阅读说明：本技术 一种基于表面声波微流控的气泡生成装置及方法 (Bubble generation device and method based on surface acoustic wave micro-fluidic ) 是由 韦学勇 金少搏 余子夷 任娟 蒋庄德 于 2019-10-28 设计创作，主要内容包括：一种基于表面声波的微流控气泡生成装置及方法,装置包括压电基底,压电基底上制作有两个以上的弧形电极对,压电基底上部键合有PDMS微流道系统,PDMS微流道系统包括两个以上的微气泡生成流道阵列,弧形电极对与PDMS微流道系统配合；方法是先将微流控气泡生成装置固定在显微镜的载物台上,然后将微流控气泡生成装置接入,开启注射泵,设置气相入口接头、液相入口接头的流速以稳定生成气泡；再将信号发生器与弧形电极对连接,调节信号发生器的输出信号以控制气泡生成的大小；本发明在保证气泡高通量生成的同时,调节输入正弦电压幅值、频率的大小,可以柔性实时调控微气泡的生成大小。(A micro-fluidic bubble generating device and method based on surface acoustic wave, the device includes the piezoelectric substrate, make more than two arc electrode pairs on the piezoelectric substrate, the upper portion of the piezoelectric substrate bonds PDMS micro-channel system, PDMS micro-channel system includes more than two micro-bubble generation flow channel arrays, the arc electrode pair cooperates with PDMS micro-channel system; fixing a micro-fluidic bubble generating device on an objective table of a microscope, then connecting the micro-fluidic bubble generating device, starting an injection pump, and setting the flow rates of a gas phase inlet joint and a liquid phase inlet joint to stably generate bubbles; then connecting the signal generator with the arc electrode pair, and adjusting the output signal of the signal generator to control the size of generated bubbles; the invention ensures the high-flux generation of bubbles, adjusts the amplitude and the frequency of the input sinusoidal voltage, and can flexibly regulate and control the generation size of micro bubbles in real time.)

1. A surface acoustic wave based microfluidic bubble generation device comprising a piezoelectric substrate (1), characterized in that: more than two arc electrode pairs are manufactured on the piezoelectric substrate (1), a PDMS micro-channel system is bonded on the upper part of the piezoelectric substrate (1), the PDMS micro-channel system comprises more than two micro-bubble generation channel arrays, and the arc electrode pairs are matched with the PDMS micro-channel system;

the PDMS micro-channel system comprises two groups of T-shaped micro-bubble generation channel arrays, wherein the first group of T-shaped micro-bubble generation channel arrays comprise a first gas-phase channel (2), a first liquid-phase channel (3), a second liquid-phase channel (5) and a second gas-phase channel (7), the inlet end of the first gas-phase channel (2) is connected with a gas-phase inlet joint (15) after being intersected with the inlet end of the second gas-phase channel (7), and the outlet end of the first gas-phase channel (2) is communicated with the middle part of the first liquid-phase channel (3); the inlet end of the first liquid phase channel (3) is connected with the liquid phase inlet joint (6) after meeting with the inlet end of the second liquid phase channel (5), and the outlet end of the first liquid phase channel (3) is connected with the first bubble collecting joint (17); the outlet end of the second gas-phase channel (7) is communicated with the middle part of the second liquid-phase channel (5), and the outlet end of the second liquid-phase channel (5) is connected with a second bubble collecting joint (16);

the second group of T-shaped microbubble generation flow channel arrays comprises a third gas-phase channel (8), a third liquid-phase channel (9), a fourth liquid-phase channel (11) and a fourth gas-phase channel (12), the inlet end of the third gas-phase channel (8) is connected with a gas-phase inlet joint (15) after intersecting with the inlet end of the fourth gas-phase channel (12), the outlet end of the third gas-phase channel (8) is communicated with the middle of the third liquid-phase channel (9), the inlet end of the third liquid-phase channel (9) is connected with a liquid-phase inlet joint (6) after intersecting with the inlet end of the fourth liquid-phase channel (11), and the outlet end of the third liquid-phase channel (3) is connected with a third bubble collecting joint (14); the outlet end of the fourth gas-phase channel (12) is communicated with the middle part of the fourth liquid-phase channel (11), and the outlet end of the fourth liquid-phase channel (11) is connected with a fourth bubble collecting joint (13).

