WO2020029153A1

WO2020029153A1 - Lamb wave resonator-based particle concentrator and operation method therefor

Info

Publication number: WO2020029153A1
Application number: PCT/CN2018/099507
Authority: WO
Inventors: 庞慰; 张鸿翔; 段学欣; 孙崇玲; 潘书婷
Original assignee: 天津大学
Priority date: 2018-08-09
Filing date: 2018-08-09
Publication date: 2020-02-13

Abstract

A Lamb wave resonator-based particle concentrator and an operation method therefor. A Lamb wave resonator-based particle concentrator (300) comprises a silicon substrate (302); a Lamb wave resonator array comprises a plurality of Lamb wave resonators (304, 306, 308, 310) located on a front surface of the silicon substrate (302) and provided at vertexes of a regular polygon, and the angle formed by the electrode strip of each Lamb wave resonator (304, 306, 308, 310) and the electrode strip of an adjacent Lamb wave resonator (304, 306, 308, 310) is equal to the inner angle of the regular polygon. The Lamb wave resonator-based particle concentrator can realize the operation, control and aggregation of micro-concentration substances in a possibly small space, and increase the concentration of a detected substance by a large multiple at a specific position in an open space, thereby further reducing the size of the particle concentrator, without the need to design a micro-channel.

Description

Particle aggregator based on lamb wave resonator and operation method thereof

Technical field

Embodiments of the present invention generally relate to the field of particle manipulation for microfluidics, and more particularly, to a Lamb wave resonator-based particle aggregator and a method of operating the same.

Background technique

In modern biomedical engineering, the operation and control of micro-scale cells and even smaller sub-micron-scale biochemical macromolecules are important means to achieve various types of biomedical engineering, such as cell imaging, biomolecule enrichment, and artificial tissue generation. . Enriching a sample of the test substance at a small concentration, locally increasing the concentration of the test substance, and driving a specific substance to a specified position are both better and more feasible solutions for improving detection sensitivity and accuracy in environmental monitoring and disease detection.

In recent years, many technologies that use physical methods to control the position of particles have appeared one after another. Because acoustic waves do not cause irreversible damage to biochemical particles and cells within a large intensity range, acoustic technologies such as acoustic fluids, ultrasonic waves, and acoustic tweezers It is widely used in specific biochemical particle manipulation such as enrichment of analytical substances, cell aggregation, particle screening, and mixing of fluid substances. However, in the prior art, it is necessary to design a microflow channel for fluid flow. The particle aggregator not only has a complicated structure, but also limits the further reduction of the size of the particle aggregator.

Summary of the invention

The present invention aims at a particle aggregator in the prior art that has a complicated structure and cannot further reduce the size of the particle aggregator. It provides a particle aggregator based on a Lamb wave resonator capable of solving the above problems and its operation. method.

According to an aspect of the present invention, a particle aggregator includes: a silicon substrate; a Lamb wave resonator array including a plurality of Lamb wave resonators, the plurality of Lamb wave resonators being located on a front surface of a silicon substrate And it is arranged at the apex of the regular polygon, wherein the angle formed by the electrode strips of each Lamb wave resonator and the electrode strips of adjacent Lamb wave resonators is equal to the internal angle of the regular polygon.

Preferably, each of the Lamb wave resonators includes a piezoelectric layer having a first portion above a rectangular cavity of the silicon substrate, and a bottom surface of the piezoelectric layer is flush with a front surface of the silicon substrate. A plurality of pairs of electrode strips, which are parallel to each other and arranged on the upper and lower surfaces of the first portion of the piezoelectric layer in an aligned manner.

Preferably, each of the Lamb wave resonators includes: a first connector on a front surface of the silicon substrate and adjacent to a first edge of a rectangular cavity; and a second connector on the silicon substrate On a front surface and adjacent to a second edge of the rectangular cavity, the first edge being opposite to the second edge, wherein a plurality of first electrode strips and a plurality of second electrodes of the plurality of pairs of electrode strips One end of the strip is connected to the first connection piece and the second connection piece in an interdigital manner, respectively.

Preferably, the plurality of first electrode strips and the plurality of second electrode strips located on the upper surface of the first portion of the piezoelectric layer are alternately connected to the first connection member and the second connection Pieces; and the plurality of first electrode strips and the plurality of second electrode strips located on the lower surface of the first portion of the piezoelectric layer are alternately connected to the second connection piece and the first connection Pieces.

Preferably, the piezoelectric layer further includes a second portion located on the front surface of the silicon substrate and adjacent to the third edge and the fourth edge of the rectangular cavity, wherein the third edge and the The fourth edge is opposite.

