JP2001296274A - Dielectric migration device, its manufacturing method and separation method of material using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric migration device, having improved collection ability of material, in a device for allowing liquid including the material to be separated to exist in a nonuniform electric field formed by a dielectric migration electrode, and executing by a dielectric migration force applied on the material. SOLUTION: In this dielectric migration device, formed by installing electrodes on a substrate, a lower part than the electrodes is formed between the facing electrodes, and thereby increase in the nonuniform electric field region is realized, to improve collection capability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectrophoresis apparatus having an improved collecting ability, a method for producing the same, and a method for separating substances using the apparatus.

[0002]

2. Description of the Related Art In recent years, with the advance of semiconductor technology, a material processing technology in units of nm to μm has been established by a fine processing technology such as photolithography, and the fine processing technology continues to advance at present.

In the field of chemistry and biochemistry, this fine processing technology is used to extract a component to be analyzed from a biological sample (extraction process), and to analyze the component using a chemical or biochemical reaction (analysis process). ), Followed by a series of chemical and biochemical analysis processes such as separation process (separation process) and detection (detection process) all integrated on a chip of several cm to several tens of cm Micro Total Analysis System (μ-TAS), Lab
Oratory on a chip] is evolving.

This μ-TAS technique shortens the analysis time, reduces the amount of sample used and the amount of reagents necessary for chemical and biochemical reactions, throughout the chemical and biochemical analysis steps, reduces It is expected to greatly contribute to reducing the analysis space.

[0005] In particular, in the separation step in μ-TAS, a capillary (thin tube) having an inner diameter of 1 mm or less made of Teflon (registered trademark), silica, or the like is used as a separation column, and a substance is applied in a high electric field. Capillary electrophoresis, in which separation is performed using the difference in electric charge of the cells, and capillary column chromatography, in which separation is performed using the difference in interaction between a column carrier and a substance using a similar capillary, have been developed. .

[0006] However, the capillary electrophoresis method requires a high voltage for separation, and the detection sensitivity is low due to the restriction of the capillary capacity in the detection area. The problem is that the capillary length for separation is limited and the capillary length is not sufficient for polymer separation, so it is suitable for separating low-molecular substances but not for high-molecular substances. have. In addition, the capillary column chromatography method has a problem in that the speed of the separation process is limited, and it is difficult to shorten the processing time.

In recent years, as one of means for solving the above-mentioned problems, when a substance is placed in a non-uniform alternating electric field, positive and negative polarization occurs in the substance, and the dielectric constant of the medium surrounding the substance is increased. Is larger than the substance, the substance moves in the direction of the lower electric field, and if the dielectric constant of the medium is smaller than the substance, the substance moves in the direction of the stronger electric field, so-called dielectrophoretic force (HAPohl: "Dielectrophoresis ", Cambridge U
niv. Press (1978), TBJones: "Electromechanics of
Particles ", Cambridge Univ. Press (1995), etc.] have attracted attention.

In this separation method, (1) the magnitude of dielectrophoretic force depends on the size and dielectric properties of a substance (particle) and is proportional to the electric field gradient. Since the electric field gradient can be made extremely large, high-voltage separation is not required as in capillary electrophoresis, and high-speed separation can be expected with a low applied voltage. (2) The place where the electric field is strong is limited to a very small area. The temperature rise due to the application of an electric field can be minimized, and a high electric field can be formed. (3) As can be seen from the fact that dielectrophoresis is a force proportional to the electric field gradient, the applied voltage Does not depend on the polarity of the dc. Therefore, the use of high-frequency alternating current suppresses the electrode reaction (electrolysis reaction) in an aqueous solution, so that the electrode itself can be integrated in a channel (sample flow path). (4) Like capillary electrophoresis In view of the fact that there is no restriction on the chamber capacity of the detection part, the improvement of the detection sensitivity can be expected, and so on, and it is considered to be the most suitable separation method in μ-TAS at present.

[0009]

However, considering the application of dielectrophoresis to μ-TAS, it is very important to improve the trapping ability. It is not yet satisfactory.

That is, if the trapping ability of the substance is improved, separation in the electrode region becomes possible, and separation with a high S / N (signal / noise) ratio is realized by holding efficiently. . Also, for example, Field-Flow, which separates by interaction between dielectrophoretic force and fluid drag acting on a substance in particular
This is because, in fractionation, separation can be performed in a short electrode region even at the same flow rate.