2. A surface acoustic wave based microfluidic bubble generation device according to claim 1, wherein: the arc-shaped electrode pairs comprise a first arc-shaped interdigital electrode pair (4) and a second pair of arc-shaped interdigital electrode pairs (10), each arc-shaped interdigital electrode pair is composed of two arc-shaped interdigital electrodes, each arc-shaped interdigital electrode comprises a plurality of pairs of interdigital electrodes, and the arc angle is 60 degrees.

3. A surface acoustic wave based microfluidic bubble generation device according to claim 2, wherein: each of the first arc-shaped interdigital electrode pair (4) and the second arc-shaped interdigital electrode pair (10) comprises 15 pairs of interdigital electrodes, the finger width is 25 micrometers, and the arc angle is 60 degrees.

4. A surface acoustic wave based microfluidic bubble generation device according to claim 2, wherein: the relative positions of the PDMS micro-channel system, the first arc-shaped interdigital electrode pair (4) and the second pair of arc-shaped interdigital electrode pairs (10) are as follows: the first arc-shaped interdigital electrode pair (4) is coincided with the symmetrical central lines of the communication ports of the first gas-phase channel (2) and the first liquid-phase channel (3), the convergence center of the arc-shaped interdigital electrode on the left of the first arc-shaped interdigital electrode pair (4) is on the runner wall close to one side of the first liquid-phase channel (3), and the convergence center of the arc-shaped interdigital electrode on the right of the first arc-shaped interdigital electrode pair (4) is on the runner wall close to one side of the second liquid-phase channel (5); the symmetrical center lines of the communication ports of the second arc-shaped interdigital electrode pair (10) and the third gas-phase channel (8) and the third liquid-phase channel (9) are coincided, the convergence center of the arc-shaped interdigital electrode on the right of the second arc-shaped interdigital electrode pair (10) is on the runner wall close to one side of the third liquid-phase channel (9), and the convergence center of the arc-shaped interdigital electrode on the right of the second arc-shaped interdigital electrode pair (10) is on the runner wall close to one side of the fourth liquid-phase channel (11).

5. A surface acoustic wave based microfluidic bubble generation device according to claim 1, wherein: the height of the channels in the PDMS micro-channel system is 80 micrometers, the width values of different parts of the channels are different, and the widths of the first gas-phase channel (2), the second gas-phase channel (7), the third gas-phase channel (8) and the fourth gas-phase channel (12) are all 30 micrometers and are arc-shaped channels; the width of the first liquid phase channel (3), the second liquid phase channel (5), the third liquid phase channel (9) and the fourth liquid phase channel (10) is 100um, and the liquid phase channel is a straight flow channel.

6. A surface acoustic wave based microfluidic bubble generation device according to claim 1, wherein: the piezoelectric substrate (1) is made of double-sided polished 128-degree Y lithium niobate.

7. A surface acoustic wave based microfluidic bubble generation device according to claim 2, wherein: the first arc-shaped interdigital electrode pair (4) and the second arc-shaped interdigital electrode pair (10) adopt a double-layer structure of 50 nm bottom-layer chromium and 200 nm upper-layer gold.

8. The method of using the surface acoustic wave microfluidics-based bubble generation device of claim 2, comprising the steps of:

1) fixing a bubble generating device based on surface acoustic wave micro-fluidic on an objective table of a microscope, and observing through an objective lens to ensure that two groups of T-shaped micro-bubbles in a PDMS micro-channel system generate a channel array which is positioned in a field of view of the microscope and has no inclination;

2) a gas phase inlet joint (15) and a liquid phase inlet joint (6) are respectively connected with a gas phase liquid storage bottle and a liquid phase liquid storage bottle on a nitrogen pressure injection pump through Teflon guide tubes, and a first bubble collecting joint (17), a second bubble collecting joint (16), a third bubble collecting joint (14) and a fourth bubble collecting joint (13) are connected with a bubble collecting container through Teflon guide tubes;

3) respectively connecting the positive pole and the negative pole of an output signal of a signal generator with the two poles of a first arc-shaped interdigital electrode pair (4) and a second arc-shaped interdigital electrode pair (10), and adjusting the output signal of the signal generator to be sine continuous output, wherein the frequency is 39.96MHz, and the voltage amplitude is 25-40 Vpp;

4) starting an injection pump, and respectively setting corresponding flow rates of a gas phase inlet joint (15) and a liquid phase inlet joint (6) to stably generate bubbles in the T-shaped micro-bubble generation flow channel array;

5) then, an output button of a signal generator is pressed, convergent surface acoustic waves are generated on the piezoelectric substrate (1), and the surface acoustic waves act on a bubble generation position to change the pressure distribution at a two-phase flow interface of a bubble generation area at a gas-liquid phase junction, so that the size of bubbles is regulated and controlled.