Preferably, the rectangular cavity includes: a bottom cavity located between a bottom surface of the rectangular cavity and a lower surface of the first portion of the piezoelectric layer or an electrode bar; and a side cavity located in the rectangle A cavity and a side wall of a second portion of the piezoelectric layer and a first portion of the piezoelectric layer.

Preferably, the Lamb wave excited in the Lamb wave resonator is introduced into the liquid in the side cavity through a solid-liquid interface to cause a liquid acoustic fluid effect.

Preferably, the regular polygon includes a regular triangle, a square, a regular pentagon, a regular hexagon, a regular seven deformation, and a regular octagon.

Preferably, the number of the electrode strips is 5 to 30 pairs.

Preferably, the width of the electrode strip is 2 μm to 80 μm; the interval between adjacent electrode strips is 1 μm to 30 μm; and the thickness of the piezoelectric layer is 0.3 μm to 4 μm.

Preferably, the sum of the width of the electrode strip and the interval is a half of the wavelength of the Lamb wave generated by the Lamb wave resonator.

According to another aspect of the present invention, a method for operating a particle aggregator based on a Lamb wave resonator is provided. The solution containing particles is dropped on a Lam wave resonator array of a particle aggregator, wherein The Lamb wave resonator array includes the same multiple Lamb wave resonators, and the angle formed by the electrode strips of each Lamb wave resonator and the electrode strips of adjacent Lamb wave resonators is equal to the internal angle of the regular polygon. ; Applying an electric signal having a frequency corresponding to a resonance frequency of the Lamb wave resonator to the each Lamb wave resonator; and each Lamb wave resonator excites a Lamb wave, and The Lamb wave is introduced into the solution in part through a solid-liquid interface to induce an acoustic fluid effect.

Preferably, each of the Lamb wave resonators excites a Lamb wave, and the Lamb wave is partially introduced into the solution through a solid-liquid interface to cause an acoustic-fluid effect further comprising: the Lamb wave resonator The lateral boundary of the resonant cavity of the resonator vibrates as a linear acoustic source of Lamb waves in the solution; in response to the linear acoustic source, the Lamb waves near the lateral boundary of the resonant cavity Surface waves propagate; and the cylindrical waves cause an acoustic fluid effect in the solution.

Preferably, the direction of flow of the solution is controlled by the acoustic fluid effect caused by the cylindrical wave to control the aggregation position of particles in the solution.

Preferably, the number of electrode pairs of the Lamb wave resonator is increased to compensate the mechanical energy transmitted to the solution in real time.

Preferably, the speed of particle aggregation in the solution is adjusted by selecting the power of the electrical signal.

The particle aggregator based on the Lamb wave resonator and the operation method thereof according to the embodiments of the present invention can realize the manipulation and aggregation of micro-concentration substances in the smallest space (microliter volume of liquid droplets), and in the open space The specific position increases the concentration of the detected object by a high factor, which can further reduce the size of the particle aggregator without the need to design a microchannel.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without paying creative labor.

1a and 1b are a perspective view and a sectional view, respectively, of a Lamb wave resonator according to an embodiment of the present invention;

2 is a simulation diagram of a three-dimensional vibration distribution of a Lamb wave resonator according to an embodiment of the present invention, wherein FIG. 2 includes a partially enlarged view of the three-dimensional vibration distribution;

3a and 3b are a top view and a perspective view of a specific example of a Lamb wave resonator array according to an embodiment of the present invention;

4 is a simulation diagram of an acoustic fluid flow field of a Lamb wave resonator array according to an embodiment of the present invention, where 400a is an acoustic fluid flow field generated by a Lamb wave resonator array in a 1 μL droplet; FIG. 400b, 400c and 400d are the distribution diagrams on the horizontal plane of the acoustic fluid flow field above the solid-liquid interface at 30 μm, 100 μm, and 170 μm, respectively;

FIG. 5 is a scanning electron microscope image of a grain of a Lamb wave resonator array according to an embodiment of the present invention, wherein FIG. 5 includes a partially enlarged view of the grain of a Lamb wave resonator array;

Figure 6a is the particle trajectory of the particle imaging velocimeter PIV system in the acoustic fluid effect of the Lamb wave resonator array; and Figure 6b is the flow distribution of the particle trajectory after the image in Figure 6a is processed by the imaging velocimeter;

FIG. 7 is a particle aggregation diagram observed at 0 seconds, 1 second, 2 seconds, 5 seconds, 20 seconds, and 2 minutes using a normal light microscope; and

8 is a flowchart of a method of operating a particle aggregator based on a Lamb wave resonator.

detailed description

In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, but not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

A particle aggregator based on a Lamb wave resonator includes: a silicon substrate; a Lamb wave resonator array including a plurality of Lamb wave resonators, and the plurality of Lam wave resonators are located on a front surface of the silicon substrate and disposed on a regular polygon At the apex of, the angle formed by the electrode strips of each Lamb wave resonator and the electrode strips of adjacent Lamb wave resonators is equal to the internal angle of the regular polygon.

