CN114308157A - Dynamic adjustable sound tweezer device based on local resonant cavity and use method thereof - Google Patents
Dynamic adjustable sound tweezer device based on local resonant cavity and use method thereof Download PDFInfo
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Abstract
The invention relates to a dynamic adjustable sound tweezer device based on a local resonant cavity, which comprises a microfluidic chip, a substrate and a piezoelectric ceramic piece, wherein the microfluidic chip comprises a microfluidic cavity, the microfluidic cavity is fixed on one surface of the substrate, and the piezoelectric ceramic piece is fixed on the other surface of the substrate; the inner part of the micro-flow cavity is divided into an upper layer and a lower layer, the upper layer is a main channel containing particles, the lower layer is a closed air cavity channel, and the lower layer is connected with the substrate. The use method of the device comprises the following steps: the piezoelectric ceramic plate generates sound wave which is transmitted into the lower layer of the micro-flow cavity through the substrate to cause the resonance of the air cavity channel, so that the sound wave is transmitted to the upper main channel of the micro-flow cavity to generate sound radiation force and sound flow effect; by using different resonant frequencies to drive the air cavity channel, the motion condition of the particles can be observed at different positions. The technical scheme of the invention can solve the problems that uniform bubble liquid level can not be generated by micro bubbles of a bubble resonance type micro-fluidic system, the repeatability of the whole control system is weak, and the robustness of ultrasonic control can not be ensured.
Description
Technical Field
The invention relates to the technical field of microfluidic chips, in particular to a dynamic adjustable sound tweezers device based on a local resonant cavity and a using method thereof.
Background
Microfluidics is a technology capable of accurately manipulating microscale fluids, can accurately manipulate particles such as cells, and has great significance for prevention, diagnosis and treatment of human diseases. In recent years, researchers have combined microfluidic technology with optical, magnetic, electrical, acoustic and other technologies to further promote the development of research in the field of microfluidic chips. Microfluidics driven in an acoustic manner has the advantages of high biosecurity, easy preparation, low cost, and the like. The acoustic microfluidic technology is also called acoustic tweezers technology, which is a technology for precisely manipulating micro-nano particle objects in microfluid by using acoustic waves. The input power required by the acoustic tweezers method is much smaller than that of the optical tweezers method, which indicates that the acoustic tweezers method has lower damage to biological particles. The penetration of the sound wave is stronger than that of the light wave, so that the sound wave can penetrate through the non-transparent medium to carry out the 'mountain-separating beating-cattle' type manipulation on the particles.
The existing bubble resonance type micro-fluidic mainly adopts resonance of air bubbles on the side wall to generate acoustic radiation force and acoustic current, so that micro-particles are controlled. Wherein the micro-particle motion state is the result of the synergy of the acoustic radiation force and the acoustic flow field. The two mechanical effects show dominant conversion along with the change of particle radius and sound wave frequency, thereby influencing the motion state of particles. When the acoustic flow effect is dominant, the particles can perform orbital rotation motion along with vortex generated by the acoustic flow; when acoustic radiation forces dominate, particles are trapped at the air/water interface. However, when the microfluid enters the flow channel, especially the effect of air pressure, a closed air cavity is formed at the position of the side wall, but due to the difference of structure and hydrophobicity, the micro-bubble cannot generate a completely uniform bubble liquid level during forming, so that the actual driving resonance frequency of the micro-bubble is greatly different from the theoretical resonance frequency. Therefore, the operation frequency of the method is unstable due to the temperature, humidity and liquid level forming condition of the preparation, so that the repeatability of the whole operation system is weak, and the robustness of the ultrasonic operation cannot be ensured.
The phononic crystal is an artificial composite structure material with periodically distributed elastic constants and densities, and can effectively realize the propagation and control of sound waves. The local resonance type phononic crystal can obtain band gap frequency far lower than Bragg scattering by selecting resonance functional elements, and realize the sub-wavelength regulation of sound waves. The subwavelength photonic crystal can realize the transmission and control of the long-wavelength sound wave at a lower frequency, and the long-wavelength characteristic has higher fault tolerance and is beneficial to improving the defect resistance and the robust characteristic of sound wave transmission. When the incident excitation frequency of the sound wave is close to the eigen-state resonance frequency of the resonance functional element, the sound wave and the resonance functional element generate strong coupling action and are expressed as a local resonance state of the sub-wavelength phononic crystal. The phononic crystal structure is introduced into the bubble resonance type micro-fluidic, so that the controllability and the robustness of the micro-fluidic can be obviously improved, and the application scene of the micro-fluidic can be favorably expanded.