In the present invention, the first and second aspects of the present invention have been made in view of such a point, and include a substance to be separated in a non-uniform electric field formed by a dielectrophoretic electrode. An object of the present invention is to provide a dielectrophoretic device in which a liquid is present and separation is performed by a dielectrophoretic force acting on the substance, in which the substance-capturing ability is improved.

[0012] An object of the invention according to claim 4 is to provide a method for manufacturing the device according to claim 1.

The invention according to claim 7 is the first invention.
It is an object of the present invention to provide a method for separating a substance using the apparatus described in (1).

[0014]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and have found that an electrode and a substrate portion of the electrode are excavated to form a portion lower than the electrode, whereby unevenness is obtained. Since the electric field region is increased and the drag of the fluid is reduced, the present inventors have conceived that the trapping ability is improved, and arrived at the present invention.

[0015] Thus, there have been many patents and articles on a separation apparatus and a method using a dielectrophoretic force, in particular, an apparatus and a method in a field-flow fractionation. There is no known device or method for improving the ability to collect substances, and no such idea is known.

According to a first aspect of the present invention, in a dielectrophoresis apparatus having electrodes provided on a substrate, means for realizing an increase in a non-uniform electric field region is formed between the opposed electrodes. Features.

According to a second aspect of the present invention, as means for realizing an increase in the non-uniform electric field region, a portion lower than the electrode is formed between the opposed electrodes. By forming the "lower part than the electrode", the non-uniform electric field region increases because the electrolysis is formed not only above but also below the electrode, and furthermore, for example, when used for Field-Flow fractionation Since the flow velocity of the fluid in this portion is reduced, the fluid drag is reduced, so that the ability to capture substances is improved.

Further, the invention according to claim 4 is characterized in that a substrate lower than the electrodes is formed between the opposing electrodes by excavating a substrate between the electrodes by physical or / and chemical means. I do. Here, the physical means is, for example, a method of excavating using an appropriate blade or the like, for example, a LIGA (Lithographile Galvanoformu) using synchrotron radiation.
ng Abformung) method, and the chemical means is, for example, etching for excavating a substrate using an etching solution for the substrate. In addition, for example, the substrate between the electrodes is also excavated by etching using a reactive gas converted into plasma by a high-frequency power supply [Reactive Ion Etching (RIE)] in which physical excavation and chemical excavation are performed simultaneously. Can be. The substrate may be excavated by appropriately combining the above-described means.

According to the present invention, a liquid containing a substance to be separated is present in a non-uniform electric field formed by a dielectrophoretic electrode, and separation is performed by a difference in dielectrophoretic force acting on the substance. The method for separating a substance is characterized in that a non-uniform electric field region is increased by a portion lower than an electrode formed between opposing electrodes, so that a trapping ability is improved.

Incidentally, dielectrophoresis (DEP)
Is a phenomenon in which neutral particles move in a non-uniform electric field due to the interaction between the conductivity and permittivity of a substance, the conductivity and permittivity of a medium, and the applied frequency. The force acting on the molecule is called dielectrophoretic force. The dielectrophoretic force is classified into two types: a positive dielectrophoretic force in which a substance moves toward a stronger electric field and a negative dielectrophoretic force in which a substance moves toward a weaker electric field. Hereinafter, a case where a positive dielectrophoretic force acts on a molecule will be described.

That is, as shown in FIG. 1, the neutral molecule placed in the electric field has a positive polarization charge + q on the downstream side of the electric field.
However, a negatively polarized charge -q is induced on the upstream side, respectively.
A force of magnitude + qE acts on + q due to the electric field E, and pulls this portion toward the upstream side of the electric field. If the molecule is neutral, the absolute values of + q and -q are equal, and if the electric field is constant regardless of location, the forces acting on both are balanced and the molecule does not move. However, when the electric field is not uniform, the force to be pulled toward the strong electric field is larger, and the molecules are driven to the strong electric field.

