JP2003066004A - Particle separation method, particle separation device, and sensor - Google Patents

Abstract

(57) [Problem] To provide a simple and fast method and apparatus for separating fine particles with high accuracy, and to realize a sensor for performing quantitative and qualitative analysis. An AC voltage is applied between electrode pairs (4, 5) to apply dielectrophoretic force to fine particles contained in a solution (9) flowing in a solution chamber (8), so that the flow force and the dielectrophoretic force balance. Collect fine particles. Since the position of the balance differs depending on the type of the fine particles, separation becomes possible. Also,
By changing the frequency of AC voltage and electric field strength,
The position of the balance can be controlled.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for separating fine particles,
The present invention relates to a particle separation device and a sensor.

[0002]

2. Description of the Related Art Conventionally, as a method for separating fine particles contained in a solution, there is a method utilizing the balance between the centrifugal force and the electrophoretic force. This is because a solution containing fine particles is placed in a field where centrifugal force acts, an electric field acting in the direction opposite to the centrifugal force is applied to generate an electrophoretic force, and the particles are placed at a position where the centrifugal force and the electrophoretic force are balanced. Is a method of separating.

For example, in Japanese Patent No. 1603224, an ion exchange membrane is used to generate an ion concentration gradient in a solution to create an electric field whose magnitude depends on the position, and to generate particles in the solution at arbitrary positions. An invention is described in which a solution such as a polymer or a particle is separated by creating a field in which a combined vector of a working centrifugal force and an electrophoretic force is directed to a balanced position.

More specifically, the force f exerted on fine particles having a charge Q, a mass M, and a specific volume v is a centrifugal force f _c and a force (electrophoretic force) f due to an electric field of a magnitude E opposite to the centrifugal force f _c. It is shown by the resultant force of _e , and becomes like the following (Equation 1).

[0005]

[Equation 1]

Here, ρ is the number density of particles, ω is the angular velocity of rotation, and r is the radius of gyration of centrifugal force. An electric field with a distribution that increases as the radius r increases from a certain point from the center of rotation is realized by installing an ion exchange membrane that produces an ion concentration gradient, and centrifugation is performed by appropriately selecting the angular velocity ω. Position r where force f _c and electrophoretic force f _e balance each other
_It realizes a separation method that determines _p , that is, collects all the same particles at the same position.

[0007] Conventionally, as a method for analyzing a solution containing various kinds of molecules and fine particles, a gel chromatography method in which a gel is used to make use of a difference in adsorption, and a high frequency non-uniform electric field is generated. There is an electrostatic chromatography method in which analysis is performed by utilizing the difference in dielectrophoretic force acting on molecules and particles.

For example, in Japanese Patent No. 3097932, molecules and particles to be sampled are added to a carrier flowing at a constant velocity from an inlet, and a dielectrophoretic force is exerted on these to cause a difference in the time required to reach the outlet. An electrostatic chromatography device for the analysis of particles and particles is described.
This is an invention relating to a chromatography device that analyzes a molecule or particle by utilizing the fact that the dielectrophoretic force acting on the molecule or particle varies in size depending on the electric dipole moment peculiar to the molecule or particle.

[0009]

The above-mentioned conventional techniques are all aimed at establishing a method and apparatus for separating molecules, particles and the like. However, the above conventional technique has the following problems.

In Japanese Patent No. 1603224, particles are aggregated and separated at a position where centrifugal force and electrophoretic force are in equilibrium. Specifically, the resultant force acting on particles at any position is always in equilibrium position. The ion-exchange membrane is used to create a gradient electric field toward However, various problems occur by using electrophoresis.
For example, since ions in the electrophoresis tank are consumed during energization, a very complicated pretreatment such as separately providing an electrolyte storage solution is required. In addition, when a DC voltage is applied to the aqueous solution, water may be electrolyzed in the vicinity of the electrodes, and safety measures may be required.

Further, in Japanese Patent No. 3097932,
By applying dielectrophoretic force to the molecules and particles contained in the carrier flowing at a constant velocity, various molecules and particles are separated from the difference in the time required to move a certain distance. However, since the separation method is based on the difference in required time, it takes some time for separation.

[0012] In view of the above, an object of the present invention is to provide a method and apparatus for separating fine particles easily and at high speed with high accuracy, and to provide a sensor for performing quantitative qualitative analysis.

[0013]

In order to solve this problem, according to the present invention, while a solution containing fine particles is flowing, the fine particles are dielectrophoresed in the direction opposite to the force of the flow, and the force of the flow is changed. This is a fine particle separation method in which the fine particles are separated at a position balanced with the dielectrophoretic force.

Then, by controlling at least one of the frequency of the AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the flow rate of the solution, the flow acting on the fine particles is controlled. It is preferable to control the position where the force of the electric field and the force of dielectrophoresis balance each other.

Further, according to the present invention, a centrifugal force is applied to a solution containing fine particles, the fine particles are subjected to dielectrophoresis in a direction opposite to the centrifugal force, and the fine particles are separated at a position where the centrifugal force and the dielectrophoretic force are balanced. This is a method for separating fine particles.

Fine particles are controlled by controlling at least one of the frequency of the AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the angular velocity for generating the centrifugal force. It is desirable to control the position where the centrifugal force and the dielectrophoretic force that act on each other balance each other.

Further, according to the present invention, an electrode pair composed of a first electrode and a second electrode, a voltage source for generating a nonuniform AC electric field between these electrodes, and a pump for flowing a solution containing fine particles. A fine particle separation device comprising a flow path and separating the fine particles at a position where the flow force acting on the fine particles and the dielectrophoretic force are balanced.

Then, by controlling at least one of the frequency of the AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the flow rate of the solution, the flow acting on the fine particles is controlled. It is preferable to control the position where the force of the force and the dielectrophoretic force balance with each other.