Disclosure of Invention
The invention aims to provide a dynamic adjustable acoustic tweezer device based on a local resonant cavity and a using method thereof, which can solve the problems that the micro-bubbles of a bubble resonance type micro-fluidic system cannot generate uniform bubble liquid level, the actual driving resonance frequency and the theoretical resonance frequency of the micro-bubbles are greatly different, the repeatability of the whole control system is weak, and the robustness of ultrasonic control cannot be ensured.
In order to solve the technical problems, the invention adopts the following technical scheme:
a dynamic adjustable acoustic tweezers device based on a local resonant cavity comprises a microfluidic chip, a substrate and a piezoelectric ceramic piece, wherein the microfluidic chip comprises a microfluidic cavity, the microfluidic cavity is fixed on one surface of the substrate, and the piezoelectric ceramic piece is fixed on the other surface of the substrate; the inner part of the micro-flow cavity is divided into an upper layer and a lower layer, the upper layer is a main channel containing particles, the lower layer is a closed air cavity channel, and the lower layer is connected with the substrate; the piezoelectric ceramic piece is connected with the micro-flow cavity through the substrate.
Further, the micro-flow cavity is fixed on the substrate by bonding or adhesion.
The main channel is a microfluid main channel for circulating fluid, and the air cavity channel is a Helmholtz cavity air channel for circulating air; the Helmholtz cavity gas channel comprises a plurality of resonant cavities respectively connected with the microfluidic main channel.
Further, at least two fluid inlet channels are arranged on one side of the main channel in a communicated mode, and at least two fluid outlet channels are arranged on the other side of the main channel in a communicated mode. The fluid inlet channel is provided with two, including a first inlet channel and a second inlet channel, wherein a first fluid inlet is arranged at the inlet of the first inlet channel, a second fluid inlet is arranged at the inlet of the second inlet channel, the first fluid inlet contains a particle sample, and the second fluid inlet contains a buffer solution without particles.
Meanwhile, the invention also provides a using method of the dynamic adjustable sound tweezer device based on the local resonant cavity, which comprises the following steps:
horizontally placing the acoustic tweezers device on an optical microscope objective table, fixing the acoustic tweezers device by using a wafer holder, and adjusting a knob of the objective table to enable a microfluidic chip channel of the acoustic tweezers device to enter the field of view of the microscope; adjusting a coarse focusing screw and a fine focusing screw of the microscope to focus on a microfluidic chip channel of the acoustic tweezers device;
slowly injecting a buffer solution into the microfluidic chip from the second fluid inlet by using a micro-injection pump until the microfluidic chip main channel is filled with the microfluidic; then slowly injecting the sample containing the particles into the microfluidic chip from the first fluid inlet by using another micro-injection pump;
connecting a signal output end of a signal generator with a lead of the piezoelectric ceramic piece, setting an output signal in the signal generator as a sinusoidal signal, and setting corresponding voltage and frequency parameters; the piezoelectric ceramic generates high-frequency vibration under the stimulation of an electric signal to cause the liquid level at the interface of a microfluid channel and a gas channel in a channel in the microfluidic chip to vibrate, and the amplitude of the vibrating liquid level can be observed under a microscope by connecting a high-speed camera;
the state of micro-flow motion can be pre-determined by calculating the relative magnitudes of the acoustic radiation force, which primarily attracts the particles toward the vibrating liquid surface, and the acoustic flow, which causes the acoustic vortex to guide the particles to make rotational motion. The motion state of the particles is under the combined action of the acoustic radiation force and the acoustic flow, and when the acoustic radiation force is dominant, the particles are captured to the liquid level; when the sound flow is dominant, the particles will rotate with the sound flow.
