KR20110119259A - Method and apparatus for the separation of two kinds of microparticles in fluid flow by using the ultrasonic wave - Google Patents

Abstract

PURPOSE: An apparatus for separating different kinds of micro particles using ultrasound wave is provided to discharge different kinds of micro particles through different discharging paths by separating the micro particles according to the size, the density, and the compressed ratio, of the micro particles. CONSTITUTION: An apparatus for separating different kinds of micro particles using ultrasound wave includes a micro-channel(10), an ultrasound wave generator(16), a reflector(18), and a controller(20). Two inlets(12a, 12b) are formed at one side of the micro-channel, and different kinds of micro particles and fluid are introduced through the inlets. Two outlets(14a, 14b) are formed at the opposite side of the micro-channel. A single transferring path(32) and a branched transferring path(34) are formed in the micro-channel. The ultrasound wave generator applies ultrasound wave to the fluid and the different kinds of micro particles. The reflector reflects the ultrasound wave. The controller controls the frequency sweep of ultrasound standing wave applied to the micro-channel.

Description

Method and apparatus for the separation of two kinds of microparticles in fluid flow by using the ultrasonic wave}

The present invention relates to an apparatus and method for separating heterogeneous microparticles using ultrasonic waves, and more particularly, using ultrasonic waves to easily separate heterogeneous microparticles in a fluid through different paths in microchannels using ultrasonic waves. It relates to a heterogeneous microparticle separation device and method.

The application of ultrasound to particles in a medium can force the particles due to acoustic radiation force. This technique enables the control of microparticles having a size of several micrometers or less suspended along the flow in the fluid, so there are many attempts to apply them to the analysis of organic particles such as cells and DNA. In particular, a variety of industries that require precise control of microparticles, such as environmental, medical, analysis, etc. are attracting much attention.

Microparticle control processes include separation, purification, harvesting, trapping, and filtration, depending on their purpose, and various mechanisms such as electromagnetic, mechanical, and optical methods are used for this purpose. Apply. Although various techniques are known as a conventional method for controlling fine particles, compared to these techniques, the method using ultrasonic waves has the advantage of controlling a large amount of particles at high speed, and above all, the acoustic radiation power of ultrasonic waves has the size of the particles. Since it is related to mechanical properties, it can be applied regardless of the electrical and magnetic properties of the particles.

Accordingly, the microparticle control technology using ultrasonic waves has a wide range of applications in various industrial fields, including biotechnology and nanotechnology.

A standing wave is a phenomenon in which two waves of the same wavelength are overlapping each other while facing each other, and appear as if the wave stays in place. At this time, there is a point where the sound pressure of the wave is always zero and a point where the sound pressure represents the maximum / minimum with time. The former is called a sound pressure antinode.

When the particle is located in the space where the standing wave is formed, the acoustic radiation force acts toward the negative or semi-negative node of the standing wave according to the relative mechanical properties of the particle. Due to the acoustic radiation force acting on these particles, the particles move to the sound pressure node or the semi-negative pressure node of the standing wave.

Standing waves are usually created by superimposing identical waves traveling in opposite directions. Normally, when an advancing wave meets and reflects on a reflector, the incident wave and the reflected wave overlap each other, so that standing ultrasonic waves are formed near the reflector. Therefore, when the ultrasonic wave is vertically incident toward the reflector, the standing ultrasonic wave can be easily generated.

The present invention has been studied in view of the above points, by using the micro-channel due to the mechanical properties of the microparticles such as the size, density, compression rate of the microparticles, using the difference in the force applied to the microparticles, microchannels An object of the present invention is to provide an apparatus and method for separating heterogeneous microparticles using ultrasonic waves, which enables the heterogeneous microparticles in a fluid flowing therein to be easily separated through different branching paths.

One embodiment of the present invention for achieving the above object is: two inlets are formed in each of the fluid and heterogeneous microparticles are injected into one side, two outlets are formed on the opposite side are separated from each other heterogeneous microparticles As a structure, therein is a microchannel of a predetermined length having a single feed path forming a straight line from the inlet to a predetermined position, and branch feed paths branched toward two outlets in the single feed path; Ultrasonic generating means mounted to one side wall of the microchannel to apply ultrasonic waves to the fluid and heterogeneous microparticles in the microchannel; A reflector formed on the other side wall surface of the microchannel to reflect ultrasonic waves; A controller for sweep control of the frequency of standing ultrasonic waves electrically connected to the ultrasonic wave generating means so that only the fine particles having high mechanical properties among the heterogeneous fine particles are transferred to the reflector; It provides a heterogeneous microparticle separation device using ultrasonic waves, characterized in that configured to include.