Technical Field

The invention relates to the technical field of microfluidics, in particular to a bubble generation device and method based on surface acoustic wave microfluidics.

Background

Microbubbles are widely used in a variety of applications such as ultrasound scanning, drug discovery, gene therapy and food industry, and among many applications, a method for generating bubbles is very important, for example, chinese patent (publication No. CN 109158039 a) discloses an ultrasound microbubble generation method that can generate bubbles having a size of 1-50um by using an ultrasound oscillation method; there are also methods currently available, including focused fluid microfluidic devices and T-type microchannel devices, which have reached a very mature level in the last 15 years, by adjusting the input pressure of a gas phase (dispersed phase) which can be rapidly sheared into microbubbles by a liquid phase (continuous phase), which is usually an oil or aqueous solution. For example, by the parallel configuration of the focusing microfluidic device and the T-type microchannel device, 10 can be produced in less than one hour¹¹Bubbles (Jeong H, Chen Z, Yadavali S, et al, Large-scale production of compounds using matched microfluidics for effective extraction of metals [ J]Lab on a Chip,2019,19, 665-. Chinese patent (publication No. CN109701430A) discloses a method for controlling a T-type microfluidic chip to generate microbubbles by using a vibrating pipeline, which can realize the formation of a monodisperse microbubble sequence; chinese patent publication No. CN 105688721A discloses a micro-fluidic chip for generating spherical micro-bubbles, which generates micro-bubbles with different diameters by adjusting the liquid flow rate.

However, in most microfluidic devices, the pressure source is usually remote from the microfluidic Chip and needs to be connected to the microfluidic Chip by a long connecting tube, the compressibility of the fluid or channel material causes a time delay (Chong Z, Tan S H, et al. active droplet generation in microfluidics [ J ]. Lab on A Chip,2015,16(1):35-58.Collins D J, Alan T, Helmerson K, et al. surface aqueous waves for on-demand production of a platelet and particle encapsulation [ J ]. Lab on A Chip,2013,13(16): 5-3231), and therefore, if the bubble size needs to be adjusted in real time according to needs, the method has some limitations, needs longer system response time to stabilize the generation of bubbles, and cannot meet the current requirements on miniaturization and integration of instruments.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a bubble generation device and method based on surface acoustic wave microfluidics, which not only have the advantage of high-speed bubble generation of the original T-shaped runner microbubble generation method, but also can perform integrated control on the bubble generation rate and the bubble generation size as required in real time by adjusting the amplitude and the frequency of input sinusoidal voltage, have small volume, are convenient to integrate with other devices to realize the miniaturization of instruments, and enhance the repeatability of the use of devices.

In order to achieve the purpose, the invention adopts the following technical scheme:

a micro-fluidic bubble generation device based on surface acoustic waves comprises a piezoelectric substrate 1, wherein more than two arc-shaped electrode pairs are manufactured on the piezoelectric substrate 1, a PDMS micro-channel system is bonded on the upper part of the piezoelectric substrate 1 and comprises more than two micro-bubble generation channel arrays, and the arc-shaped electrode pairs are matched with the PDMS micro-channel system;

the PDMS micro flow channel system comprises two groups of T-shaped micro-bubble generation flow channel arrays, wherein the first group of T-shaped micro-bubble generation flow channel array comprises a first gas-phase channel 2, a first liquid-phase channel 3, a second liquid-phase channel 5 and a second gas-phase channel 7, the inlet end of the first gas-phase channel 2 is connected with a gas-phase inlet joint 15 after meeting with the inlet end of the second gas-phase channel 7, and the outlet end of the first gas-phase channel 2 is communicated with the middle part of the first liquid-phase channel 3; the inlet end of the first liquid phase channel 3 is connected with the liquid phase inlet joint 6 after meeting with the inlet end of the second liquid phase channel 5, and the outlet end of the first liquid phase channel 3 is connected with the first bubble collecting joint 17; the outlet end of the second gas-phase channel 7 is communicated with the middle part of the second liquid-phase channel 5, and the outlet end of the second liquid-phase channel 5 is connected with a second bubble collecting joint 16;