3a and 3b are a top view and a perspective view of a specific example of a Lamb wave resonator array according to an embodiment of the present invention. The Lamb wave resonator array will be described in detail below with reference to FIGS. 3a and 3b. The number of components shown in the drawings is only for the purpose of illustration and is not intended to limit the scope of protection of the present invention.

For example, referring to FIGS. 3a and 3b, a Lamb wave resonator-based particle aggregator 300 includes: a silicon substrate 302; a Lamb wave resonator array including four Lamb wave resonators, and four Lamb wave resonators located at The front surface of the silicon substrate is located at the apex of the square, wherein the angle formed by the electrode strips of each Lamb wave resonator and the electrode strips of adjacent Lamb wave resonators is equal to the internal angle of the regular polygon, in other words In other words, the electrode strips of each Lamb wave resonator are perpendicular to the electrode strips of adjacent Lamb wave resonators.

Hereinafter, a particle aggregator based on a Lamb wave resonator will be described in detail with reference to FIGS. 1a, 1b, 3a, and 3b.

In one embodiment, the Lamb wave resonator-based particle aggregator 300 includes: a silicon substrate 302; a Lamb wave resonator array including a plurality of Lamb wave resonators 304, 306, 308, and 310, and a plurality of Lamb waves The wave resonator is located on the front surface of the silicon substrate 302 and is arranged at the vertex of the regular polygon, wherein the angle formed by the electrode strips of each Lamb wave resonator and the electrode strips of adjacent Lamb wave resonators is equal to the regular polygon The internal angles are equal. In practical applications, regular polygons can include regular triangles, squares, regular pentagons, regular hexagons, regular seven deformations, and regular octagons. When the regular polygon is a square, the electrode strips of the Lamb wave resonator 304 are perpendicular to the electrode strips of adjacent Lamb wave resonators 306 and 308; and when the regular polygon is a regular triangle, a regular pentagon, and a regular hexagon , Regular seven deformation and regular octagon, the angle formed by the electrode strip of the Lamb wave resonator and the adjacent strip of the lamb wave resonator is equal to the regular triangle, regular pentagon, regular hexagon, regular seven deformation and regular octagon The interior angles of the shapes are equal. Squares are shown herein in Figures 3a and 3b, but the invention is not limited to squares.

In an embodiment of the present invention, referring to FIGS. 1 a and 1 b, the Lamb wave resonators 304, 306, 308, and 310 may be the same as the Lamb wave resonator 100. Each Lamb wave resonator 100 includes: a piezoelectric layer 104 having a first portion above a rectangular cavity of a silicon substrate 102, a bottom surface 112 of the piezoelectric layer being flush with the front surface 110 of the silicon substrate; a plurality of pairs of electrode strips, They are arranged parallel to each other and aligned on the upper and lower surfaces of the first portion of the piezoelectric layer 104, for example, paired electrode strips 118-1 and 108-8, 108-1 and 118-9, 118-2 and 108- 9, 108-2 and 118-10, 118-3 and 108-10, and 108-3 and 118-11 are located on the upper and lower surfaces of the first portion of the piezoelectric layer 104, respectively. The number of electrode bars is 5 to 30 pairs. In a preferred embodiment, the number of electrode strips is 15 pairs, for example, 108-1, 108-2, 108-3, 108-4, 108-5, 108-6, 108-7, 118-1, 118- The 15 electrode strips 2, 118-3, 118-4, 118-5, 118-6, 118-7, and 118-8 are electrode strips located on the upper surface of the first part of the piezoelectric layer and are in contact with these electrodes. The 15 corresponding electrode strips are located on the lower surface of the first part of the piezoelectric layer. The width W ₁ of the electrode strip is 2 μm to 80 μm; the interval W ₂ between adjacent electrode strips is 1 μm to 30 μm; and the thickness T of the piezoelectric layer is 0.3 μm to 4 μm. The sum of the width and interval of the electrode strip (W ₁ + W ₂ ) is one half of the wavelength of the Lamb wave generated by the Lamb wave resonator. In addition, the length L of the electrode strip is 50 μm to 500 μm.