Another embodiment of the present invention for achieving the above object is the ultrasonic wave generating means is attached to one side, the other side is the step of introducing the heterogeneous microparticles in the microchannel formed with a reflector at the same time the fluid at a predetermined speed; Applying ultrasonic waves in the microchannel while the ultrasonic waves generated by the ultrasonic wave generating means are reflected on the reflector; Performing frequency sweep control on the standing ultrasonic waves; A step in which the force generated by the ultrasonic waves acts on the heterogeneous microparticles, and the acoustic radiation power of the ultrasonic waves acting on the heterogeneous microparticles varies according to the size, density, and compression ratio of the microparticles; Only fine particles with large acoustic radiation force acted by ultrasonic waves are sequentially transferred to the maximum adjacent position of the reflector while moving each sound pressure node of the standing ultrasonic wave according to the frequency sweep control. Separating the particles from each other; Microparticles with large acoustic radiation force acting by ultrasonic wave are discharged and separated together with fluid through one of the branch transfer paths of the microchannel, while microparticles with small acoustic radiation force acting by ultrasonic wave are the other one of the branch transfer path. Separating the discharge through; It provides a method for separating heterogeneous microparticles using ultrasonic waves, characterized in that consisting of.

Through the above problem solving means, the present invention provides the following effects.

According to the present invention, by allowing heterogeneous microparticles to flow in a microchannel with a fluid, and simultaneously applying standing ultrasonic waves into the microchannel through frequency sweep control, the mechanical properties such as size, density, and compression ratio of heterogeneous microparticles are applied. Therefore, only microparticles with a large acoustic radiation force acting by ultrasonic waves move in a specific direction while moving each sound pressure node of standing ultrasonic waves, and are separated from microparticles with small acoustic radiation force acting by ultrasonic waves among predetermined microparticles. By discharging each heterogeneous microparticles into different branch feed paths, the heterogeneous microparticles can be easily separated.

By applying the apparatus and method of the present invention, it is possible to separate and purify heterogeneous microparticles at high speed, so as to measure environmental pollution such as cell or DNA control for bio and medical analysis, nano engineering field, air pollutants and fine dust It can be applied to various fields.

1 is a schematic view showing a heterogeneous microparticle separation device using ultrasonic waves according to the present invention.
Figure 2 is a perspective view showing an example of the structure of the micro-channel of the configuration of the heterogeneous microparticle separation apparatus using ultrasonic waves according to the present invention.
Figure 3 is a graph showing an example of the frequency sweep control of the ultrasonic wave for the separation of heterogeneous microparticles according to the present invention.
FIG. 4 is a view for explaining that only fine particles having a large acoustic radiation force by ultrasonic waves of heterogeneous fine particles are transported along a sound pressure node of standing ultrasonic waves by the frequency sweep control of FIG. 3.
5 is a test result of the microparticle separation device according to the present invention, the result of observing the position of the heterogeneous microparticles in the microchannel according to the frequency sweep period of the ultrasonic wave,
6 is a schematic diagram illustrating a principle in which a standing ultrasonic field is formed by a reflector;
7 is a conceptual diagram illustrating the movement of fine particles to each sound pressure node or semi-negative pressure node of the standing ultrasonic wave.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view showing a heterogeneous microparticle separation apparatus using ultrasonic waves according to the present invention, and FIG. 2 is a perspective view showing an example of the structure of the microchannels in the configuration of the heterogeneous microparticle separation apparatus using ultrasonic waves according to the present invention. 3 and 4 are graphs illustrating the frequency sweep control of the heterogeneous microparticle separator and the separation principle of the heterogeneous microparticles according to the present invention.

The present invention controls the position of heterogeneous microparticles flowing with a fluid in a microchannel using ultrasonic waves, and thus acts on the microparticles by ultrasonic waves due to differences in mechanical properties such as size, density, and compression ratio of the heterogeneous microparticles. The main point is that the microparticles with small acoustic radiation force stay in place, and at the same time, the ultrasonic particles with large acoustic radiation force acting on the microparticles are transferred to one side to separate heterogeneous microparticles from each other. have.