the second group of T-shaped microbubble generation flow channel arrays comprises a third gas phase channel 8, a third liquid phase channel 9, a fourth liquid phase channel 11 and a fourth gas phase channel 12, wherein the inlet end of the third gas phase channel 8 is connected with a gas phase inlet joint 15 after meeting the inlet end of the fourth gas phase channel 12, the outlet end of the third gas phase channel 8 is communicated with the middle part of the third liquid phase channel 9, the inlet end of the third liquid phase channel 9 is connected with a liquid phase inlet joint 6 after meeting the inlet end of the fourth liquid phase channel 11, and the outlet end of the third liquid phase channel 3 is connected with a third bubble collecting joint 14; the outlet end of the fourth gas phase channel 12 is communicated with the middle part of the fourth liquid phase channel 11, and the outlet end of the fourth liquid phase channel 11 is connected with a fourth bubble collecting joint 13;

the arc-shaped electrode pairs comprise a first arc-shaped interdigital electrode pair 4 and a second arc-shaped interdigital electrode pair 10, each arc-shaped interdigital electrode pair is composed of two arc-shaped interdigital electrodes, each arc-shaped interdigital electrode comprises a plurality of pairs of interdigital electrodes, and the arc angle is 60 degrees.

Each of the first pair of arc-shaped interdigital electrodes 4 and the second pair of arc-shaped interdigital electrodes 10 includes 15 pairs of interdigital electrodes, the finger width is 25 micrometers, and the arc angle is 60 °.

The relative positions of the PDMS micro-channel system, the first arc-shaped interdigital electrode pair 4 and the second arc-shaped interdigital electrode pair 10 are as follows: the first arc-shaped interdigital electrode pair 4 is coincided with symmetrical center lines of communication ports of the first gas-phase channel 2 and the first liquid-phase channel 3, the convergence center of the arc-shaped interdigital electrode on the left of the first arc-shaped interdigital electrode pair 4 is on the flow channel wall close to one side of the first liquid-phase channel 3, and the convergence center of the arc-shaped interdigital electrode on the right of the first arc-shaped interdigital electrode pair 4 is on the flow channel wall close to one side of the second liquid-phase channel 5; the second arc-shaped interdigital electrode pair 10 is coincided with the symmetrical central lines of the communication ports of the third gas-phase channel 8 and the third liquid-phase channel 9, the convergence center of the arc-shaped interdigital electrode on the right of the second arc-shaped interdigital electrode pair 10 is on the runner wall close to one side of the third liquid-phase channel 9, and the convergence center of the arc-shaped interdigital electrode on the right of the second arc-shaped interdigital electrode pair 10 is on the runner wall close to one side of the fourth liquid-phase channel 11.

The height of the channels in the PDMS micro-channel system is 80 micrometers, the width values of different parts of the channels are different, and the widths of the first gas-phase channel 2, the second gas-phase channel 7, the third gas-phase channel 8 and the fourth gas-phase channel 12 are all 30 micrometers and are arc-shaped channels; the width of the first liquid phase channel 3, the second liquid phase channel 5, the third liquid phase channel 9 and the fourth liquid phase channel 10 is 100um, and the liquid phase channels are straight flow channels.

The piezoelectric substrate 1 is made of double-sided polished 128-degree Y lithium niobate.

The first arc-shaped interdigital electrode pair 4 and the second arc-shaped interdigital electrode pair 10 adopt a double-layer structure of 50 nm bottom chromium and 200 nm top gold.