By driving the microfluidic resonance with different frequencies, the movement of the particles at different locations can be manipulated using, for example, first, second, and third resonant frequencies.
Wherein the particles are subjected to in a microfluidAcoustic radiation force of FRThe calculation formula is as follows:
in the formula, ρfAs a microfluidic density, RaRadius of the vibrating liquid surface, RpThe radius of the particles, d the distance between the particles and the liquid level, omega the angular frequency of the sound wave, and epsilon the amplitude of the vibration liquid level;
phi (rho) is a relative density coefficient, and the calculation formula is as follows:
φ(ρ)＝3(ρp-ρf)/(2ρp+ρf)
in the formula, ρpAnd ρfDensity of microparticles and microfluidics, respectively;
the oscillating liquid level forms an acoustic flow in the microfluid, and the speed of the acoustic flow is expressed by the following expression:
wherein the particles are subjected to a viscous force F caused by acoustic flow in the microfluidAsThe calculation formula is as follows:
FAs＝6πμRpu
where μ is the dynamic viscosity coefficient of the fluid.
Wherein, the calculation formula of the ratio of the acoustic radiation force to the viscous force caused by the acoustic flow is as follows:
FR/FAs≈ρfμ-1φ(ρ)Rp 2ω
in the formula, ρfMu and phi (p) are all microfluidic or microparticle physical parameters, constant values for a defined microparticle sample; the ratio of acoustic radiation force to acoustic flow induced viscous force is therefore only related to the particle diameter and the manipulation frequency of the acoustic wave. In other words, for particle samples with different diameters, the motion state of the particles can be changed, and only the input frequency of the sound wave needs to be adjusted.
The dynamic adjustable sound tweezer device based on the local resonant cavity has the advantages of simple structure, easiness in operation and lower cost; the Helmholtz resonant cavity is adopted to replace the traditional side wall air bubble, so that the resonant frequency of the traditional side wall air bubble can be reduced by 1-2 orders of magnitude, the frequency range of ultrasonic control is effectively reduced, the robustness of ultrasonic control is improved, and the error range of the actual working frequency is reduced; the device controls cells, has no marks and no damage, does not influence the activity of the cells, is favorable for rotary control of the cells and operations such as 3D imaging observation and gene transfection of the cells, and has great application in biomedicine and clinic.
Under the action of the local resonance frequency of the sound wave, the air cavity generates resonance and drives the microfluid to move. The generation of acoustic radiation force and acoustic flow force at the air and microfluidic interface, depending on the density, volumetric compressibility, diameter and drive frequency of the particles, allows for dynamic modulation of the non-contact state of motion of different particles. The dynamic regulation and control of particles are realized by adopting different frequency drives, which is beneficial to improving the control capability of the acoustic tweezers device; meanwhile, the resonance frequency of the Helmholtz resonant cavities is related to the volume of the Helmholtz resonant cavities, the volume of the Helmholtz resonant cavities has designability, and different frequencies can be used for driving different Helmholtz resonant cavities by changing the volumes of different Helmholtz resonant cavities, so that fixed-point driving at different positions is further realized.
Drawings
FIG. 1 is a schematic structural diagram of a local resonant cavity-based dynamically adjustable acoustic tweezer apparatus according to the present invention;
FIG. 2 is a schematic diagram of a microfluidic interlayer structure;
FIG. 3 is a graph of resonance frequency for resonance type and conventional bubble;
FIG. 4 is a first, second, and third order modal sound pressure distribution plot;
FIG. 5 is a schematic view of an acoustic streaming field;
fig. 6 shows the experimental effect of controlling the particles by the dynamic adjustable acoustic tweezers device based on the local resonant cavity.
In the figure: 1. a glass slide; 2. a microfluidic chip; 3. piezoelectric ceramic plates; 401. a first fluid inlet; 402. a second fluid inlet; 403. a first inlet channel; 404. a second inlet channel; 5. a main channel; 6. an air cavity channel; 701. a first fluid outlet; 702. a second fluid outlet; 703. a first outlet passage; 704. a second outlet passage.
Detailed Description
In order that the objects and advantages of the invention will be more clearly understood, the following description is given in conjunction with the accompanying examples. It is to be understood that the following text is merely illustrative of one or more specific embodiments of the invention and does not strictly limit the scope of the invention as specifically claimed.
