] In this scheme, plasma bonding is achieved by the thin film layer and cavity deposited on the surface of the phononic crystal plate, the materials of which are SiO2 and PDMS respectively.

[0042] For details, see Figure 1 , (1) using an organic solvent such as isopropanol to clean the surface of the phononic crystal plate and the PDMS cavity to remove impurities such as grease and dust, and then drying;

[0043] (2) A 100-nanometer-thick thin film layer, i.e., the intermediate thin film layer, is deposited on the surface of the phononic crystal plate by physical vapor deposition (PVD). The material of the intermediate thin 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 a 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.

[0044] (3) Place the deposited phononic crystal plate-intermediate film layer and PDMS into an oxygen plasma cleaner to perform plasma treatment on the surface to be bonded. Then, attach the two together and wait for a few minutes to complete the irreversible bonding. The specific waiting time is related to the material, cleaning time, etc.

[0045] 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 a packaged microfluidic cavity, and then laminating the packaged microfluidic cavity on the phononic crystal plate (plasma treatment is not performed in this step, and in fact no bond is generated 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).

[0046] In the original scheme, once the bonding is completed, the phononic crystal plate and the cavity can no longer be separated. When the cavity is blocked, the entire chip needs to be replaced. This alternative scheme no longer bonds the phononic crystal plate and the cavity, but bonds a thin layer of material such as PDMS film / glass sheet to the microfluidic cavity to achieve the encapsulation of the cavity, and then adheres the encapsulated cavity to the phononic crystal plate by intermolecular forces. Since the cavity is closed at this time, separation and leakage will not occur. When the cavity is blocked, the cavity can be directly replaced and re-encapsulated without replacing the phononic crystal plate; in addition, since the encapsulated cavity is separated from the phononic crystal plate, the position of the channel can be adjusted during use, which is more flexible. Figure 8 As shown, in the presence of a thin film, the acoustic field in the cavity still maintains the shape when there is no cavity, which can be used for particle manipulation.

[0047] Another method that can be implemented in the present application is: the connection includes coating the thin film layer on the phononic crystal plate and the microfluidic cavity respectively, and then subjecting the coated phononic crystal plate and the coated microfluidic cavity to be bonded with oxygen plasma, and then bonding the coated phononic crystal plate and the coated microfluidic cavity. In this scheme, the plasma bonding is achieved by the thin film layer and the thin film layer deposited on the surface of the phononic crystal plate and the PDMS. The materials are SiO2 and SiO2 respectively.

[0048] The present application also provides an acoustic microfluidic device, an acoustic microfluidic chip prepared by the acoustic microfluidic chip preparation method. The material, size, shape and placement of the microfluidic cavity can be adjusted according to the field form of the phononic crystal plate and the need for particle manipulation; the material of the intermediate film layer needs to be selected to be a material that can be deposited on the surface of the phononic crystal plate and can be bonded with PDMS by oxygen plasma.

[0049] Furthermore, it comprises a sample delivery and collection module, the acoustic microfluidic chip and an ultrasonic excitation module which are connected in sequence.

[0050] Furthermore, the sample delivery and collection module comprises 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.

[0051] The syringe pump is connected to the microfluidic cavity and the collection device with a hose. After the syringe pump injects the sample into the microfluidic cavity, the particles can be manipulated under the action of the acoustic field in the channel. The acoustic microfluidic chip module consists of three parts: the phononic crystal plate, the middle film layer, and the microfluidic cavity.

[0052] 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.

[0053] 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.

[0054] Ultrasonic excitation of the phononic crystal plate to resonate, using the acoustic radiation force generated by the periodic spatial distribution of the local strong sound field generated by the resonance, to capture and arrange particles in a static or flowing state in the microfluidic cavity, or to manipulate the particles using the acoustic flow in the cavity induced by the phononic crystal plate. The incident flow velocity and incident sound pressure can be adjusted according to needs to adjust the control effect.

[0055] For a phononic crystal plate made of stainless steel 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 as follows: Figure 3 As shown in the figure. Under the vertical incidence of a 4MHz plane wave, the phononic crystal plate completely immersed in water will resonate, and a non-leaking Lamb wave of A0 mode will be generated in the plate. The sound field is as shown in the figure. Figure 3 As shown. In the horizontal direction, the acoustic field is similar to the standing wave distribution, and the particles can be captured to the pressure node under the action of the radiation force; in the vertical direction, the radiation force can capture the particles to the surface of the phononic crystal plate. When there is a PDMS cavity on the phononic crystal plate, it can be seen that the acoustic field in the cavity has no obvious distortion, and the shape of the acoustic field without the cavity is maintained, as shown in Figure 4 As shown. Therefore, particle manipulation can be performed. In addition, it can be seen Figure 4 With adjustable cavity width, it can form Figure 3 Narrower microfluidic channels.

[0056] Example

[0057] First follow Figure 1 As shown in the process, a 100nm thick SiO2 intermediate film layer is 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 by a vacuum sputtering coating machine, and then bonded with a linear PDMS cavity with a width of 2mm and a length of 3cm to form a new acoustic microfluidic chip, as shown in FIG. Figure 5 and 6 shown.

[0058] Next, the chip is placed in a water tank, and a planar transducer is placed directly below the chip, such as Fig.10As shown, the ultrasonic excitation module is used to make the phononic crystal plate resonate and generate an acoustic field in the cavity. A mixed polystyrene particle suspension with a diameter of 20 microns and 10 microns is delivered into the microfluidic cavity through a syringe pump at a flow rate of 20 microliters / minute. By adjusting the input power, under the action of the acoustic field capture force, the 20-micron diameter particles are captured on the surface of the phononic crystal plate, while the 10-micron diameter particles flow through the channel, thereby achieving the separation of particles under flow conditions.

[0059] Although the present application is 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 in the present application within the principles and scope disclosed in 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 included in the equivalent literal meaning or scope 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.

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