As described above, the molecules in the solution move variously in the electric field region in accordance with the dielectrophoretic force generated in the molecules. For example, the movement of the molecules in the field-flow fractionation is caused by the dielectrophoresis generated in the molecules. In addition to the force Fd, the fluid drag (drag due to the flow in the flow path) Fv and the thermal motion Fth
Is governed by three factors: That is, Fd >> Fv +
In the case of Fth, molecules are trapped on the electrode,
In the case of Fd << Fv + Fth, molecules flow out of the flow channel regardless of the electric field. Also, Fd ≒ Fv +
In the case of Fth, the molecule is carried downstream while repeating adsorption and desorption to the electrode, and as a result, reaches the outlet with a delay from the flow in the original flow path.

In the present invention, since a non-uniform electric field is formed below the electrodes by excavating deeply between the opposing electrodes, the non-uniform electric field region increases, and the fluid flow in this part is increased. And the drag Fv of the fluid is reduced, so that Fd becomes larger and Fv becomes smaller under the above-mentioned conditions, so that the collection rate is improved. Further, the particles trapped by the electric field formed below the electrodes are located at the “lower part than the electrodes”, so that they are less likely to flow out.

[0024]

Next, an embodiment of the present invention will be described.

FIG. 2 shows an embodiment of the present invention, in which a convex (post) 2 on a substrate (glass substrate) 1 supports electrodes 3 at intervals in the longitudinal direction. .

As shown in FIG. 2 (B), a “part lower than the electrode” (communication groove) 4 having a semicircular cross section is formed between the opposing electrodes 3, 3. 4 is FIG.
As shown in (A), communication is made at a portion other than the convex object 2. However, as shown in FIG. 3B, the electrode 3 is supported by a wall (convex) 2 ', and the adjacent grooves 4', 4 'are separated by the wall 2' so as not to communicate with each other. But it doesn't hurt.

In the embodiment shown in FIGS. 2 and 3, the portions other than the projections 2 and 2 'are "the portions lower than the electrode 3".
(4 and 4 ').

However, it is permissible to provide a single recess or a plurality of recesses (holes) at a part between the opposed electrodes 3 and 3, but as shown in FIGS. 2 and 3, all of the opposed electrodes are provided. Alternatively, a portion that is mostly lower than the electrode (4
Alternatively, the formation in 4 ′) is preferable because the trapping ability is improved.

When a concave portion (hole) is provided in a part between the opposing electrodes 3, 3, it is preferable to provide the concave portion 5 in the minimum gap 5 between the opposing electrodes. This is because this portion has a high electric field strength, and if provided in this portion, the trapping ability is further improved. However, if the entirety including this portion is formed, the portion for trapping molecules is increased, so that the trapping ability is further improved.

The width of the groove 4 (in the case shown in FIGS. 2 and 3,
The same as the distance between the electrodes 3 and 3) greatly affects the electric field strength, but is appropriately determined depending on the size of the substance to be subjected to the induction electrophoresis, and cannot be said unconditionally. In the case of a substance having a micrometer size, the diameter is preferably 100 times or less and 1 or more times the diameter of the substance, more preferably 1 time or more.
It is preferable that the area be 0 times or less and 1 time or more. In the case of biomolecules such as proteins and genes, for example, peptide chains,
For proteins and the like, it is usually 10 μm or less and 1 nm or more, preferably 5 μm or less and 1 nm or more. In the case of nucleotide chains (polynucleotides, oligonucleotides) and the like,
It is usually 100 μm or less and 1 nm or more, preferably 50 μm or less and 1 nm or more.

Generally, as the depth increases, the portion for trapping molecules increases, and in particular, in the case of Field-Flow fractionation, the flow velocity in the groove portion is suppressed, and the trapping ability (trapping rate) is improved. However, if the depth is too deep, when it is necessary to measure the molecules trapped on the electrode by dielectrophoresis, the trapped molecules may be hardly released from the groove portion or may not be released. Therefore, the depth of the groove is preferably 10 times or less and 1/1000 times or more, more preferably 1 time or less and 1/1000 times or more the width of the groove.

If the depth of the groove is formed by isotropic etching as shown in FIGS. 2 and 3 (A), if the groove is dug beyond the electrode width, all the protrusions 2 holding the electrode 3 are cut off. As a result, the electrode 3 peels off. Therefore, when a groove is formed by this method, the depth of the groove is １ ／ or less of the maximum electrode width.