That is, the present invention uses a sweep control method that gradually increases the frequency of the ultrasonic wave and decreases it suddenly, so that the acoustic radiation force acting on the microparticles by the ultrasonic wave is large among heterogeneous microparticles flowing in the fluid in the microchannel. Only microparticles are transported in one direction and are collected, so that different types of microparticles can be separated separately through different branching paths.

The heterogeneous microparticle separation apparatus of the present invention has an ultrasonic wave in the microchannel 10 having two inlets 12a and 12b and two outlets 14a and 14b, and fluids and heterogeneous microparticles in the microchannel 10. Ultrasonic wave generation means 16 for applying a, a reflector 18 for reflecting the ultrasonic waves applied into the fine channel 10, and a control unit 20 for the frequency sweep control for the ultrasonic waves.

The microchannel 10 has two inlets 12a and 12b into which fluid and heterogeneous microparticles are introduced, respectively, and two outlets 14a and 14b through which the heterogeneous microparticles separated from each other exit. ) Is formed, the inside is formed of a hollow transfer passage 30 from the inlet (12a, 12b) to the outlet (14a, 14b).

More specifically, the hollow feed passage 30 of the microchannel 10 has a single feed path 32 that forms a straight line from the inlets 12a and 12b to a predetermined position, and the two of the single feed path 32. It is divided into branch feed paths 34 branched toward the outlets 14a and 14b.

At this time, the inlet 12a of the microchannel 10 is connected to the first tank 25 filled with heterogeneous microparticles having different mechanical properties such as size, density, and compression ratio, and the other inlet 12b. A second tank 26 for storing pure fluid (eg, water) containing no particles is connected via a pump 28, and the outlets 14a and 14b of the microchannel 10 are separated from each other. The third tank 36 and the fourth tank 38 for storing respective heterogeneous fine particles are connected through a line.

The ultrasonic wave generating means 16 is integrally mounted on one side of the microchannel 10 to apply standing ultrasonic waves to the microparticles in the fluid flowing in the microchannel 10, and a piezoelectric ultrasonic transducer or the like can be used. have.

Preferably, the ultrasonic wave generating means 16 is mounted on one side wall surface of the microchannel 10, the single transfer path 32 of the hollow transfer path 30 at the inlet (12a, 12b) of the microchannel 10 Is mounted in the section is formed, the ultrasonic wave is applied to the fluid and heterogeneous microparticles flowing through the single feed path (32).

In this case, the ultrasonic generator 16 is a kind of control unit 20 capable of varying the frequency of ultrasonic waves, and is connected to a power amplifier 22 and a signal generator 24.

On the other hand, as the microchannel 10 itself is made of a material (for example, carbon steel) that the acoustic impedance is larger than the fluid and the ultrasonic waves are well reflected, the other side wall surface of the microchannel 10 itself is the reflector 18. On the other hand, one side wall surface of the microchannel 10 on which the ultrasonic wave generating means 16 is mounted has an acoustic impedance similar to that of a fluid so that ultrasonic waves can be easily transmitted (eg, acrylic material). It consists of layer 17.

Here, the heterogeneous microparticle separation method using the ultrasonic wave of the present invention based on the above configuration will be described.

When the ultrasonic wave generated by the ultrasonic wave generating means of the present invention is applied in the microchannel, the acoustic radiation force acting on the microparticles by the ultrasonic wave is due to the difference in mechanical properties such as size, density, and compression ratio among heterogeneous microparticles in the microchannel. Small microparticles stay in place, and microparticles with large acoustic radiation acting on the microparticles by ultrasonic waves by frequency sweep control of the standing ultrasonic wave are reflected along the sound pressure node line of the standing ultrasonic wave. After moving to the) side, the mechanical properties of the heterogeneous microparticles can be separated through different branch transfer paths, the main point is to enable the high-speed separation and purification of the heterogeneous microparticles.

To this end, first, heterogeneous microparticles (microparticles having different acoustic radioactive forces acting by ultrasonic waves due to differences in size, density, and compression ratio) stored in the first tank 25 are formed at the entrance of the microchannel 10 ( 12a) of the inlet 12b of the microchannel 10 by driving the pump 28 with a pure fluid (for example, water) in which the fine particles stored in the second tank 26 are not mixed. The heterogeneous microparticles are flowed along the single feed path 32 in the microchannel 10 by the flow of the fluid.