Example 1
The technical scheme adopted by the embodiment is as shown in fig. 1, and the dynamic adjustable acoustic tweezers device based on the local resonant cavity comprises a glass slide 1, wherein a microfluidic chip 2 and a piezoelectric ceramic piece 3 arranged on the other surface of the glass slide 1 are arranged on the glass slide 1; the micro-fluidic chip 2 is provided with a hollow channel, the hollow channel comprises a main channel 5 and a lower air cavity channel 6, one side of the main channel 5 is communicated with two fluid inlet channels for particles to flow in, and the other side of the main channel 5 is communicated with two fluid outlet channels for particles to flow out; the piezoelectric ceramic piece 3 is arranged on one side of the microfluidic chip 2 close to the fluid inlet channel, and the piezoelectric ceramic piece 3 is externally connected with a signal generator and a power amplifier through a lead for driving; the piezoelectric ceramic sheet 3 of the present embodiment is made by placing a piezoelectric ceramic dielectric material between two copper circular electrodes, and when an ac signal is applied to the two electrodes, the piezoelectric sheet vibrates according to the magnitude and frequency of the signal.
Specifically, a first fluid inlet 401 is provided at the inlet of a first inlet channel 403 located at the upper left side of fig. 1, the first fluid inlet 401 contains a particulate sample, and a second fluid inlet 402 is provided at the inlet of a second inlet channel 404 located at the lower left side of fig. 1, the second fluid inlet 402 contains a particulate-free buffer solution for regulating the flow rate in the microfluidic channel. The number of the fluid outlet channels is two, namely a first outlet channel 703 located at the upper right side of fig. 1 and a second outlet channel 704 located at the lower right side of fig. 1, a first fluid outlet 701 is arranged at the outlet of the first outlet channel 703, and a second fluid outlet 702 is arranged at the outlet of the second outlet channel.
The microfluidic chip of the embodiment is made of PDMS (polydimethylsiloxane), is a hydrophobic organic silicon material, has the characteristics of physiological inertia, good chemical stability, low cost, high transparency, simplicity in use and the like, is bonded with a glass slide, and has a microfluidic channel layer with a height of 50 um.
The PDMS microfluidic chip is internally provided with a designed acoustic resonant cavity, and the acoustic resonant cavity can realize resonance at different positions under the driving of different frequencies, so that the particles can be controlled to dynamically move under the driving of the frequencies.
The preparation process of the microfluidic channel layer of the embodiment specifically comprises the following steps:
first, a photoresist (SU-83050, Microchem) was spin-coated onto a 3 inch single-sided polished silicon wafer;
after pre-baking, the photoresist layer was patterned by uv light using a mask aligner (MJB4, sussomicrotec) and a printing photomask;
after baking, the uncured resist was dissolved using SU-8 developer (PGMEA, microchem corp) and then a main mold having a microchannel structure was obtained;
placing the main mold on a high-temperature plane at 200 deg.C for 5min to strengthen the main mold;
then, the micro-channels are replicated on the master mold using a micro-molding process. Pouring mixed polydimethylsiloxane (PDMS and curing agent in a weight ratio of 10: 1) onto the obtained SU-8 master mold, and degassing; after curing in an oven at 65 ℃ for 3 hours, the PDMS was peeled off from the master mold; and then perforated at the locations of the first fluid inlet 401, the second fluid inlet 402, the first fluid outlet 701 and the second fluid outlet 702.
Finally, the PDMS chip was bonded to the slide using an oxygen Plasma machine (PDC-002, Harrick Plasma); the microfluidic chip device was stored in an oven at 65 ℃ for more than half an hour to improve the adhesive strength.
The design and the working process of the microfluidic intermediate layer channel are as follows:
as shown in fig. 2, the upper part is a microfluid main channel, the width of the main channel is 500um, the lower part is resonant cavities arranged at equal intervals, and the interval of the resonant cavities is 1 mm; the width of the neck of the resonant cavity is 40um, and the length of the neck of the resonant cavity is 100 um; the resonant cavity is square, the length and the width of the resonant cavity are both 500um, and the change of the shape of the resonant cavity has no influence on the result, so that the shape of the resonant cavity can be circular, oval, square or other closed shapes; the width of the endmost channel connecting the resonant cavities is 50 um.