Further, according to the present invention, an electrode pair composed of a first electrode and a second electrode, a voltage source for generating a non-uniform AC electric field between these electrodes, and a container for containing a solution containing fine particles are provided. The container is held by a rotating body for imparting a centrifugal force to the fine particles, and is a fine particle separation device for separating the fine particles at a position where the centrifugal force acting on the fine particles and the dielectrophoretic force are balanced. Is.

Then, by controlling at least one of the frequency of the AC electric field applied when the dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the angular velocity of the rotating body, the fine particles are worked. It is preferable to control the position where the centrifugal force and the dielectrophoretic force balance each other.

Further, according to the present invention, an electrode pair composed of a first electrode and a second electrode, a voltage source for generating a non-uniform AC electric field between these electrodes, and a pump for flowing a solution containing fine particles. A flow path and a concentration measuring device for measuring the concentration of the fine particles are provided, the fine particles are separated at a position where the flow force acting on the fine particles and the dielectrophoretic force are balanced, and the fine particle concentration in the separated state is described above. This is a sensor that measures with a concentration measuring device.

By controlling at least one of the frequency of the AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the flow rate of the solution, the concentration of the fine particles is measured. It is better to control it so that it is located at the site.

Further, according to the present invention, an electrode pair composed of a first electrode and a second electrode, a voltage source for generating a nonuniform AC electric field between these electrodes, a container for containing a solution containing fine particles, A concentration measuring device for measuring the concentration of the fine particles, wherein the container is held by a rotating body for imparting a centrifugal force to the fine particles, a position where the centrifugal force acting on the fine particles and the dielectrophoretic force are balanced. The above-mentioned fine particles are separated into, and the concentration of the separated fine particles is measured by the concentration measuring device.

Then, by controlling at least one of the frequency of the AC electric field applied when the dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the angular velocity of the rotating body, the concentration of the fine particles is increased. It is better to control so that it is located at the measurement site.

It is preferable that the concentration measuring device utilizes the surface plasmon resonance phenomenon.

Alternatively, the above-mentioned concentration measuring device is provided with a light source and a photodetector, and the light emitted from the light source is transmitted through a solution containing fine particles and is measured by the photodetector, whereby the light absorption by the fine particles is measured. May be obtained, and the concentration of fine particles may be obtained from this value.

According to the present invention, it is possible to obtain a method and an apparatus for separating fine particles with high precision at a simple and high speed, and a sensor for performing quantitative qualitative analysis.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings and mathematical formulas.

(Embodiment 1) In the present invention, in a flow in which a solution containing fine particles has a flow velocity distribution in the flow direction,
By applying a dielectrophoretic force to the particles in the direction opposite to the flow force and staying at a position where the flow force and the dielectrophoretic force are balanced, a method for separating various types of particles contained in a solution or It relates to the device and a sensor for analyzing the separation. In particular, biochemical analysis that selectively extracts or separates desired fine particles from a solution containing fine particles of various types of proteins, cells, macromolecules, etc.
It is preferably used for drug discovery, DNA analysis, high throughput screening and the like.

FIG. 1 is a schematic view showing an embodiment in which a single type of fine particles A are separated by using a flow force and a dielectrophoretic force. In FIG. 1A, a housing 1 is provided with a fan-shaped solution chamber 8 having a constant thickness, and a solution inlet 2 is provided at the end of the fan having a narrow width. A solution outlet 3 is provided at the end on the spread side.
Further, a first electrode 4 and a second electrode 5 are provided between the solution inflow port 2 and the solution outflow port 3, and these electrodes are respectively connected to an AC voltage source (not shown). The electric field strength between the first electrode 4 and the second electrode 5 becomes closer to the first electrode 4, and the electric field lines become denser. Therefore, the electric field strength becomes stronger toward the left in the figure. 1 (b)
FIG. 3 is a sectional view taken along the line MM ′ of FIG. The flow path 6 including the solution chamber 8 is filled with the solution 9 including the fine particles A, and the solution 9 is circulated in the flow path 6 at a constant flow rate by the pump 7.

Here, in FIG. 1, r is such that the position of the solution inlet 2 is r _in , the first electrode 4 is r ₁ , the second electrode 5 is r ₂ , and the solution outlet 3 is r _out. Set the coordinates. Under such conditions, the force F _f of the flow acting on the fine particles A contained in the solution 9 in the solution chamber 8 is
It is shown by the formula.

[0032]

[Equation 2]

Here, μ is the viscosity coefficient of the solution 9, a is the radius of the fine particles A, and V (r) is the flow velocity. The flow velocity V (r) is a function of the position r. In this case, since the circulation flow rate is constant and the thickness of the solution chamber 8 is constant, V (r) is a function inversely proportional to r. Become. A graph showing the relationship between the position r and the flow force F _f is shown in FIG.
The direction in which the force acts is the + r direction.

Next, the dielectrophoretic force F _d acting on the fine particles A will be described. F _d is expressed by the following equation (3).

[0035]

[Equation 3]

Here, ε _m is the dielectric constant of the solution 9, E is the effective value of the electric field strength generated by the two electrodes 4 and 5, ω is the angular frequency of the AC voltage source, Re [] is the real part, and ▽ is The differential operators for finding the gradient are shown below. Further, K ^* (ω) is a Clausius-Mossoty function and is defined by the following equation (4).

[0037]

[Equation 4]

Here, ε _p ^* is the complex permittivity of the fine particles A, ε
_m ^* is the complex permittivity of solution 9, ε _p is the permittivity of fine particles A, ε _m
Represents the dielectric constant of the solution 9, σ _p represents the conductivity of the fine particles A, σ _m represents the conductivity of the solution 9, and j represents the imaginary unit. The effective value E (r) of the electric field strength is a function of the position r, and its magnitude simply decreases as r increases. Therefore, the slope of the square of the effective value E also simply decreases with an increase in r. A graph showing the relationship between the position r and the dielectrophoretic force F _d is also shown in FIG. As for the force direction, when Re [K ^* (ω)] is positive, the electric field strength is strong, and when it is negative, the electric field strength is weak. Here, a positive case, that is, a case where a force acts in the −r direction will be described below.