As shown in FIG. 3B, when the silicon wafer is formed by anisotropic etching, the etching proceeds only in the depth direction at an angle of 55 degrees. Therefore, when etching by this method, the maximum distance in the depth direction is:
(Distance between electrodes ÷ 2) × 1.42 (tan 55 degrees). As shown in FIG. 3C, when the film is formed by RIE, LIGA, or the like, the etching proceeds almost vertically. Therefore, when etching is performed by these methods, the depth of the groove is in the above-mentioned range, that is, preferably 10 times or less 1/1000 times or more, more preferably 1 time or less 1 / times of the groove depth.
1000 times or more.

The spacing between the grooves (= the width of the electrode itself) does not depend on the object of separation, provided that the separation is limited to positive dielectrophoresis. Normally 50 μm due to the processing accuracy of the fine processing technology
1 nm or less, preferably 10 μm or less and 1 nm or more.

The isotropic etching shown in FIG. 3A is formed by etching a glass substrate or a plastic substrate. The isotropic etching supports the electrode 3 on the wall 2 on the substrate, and the adjacent grooves 4, 4
In the case where the electrodes 3 are formed so as to be isolated from each other, or when the electrodes 3 are supported by the protrusions 2 on the substrate and the adjacent grooves (communication grooves) 4 and 4 are formed to communicate with each other, Thus, various shapes are formed.

The anisotropic etching shown in FIG. 3B is formed by etching a silicon substrate. In this case, the electrode 3 is supported on the wall 2 'on the substrate, and the adjacent grooves 4', 4 'are isolated by the wall 2'. The RIE shown in FIG.
₂ formed by etching a substrate or the like,
LIGA is formed by etching a polymer, ceramic, plastic substrate, or the like. In these cases, the electrode 3 is supported on a wall 2 "on the substrate, and the adjacent grooves 4", 4 "are isolated by the wall 2".

In the isotropic etching shown in FIGS. 2 and 3A, the groove or the communication groove 4 is generally formed in a semicircular or semielliptical cross section. When a groove is formed by anisotropic etching shown in FIG. 3B, generally, the groove 4 'is finally etched in a substantially V shape through a substantially trapezoidal cross section. When a groove is formed by RIE, LIGA, or the like shown in FIG. 3C, etching is generally performed in a substantially rectangular cross section. Therefore, although various cross-sectional shapes are formed depending on the method of etching and the method of forming the “portion lower than the electrode”, in the present invention, the “portion lower than the electrode” (communication groove, groove, concave portion, etc.) is formed. The shape is not particularly limited.

The wall or projection 2 shown in FIG. 3A is formed in a shape in which the central portion is constricted, and the wall 2 'shown in FIG. 3B is formed in a trapezoidal shape. The wall 2 ″ of C) is formed in a square shape, but the wall or convex body 2, the wall 2 ′, and the wall 2 ″ may have any shape as long as the electrode 3 can be supported. There is no particular limitation.

The electrode 3 used in the present invention is made of a conductive material such as aluminum, gold or the like, and its structure is a dielectrophoretic force, that is, a material capable of generating a non-uniform electric field in the horizontal and vertical directions. Well, for example, interdigital shapes [J. Phys. D: Appl. Phys. 258, 81-88, (1992), Biochi
m. Biophys. Acta., 964, 221-230, (1988) and the like.

More specifically, as shown in FIG.
(A) A shape in which a large number of triangular outward protruding portions 7a are formed at intervals above and below the linear band portion 6, and (B) A rectangular outer portion faces above and below the linear band portion 6. Projection 7b
(C) a shape in which a large number of trapezoidal outward protruding portions 7c are formed above and below the linear band-shaped portion 6 opposed to each other, and (D) a sinusoidal waveform in the up and down direction. A shape in which a large number of convex portions 8 and concave portions 9 (concave portions 9 and convex portions 8) of the same sine wave are vertically arranged facing each other in a straight line, and It is preferable that a large number of 8 'and concave portions 9' (concave portions 9 'and convex portions 8') are vertically arranged so as to be linearly connected to each other. However, any electrode that can be used for dielectrophoresis can be used,
There is no particular limitation.

Such electrodes are usually made of, for example, glass,
Plastic, quartz, on a substrate made of a non-conductive material such as silicon, a fine processing technology known per se [Biochim.
Biophys. Acta., 964, 221-230 etc.] and one or more pairs of electrodes having the above-mentioned shapes are provided in a comb-like shape. The distance between the opposing (adjacent) electrodes 3 is not particularly limited as long as a non-uniform AC electric field having a strong electric field strength can be formed, and should be appropriately set depending on the kind of the target molecule.