In the embodiment of the present invention, each Lamb wave resonator further includes: a first connection member 106 on the front surface of the silicon substrate 102 and adjacent to the first edge of the rectangular cavity; and a second connection member 116 on the On the front surface of the silicon substrate 102 and adjacent to the second edge of the rectangular cavity, the first edge is opposite to the second edge, wherein one end of the plurality of first electrode strips and the plurality of second electrode strips in the plurality of pairs of electrode strips is Interdigitated connections to the first and second connectors, for example, multiple first electrode strips 108-1, 108-2, 108-3, 108-4, 108-5, 108-6, One end of 108-7 and multiple second electrode bars 118-1, 118-2, 118-3, 118-4, 118-5, 118-6, 118-7, and 118-8 are connected to 106 and 116, respectively . The plurality of first electrode strips and the plurality of second electrode strips located on the upper surface of the first portion of the piezoelectric layer 104 are alternately connected to the first connection member and the second connection member, for example, the plurality of first electrode strips 108- 1, 108-2, 108-3, and a plurality of second electrode strips 118-1, 118-2, and 118-3 are all located on the upper surface of the first portion of the piezoelectric layer and are connected to the first connection member 106 and the first portion, respectively. Two connecting members 116; and a plurality of first electrode bars and a plurality of second electrode bars on the lower surface of the first portion of the piezoelectric layer are alternately connected to the second connecting member and the first connecting member, for example, a plurality of An electrode strip 108-8, 108-9, 108-10 and a plurality of second electrode strips 118-9, 118-10, and 118-11 are located on the lower surface of the first portion of the piezoelectric layer 104 and are connected to the first A connection member 106 and a second connection member 116. In addition, the piezoelectric layer 104 further includes a second portion on the front surface of the silicon substrate 102 and adjacent to the third edge and the fourth edge of the rectangular cavity, wherein the third edge is opposite to the fourth edge.

In an embodiment, the rectangular cavity includes: a bottom cavity 114 located between a bottom surface of the rectangular cavity and a lower surface of the first portion of the piezoelectric layer 104 or an electrode bar; and a side cavity 116 located in the rectangular cavity and Between the side wall of the second portion of the piezoelectric layer and the first portion of the piezoelectric layer. The Lamb wave excited in the Lamb wave resonator is introduced into the liquid in the side cavity through the solid-liquid interface to cause a liquid acoustic fluid effect.

Referring to FIG. 8, according to an embodiment of the present invention, a method 800 of operating a particle aggregator based on a Lamb wave resonator, includes, in step 802, dropping a solution containing particles on a Lam wave resonator array of a particle aggregator. Wherein, the Lamb wave resonator array includes the same multiple Lamb wave resonators, and the angle formed by the electrode strips of each Lamb wave resonator and the electrode strips of adjacent Lamb wave resonators is equal to that of a regular polygon. The internal angles are equal; in step 804, an electric signal having a frequency corresponding to the resonance frequency of the Lamb wave resonator is applied to each Lamb wave resonator; and in step 806, each Lamb wave resonator is excited Lamb waves, and the Lamb waves are introduced into the solution in part through the solid-liquid interface to trigger the acoustic fluid effect.

In an embodiment, each Lamb wave resonator excites the Lamb wave, and the Lamb wave is partially introduced into the solution through the solid-liquid interface to cause an acoustic fluid effect. The method further includes: a lateral direction of the resonance cavity of the Lamb wave resonator. Boundary vibrations act as linear acoustic sources of Lamb waves in solution; in response to linear acoustic sources, Lamb waves near the lateral boundaries of the cavity travel in the form of cylindrical waves in solution; and cylindrical waves in solution Inducing the acoustic fluid effect. The flow direction of the solution is controlled by the acoustic fluid effect induced by the cylindrical wave, so as to control the aggregation position of the particles in the solution. The rate of particle aggregation in the solution is adjusted by selecting the power of the electrical signal. Before the operation method starts, the number of electrode pairs of the Lamb wave resonator is increased to compensate the mechanical energy transmitted to the solution in real time.

The particle aggregator based on the Lamb wave resonator and the operation method thereof according to the embodiments of the present invention can realize the manipulation and aggregation of micro-concentration substances in the smallest space (microliter volume of liquid droplets), and in the open space The specific position of the high-fold increase of the concentration of the detected object can further reduce the size of the particle aggregator without the need to design a microchannel, thereby reducing the complexity of the particle aggregator.

Hereinafter, the Lamb wave resonator array will be described in detail by way of specific examples with reference to the drawings.

The invention designs a resonator array including four 386 MHz Lamb wave resonators, and simulates and analyzes the fluid flow and characteristics of the array in a microliter of droplets. According to the designed and manufactured array device, in the experiment, nine microvortexes were generated in one microliter of droplets in accordance with the simulation results. The experiment showed the effect of the array device on the particles in the droplets: at a specific power in a microliter of droplets in the open space to achieve rapid aggregation of particles, the aggregation rate can reach 250 per second in the first 20 seconds The aggregation of tens of thousands of 3 micron diameter particles was achieved within 2 minutes.