When the solution 9 flowing in the solution chamber 8 is subjected to dielectrophoresis, a flow force F _f and a dielectrophoretic force F _d act on the fine particles A contained in the solution 9. The fine particles A move in the solution 9 due to the resultant force F = F _f −F _d . FIG. 3 shows a graph showing the relationship between the position r and the resultant force F. The position indicated by r = r _a is the position at which the resultant force F = 0, and the fine particles A located there are retained here. On the other hand, in the region of r ₁ <r <r _a , _a force acts on the fine particles A in the + r direction, and in the region of r _a <r <r ₂ , _a force acts on the fine particles A in the −r direction. All the fine particles A existing in the sandwiched region are collected at the position r _a . In addition, the region not sandwiched by the electrodes, that is, r
The fine particles A located at <r ₁ and r ₂ <r always move to the region sandwiched by the electrodes due to the flow, resulting in the solution 9
It is possible to collect all the fine particles A contained in the position r _a .

Next, a method for separating the fine particles separately when the solution 9 contains a plurality of types of fine particles will be described. The n kinds of fine particles contained in the solution 9 each have a unique particle radius, dielectric constant, and conductivity.
That is, the flow force F _f acting on each particle and the dielectrophoretic force F _d show different values due to the difference in these intrinsic parameters. Therefore, the position where the two forces balance with each other (the position where the resultant force = 0) also shows a value unique to each fine particle, and separation is possible. Also, all fine particles are r ₁
When the equilibrium position cannot be provided in the region of <r ₂ , at least one of the effective value E of the electric field strength, the angular frequency ω of the AC voltage source, the voltage application time of the AC electric field, and the flow rate flowing in the flow path 6 By changing one
(Equation 2) and (Equation 3) show that the balance position can be provided.

Although the case where the positive dielectrophoresis works has been described above, there is a case where the negative dielectrophoresis works depending on the type of the fine particles, and in this case, it can be explained as follows. Similar to FIG. 1, FIG. 4 is a schematic diagram showing an embodiment in the case of separating a single type of fine particles B by using the force of flow and the dielectrophoretic force. The schematic diagram shown in FIG. The only difference is that the left and right are reversed. That is, the configuration other than the solution inlet 10 and the solution outlet 11 is the same as in FIG.

At this time, the relationship between the flow force F _f acting on the fine particles B contained in the solution 12 and the position r is shown in FIG. The direction of the force is + r direction. Further, the dielectrophoretic force F acting on the fine particles B contained in the solution 12
_d acts in the direction of weak electric field strength, that is, in the -r direction,
Its size simply increases as r increases.
A graph showing the relationship between the position r and the dielectrophoretic force F _d is also shown in FIG.

FIG. 6 is a graph showing the relationship between the position r and the resultant force F. The position represented by r = r _b is a position where the resultant force F = 0, and the fine particles B located here are shown to stay there. On the other hand, in the region of r ₁ <r <r _b , a force acts on the fine particles B in the + r direction, and r _b <r <
In the region of r ₂ , a force acts on the fine particles B in the −r direction, so all the fine particles B existing in the region sandwiched by the electrodes are
Collected at position r _b . Further, the fine particles B located in a region not sandwiched by the electrodes, that is, r <r ₁ and r ₂ <r,
Because it always moves to the area sandwiched by the electrodes due to the flow,
As a result, all the fine particles B contained in the solution 12 are moved to the position r
can be collected in _b .

Further, as in the case where the positive dielectrophoresis works, when the solution 12 contains a plurality of kinds of fine particles, each of them is different due to the difference in these peculiar parameters such as particle radius, dielectric constant and conductivity. The force F _{f of the} flow acting on the fine particles of F and the dielectrophoretic force F _d show different values, and the position where the two forces balance (the position where the total force becomes 0) also shows a unique value for each fine particle. Separation becomes possible, and the balance position is changed by changing at least one of the effective value E of the electric field strength, the angular frequency ω of the AC voltage source, the voltage application time of the AC electric field, and the flow rate flowing in the flow path 6. Can be controlled.

In the present embodiment, the fine particles are treated as spheres for simplification, but in practice, even in the case of a protein or polymer having a complicated shape, the formula is complicated but the principle is the same. It goes without saying that such an effect can be obtained.

(Embodiment 2) (Embodiment 1)
A separation method using the equilibrium between the force of the flow whose velocity decreases monotonically and the positive dielectrophoretic force using FIG. 1 and the force of the flow whose velocity monotonically increases and the negative dielectrophoretic force using FIG. The separation method using balancing was explained. In FIG. 1 and FIG. 4, the flow path on which dielectrophoresis is applied has a fan shape, and two electrodes are located upstream and downstream of the flow. The separation method utilizing the equilibrium with and can exert its effect even when various other forms are used for the flow and the electrode arrangement. That is, the resultant force F of the flow force F _f and the dielectrophoretic force F _d has a balance position where F = 0 in the solution chamber, and at a place deviated from the balance position, the resultant force F toward the balance position is If you set up a working place,
It becomes possible to separate the fine particles contained in the solution. In this embodiment, some specific modes for embodying the method for separating particles described in (Embodiment 1) will be described.

FIG. 7 is a schematic view showing an embodiment in which the fine particles are separated by using the flow force and the dielectrophoretic force. Case 2
1, a circular solution chamber 27 having a constant thickness is formed, a solution inlet 22 is provided at the center of the circle, and a solution outlet 23 is provided at the outer periphery of the circle. In addition, the solution inlet 2
A first electrode 24 and a second electrode 25 are respectively provided between the 2 and the solution outlet 23, and these electrodes are respectively connected to an AC voltage source (not shown). Regarding the electric field strength between the first electrode 24 and the second electrode 25, the electric field lines become closer to the first electrode 24, so that the electric field strength becomes stronger toward the center of the solution chamber 27. The flow path 26 including the solution chamber 27 includes a solution 28 including the fine particles B.
The solution 28 is circulated in the flow path 26 at a constant flow rate by a pump (not shown).