The buffer solution is slowly injected into the inlet of the microfluidic channel, the buffer solution is filled in the main channel 5, and as the width of the neck of the Helmholtz resonant cavity is far smaller than that of the main channel, and the flow resistance at the neck of the Helmholtz resonant cavity is far larger than that of the main channel, the buffer solution mainly flows in the main channel and cannot flow into the Helmholtz resonant cavity region below; meanwhile, the lower Helmholtz resonant cavity is a closed area, in the buffer filling process, part of air in the main channel can be compressed to the lower Helmholtz resonant cavity, so that the pressure of gas in the lower Helmholtz resonant cavity is increased, and the buffer fluid is further limited to enter the lower Helmholtz resonant cavity due to the existence of pressure difference. Finally, the formed microfluid middle layer channel is divided into two parts, wherein the upper part is a microfluid main channel filled with buffer solution, and the lower part is a Helmholtz resonant cavity area filled with air; the two regions form a stable liquid/gas interface at the upper side of the neck of the Helmholtz resonator.
Example 2
The technical scheme adopted by the embodiment is a using method of a dynamic adjustable sound tweezer device based on a local resonant cavity, and the using method comprises the following steps:
horizontally placing the acoustic tweezers device on an optical microscope objective table, fixing the acoustic tweezers device by using a wafer holder, and adjusting a knob of the objective table to enable a microfluidic chip channel of the acoustic tweezers device to enter the field of view of the microscope; adjusting a coarse focusing screw and a fine focusing screw of the microscope to focus on a microfluidic chip channel of the acoustic tweezers device;
slowly injecting a buffer solution without particles into the micro-fluidic chip from the second fluid inlet by using a micro-injection pump until the micro-fluid fills the main channel of the micro-fluidic chip; then slowly injecting the sample containing the particles into the microfluidic chip from the first fluid inlet by using another micro-injection pump;
connecting a signal output end of a signal generator with a lead of the piezoelectric ceramic piece, setting an output signal in the signal generator as a sinusoidal signal, and setting corresponding voltage and frequency parameters; the piezoelectric ceramic generates high-frequency vibration under the stimulation of an electric signal to cause the liquid level at the interface of a microfluid channel and a gas channel in a channel in the microfluidic chip to vibrate, and the amplitude of the vibrating liquid level can be observed under a microscope by connecting a high-speed camera;
the state of micro-flow motion can be pre-determined by calculating the relative magnitudes of the acoustic radiation force, which primarily attracts the particles toward the vibrating liquid surface, and the acoustic flow, which causes the acoustic vortex to guide the particles to make rotational motion. The motion state of the particles is under the combined action of the acoustic radiation force and the acoustic flow, and when the acoustic radiation force is dominant, the particles are captured to the liquid level; when the sound flow is dominant, the particles will rotate with the sound flow.
By driving the microfluidic resonance with different frequencies, the movement of the particles at different locations can be manipulated using, for example, first, second, and third resonant frequencies.
The acoustic resonance modes of the microfluidic intermediate layer are then calculated in finite element software, due to the acoustic impedance Z of the liquidl(Z is ρ c, density ρ is 1000kg/m3Speed c 1500m/s) much greater than the acoustic impedance Z of airg(Density rho. 1.25 kg/m)3The velocity c is 340m/s), so the influence of the upper microfluid can be neglected in calculating the resonance frequency of the helmholtz resonator.
The calculated geometry is shown as the air chamber portion in fig. 2, and the finite element method results are shown in fig. 3.