At the same time, the ultrasonic wave generating means 16 mounted on one side wall surface of the microchannel 10 generates ultrasonic waves.

Thus, when the ultrasonic wave generated by the ultrasonic wave generating means 16 is reflected on the reflector 18 of the microchannel 10, as shown in FIG. 6, a sound pressure node and a sound pressure antinode ) Is a state in which a standing wave-shaped ultrasonic field is repeated in a single feed path 32 of the microchannel 10, and at the same time, the standing ultrasonic wave is a single feed path of the microchannel 10. It acts on heterogeneous microparticles flowing along 32).

Therefore, as shown in FIG. 7 to which microparticles widely spread in the fluid in the single feed path 32 of the microchannel 10 are attached to each sound pressure node or semi-negative pressure node of the standing ultrasonic wave, the alignment is performed. This is because the acoustic radiation force as shown in Equation 1 below is applied to the fine particles under the condition that the standing ultrasonic waves are applied.

In Equation 1 above, P denotes a sound pressure, V denotes a volume of particles, λ denotes a wavelength of ultrasonic waves, β denotes a particle compression rate, ρ denotes a particle density, and z denotes a particle position.

In this way, heterogeneous microparticles in the fluid flowing in the single feed path 32 of the microchannel 10 move to each sound pressure node of the standing ultrasonic waves first applied, but due to differences in size, density, and compression ratio of the heterogeneous microparticles Microparticles with small acoustic radiation force acting on the microparticles by ultrasonic waves remain in place, while microparticles with large acoustic radiation force acting on the microparticles by ultrasonic waves move along each sound pressure node of the standing ultrasonic wave. do.

To this end, a frequency sweep control is performed to gradually raise the frequency of the standing ultrasonic wave to the upper limit, and then abruptly lower the frequency of the first applied lower limit value, which is performed by the power amplifier 22 and the signal generator 24. It is made by the control operation of the control unit 20 consisting of.

Therefore, if the frequency of the standing ultrasonic wave continues to increase, the number of sound pressure nodes of the standing ultrasonic wave increases and the position moves toward the reflector 18. At this time, the acoustic radiation force acting on the microparticles by the ultrasonic wave according to the sweep period of the standing ultrasonic frequency. These large fine particles move well toward the reflector 18 along the negative pressure node, but small particles having small acoustic radiation force acting on the fine particles by ultrasonic waves cannot move along the negative pressure node.

At this time, when the sound pressure node of the standing ultrasonic wave applied in the single feed path 32 of the microchannel 10 increases by the frequency sweep control, the sound pressure node closer to the reflector 18 has a change in position according to frequency. The larger the distance from the reflector 18, the greater the change in the position of the sound pressure node, which is always at this boundary because of the large difference in acoustic impedance at the boundary between the single channel path 32 and the reflector 18 of the microchannel 10. This is because the semi-negative pressure nodes of the standing ultrasonic waves are generated.

Therefore, the microparticles with a large acoustic radiation force acting by the ultrasonic waves can move toward the reflector 18 as the frequency increases so that the microparticles can move well along the sound pressure node.

Thus, as the frequency sweep control gradually raises the frequency of the ultrasonic wave to an upper limit and then suddenly lowers it to the frequency level of the initially applied lower limit, the acoustic radiation force acting on the microparticles by the ultrasonic wave among heterogeneous microparticles. Only these large microparticles continue to align with the next sound pressure node towards the reflector 18, whereas the small acoustic radiation force acting on the microparticles by the ultrasonic wave follows the position change of the sound pressure node. It can't go and stay in place and flow with the fluid.

Therefore, among the heterogeneous microparticles in the fluid, the microparticles having small acoustic radiation force acting on the microparticles by the ultrasonic wave exit through the one of the branch transfer paths 34 of the microchannel 10 to the outlet 14a. At the same time, the microparticles having a large acoustic radiation force acting on the microparticles by the ultrasonic waves exit the outlet 14b through the other one of the branch transfer paths 34, and are concentrated in the third tank and the fourth tank 38, respectively. Are stored as is.

On the other hand, the length of the microchannel 10 can be selectively adjusted according to the flow rate of the fluid.

Here, an apparatus and method for separating microparticles in a fluid using ultrasonic waves according to the present invention will be described in more detail as an embodiment.

Example

As an embodiment of the present invention, a small module composed of a microchannel 10 having a width of 1.5 mm was manufactured, and the module was made of acrylic and carbon steel.