At this time, the solution 28 in the solution chamber 27
The flow force F _f acting on the fine particles B contained in is expressed by (Equation 2) as in (Embodiment 1). Further, the dielectrophoretic force F _d acting on the fine particles B is also represented by (Equation 3).
A detailed description is omitted because it was performed in (Embodiment 1), but since a non-uniform electric field is formed even in the case of the circular solution chamber 27, the + r direction (from the center is the same as in the case of the fan-shaped solution chamber). Using the balance between the force F _{f of the} flow acting in the outward direction and the positive dielectrophoretic force F _d acting in the −r direction (the direction toward the center), the fine particles B are collected at the balance position r _b. You can

FIG. 8 is a schematic view showing an embodiment in which the fine particles are separated by using the flow force and the dielectrophoretic force. Case 3
1, a fan-shaped solution chamber 37 having a constant thickness is formed, and a solution inlet 3 is formed at the end of the fan having a narrow width.
2, a solution outlet 33 is provided at the end of the fan on the side where the width of the fan is widened. Further, the solution inlet 32 and the solution outlet 3
A first electrode 34 and a second electrode 35 are provided along the flow direction between the electrodes 3, and these electrodes are connected to an AC voltage source (not shown). The electric field strength between the first electrode 34 and the second electrode 35 becomes stronger as it gets closer to the solution inlet 32. The flow path 36 including the solution chamber 37 is filled with the solution 38 containing the fine particles C, and the solution 38 is supplied to the flow path 26 by a pump (not shown).
It circulates at a constant flow rate.

At this time, the solution 38 in the solution chamber 37
The flow force F _f acting on the fine particles C contained in is expressed by (Equation 2), and the dielectrophoretic force F _d acting on the fine particles C is also expressed by (Equation 3). Although a detailed description is omitted, a non-uniform electric field is formed even if electrodes arranged along the flow are used. Therefore, as in the case of (Embodiment 1), the flow force F _f acting in the + r direction and By utilizing the balance with the positive dielectrophoretic force F _d acting in the −r direction, the fine particles C can be collected at the balance position r _c .

Although not shown, two rectangular metal plates having an electrode function are made to face each other in a structure similar to that shown in FIG. 8, and when a solution is flown between the metal plates, Needless to say, the same effect can be obtained by setting the cross-sectional area of the outlet to be larger than the cross-sectional area of the inlet.

FIG. 9 is a schematic diagram showing an embodiment in which fine particles are separated by using the force of flow and the force of dielectrophoresis. Case 4
1, an elongated solution chamber 47 having a constant thickness and width is formed, and the solution 48 containing the fine particles D is supplied to the solution inlet 4
2 and flows out from the solution outlet 43. Solution 48
Is circulated in the flow path 46 at a constant flow rate by a pump (not shown). In addition, the electrode installation space 4 is provided in the housing 41.
9 is provided, and a first electrode 44 and a second electrode 45 are provided therein, and these electrodes are respectively connected to an AC voltage source (not shown). Note that the electrode installation space 49 is filled with a dielectric, and the type thereof is preferably gas such as air or nitrogen, liquid such as water or ethyl alcohol, or solid such as PMMA or glass. The first electrode 44 and the second electrode 45 have a shape in which the distance between the electrodes rapidly expands toward the downstream side, and the electric field strength becomes weaker toward the downstream side.

At this time, the flow force F _f acting on the fine particles D contained in the solution 48 flowing in the solution chamber 47 and the dielectrophoretic force F _d become a graph as shown in FIG.
Since the flow cross-sectional area and the flow rate are constant, the flow force F _f has a constant value. On the other hand, the dielectrophoretic force F _d has an electrode shape and an arrangement such that the electric field strength E (r) has a strength distribution that draws a part of an arc, so the magnitude of the gradient of E (r) ² is downstream. Therefore, the dielectrophoretic force F _d becomes a graph as shown in FIG. FIG. 11 shows a graph showing the relationship between the position r and the resultant force F. the position indicated by r = r _d is
The position where the resultant force F = 0, and the fine particles D located here
Means stay here. On the other hand, in the region of r <r _d, the force acts on the + r direction microparticles D, in the area of r _d <r, the force acts in the -r direction to the microparticles D, the fine particles D in all positions r _d You can collect.

As described above, the resultant force F of the flow force F _f and the dielectrophoretic force F _d has the equilibrium position where F = 0 in the solution chamber, and the equilibrium is present at the position deviated from the equilibrium position. If the flow shape and the electrode arrangement are configured so that the resultant force F toward the position acts, it becomes possible to separate the fine particles contained in the solution into the balanced positions.

(Embodiment 3) The present invention applies a dielectrophoretic force to fine particles in the direction opposite to the centrifugal force in a field in which a centrifugal force acts on a solution containing the fine particles, and the centrifugal force and the dielectrophoretic force are applied. The present invention relates to a method and apparatus for separating various types of fine particles contained in a solution by utilizing staying in a balanced position, and a sensor for analyzing the separated particles. The present invention is also suitably used for biochemical analysis, drug discovery, DNA analysis, high-throughput screening, etc., in which desired molecules are selectively extracted or separated and analyzed from a solution containing various types of proteins and macromolecules. .