In order to relatively concentrate the excitation of the acoustic fluid in a relatively small liquid space, a relatively high-frequency 386 MHz (but the invention is not limited to this specific frequency) Lamb wave resonator is used for research, because the Lamb wave resonator in this frequency band The electrode has a short space period, and the acoustic flow force of the sound waves in the liquid is relatively short. It can arrange multiple resonators on a smaller grain area, thereby stimulating more detailed fluid-oriented motion. FIG. 1a is an overall side view of the structure of a Lamb wave resonator used in the present invention; FIG. 1b is a schematic cross-sectional structure diagram of a Lamb wave resonator in a liquid environment. The Lamb wave resonator used in the present invention and the schematic diagram of the structure shown in Figs. 1a and 1b in water. The piezoelectric layer is composed of aluminum nitride (but not limited to aluminum nitride material). Interdigital transducer (IDT) composed of molybdenum (but not limited to molybdenum), wherein some of these electrodes are connected to the first connection member as the first electrode, for example, the cathode, and other of these electrodes are connected To the second connection member serves as a second electrode, for example, an anode. Specifically, adjacent electrodes are connected to different electrodes and have different polarities, and in addition, an electrode above an upper surface of the piezoelectric layer is aligned with an electrode on a lower surface of the piezoelectric layer and connected to different electrodes, and Has different polarities. The relevant geometric dimensions are: electrode width W ₁ = 10 μm, electrode spacing W ₂ = 3 μm, electrode length L = 150 μm, number of electrode pairs N = 15, and piezoelectric layer thickness T = 1.5 μm. The Lamb wave resonator thus designed has a natural frequency. The sum of the electrode width and the electrode pitch (W ₁ + W ₂ ) is the same as 1/2 of the Lamb wave generated by the Lamb wave resonator. According to the difference from traditional surface acoustic wave (SAW) devices, the resonant cavity of the Lamb wave resonator is released and suspended above the silicon substrate, which prevents the mechanical energy of the acoustic wave from leaking directly from the resonant cavity to Substrate. When an AC signal is input to the IDT, a Lamb wave S0 mode is generated in the resonant cavity, and propagates in the cavity in a horizontal direction perpendicular to the electrode strip and forms a standing wave.

Different from working in air, in the liquid, on the outer side of the outermost electrode strip, that is, at the lateral boundary where the aluminum nitride is etched to form the cavity, the Lamb wave excited in the resonator will partially pass through the solid The liquid interface is introduced into the liquid and is not completely confined to the solid. This side leaking acoustic wave directly causes liquid acoustic fluid effect, and this acoustic wave propagation form is also significantly different from the SAW acoustic fluid effect. Due to the geometrical dimension T << (W ₁ + W ₂ ) <L of the resonant cavity, the boundary vibration of the resonant cavity, as the sound source of the sound waves in the liquid, can be regarded as a "line acoustic source", so the liquid is lateral to the resonant cavity The acoustic wave near the boundary can be regarded as a cylindrical wave, and the acoustic fluid effect induced in a liquid by a Lamb wave resonator is exactly the kind of cylindrical wave excitation.

Due to the leakage of acoustic waves at both ends of the resonator, the quality factor of the resonator is reduced. In order to minimize the influence of the acoustic wave leakage at the two ends on the resonator itself, the best way is to increase the number of resonator electrode pairs N, and more pairs of electrodes can be used as the excitation source of Lamb waves by the inverse piezoelectric effect to achieve real-time Compensate the mechanical energy transmitted to the liquid. Therefore, the present invention uses a resonator with N = 15 (but not limited to 15) as the actuator.

FIG. 2 is a three-dimensional vibration distribution diagram of a Lamb wave resonator at 386 MHz and a sound pressure distribution diagram 200 of a pressure wave in a surrounding liquid, where FIG. 2 includes a three-dimensional vibration distribution diagram of a Lamb wave resonator and a surrounding liquid. Local amplifier for sound pressure profile of medium pressure waves. Calculated through finite element simulation of the physical field, under the input of 12.5mW power and frequency 386MHz, the vibration distribution of the device and the sound pressure distribution 202 in the surrounding liquid (as shown in Figure 2). Among them, the frequency of the electric signal is selected according to the natural frequency of the Lamb wave resonator. A column of Lamb wave S0 standing waves with 15 nodes resonates in a resonant cavity. There is also vibration of the sound field in the liquid around the resonator. On the outside of the electrode strip located at the outermost edge of the resonator, that is, at the lateral boundary of the piezoelectric layer, the vibration of the resonator causes the vibration of the liquid, and a column of cylindrical pressure waves flows into the liquid from the edge of the resonator. The maximum sound pressure amplitude of the cylindrical pressure wave is 6.2 MPa, which appears on the symmetrical center plane of the resonator. At a position gradually approaching the end of the electrode bar, the sound pressure in the liquid is also weakened by the weakening of the resonator vibration.