The finite element method calculates the resonant frequency of the air cavity by the following steps:
1. firstly, establishing a calculated geometric model in finite element software, considering the action of acoustic impedance, and only establishing a geometric structure of a gas channel;
2. the material property was set to air and the density was defined to be 1.25kg/m3The sound velocity is defined as 340 m/s;
3. setting boundary conditions, wherein the solid boundary and the liquid boundary which can be contacted with the air domain are set as hard sound field boundaries because the acoustic impedance of the solid and the liquid is more than 3 orders of magnitude larger than that of the air domain;
4. setting the size of a finite element grid, wherein the maximum size of the finite element grid is less than one fifth of the wavelength of the calculated sound wave, and the maximum size of the finite element grid in the calculation model is set to be 10um so as to ensure the calculation precision of the finite element;
5. and (3) establishing a rigidity matrix and a mass matrix of the finite element model, solving a characteristic value of the finite element model, wherein the characteristic value is the resonance frequency of the air domain, and calculating the first three-order resonance frequency of the finite element model as an example in the example.
The first three resonant frequencies are respectively 17kHz, 30kHz and 36 kHz; meanwhile, the resonant frequency of the traditional side wall air bubble with the same width is also calculated, and the calculation formula of the resonant frequency of the traditional side wall air bubble is as follows:
The calculation results are shown in the square points in fig. 3, and it can be found that the resonance frequencies of the conventional sidewall air bubbles are all above 1 MHz.
Comparing the resonant frequency of the conventional sidewall air bubble with that of the Helmholtz resonant cavity, it is found that the resonant frequency of the Helmholtz resonant cavity is increased to be much lower than that of the sidewall air bubble; it is demonstrated that the acoustic tweezer apparatus with helmholtz resonator of the present invention is advantageous for reducing the resonance frequency.
In the experimental process, a signal generator is used for generating excitation, a sine signal is selected, the frequency is 17kHz, and the voltage is 10V; the signal generator is directly connected with the piezoelectric ceramic plate; because the invention uses the acoustic wave, the microfluid can be driven to move without a power amplifier, thereby reducing the experiment control difficulty and requirement and greatly reducing the cost of the acoustic tweezers device.
The oscillation of the microfluid at the interface can be observed under an optical microscope, and the oscillating microfluid generates acoustic radiation force and acoustic flow, and the acoustic flow is schematically shown in fig. 5; by slowly injecting the buffer solution containing the particles from the channel inlet 401, the particles can be observed to be concentrated at two side positions, the particles can be observed to rotate at the two side positions, and the particle movement control effect is shown in fig. 6.
In particular, using a second order resonant frequency of 30KHz, the sound field resonates at all locations, and therefore particle motion can be observed at global locations; in particular, using the third order resonant frequency of 36KHz, the sound field resonates at all intermediate positions, and therefore, the particle motion at the intermediate positions can be observed.
According to the application method of the dynamic adjustable sound tweezer device based on the local resonant cavity, the sound tweezer device is used for carrying out rotary motion control on the particles, generally speaking, two-dimensional images of the particles can only be statically observed under an optical microscope, but the method adopts a means capable of rotating an observed object, realizes three-dimensional observation of the particles by combining image processing, and provides a new technical means for 3D imaging of cells and the like. In addition, the invention can also be applied to the field of ultrasonic cavitation, and realizes gene transfection of cells through sound wave control.
The present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent changes and substitutions without departing from the principle of the present invention after learning the content of the present invention, and these equivalent changes and substitutions should be considered as belonging to the protection scope of the present invention.
Claims (9)
1. The utility model provides a developments adjustable sound tweezers device based on local resonant cavity which characterized in that: the micro-fluidic chip comprises a micro-fluidic cavity, the micro-fluidic cavity is fixed on one surface of the substrate, and the piezoelectric ceramic piece is fixed on the other surface of the substrate; the inner part of the micro-flow cavity is divided into an upper layer and a lower layer, the upper layer is a main channel containing particles, the lower layer is a closed air cavity channel, and the lower layer is connected with the substrate; the piezoelectric ceramic piece is connected with the micro-flow cavity through the substrate.
2. The local resonator based dynamically adjustable acoustic tweezer apparatus of claim 1, wherein: the micro-flow cavity is fixed on the substrate by bonding or adhesion.
3. The local resonator based dynamically adjustable acoustic tweezer apparatus of claim 1, wherein: the main channel is a microfluid main channel for circulating fluid, and the air cavity channel is a Helmholtz cavity air channel for circulating air.