The thickness of the electrode 3 may be the same as the conventional one, and specifically, is usually 0.5 nm or more, preferably 0.5 nm to
It is 1 nm, more preferably 1 nm to 1000 nm.

The electrode 3 may be the same as the conventional one except for the thickness, and an organic thin film may be coated on the electrode in order to prevent adsorption of various substances on the electrode.

The dielectrophoretic apparatus of the present invention is manufactured in the same manner as in the prior art except for the “lower part than the electrode” (communication groove 4, groove 4 ′, concave portion, etc.) such as the dielectrophoretic electrode and the flow path. What is necessary is just to form.

In order to form the “part lower than the electrode”,
For example, a method of excavating using a suitable cutting tool or the like, or a LIGA (Lithographile) using synchrotron radiation, for example.
Physical means such as the Galvanoformung Abformung method, for example, chemical means such as etching for excavating a substrate using an etchant for the substrate, or etching using a reactive gas which is turned into plasma by a high-frequency power supply [Reactive Ion Etching: Reactive Ion Etching (RIE)] may be used to excavate and form the substrate between the electrodes by physical or chemical means. The substrate may be excavated by appropriately combining the above-described means.

As the etching solution, a known etching solution may be selected according to the material of the substrate. When a portion lower than the electrode is formed in a part of the substrate, a portion which is not desired to be excavated is appropriately masked. Etching.

In order to carry out the separation method of the present invention using the dielectrophoresis apparatus of the present invention, the separation method itself may be performed in the same manner as in the prior art.

That is, a liquid containing a substance to be separated, for example, two or more substances (molecules or particles) dissolved or suspended in a non-uniform electric field formed using the electrodes (electrode substrates) as described above. The liquid may be separated by the difference in dielectrophoretic force acting on the substance in the presence of the liquid.

In general, a non-uniform electric field is formed in the flow path on the substrate in the horizontal and vertical directions, a liquid containing a substance to be separated flows from an inlet, and the liquid is separated by a difference in dielectrophoretic force acting on the substance. Just do it. However, it is of course possible to separate the components retained in a specific portion of the electrode and the components not retained without causing a flow.

In order to perform separation by the difference in dielectrophoretic force acting on a substance (molecule, particle), the electrode is separated into molecules and the like not retained in a specific portion of the electrode, or receives a stronger dielectrophoretic force. Molecules and the like move later than molecules and the like that receive weak dielectrophoretic force, and may be separated by utilizing the difference in movement time.

As shown by the arrows in FIG. 5, when a liquid containing a substance to be separated flows from the direction intersecting the length direction of the electrode into the flow path of the apparatus of the present invention, the flow velocity in the communication groove 4 is increased. It is slower than the path portion, and the drag Fv of the fluid applied to the molecules entering the communication groove 4 can be reduced. In addition, electrodes 3,
By forming the communication groove 4 between the three, the range of influence of the electric field is widened, and the place where trapped molecules are stocked is widened, so that it is considered that the collection rate is improved.

The measuring method of the present invention may be carried out in accordance with the above-mentioned method known per se, except that the separation method of the present invention is used, and the reagents used may be those known per se. May be selected as appropriate.

Hereinafter, the present invention will be described more specifically with reference to Examples and Reference Examples, but the present invention is not limited thereto.

[0054]

[Example] Reference Example 1: Preparation of dielectrophoretic electrode substrate Minimum gap 7 μm, electrode pitch 20 μm, number of electrodes 2016 (10
08 pairs) was designed, and based on this, a photomask for electrode fabrication was fabricated.

That is, a resist was applied to a glass substrate on which aluminum was deposited, and an electrode pattern as designed as described above was drawn by an electron beam drawing apparatus. Then, the resist was developed and aluminum was etched to produce a photomask. .

The production of the electrode substrate was carried out as follows in accordance with the method described in Illustrated Photofabrication, Takao Hashimoto, Sogo Denshi Shuppan, (1985).

That is, after the photomask prepared as described above was brought into close contact with the resist-coated aluminum-deposited glass substrate, the electrode pattern was exposed with a mercury lamp. The electrode glass substrate after the exposure was prepared by developing the resist and etching the aluminum surface, and then removing the resist remaining on the aluminum surface.