The use method of the bubble generation device based on the surface acoustic wave microfluidics comprises the following steps:

1) fixing a bubble generating device based on surface acoustic wave micro-fluidic on an objective table of a microscope, and observing through an objective lens to ensure that two groups of T-shaped micro-bubbles in a PDMS micro-channel system generate a channel array which is positioned in a field of view of the microscope and has no inclination;

2) the gas-phase inlet connector 15 and the liquid-phase inlet connector 6 are respectively connected with a gas-phase liquid storage bottle and a liquid-phase liquid storage bottle on the nitrogen pressure injection pump through Teflon guide tubes, and the first bubble collecting connector 17, the second bubble collecting connector 16, the third bubble collecting connector 14 and the fourth bubble collecting connector 13 are connected with a bubble collecting container through Teflon guide tubes;

3) respectively connecting the positive pole and the negative pole of an output signal of a signal generator with the two poles of the first arc-shaped interdigital electrode pair 4 and the second arc-shaped interdigital electrode pair 10, and adjusting the output signal of the signal generator to be sine continuous output, wherein the frequency is 39.96MHz, and the voltage amplitude is 25-40 Vpp;

4) starting the injection pump, and respectively setting corresponding flow rates for the gas phase inlet joint 15 and the liquid phase inlet joint 6 to stably generate bubbles in the T-shaped microbubble generation flow channel array;

5) then, an output button of a signal generator is pressed, convergent surface acoustic waves are generated on the piezoelectric substrate 1, and the surface acoustic waves act on a bubble generation position to change the pressure distribution at a two-phase flow interface of a bubble generation area at a gas-phase-liquid-phase intersection, so that the size of bubbles is regulated.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention can overcome the defect that the traditional bubble generation method excessively depends on the structure and the flow rate of the micro-channel, ensures the high-flux generation of bubbles, adjusts the amplitude and the frequency of the input sinusoidal voltage, and can flexibly regulate and control the generation size of micro-bubbles in real time.

(2) The T-shaped micro-bubble generation flow channel array formed by combining the gas phase channel and the liquid phase channel can be expanded continuously to generate bubbles in a larger scale at a high flux.

(3) The device can realize high-flux generation of the bubbles of the oil-in-gas and the water-in-gas.

(4) The device has smaller volume, generates bubbles quickly and uniformly, is convenient to integrate with other devices, and realizes more complex functions.

Drawings

Fig. 1 is an isometric view of a surface acoustic wave based microfluidic bubble generation device of the present invention.

Fig. 2 is a schematic diagram of bubble generation of the microfluidic bubble generation device based on surface acoustic waves according to the present invention.

Fig. 3 is a bubble generation diagram under a microscope of the surface acoustic wave based microfluidic bubble generation device of the present invention.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

Referring to fig. 1, a micro-fluidic bubble generating device based on surface acoustic waves comprises a piezoelectric substrate 1, two arc electrode pairs are directly manufactured on the piezoelectric substrate 1 through photoetching, sputtering and stripping processes, a PDMS micro-channel system is bonded on the upper portion of the piezoelectric substrate 1 and comprises more than two micro-bubble generating channel arrays, the arc electrode pairs are matched with the PDMS micro-channel system, and the PDMS micro-channel system is used for accommodating gas-phase solution and liquid-phase solution samples, providing an environment for generating bubbles and conveying the generated bubbles to a bubble collecting port;

the PDMS micro flow channel system comprises two groups of T-shaped micro-bubble generation flow channel arrays, wherein the first group of T-shaped micro-bubble generation flow channel array comprises a first gas-phase channel 2, a first liquid-phase channel 3, a second liquid-phase channel 5 and a second gas-phase channel 7, the inlet end of the first gas-phase channel 2 is connected with a gas-phase inlet joint 15 after meeting with the inlet end of the second gas-phase channel 7, and the outlet end of the first gas-phase channel 2 is communicated with the middle part of the first liquid-phase channel 3; the inlet end of the first liquid phase channel 3 is connected with the liquid phase inlet joint 6 after meeting with the inlet end of the second liquid phase channel 5, and the outlet end of the first liquid phase channel 3 is connected with the first bubble collecting joint 17; the outlet end of the second gas-phase channel 7 is communicated with the middle part of the second liquid-phase channel 5, and the outlet end of the second liquid-phase channel 5 is connected with a second bubble collecting joint 16;

the second group of T-shaped microbubble generation flow channel arrays comprises a third gas phase channel 8, a third liquid phase channel 9, a fourth liquid phase channel 11 and a fourth gas phase channel 12, wherein the inlet end of the third gas phase channel 8 is connected with a gas phase inlet joint 15 after meeting the inlet end of the fourth gas phase channel 12, the outlet end of the third gas phase channel 8 is communicated with the middle part of the third liquid phase channel 9, the inlet end of the third liquid phase channel 9 is connected with a liquid phase inlet joint 6 after meeting the inlet end of the fourth liquid phase channel 11, and the outlet end of the third liquid phase channel 3 is connected with a third bubble collecting joint 14; the outlet end of the fourth gas phase channel 12 is communicated with the middle part of the fourth liquid phase channel 11, and the outlet end of the fourth liquid phase channel 11 is connected with a fourth bubble collecting joint 13;