FIG. 12 is a schematic diagram showing an embodiment in which a single type of fine particles E are separated by using centrifugal force and dielectrophoretic force. In FIG. 12, an elongated solution chamber 64 having a uniform thickness and width is formed in a housing 61, and a solution 65 containing fine particles E is filled in the interior thereof. Further, an electrode installation space 66 is provided in the housing 61, and a first electrode 62 and a second electrode 63 are provided therein, and these electrodes are connected to an AC voltage source (not shown). ing. The electrode installation space 66 is filled with a dielectric substance, and the type thereof is a gas such as air or nitrogen, a liquid such as water or ethyl alcohol, or P.
Solids such as MMA and glass are preferably used. The first electrode 62 and the second electrode 63 have a shape in which the distance between the first electrode 62 and the second electrode 63 rapidly expands toward the right in FIG. 12, and the electric field strength decreases toward the right. Further, the housing 61 is the rotating body 6.
It is installed at No. 7 and rotates at an angular velocity ω _c .

Here, in FIG. 12, the rotation of the rotating body 67 is
The center of rotation is r = 0, and the left end of the solution chamber 64 is r₃,
The right end is r_FourThe r coordinate is set so that like this
Solution 65 in the solution chamber 64 under various conditions.
Centrifugal force F acting on the fine particles E _cIs the following (Equation 5)
Shown.

[0058]

[Equation 5]

Here, M and v are the mass and specific volume of the fine particles E, and ρ is the number density of the fine particles E. As the equation shows, the centrifugal force F _c (r) is a function proportional to the position r. FIG. 13 is a graph showing the relationship between the position r and the centrifugal force F _c .
Shown in. The direction in which the force acts is the + r direction.

Next, the dielectrophoretic force F _d acting on the fine particles E will be described. F _d is expressed by the following equation (6).

[0061]

[Equation 6]

Here, ε _m is the dielectric constant of the solution 65, E is the effective value of the electric field strength generated by the two electrodes 62 and 63,
ω is the angular frequency of the AC voltage source, Re [] is the real part, and ∇ is the differential operator for finding the gradient. Also, K
^* (Ω) is the Clausius-Mossoti function, and is defined by the following equation (7).

[0063]

[Equation 7]

Here, ε _p ^* is the complex permittivity of the fine particles E, ε
_m ^* is the complex permittivity of the solution 65, ε _p is the permittivity of the fine particles E,
ε _m is the dielectric constant of the solution 65, σ _p is the electrical conductivity of the fine particles E, σ _m
Indicates the conductivity of the solution 65, and j indicates the imaginary unit. Since the effective shape E (r) of the electric field strength has such an electrode shape and arrangement that the intensity distribution draws a part of a circular arc,
The magnitude of the gradient of (r) ² increases toward the right in the figure, so the dielectrophoretic force F _d becomes a graph as shown in FIG. 13. The direction of force is as follows when Re [K ^* (ω)] is positive,
That is, the case of working in the −r direction is set.

When dielectrophoresis is applied to the solution 65 while the casing 61 is rotating at the angular velocity ωc, the centrifugal force F _c and the dielectrophoretic force F _d act on the fine particles E contained in the solution 65. The fine particles E move in the solution 65 by the resultant force F = F _c −F _d . FIG. 14 shows a graph showing the relationship between the position r and the resultant force F. the position indicated by r = r _e is the position where the resultant force F = 0, the fine particles E which is located here represents that stay here. On the other hand, r ₃
<R <a region of r _e is the particle E + r direction force acts in the area of r _e <r <r _4, the force acts in the -r direction to the microparticles E, present in the solution chamber 64 All the fine particles E to be collected can be collected at the position r _e .

Next, a method of separating the fine particles separately when the solution 65 contains plural kinds of fine particles will be described. The n kinds of fine particles contained in the solution 65 are
Each has its own particle radius, mass, specific volume, dielectric constant, and conductivity. That is, the centrifugal force F _c and the dielectrophoretic force F _d acting on the respective particles show different values due to the difference in these intrinsic parameters. Therefore, the position where the two forces balance with each other (the position where the resultant force = 0) also shows a value unique to each fine particle, and separation is possible. Further, when all the fine particles cannot have a balanced position in the region of r ₃ <r ₄ , the effective value E of the electric field strength, the angular frequency ω of the AC voltage source, the voltage application time of the AC electric field, the rotating body 6
(Equation 5) and (Equation 6) show that the equilibrium position can be obtained by changing at least one of the angular velocities ω _c of 7.

Although the case where the positive dielectrophoresis works has been described above, there is a case where the negative dielectrophoresis works depending on the type of the fine particles. This case will be described below with reference to the drawings.

FIG. 15 shows that the centrifugal force and the dielectrophoretic force are used.
It is a schematic diagram which shows one form which isolate | separates a fine particle. Case 7
1, a fan-shaped solution chamber 74 is formed,
A solution 75 containing the fine particles G is filled inside. Melting
At the end of the liquid chamber 74 on the side where the width of the fan widens,
Electrode 72 has a second electrode 73 at the narrowed end.
Are provided and these electrodes are not shown
It is connected to an AC voltage source. The first electrode 72 and the second
The electric field strength between the electrodes 73 becomes closer to the first electrode 72.
become weak. Further, the housing 71 is installed on the rotating body 76.
Cage, angular velocity ω _cIt rotates with.

At this time, the fine particles G contained in the solution 75
The relationship between the centrifugal force F _c acting on the and the position r is shown in FIG. The direction of force is the + r direction. Also, the fine particles G
The dielectrophoretic force F _d that acts on the element acts in the direction in which the electric field strength is weak, that is, in the −r direction, and its magnitude simply increases as r increases. The relationship between the position r and the dielectrophoretic force F _d is also shown in FIG.

FIG. 17 shows a graph showing the relationship between the position r and the resultant force F thereof. The position indicated by r = r _g is a position where the resultant force F = 0, and the fine particles G located here are shown to stay here. On the other hand, in the region of r <r _g , the force acts on the fine particles G in the + r direction, and in the region of r _g <r, the force acts in the −r direction on the fine particles G, and therefore exists in the region sandwiched by the electrodes. All the fine particles G to be collected can be collected at the position r _g .