Example 1: "Parts Lower than Electrodes" are Formed on a Substrate by Etching As shown in FIG. 6, a glass substrate 1 of an induction electrophoretic electrode manufactured as described in Reference Example 1 was etched. A communication groove 4 was formed in a portion of the substrate 1 facing the electrode 3.

As an etching solution, sodium fluoride sulfuric acid (NH ₄ F 3%, H ₂ SO ₄ , H ₂ O) was used. Sodium fluoride sulfuric acid has the property of dissolving both glass and aluminum, but the rate of etching glass is much faster than the rate of etching aluminum. Can be etched.

Assuming that the thickness of the electrode aluminum is 40 nm,
When the etching was performed at a depth of 3 μm or more, the electrode was observed to be bent by a water flow when the etching solution was washed with pure water. However, when the etching was performed at a thickness of 250 nm, the electrode was not bent.

The etching was performed as described above, and the relationship between the etching time (sec.) And the depth (μm) of the communication groove formed between the electrodes was measured. As a result, as shown in FIG. 7, the etching time and the depth of the formed groove showed a proportional relationship. The depth of the groove was measured by cutting the electrode with a glass cutter and observing the cross section with a microscope. Reference Example 2 Fabrication of Electrode Substrate Having Flow Channel In order to separate molecules by moving molecules in a non-uniform electric field, a flow channel was formed on the electrode substrate fabricated in Example 1 using silicon rubber.

The silicon rubber flow channel for sending the solution in which the molecules were dissolved on the electrode was designed to have a depth of 25 μm and a width of 400 μm, and to pass through the region where the electrode was arranged on the electrode substrate.

The fabrication is illustrated by photo fabrication,
Performed according to the method described in Takao Hashimoto, Sogo Denshi Shuppan, 1985. First, a sheet-shaped negative resist having a thickness of 25 μm was attached to a glass plate, and then exposed using a photomask designed for producing a channel, and then the negative resist was developed. Uncured silicone rubber was poured using the negative resist substrate as a mold, and then cured to produce a silicone rubber having a concave surface with a height of 25 μm at the portion where the electrodes were arranged.

The electrode substrate and the silicone rubber flow path are adhered to each other with a two-liquid curing type silicone rubber so that the silicon rubber concave surface is located on the region of the electrode substrate where the electrodes are arranged. Insert the syringe into the electrode substrate,
A device for sending a solution in which molecules are dissolved on the electrode was added.

Example 2 Bovine Serum Albumin (BSA)
Measurement of collection rate of protein An electrode in which a communication groove having a depth of 2 μm or 4 μm was formed as in Example 1 and a flow path was formed as described in Reference Example 2, An induction electrophoresis chromatography device was prepared, and the collection rate of this device was measured as described below. For comparison, the collection rate was also measured for an inductive electrophoresis chromatography device produced in the same manner except that no communication groove was formed.

(Sample) As a sample, 60 μg / ml of FITC-labeled BSA (molecular weight: about 65 kD) was used.

(Operation) In order to prevent protein molecules from adsorbing to the electrode substrate and the flow channel, the surface of the flow channel was blocked using Block A (manufactured by Snow Brand Milk Products Co., Ltd.).
Labeled BSA was subjected to induction migration chromatography.

The average flow rate of the sample used was 556 μm
/ Sec. And electric field application is 30 to 12 from the start of measurement.
Performed during 0 seconds. The applied electric field strength at this time is as follows:
14 Mv / m, 2.5 Mv / m, 2.86 Mv / m
The collection rate was measured for each species.

The collection rate was determined by the following equation.

Collection rate (%) = [(I ₀ -I _min ) × 1
00] / (I ₀ −I _back ) where I ₀ represents a steady-state value of the fluorescence intensity before the electric field is applied,
I _min represents the minimum value of the fluorescence intensity during the application of the electric field, and I _min
back represents the background. (Results) The results are shown in FIG. In FIG. 8,-△-indicates the results obtained by using a 4 μm deep,-□-indicates a depth of 2 μm, and-◇-indicates a depth of 0 μm using an electrophoresis chromatography apparatus.

As is clear from the results shown in FIG. 8, the trapping rate (%) increases as the depth of the groove increases. At 2.86 Mv / m, the apparatus of the present invention having a communication groove of 4 μm has The trapping efficiency is about 40% compared to the trapping rate of 28% of the conventional apparatus, and the trapping rate is improved by about 43%. In other words, the trapping ability of the target substance can be improved by using the apparatus of the present invention. It can be seen that is significantly improved.