gas and liquid phases (oil phase or water phase) are respectively introduced into the gas phase inlet joint 15 and the liquid phase inlet joint 6, the gas phase is sheared by the liquid phase to generate micro-bubbles at the position where the outlet end of the first gas phase channel 2 is communicated with the middle part of the first liquid phase channel 3, the outlet end of the second gas phase channel 7 is communicated with the middle part of the second liquid phase channel 5, the outlet end of the third gas phase channel 8 is communicated with the middle part of the third liquid phase channel 9, and the middle part of the fourth liquid phase channel 11 is communicated with the fourth gas phase channel 12, as shown in fig. 2; the first bubble collecting connector 17, the second bubble collecting connector 16, the third bubble collecting connector 14 and the fourth bubble collecting connector 13 are used for collecting generated micro-bubbles.

The arc-shaped electrode pairs comprise a first arc-shaped interdigital electrode pair 4 and a second arc-shaped interdigital electrode pair 10, each arc-shaped interdigital electrode pair is composed of two arc-shaped interdigital electrodes, each arc-shaped interdigital electrode comprises a plurality of pairs of interdigital electrodes, the arc angle is 60 degrees, and the arc-shaped interdigital electrodes are used for generating and converging surface acoustic waves on the surface of the piezoelectric substrate 1.

Each of the first pair of arc-shaped interdigital electrodes 4 and the second pair of arc-shaped interdigital electrodes 10 comprises 15 pairs of interdigital electrodes, the finger width is 25 micrometers, and surface acoustic waves with the frequency of 39.96MHz can be generated on the surface of the piezoelectric substrate 1 under the drive of a sinusoidal alternating voltage.

The relative positions of the PDMS micro-channel system, the first arc-shaped interdigital electrode pair 4 and the second arc-shaped interdigital electrode pair 10 are as follows: the first arc-shaped interdigital electrode pair 4 is coincided with symmetrical center lines of communication ports of the first gas-phase channel 2 and the first liquid-phase channel 3, the convergence center of the arc-shaped interdigital electrode on the left of the first arc-shaped interdigital electrode pair 4 is on the flow channel wall close to one side of the first liquid-phase channel 3, and the convergence center of the arc-shaped interdigital electrode on the right of the first arc-shaped interdigital electrode pair 4 is on the flow channel wall close to one side of the second liquid-phase channel 5; the second arc-shaped interdigital electrode pair 10 is coincided with the symmetrical central lines of the communication ports of the third gas-phase channel 8 and the third liquid-phase channel 9, the convergence center of the right arc-shaped interdigital electrode on the second arc-shaped interdigital electrode pair 10 is on the runner wall close to one side of the third liquid-phase channel 9, and the convergence center of the right arc-shaped interdigital electrode on the second arc-shaped interdigital electrode pair 10 is on the runner wall close to one side of the fourth liquid-phase channel 11; the piezoelectric substrate 1 generates a converged surface acoustic wave, the surface acoustic wave acts on a position where an outlet end of a first gas-phase channel 2 is communicated with the middle of a first liquid-phase channel 3, a position where an outlet end of a second gas-phase channel 7 is communicated with the middle of a second liquid-phase channel 5, a position where an outlet end of a third gas-phase channel 8 is communicated with the middle of a third liquid-phase channel 9, and a bubble generation area where the middle of a fourth liquid-phase channel 11 is communicated with a fourth gas-phase channel 12, so that the pressure distribution at a two-phase flow interface of the bubble generation area at a gas-phase-liquid-phase junction is changed, and the regulation and control.

The height of the channels in the PDMS micro-channel system is 80 micrometers, the width values of different parts of the channels are different, and the widths of the first gas-phase channel 2, the second gas-phase channel 7, the third gas-phase channel 8 and the fourth gas-phase channel 12 are all 30 micrometers and are arc-shaped channels; the width of the first liquid phase channel 3, the second liquid phase channel 5, the third liquid phase channel 9 and the fourth liquid phase channel 10 is 100um, and the liquid phase channels are straight flow channels.