That is, it has two inlets 12a and 12b and two outlets 14a and 14b, and there is formed a single feed path 32 starting at the inlet 12 and at the end of the single feed path 32 at the same time. The microchannel 10 having the branch transfer path 34 was made of carbon steel, and one side wall surface of the microchannel 10 to which the ultrasonic wave generating means 16 was attached was made of acrylic material, and of course, the microchannel 10. The other side wall of was made of the reflector 18 made of carbon steel.

In addition, the single feed path 32 and the branch feed path 34 were exposed to observe the inside of the microchannel 10, and the exposed surface was sealed with a transparent glass material.

In addition, a piezoelectric ultrasonic transducer is mounted on one side wall of the microchannel 10 as the ultrasonic generator 16, and the power amplifier 22 and the signal generator 24 are piezoelectric ultrasonic transducers for controlling the frequency of ultrasonic waves. Connected to, and installed a CCD camera and a monitor that can photograph the inside of the micro-channel 10 adjacent.

At this time, the heterogeneous microparticles introduced through the inlet 12a of the microchannel 10 used polystyrene particles having different diameters of 25 micrometers and 6 micrometers, respectively, and the fluid introduced through the inlet 12b. Used water.

Test Example

The piezoelectric ultrasonic transducer, which is an ultrasonic wave generating means 16, is injected with polystyrene particles having a diameter of 25 micrometers and 6 micrometers, respectively, as heterogeneous microparticles to the inlet 12a of the microchannel 10 module manufactured according to the above embodiment. In the producer, the first 1.75 MHz ultrasonic wave was applied in a single feed path 32 in the microchannel 10, and then the heterogeneous microparticles were changed while gradually increasing the frequency of the ultrasonic wave generating means 16 from 1.75 MHz to 3.05 MHz. The focusing position of was observed and the position of each sound pressure node was measured using a CCD camera. The measurement results are as shown in FIG.

As shown in the image of FIG. 5A, when the fluid and the heterogeneous microparticles are introduced into the microchannel 10, the heterogeneous microparticles are mixed with each other and collected on one side (the opposite side of the reflector) of the microchannel 10. 5b and 5c, the standing ultrasonic waves are applied through the frequency sweep control so that only 25 micrometer diameter polystyrene particles having a large acoustic radiation force acting by the ultrasonic wave among the heterogeneous microparticles move toward the reflector 18, while the ultrasonic wave It can be seen that the polystyrene particles having a small acoustic radiation force acting on the microparticles with a diameter of 6 micrometers do not move in the transverse direction of the channel but flow with the fluid in the channel direction.

In addition, as shown in the image of FIG. 5D, the microparticles having a small acoustic radiation force acting on the microparticles by ultrasonic waves exit through the outlet 14a through one of the branch transfer paths 34 of the microchannel 10. At the same time, it can be seen that the microparticles having a large acoustic radiation force acting on the microparticles by ultrasonic waves exit through the other of the branch transfer paths 34 to the outlet 14b.

As described above, according to the present invention, frequency sweep control is repeatedly applied to a standing ultrasonic wave having a sound pressure node to the heterogeneous microparticles, so that the fine particles having a large acoustic radiation force acting on the microparticles by ultrasonic waves of the heterogeneous microparticles By moving in a specific direction along the sound pressure node, it is possible to easily separate the large particles and the small particles having a large acoustic radiation force acting on the microparticles by ultrasonic waves, respectively through a predetermined branching path.

10: fine channel 12a, 12b: inlet
14a, 14b: Exit 16: Ultrasonic generating means
17: ultrasonic matching layer 18: reflector
20: control unit 22: power amplifier
24: signal generator 25: the first tank
26: the second tank 28: the pump
30: hollow feed path 32: single feed path
34: branch feed route 36: third tank
38: fourth tank

Claims (10)