4. The local resonator based dynamically adjustable acoustic tweezer apparatus of claim 3, wherein: the Helmholtz cavity gas channel comprises a plurality of resonant cavities which are respectively connected with the microfluid main channel.
5. The local resonator based dynamically adjustable acoustic tweezer apparatus of claim 1, wherein: at least two fluid inlet channels are arranged on one side of the main channel in a communicated mode, and at least two fluid outlet channels are arranged on the other side of the main channel in a communicated mode.
6. The local resonator based dynamically adjustable acoustic tweezer apparatus of claim 5, wherein: the fluid inlet channel is provided with two, including a first inlet channel and a second inlet channel, wherein a first fluid inlet is arranged at the inlet of the first inlet channel, a second fluid inlet is arranged at the inlet of the second inlet channel, the first fluid inlet contains a particle sample, and the second fluid inlet contains a buffer solution without particles.
7. Use method of the local resonator based dynamically adjustable acoustic tweezer apparatus according to any of claims 1 to 6, comprising the following steps:
horizontally placing the acoustic tweezers device on an optical microscope objective table and fixing the acoustic tweezers device, and adjusting a knob of the objective table to enable a microfluidic chip channel of the acoustic tweezers device to enter the field of view of the microscope; adjusting a coarse focusing screw and a fine focusing screw of the microscope to focus on a microfluidic chip channel of the acoustic tweezers device;
injecting a buffer solution without particles into the microfluidic chip from the second fluid inlet by using a syringe pump until the microfluidic main channel is filled with the buffer solution; then injecting a buffer solution containing the particle sample into the microfluidic chip from the first fluid inlet;
connecting the signal output end of a signal generator with a lead of a piezoelectric ceramic piece, wherein the piezoelectric ceramic piece vibrates under the stimulation of an electric signal to cause the liquid level at the interface of a microfluid channel and an air cavity channel in a main channel of the microfluidic chip to vibrate, and connecting a high-speed camera to observe the amplitude of the vibrating liquid level under a microscope;
the state of the particle motion is pre-judged by calculating the relative sizes of the acoustic radiation force and the acoustic flow; the motion state of the particles is under the combined action of the acoustic radiation force and the acoustic flow, and when the acoustic radiation force is dominant, the particles are captured to the liquid level; when the sound flow plays a leading role, the particles can rotate along with the sound flow;
by driving the microfluidic resonance with different frequencies, the particles are manipulated to move at different locations.
8. The use method of the local resonator-based dynamically adjustable acoustic tweezer apparatus of claim 7, wherein: the particles are subjected to an acoustic radiation force F in the microfluidRThe calculation formula is as follows:
in the formula, ρfAs a microfluidic density, RaRadius of the vibrating liquid surface, RpThe radius of the particles, d the distance between the particles and the liquid level, omega the angular frequency of the sound wave, and epsilon the amplitude of the vibration liquid level;
phi (rho) is a relative density coefficient, and the calculation formula is as follows:
φ(ρ)＝3(ρp-ρf)/(2ρp+ρf)
in the formula, ρpAnd ρfDensity of microparticles and microfluidics, respectively;
the oscillating liquid level forms an acoustic flow in the microfluid, and the speed of the acoustic flow is expressed by the following expression:
9. the use method of the local resonator-based dynamically adjustable acoustic tweezer apparatus of claim 8, wherein: viscous forces F induced by acoustic flow of particles in a microfluidic deviceAsThe calculation formula is as follows:
FAs＝6πμRpu
wherein μ is the dynamic viscosity coefficient of the fluid;
the calculation formula of the ratio of the acoustic radiation force to the viscous force caused by the acoustic flow is as follows:
FR/FAs≈ρfμ-1φ(ρ)Rp 2ω
in the formula, ρfMu and phi (p) are all microfluidic or microparticle physical parameters, constant values for a defined microparticle sample.
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| WO2014204410A1 (en) * | 2013-06-21 | 2014-12-24 | Agency For Science, Technology And Research | Energy harvesting device and method of harvesting energy |
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| CN115105928A (en) * | 2022-07-05 | 2022-09-27 | 南京大学 | Promoting CO 2 Decarburization device and method for absorbing mass transfer rate |
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