The total force F of the centrifugal force F _c and the dielectrophoretic force F _d
However, if the electrode shape and the electrode arrangement are configured so that the equilibrium position where F = 0 is set in the solution chamber and the resultant force F toward the equilibrium position works at a position deviated from the equilibrium position, it is included in the solution. It goes without saying that it becomes possible to separate the fine particles into a balanced position.

Further, in the present embodiment, the fine particles are treated as spheres for simplification, but in practice, even in the case of proteins and polymers having complicated shapes, the formula is complicated but the principle is the same. It goes without saying that such an effect can be obtained.

(Embodiment 4) In this embodiment, a sensor for quantitatively and qualitatively analyzing fine particles by using the fine particle separation method described above will be specifically described.

FIG. 18 is a schematic diagram showing an embodiment of a sensor for performing qualitative and quantitative analysis of fine particles by using a fine particle separation method utilizing flow force and dielectrophoretic force and the surface plasmon resonance phenomenon. The method shown in FIG. 1 is used for the separation. The housing 101 has a constant thickness, and when viewed from above, a fan-shaped solution chamber 107 as shown in FIG. 1 is formed, and constitutes a part of the flow path 106. The solution inlet 1 is located at the end of the fan with the narrower width.
02 has a solution outlet 10 at the end of the fan on the side where the width of the fan is widened.
3 is provided. Further, the first electrode 104 and the second electrode 10 are provided between the solution inlet 102 and the solution outlet 103.
5 are provided, and these electrodes are connected to an AC voltage source (not shown). The electric field strength between the first electrode 104 and the second electrode 105 becomes closer to the first electrode 104, and the electric force line becomes denser. Therefore, the electric field strength becomes stronger toward the left in the figure. Solution chamber 10
The flow path 106 containing 7 is filled with a solution 108 containing fine particles, and the solution 108 is circulated in the flow path 106 at a constant flow rate by a pump (not shown). At this time, the flow force F _f and the dielectrophoretic force F _d acting on the particles are shown in FIG. 2, and the resultant force is shown in FIG. That is, all the fine particles contained in the solution 108 have a resultant force F =
Collected in a balanced position of 0.

On the other hand, the incident light 1 emitted from the light source 109
Reference numeral 12 denotes the first lens 110, the second lens 111, the prism 113, and the glass 11 forming the bottom surface of the housing 101.
Then, the metal thin film 114 is irradiated with the light through the line 5. The light source is a laser diode that oscillates a single wavelength, and the first lens 110 and the second lens 111 are adjusted so that the incident light 112 is focused on the metal thin film 114. That is, the incident light 112 has an incident angle range defined by the size of the lens, the focal length, the refractive index of the prism, and the like.
The metal thin film 114 is preferably an Au thin film, but other metals such as Ag, Cu, Al, and Pt may be used as long as they cause the surface plasmon resonance phenomenon. Further, the surface of the metal thin film 114 has a thickness of 100 nm.
It is preferably coated with the following non-metal substances, but it does not have to be coated.

Reflected light 116 reflected by the metal thin film 114
Is again transmitted through the glass 115 and the prism 113, and is irradiated on the photodetector 117, where the light amount is detected for each incident angle. The photodetector 117 is preferably composed of a CCD or array sensor. The prism 113 and the glass 115 are in close contact with each other with a matching oil (not shown). In FIG. 18, the entire bottom surface of the housing 101 is made of glass, but even if the entire housing 101 is made of glass,
Only the portion that transmits the incident light 112 and the reflected light 116 may be made of glass.

A method for performing qualitative and quantitative analysis of fine particles using the above-mentioned structure will be described. At least one of the effective value E of the electric field strength, the angular frequency ω of the AC voltage source, the voltage application time of the AC electric field, and the flow rate flowing in the flow path 106 so that any kind of fine particles in the solution 108 gather on the metal thin film 114. Control one or the other. Since the fine particles have a parameter peculiar to the substance, the fine particles are the metal thin film 114.
The type of the fine particles can be identified from the effective value E of the electric field strength when gathered above and the angular frequency ω of the AC voltage source.

Further, the refractive index of the fine particles, that is, the concentration can be quantitatively obtained by utilizing the surface plasmon resonance phenomenon in a state where the fine particles are collected on the metal thin film 114. The angle at which the light amount of the reflected light 116 from the metal thin film 114 is most reduced, that is, the angle of the incident light 112 that satisfies the condition that the surface plasmon resonance occurs is measured. This angle measurement is performed even in the state where the fine particles are not separated, and the concentration of the fine particles is obtained from the angle difference between the unseparated state and the separated state.

As a matter of course, in determining the concentration of a solution having an unknown concentration, a reference solution having a known concentration is measured and compared with it.

Further, the light source 109, the photodetector 117, the AC voltage source, and the pump are each connected to a control arithmetic unit (not shown), and the procedure is programmed in advance or the operator can change the situation. Equipment control, measurement, detection,
Calculations, recordings, etc. can be performed.

Further, in this embodiment, the flow force and the dielectrophoretic force are used to separate the fine particles, but the centrifugal force may be used instead of the flow force, and the centrifugal force may be used. In this case, the parameter controlled to collect the fine particles on the metal thin film 114 is not the flow rate flowing in the flow path but the angular velocity of the rotating body, and the same effect can be obtained by the method using centrifugal force and dielectrophoretic force. It goes without saying that you can get

(Fifth Embodiment) In the present embodiment, similarly to (Fourth Embodiment), a sensor for quantitatively and qualitatively analyzing fine particles using the fine particle separation method described above will be specifically described.