Because the flow induced by the acoustic fluid effect of the cylindrical wave excited by the Lamb wave resonator is not in the horizontal plane, but has an inclination angle in the three-dimensional space, the arrangement and combination design of multiple Lamb wave resonators can not only In addition to the horizontal flow of the fluid, the vertical flow of the fluid can be controlled to a certain extent, and the position of the particles in the fluid in the vertical direction can be controlled to prevent the particles from falling on the surface of the solid device due to settling and other reasons. Its performance. Figures 3a and 3b are Lamb wave resonator array designs for particle manipulation, where Figure 3a is a top view of the distribution on a silicon substrate; Figure 3b is a 1 μL droplet added on a Lamb wave resonator array device schematic diagram. In the present invention, the Lamb wave resonator array designed on a single silicon die is shown in Fig. 3a and Fig. 3b. By using the acoustic fluid effect of the device, the microliter-level droplets located thereon can be applied. Internal particles perform small range manipulation.

Four identical Lamb wave resonators are located on a square die with a side length of 1.5 mm, and the device centers of the four Lamb wave resonators are located on the four vertices of a square with a side length of 550 μm (the length of the side length is not limited to 550 μm ). This distance distribution not only keeps the overall device size on the order of magnitude (about one-tenth the size of a SAW device that achieves similar functions), but also between each resonator is sufficiently large (relative to resonance The size of the device itself) ensures a sufficiently large range of acoustic fluid effects. The direction of the electrode strips of each resonator is parallel to one side of the square, the electrode strips of adjacent resonators are perpendicular to each other, and the electrode strips of the diagonally positioned resonators are parallel to each other. The four Lamb wave resonators placed in this circulation generate oblique upward sound current forces according to their respective azimuth angles. The four sound current forces that constitute the circulation direction cooperate to produce a strong counterclockwise in the center of the entire grain. vortex. The particles inside the vortex will be subjected to the drag force of the liquid to cause directional motion.

A physical field finite element analysis model was established according to the above dimensions, and the acoustic fluid effects of the Lamb wave resonator array were simulated and calculated. The input power of each device is still 12.5 mW, and the droplet volume is 1 μL. The overall flow field figure calculated is shown in 400a in FIG. 4. Specifically, the particle aggregation speed in the solution can be adjusted by changing the input power. For example, when the input power is greater than 12.5mW, the particle aggregation speed in the solution can be increased. Conversely, when the input power is less than 12.5mW, the adjustment can be reduced. The rate of particle aggregation in the solution. Each Lamb wave resonator excites four vortices around its own. The counter-clockwise main vortex located at the center of the overall grain is just a superposition of one vortex excited by each Lamb wave resonator. There are 8 secondary vortices at the edge of the droplets around the main vortex. The entire 9 vortexes are filled with the entire 1 μL droplet. Since the acoustic fluid induced by each resonator at the center of the main vortex is tilted upward, the excitation effect of the four resonators is superimposed on the center of the main vortex, the horizontal components of the fluid flow cancel each other out, and the vertical direction is superimposed. After forming an upward component. Therefore, the flow at the center of the main vortex is upward, and the fluid in the main vortex also flows upward counterclockwise. This also makes the particles in the main vortex move upward with the fluid spiral due to the drag force, so that they will not settle on the solid-liquid contact surface and affect the vibration of the resonator.

400b, 400c, and 400d in FIG. 4 describe the distribution of the flow field on a horizontal plane at 30 μm, 100 μm, and 170 μm above the solid-liquid interface. At the edge of the main vortex, the place closest to the edge of the resonator has the largest flow velocity, because these are the locations where the acoustic current forces that cause the main vortex are located. As the height increases, the cross-section of the droplet becomes smaller, and the space occupied by the eight sub-vortexes gradually decreases, while the range of action of the main vortex does not decrease due to the smaller cross-sectional area. At a distance of 170 μm (400 d) from the bottom surface, the main vortex has taken up the entire cross-section, which provides the necessary conditions for particles to gather inside the main vortex without becoming involved in the secondary vortex.