Two inlets 12a and 12b into which fluid and heterogeneous microparticles are respectively injected are formed on one side, and two outlets 14a and 14b through which heterogeneous microparticles are separated from each other are formed. There is a single feed path 32 which forms a straight line from the inlet 12a, 12b to a predetermined position, and the branch feed path 34 branched from the single feed path 32 toward the two outlets 14a, 14b. A microchannel 10 of length;
Ultrasonic generating means (16) mounted on one side wall of the microchannel (10) to apply ultrasonic waves to the fluid and heterogeneous microparticles in the microchannel;
A reflector 18 formed on the other side wall surface of the microchannel 10 to reflect ultrasonic waves;
The controller 20 is electrically connected to the ultrasonic generator 16 so as to transfer only the fine particles having high mechanical properties among the heterogeneous microparticles toward the reflector 18 to control frequency sweep of standing ultrasonic waves applied in the microchannel 10. );
Heterogeneous microparticle separation device using ultrasonic waves, characterized in that configured to include.
The method according to claim 1,
The ultrasonic generation means 16 is a heterogeneous microparticle separation device using ultrasonic waves, characterized in that the piezoelectric ultrasonic transducer.
The method according to claim 1,
The control unit 20 is a heterogeneous microparticle separation device using ultrasonic waves, characterized in that consisting of a power amplifier 22 and a signal generator 24 sequentially connected to the ultrasonic wave generating means (16).
The method according to claim 1,
The microchannel 10 is made of a material that has a large acoustic impedance and is not easily transmitted from the fluid by ultrasonic waves, so that the other side wall surface of the microchannel 10 is formed of a reflector 18, heterogeneous microparticles using ultrasonic waves. Separation device.
The method according to claim 1,
One side wall surface of the microchannel (10) on which the ultrasonic wave generating means (16) is mounted is a heterogeneous microparticle separation device using ultrasonic waves, characterized in that the acoustic impedance is made of a material that is well transmitted through the ultrasonic wave as a fluid.
A step of introducing heterogeneous microparticles into the microchannel 10 having the ultrasonic generator 16 attached to one side and the reflector 18 formed on the other side, and simultaneously introducing the fluid at a predetermined speed;
Applying ultrasonic waves in the microchannels 10 while the ultrasonic waves generated by the ultrasonic wave generator 16 are reflected by the reflector 18;
Performing frequency sweep control on the standing ultrasonic waves;
A step in which the force generated by the ultrasonic waves acts on the heterogeneous microparticles, but the acoustic radiation force acting on the microparticles by ultrasonic waves is different due to the difference in size, density, and compression ratio of the heterogeneous microparticles;
Only microparticles having a large acoustic radiation force acting on the microparticles by ultrasonic waves are sequentially transferred to the maximum adjacent position of the reflector 18 while moving the sound pressure nodes of the standing ultrasonic waves according to the frequency sweep control, and the microparticles by the ultrasonic waves. Separating the microparticles from each other because the acoustic radiation force acting on the small particles does not move to the reflector;
Microparticles having a large acoustic radiation force acting on the microparticles by the ultrasonic wave are discharged and separated together with the fluid through one of the branch transfer paths of the microchannel, and microparticles having a small acoustic radiation force acting on the microparticles by the ultrasonic wave Discharge separation through the other of the branch feed path;
Heterogeneous microparticle separation method using ultrasonic waves, characterized in that consisting of.
The method of claim 6,
Frequency sweep control for the standing ultrasonic wave;
Gradually raising the frequency of the standing ultrasonic waves at a predetermined sweep period from a frequency of a predetermined lower limit to a frequency of an upper limit;
After the frequency of the standing ultrasonic waves reaches the upper limit, abruptly lowering to the lower limit frequency;
Heterogeneous microparticle separation method using ultrasonic waves, characterized in that to proceed repeatedly.
The method according to claim 6 or 7,
In the process of raising the frequency during the frequency sweep control, the number of sound pressure nodes of the standing ultrasonic wave increases and the position of the sound pressure nodes is moved toward the reflector, so that only the fine particles having a large acoustic radiation force acting on the microparticles by ultrasonic waves are transferred to the reflector. Heterogeneous microparticle separation method using an ultrasonic wave.
The method according to claim 6 or 7,
In the process of lowering the frequency during the frequency sweep control, the number of sound pressure nodes of the standing ultrasonic waves decreases and the position of the sound pressure nodes suddenly changes, so that only the fine particles having a large acoustic radiation force acting on the microparticles by ultrasonic waves are closer to the reflector side. Heterogeneous microparticle separation method using ultrasonic waves, characterized in that moving to the node.
The method of claim 6,
Method for separating heterogeneous microparticles using ultrasonic waves, characterized in that the semi-negative pressure node of the standing ultrasonic wave is always generated at the boundary between the heterogeneous microparticle flow passage in the microchannel (10) and the reflector (18).

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