FIG. 19 is a schematic view showing an embodiment of a sensor for performing a qualitative and quantitative analysis of fine particles by using a fine particle separation method utilizing flow force and dielectrophoretic force and a light absorption phenomenon. Regarding the separation, the method shown in FIG. 1 is used. The housing 121 has a constant thickness, and when viewed from above, the fan-shaped solution chamber 127 as shown in FIG.
Is formed and constitutes a part of the flow path 126.
A solution inlet 122 is provided at the end on the side where the width of the fan is narrowed, and a solution outlet 123 is provided at the end on the side where the width of the fan is widened. Further, the solution inlet 122 and the solution outlet 123
A first electrode 124 and a second electrode 125 are provided between the electrodes, and these electrodes are connected to an AC voltage source (not shown). Regarding the electric field strength between the first electrode 124 and the second electrode 125, the electric field lines become closer to the first electrode 124, so that the electric field strength becomes stronger toward the left in the figure. The flow channel 126 including the solution chamber 127 is filled with the solution 128 including fine particles,
The solution 128 is supplied to a channel 126 by a pump (not shown).
It circulates at a constant flow rate. At this time, the flow force F _f acting on the particles and the dielectrophoretic force F _d are shown in FIG.
These resultant forces are shown in FIG. That is, all the fine particles contained in the solution 128 are collected at the equilibrium position where the resultant force F = 0.

On the other hand, the inspection light 1 emitted from the light source 129
33 is irradiated into the solution 128 via the first lens 130, the second lens 131, the third lens 132, and the glass 135 forming the bottom surface of the housing 121. Light source 12
9 is preferably a laser diode that oscillates a single wavelength, and the first lens 130, the second lens 131, and the third lens 132 have a beam width of the inspection light 133 of the solution 128.
It is adjusted to be constant in.

The inspection light 133 transmitted through the solution 128 is
The light is transmitted through the glass 136 and irradiated onto the photodetector 134, where the amount of transmitted light is detected. The photodetector 134 is preferably composed of a photodiode or CCD.
In FIG. 19, the bottom surface and the entire top surface of the housing 121 are made of glass, but the entire housing 121 may be made of glass, or only the portion that transmits the inspection light 133 may be made of glass.

A method for performing qualitative and quantitative analysis of fine particles using the above-mentioned structure will be described. The effective value E of the electric field strength, the angular frequency ω of the AC voltage source, the voltage application time of the AC electric field, and the flow rate flowing in the flow path 126 are set so that any kind of fine particles in the solution 128 may be collected on the optical path of the inspection light 133. Control at least one. Since the fine particles have parameters specific to the substance, the fine particles have the inspection light 1
The type of the fine particles can be identified from the effective value E of the electric field strength when gathered on the optical path 33 and the angular frequency ω of the AC voltage source.

Further, the concentration of the fine particles can be quantitatively obtained by utilizing the light absorption phenomenon while the fine particles are collected on the optical path of the inspection light 133. This concentration measurement is performed even when the fine particles are not separated, and the concentration of the fine particles is obtained from the difference in light absorption between the unseparated state and the separated state.

Further, the light source 129, the photodetector 134, the AC voltage source, and the pump are each connected to a control arithmetic unit (not shown), and the procedure may be programmed in advance or the operator may change the situation. Equipment control, measurement, detection,
Calculations, recordings, etc. can be performed.

Further, in the present embodiment, the flow force and the dielectrophoretic force are used to separate the fine particles, but the centrifugal force may be used instead of the flow force, and the centrifugal force may be used. In this case, the parameter to be controlled in order to collect the fine particles on the optical path of the inspection light 133 is only the angular velocity of the rotating body instead of the flow rate flowing in the flow path, and the method using centrifugal force and dielectrophoretic force is the same. It goes without saying that the effect of can be obtained.

[0090]

As described above, according to the present invention,
It is possible to realize a method and an apparatus for separating fine particles at high speed with high accuracy, and a sensor for performing quantitative qualitative analysis.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing position dependence of flow force and dielectrophoretic force according to one embodiment of the present invention.

FIG. 3 is a characteristic diagram showing position dependency of resultant force according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 5 is a characteristic diagram showing position dependence of flow force and dielectrophoretic force according to one embodiment of the present invention.

FIG. 6 is a characteristic diagram showing position dependency of resultant force according to an embodiment of the present invention.

FIG. 7 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 8 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 9 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 10 is a characteristic diagram showing position dependence of flow force and dielectrophoretic force according to an embodiment of the present invention.

FIG. 11 is a characteristic diagram showing position dependency of resultant force according to an embodiment of the present invention.

FIG. 12 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 13 is a characteristic diagram showing position dependence of centrifugal force and dielectrophoretic force according to an embodiment of the present invention.

FIG. 14 is a characteristic diagram showing position dependency of resultant force according to an embodiment of the present invention.

FIG. 15 is a schematic diagram showing a particle separation method according to an embodiment of the present invention.

FIG. 16 is a characteristic diagram showing position dependence of centrifugal force and dielectrophoretic force according to an embodiment of the present invention.

FIG. 17 is a characteristic diagram showing the position dependence of the resultant force according to the embodiment of the present invention.

FIG. 18 is a schematic diagram showing a sensor for performing qualitative and quantitative analysis according to an embodiment of the present invention.

FIG. 19 is a schematic diagram showing a sensor for performing qualitative quantitative analysis according to an embodiment of the present invention.