According to the size parameters of the Lamb wave resonator determined above and the size of the Lamb wave resonator array, a layout is made and actual manufacturing is performed. FIG. 5 is a scanning electron microscope view of a manufactured Lamb wave resonator array die, wherein FIG. 5 includes a partially enlarged view of a part of the Lamb wave resonator array. After the process is completed, the wafer is diced. The physical image and scanning electron microscope image of the single Lamb wave resonator array grain finally obtained are shown in FIG. 5. The four Lamb wave resonators are placed according to the designed position. The light-colored part connecting the electrodes of each resonator is a metal electrode, which is used to connect the electrodes of all the resonators to the positions where the probes are tested and wired. Each resonator is tiled directly on the silicon substrate instead of using a thin support structure to ensure its structural stability in the liquid flow field. Outside the electrode at the outermost edge of the resonator, the area where the A1N film is etched is clearly visible, and the boundary of the Lamb wave resonator is also formed. The acoustic fluid effect of each resonator in the liquid is mainly located here. For each grain only 1.5 * 1.5 * 0.4mm ³ in size, its size has obvious advantages.

A 3 μm diameter polystyrene bead solution with fluorescence was used in the experiment. Figure 6a is a particle trajectory image taken using a laser-based particle imaging velocimetry (Particle Image Velocimetry (PIV)). It adopts a method of continuously exposing 20 frames per second, and superimposing and presenting continuous 20 frames of images. Thus, the dot map of each frame of particles can be connected into a particle trajectory map as shown in FIG. 6a. The position and shape of the main vortex and the eight secondary vortices can be clearly distinguished in the figure. By calculating the change in particle position for each frame, the velocity distribution of particle motion can be calculated. The normalized particle velocity distribution is shown in Figure 6b. The experimental results are highly consistent with the simulation results in Figure 4, thereby realizing the experiment. Mutual verification of observed particle trajectories and simulated physical fields.

The complete particle aggregation process was photographed with a constant light objective lens at a power input of 50mW, and screenshots at various times are shown in a-f in FIG. 7. At the initial moment when the droplet is added above the device, due to the hydrophobicity of silicon, the particles are uniformly suspended and distributed in the droplet. At the moment of the input power, the particle distribution has not yet aggregated in the droplet (see Figure 7) A); after 1 second of power input, the particles inside the main vortex begin to gather towards the center of the vortex, forming a preliminary cluster on the surface of the droplet (see b) in Figure 7; after 2 seconds of power input, the aggregation The particles of the cluster gradually increase, the center of the cluster is filled with particles, and the gap gradually decreases (see c in Fig. 7); after 5 seconds, the aggregation area is completely formed, the radius of the aggregation area rapidly increases to 100 μm, and the particles in the aggregation area are sufficiently rich. The set has no gap (see d in Figure 7); when it reaches 20 seconds, the radius of the aggregation zone continues to increase, and it is estimated that the enrichment rate of particles in the first 20 seconds can reach 250s-1 (see e in Figure 7); continuous power supply 2 Minutes, about 104 particles aggregated to the center of the main vortex, and the radius of the aggregation area reached 220 μm. After that, the aggregation area no longer increased, and most of the particles in the solution were concentrated near the upper surface of the droplet center (see f in Figure 7). ). Therefore, the Lamb wave resonator array according to the embodiment of the present invention can more quickly gather particles in very small droplets at the center of the Lamb wave resonator array in an open space, so as to be able to Detection of particles in.

The Lamb wave resonator array according to the embodiment of the present invention can be used to detect harmful substances and pollutants in the surrounding environment, such as the measurement of PM2.5; it can be used to detect cells in medicine; and to detect trace drugs. The particles in the solution are collected at a specific position (for example, a center position) of the Lamb wave resonator array to enable detection and analysis of the particles in the solution.

The invention designs a Lamb wave resonator array as an acoustic fluid driver for the field of microfluidic particle manipulation, and successfully achieves the manipulation and aggregation of biological particles in a microliter of droplets, and the device can be used multiple times repeat. The device is designed to achieve particle aggregation in microliter droplets in open spaces without microfluidic channels. This design promotes the development and progress of microfluidic technology to smaller scale and open microfluidic systems.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not limited thereto. Although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not depart from the essence of the corresponding technical solutions range.