Example 3 Measurement of Collection Rate for 500 bp DNA Using 500 bp DNA labeled with the intercalator fluorescent dye YOYO-1 (Molecular Probes) as a sample, the groove depth was determined in the same manner as in Example 2. 0 μm,
The collection rate (%) was measured with a 2 μm and 4 μm induction electrophoresis chromatography apparatus.

FIG. 9 shows the results. In FIG. 9,-△-is 4 μm in depth,-□-is 2 μm in depth, and-◇-is 0 μm in depth.
2 shows the results obtained by using an induction electrophoresis chromatography apparatus having a communication groove of No.

As is apparent from the results shown in FIG. 9, even in this case, when the electric field strength is 1.5 Mv / m or more, the depth is 4 μm.
The device of the present invention in which m communication grooves were formed improved the collection rate (%) by about 20% as compared with the conventional device having no communication grooves.

[0075]

As described above, according to the present invention, a portion which is lower than the electrode is provided between the opposing electrodes, which has not been performed at all, so that the separation of a substance by induction migration can be performed extremely. This is a tremendous effect that the collection rate, which plays an important role, is significantly improved, and is therefore an extremely innovative invention.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of dielectrophoresis.

FIG. 2 is a plan view (A) and a cross-sectional view (B) showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of “a part lower than an electrode” of the present invention formed by isotropic etching (A), anisotropic etching (B), and RIE or LIGA (C).

FIG. 4 is a plan view showing an example of an electrode used in the present invention.

FIG. 5 is a cross-sectional view of the induction electrophoresis chromatography device of the present invention.

FIG. 6 is a cross-sectional view showing an example of forming a “part lower than an electrode” on a substrate by the method of the present invention.

FIG. 7 is a graph showing a relationship between an etching time measured in Example 1 and a groove depth.

FIG. 8 is a graph showing the measurement of the bovine serum albumin (BSA) collection rate using the induction electrophoresis chromatography apparatus of the present invention and a conventional induction electrophoresis chromatography apparatus.

FIG. 9 shows the results obtained by using the induction electrophoresis chromatography apparatus of the present invention and a conventional induction electrophoresis chromatography apparatus.
It is the graph which measured the collection rate about 0bpDNA.

[Explanation of symbols]

 1: Substrate 2: Convex object (post) 2 ': Convex object (wall) 3: Electrode 4: Area lower than electrode (communication groove) 4': Area lower than electrode (groove) 5: Between electrodes Minimum gap

Claims (7)

[Claims] 1. A dielectrophoretic device in which electrodes are provided on a substrate, wherein a structure for increasing a non-uniform electric field region is formed between the opposing electrodes. 2. A dielectrophoretic device in which electrodes are provided on a substrate, wherein a portion lower than the electrodes is formed between the opposing electrodes. 3. The dielectrophoretic device according to claim 2, wherein the electrode is held by a convex on the substrate, and a portion lower than the electrode is formed between the opposed electrodes. 4. A substrate according to claim 1, wherein a substrate lower than said electrode is formed between said opposing electrodes by excavating a substrate between said electrodes by physical and / or chemical means. The method for producing a dielectrophoresis apparatus according to claim 1. 5. The method according to claim 4, wherein the chemical means is etching using an etchant for a substrate of the dielectrophoresis apparatus.
3. The method for manufacturing a dielectrophoretic apparatus according to item 1. 6. A method for separating a substance in which a liquid containing a substance to be separated is present in a non-uniform electric field formed by a dielectrophoretic electrode and separation is performed by a difference in dielectrophoretic force acting on the substance. A method for separating a substance, characterized in that the ability to trap a substance is improved by realizing an increase in a non-uniform electric field region by a portion lower than an electrode formed between the electrodes. 7. A method for separating a substance in which a liquid containing a substance to be separated is caused to flow in a non-uniform electric field formed by a dielectrophoretic electrode and separation is performed by an interaction between dielectrophoretic force and fluid drag acting on the substance. 7. The separation method according to claim 6, wherein a portion lower than the electrodes formed between the opposing electrodes realizes an increase in the non-uniform electric field region and a reduction in the fluid drag, thereby improving the trapping ability of the substance.