The piezoelectric substrate 1 is made of double-sided polished 128-degree Y lithium niobate.

The first arc-shaped interdigital electrode pair 4 and the second pair of arc-shaped interdigital electrode pairs 10 adopt a double-layer structure of bottom layer chromium of 50 nanometers and upper layer gold of 200 nanometers, wherein the chromium is used as an adhesion layer for enhancing the adhesion strength of the gold and the piezoelectric substrate 1, and the gold is used as a conductive layer.

The PDMS micro-channel system is made of Polydimethylsiloxane (PDMS) with good light transmittance and biocompatibility, and is convenient for optically monitoring and recording the bubble generation process.

The use method of the bubble generation device based on the surface acoustic wave microfluidics comprises the following steps:

1) fixing a bubble generating device based on surface acoustic wave micro-fluidic on an objective table of a microscope, and observing through an objective lens to ensure that two groups of T-shaped micro-bubbles in a PDMS micro-channel system generate a channel array which is positioned in a field of view of the microscope and has no inclination;

2) the gas-phase inlet connector 15 and the liquid-phase inlet connector 6 are respectively connected with a gas-phase liquid storage bottle and a liquid-phase liquid storage bottle on the nitrogen pressure injection pump through Teflon guide tubes, and the first bubble collecting connector 17, the second bubble collecting connector 16, the third bubble collecting connector 14 and the fourth bubble collecting connector 13 are connected with a bubble collecting container through Teflon guide tubes;

3) respectively connecting the positive pole and the negative pole of an output signal of a signal generator with the two poles of the first arc-shaped interdigital electrode pair 4 and the second arc-shaped interdigital electrode pair 10, and adjusting the output signal of the signal generator to be sine continuous output, wherein the frequency is 39.96MHz, and the voltage amplitude is 25-40 Vpp;

4) starting the injection pump, setting corresponding flow rates at the gas-phase inlet joint 15 and the liquid-phase inlet joint 6 respectively, generating a flow channel array by the first group of T-shaped micro-bubbles, and stably generating bubbles at the position of the flow channel array by the second group of T-shaped micro-bubbles;

5) then, an output button of a signal generator is pressed, convergent surface acoustic waves are generated on the piezoelectric substrate 1, and the surface acoustic waves act on a bubble generation position to change the pressure distribution at a two-phase flow interface of a bubble generation area at a gas-phase-liquid-phase intersection, so that the size of bubbles is regulated.

Referring to fig. 2, the generation process of the bubbles in the PDMS micro flow channel system 1 is as follows: gas as a gas phase enters a first gas phase channel 2, a second gas phase channel 7, a third gas phase channel 8 and a fourth gas phase channel 12, a liquid phase enters a first liquid phase channel 3, a second liquid phase channel 5, a third liquid phase channel 9 and a fourth liquid phase channel 11, the input flow rates of the gas phase and the liquid phase are adjusted through an injection pump, the liquid phase shears the gas phase to generate micro-bubbles at a position where an outlet end of the first gas phase channel 2 is communicated with the middle part of the first liquid phase channel 3, a position where an outlet end of the second gas phase channel 7 is communicated with the middle part of the second liquid phase channel 5, a position where an outlet end of the third gas phase channel 8 is communicated with the middle part of the third liquid phase channel 9, a position where the middle part of the fourth liquid phase channel 11 is communicated with the fourth gas phase channel 12, the micro-bubbles are generated on a piezoelectric substrate by the shearing of the gas phase, and are converged, and act on the position where an outlet, the pressure distribution at the two-phase flow interface of the bubble generation area at the gas-liquid phase intersection is changed by the bubble generation area at the position where the outlet end of the second gas phase channel 7 is communicated with the middle part of the second liquid phase channel 5, the outlet end of the third gas phase channel 8 is communicated with the middle part of the third liquid phase channel 9, and the middle part of the fourth liquid phase channel 11 is communicated with the fourth gas phase channel 12, so that the regulation and control of the bubble size are realized; the generation size of the bubbles can be flexibly regulated by adjusting the input voltage amplitude and the frequency parameter of the sinusoidal alternating voltage, and the continuous generation of the microbubbles is realized, as shown in fig. 3.