Claims

A particle aggregator based on a Lamb wave resonator, comprising:

Silicon substrate

A Lamb wave resonator array includes a plurality of Lamb wave resonators, which are located on a front surface of a silicon substrate and are disposed at the vertices of a regular polygon, wherein each Lamb wave resonator The angle formed by the electrode strips and the electrode strips of adjacent Lamb wave resonators is equal to the internal angle of the regular polygon.
The particle aggregator based on a Lamb wave resonator according to claim 1, wherein each of the Lamb wave resonators comprises:

A piezoelectric layer having a first portion above a rectangular cavity of the silicon substrate, a bottom surface of the piezoelectric layer being flush with a front surface of the silicon substrate;

A plurality of pairs of electrode strips are arranged on the upper and lower surfaces of the first portion of the piezoelectric layer in parallel and aligned with each other.
The particle aggregator based on a Lamb wave resonator according to claim 2, wherein each Lamb wave resonator comprises:

A first connector on a front surface of the silicon substrate and adjacent to a first edge of a rectangular cavity; and

A second connector, located on the front surface of the silicon substrate and adjacent to a second edge of the rectangular cavity, the first edge being opposite to the second edge,

Wherein, one ends of the plurality of first electrode strips and the plurality of second electrode strips of the plurality of pairs of electrode strips are respectively connected to the first connection piece and the second connection piece in an interdigital manner.
The particle aggregator based on a Lamb wave resonator according to claim 3, wherein

The plurality of first electrode strips and the plurality of second electrode strips on an upper surface of the first portion of the piezoelectric layer are alternately connected to the first connection member and the second connection member; and

The plurality of first electrode strips and the plurality of second electrode strips located on the lower surface of the first portion of the piezoelectric layer are alternately connected to the second connection member and the first connection member.
The particle aggregator based on a Lamb wave resonator according to claim 2, wherein the piezoelectric layer further comprises a third edge of the rectangular cavity and a third edge of the rectangular cavity located on a front surface of the silicon substrate and A second portion adjacent to a fourth edge, wherein the third edge is opposite to the fourth edge.
The particle aggregator based on a Lamb wave resonator according to claim 5, wherein the rectangular cavity comprises:

A bottom cavity between a bottom surface of the rectangular cavity and a lower surface or an electrode strip of a first portion of the piezoelectric layer; and

The side cavity is located between the rectangular cavity and a sidewall of the second portion of the piezoelectric layer and the first portion of the piezoelectric layer.
The particle aggregator based on a Lamb wave resonator according to claim 6, wherein the Lamb wave excited in the Lamb wave resonator is introduced into the side cavity through a solid-liquid interface. Liquid to induce liquid acoustic fluid effect.
The particle aggregator based on a Lamb wave resonator according to claim 1, wherein the regular polygon includes a regular triangle, a square, a regular pentagon, a regular hexagon, a regular seven deformation, and a regular octagon.
The particle aggregator based on a Lamb wave resonator according to claim 1, wherein the number of the electrode strips is 5 to 30 pairs.
The particle aggregator based on a Lamb wave resonator according to claim 2, wherein the width of the electrode strip is 2 μm to 80 μm;

The interval between adjacent electrode strips is 1 μm to 30 μm; and

The thickness of the piezoelectric layer is 0.3 μm to 4 μm.
The particle aggregator based on a Lamb wave resonator according to claim 1, wherein a sum of a width of the electrode strip and the interval is a wavelength of a Lamb wave generated by the Lamb wave resonator. Half.
A method for operating a particle aggregator based on a Lamb wave resonator is characterized in that:

The particle-containing solution is dropped on a Lamb wave resonator array of a particle aggregator, wherein the Lamb wave resonator array includes the same multiple Lamb wave resonators, and each Lamb wave resonator The angle formed by the electrode strip and the electrode strip of the adjacent Lamb wave resonator is equal to the internal angle of the regular polygon;

Applying an electric signal having a frequency corresponding to a resonance frequency of the Lamb wave resonator to each of the Lamb wave resonators; and

Each of the Lamb wave resonators excites a Lamb wave, and the Lamb wave is partially introduced into the solution through a solid-liquid interface to cause an acoustic fluid effect.
The operating method according to claim 12, wherein each of the Lamb wave resonators excites Lamb waves, and the Lamb waves are partially introduced into the solution through a solid-liquid interface to cause an acoustic fluid The effects further include:

The lateral boundary of the resonant cavity of the Lamb wave resonator vibrates as a linear sound source of the Lamb wave in the solution;

In response to the line acoustic source, a Lamb wave near a lateral boundary of the resonant cavity propagates in the form of a cylindrical wave in the solution; and

The cylindrical wave causes an acoustic fluid effect in the solution.
The operation method according to claim 12, wherein:

The flow direction of the solution is controlled by the acoustic fluid effect caused by the cylindrical wave to control the aggregation position of the particles in the solution.
The operation method according to claim 12, wherein:

The number of electrode pairs of the Lamb wave resonator is increased to compensate the mechanical energy transmitted into the solution in real time.
The operating method according to claim 14, wherein:

The particle aggregation speed in the solution is adjusted by selecting the power of the electrical signal.