[Explanation of symbols]

1, 21, 31, 41, 61, 71, 101, 121
Cases 2, 10, 22, 32, 42, 102, 122 Solution inlets 3, 11, 23, 33, 43, 103, 123 Solution outlets 4, 24, 34, 44, 62, 72, 104, 124
First electrodes 5, 25, 35, 45, 63, 73, 105, 125
Second electrode 6, 26, 36, 46, 106, 126 Channel 7 Pump 8, 27, 37, 47, 64, 74, 107, 127
Solution chambers 9, 12, 28, 38, 48, 65, 75, 108, 1
28 solution 49, 66 electrode installation space 67, 76 rotor 109, 129 light source 110, 130 first lens 111, 131 second lens 112 incident light 113 prism 114 metal thin film 115, 135, 136 glass 116 reflected light 117, 134 Photodetector 132 Third Lens 133 Inspection Light

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01N 21/27 G01N 21/59 Z 21/59 27/26 301C 331K 331Z F term (reference) 2G059 AA01 AA02 BB04 BB06 BB09 CC19 EE01 EE02 GG01 JJ11 JJ12 KK01 KK04 MM01 MM10 4D054 FB01 FB20 4D057 AA00 AB01 AC06 AD05 AE02 BC05 BC11 CA01

Claims (21)

[Claims] 1. A fine particle that dielectrophores in the direction opposite to the force of the flow in a solution containing the fine particle and separates the fine particle at a position where the force of the flow and the dielectrophoretic force are balanced. Separation method. 2. The flow acting on the fine particles by controlling at least one of the frequency of the AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the flow rate of the solution. The method for separating fine particles according to claim 1, wherein a position where the force of the magnetic field and the dielectrophoretic force balance each other is controlled. 3. A fine particle separation method in which a centrifugal force is applied to a solution containing fine particles, the fine particles are subjected to dielectrophoresis in the direction opposite to the centrifugal force, and the fine particles are separated at a position where the centrifugal force and the dielectrophoretic force are balanced. 4. The fine particles are controlled by controlling at least one of a frequency of an AC electric field applied when dielectrophoresis is generated, a voltage value of the AC electric field, a voltage application time of the AC electric field, and an angular velocity for generating a centrifugal force. The method for separating fine particles according to claim 3, wherein a position where the centrifugal force and the dielectrophoretic force acting on each other are balanced is controlled. 5. The fine particle separation method according to claim 1, wherein the dielectrophoretic force is a positive dielectrophoretic force that acts in a direction in which the electric field strength is high. 6. The method for separating fine particles according to claim 1, wherein the dielectrophoretic force is a negative dielectrophoretic force acting in a direction in which the electric field strength is weak. 7. An electrode pair consisting of a first electrode and a second electrode, a voltage source for generating a non-uniform AC electric field between these electrodes, a pump and a channel for flowing a solution containing fine particles. A fine particle separation device comprising the fine particles and separating the fine particles at a position where the flow force acting on the fine particles and the dielectrophoretic force are balanced. 8. The flow acting on the fine particles by controlling at least one of the frequency of the AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the flow rate of the solution. 8. The particle separation device according to claim 7, which controls the position where the force of the magnetic field and the force of dielectrophoresis balance each other. 9. An electrode pair comprising a first electrode and a second electrode, a voltage source for generating a non-uniform AC electric field between these electrodes, and a container for containing a solution containing fine particles,
A fine particle separation device in which the container is held by a rotating body for applying a centrifugal force to the fine particles, and separates the fine particles at a position where the centrifugal force acting on the fine particles and the dielectrophoretic force are balanced. 10. Fine particles are controlled by controlling at least one of the frequency of an AC electric field applied when dielectrophoresis is generated, the voltage value of the AC electric field, the voltage application time of the AC electric field, and the angular velocity of a rotating body. The fine particle separation device according to claim 9, which controls a position where the centrifugal force and the dielectrophoretic force balance each other. 11. The fine particle separation device according to claim 7, wherein the dielectrophoretic force is a positive dielectrophoretic force that acts in a direction in which the electric field strength is high. 12. The fine particle separation device according to claim 7, wherein the dielectrophoretic force is a negative dielectrophoretic force acting in a direction in which the electric field strength is weak. 13. An electrode pair consisting of a first electrode and a second electrode, a voltage source for generating a non-uniform AC electric field between these electrodes, a pump and a channel for flowing a solution containing fine particles, A concentration measuring device for measuring the concentration of the fine particles is provided, the fine particles are separated at a position where the flow force acting on the fine particles and the dielectrophoretic force are balanced, and the fine particle concentration in the separated state is measured by the concentration measuring device. The sensor to measure. 14. The concentration of fine particles is measured by controlling at least one of a frequency of an AC electric field applied when dielectrophoresis is generated, a voltage value of the AC electric field, a voltage application time of the AC electric field, and a flow rate of a solution. The sensor according to claim 13, which is controlled so as to be located at the site. 15. An electrode pair consisting of a first electrode and a second electrode, a voltage source for generating a non-uniform AC electric field between these electrodes, a container containing a solution containing fine particles, and a concentration of the fine particles. And a concentration measuring device for measuring, the container is held by a rotating body for imparting a centrifugal force to the fine particles, the centrifugal force acting on the fine particles and the dielectrophoretic force to balance the fine particles at a position. A sensor for separating and measuring the concentration of fine particles in the separated state by the concentration measuring device. 16. The concentration of fine particles is controlled by controlling at least one of a frequency of an AC electric field applied when dielectrophoresis is generated, a voltage value of the AC electric field, a voltage application time of the AC electric field, and an angular velocity of a rotating body. The sensor according to claim 15, which is controlled so as to be located at a measurement site. 17. The sensor according to claim 13, wherein the dielectrophoretic force is a positive dielectrophoretic force that acts in a direction in which the electric field strength is high. 18. The sensor according to claim 13, wherein the dielectrophoretic force is a negative dielectrophoretic force acting in a direction in which the electric field strength is weak. 19. The sensor according to claim 13, wherein the concentration measuring device uses a surface plasmon resonance phenomenon. 20. The concentration measuring device comprises a light source and a photodetector, wherein the light emitted from the light source is transmitted through a solution containing fine particles and is measured by the photodetector to measure the absorbance of light by the fine particles. The sensor according to any one of claims 13 to 16, wherein the sensor determines the concentration of fine particles from this value. 21. The sensor according to claim 20, wherein the light emitted from the light source is laser light.