JP2003215378A - Method for forming particulate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of easily arranging fine particles to produce a periodic structure of μm order. <P>SOLUTION: In a method for forming a particulate film, fine particles are arranged in a hyperbola type quadruple electrode by applying an electric field which varies at high frequency. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for forming a fine particle film in which fine particles are aligned by applying an electric field.

[0002]

2. Description of the Related Art A fine particle crystal in which fine particles such as colloidal particles are regularly arranged in a two-dimensional or three-dimensional manner can be used as a non-linear optical material / optical element. Has been done. Therefore, in recent years, researches for producing such fine particle crystals have been actively conducted.

For example, in order to realize a microphotonic device that makes use of the light propagation characteristics characteristic of a photonic crystal, a technique for producing a three-dimensional photonic crystal capable of strongly confining light in the crystal has been proposed. It needs to be established.

Various methods have been attempted up to now for the production of such a three-dimensional photonic crystal. In the wavelength region of microwave to millimeter wave, a dielectric is mechanically used to form a dielectric. The technique of making a hole is used. However, when manufacturing a photonic crystal having a photonic bandgap in the optical wavelength region, fine three-dimensional processing of about a half wavelength is indispensable, and the above method cannot be adopted.

Up to now, there have been reported methods for producing a photonic crystal using various semiconductor process technologies, and it is possible to use these to produce a three-dimensional photonic crystal. Since two-dimensional processing, that is, thin film formation and etching, is fundamental, it is essentially difficult to produce a three-dimensional photonic crystal with several tens of cycles using these methods.

Therefore, in recent years, a method for easily producing a three-dimensional periodic structure of the order of micrometers has been developed by packing and arranging micro particles of the order of micro and submicrons in a three-dimensional manner.

Examples of these methods include a convective accumulation method in which a polymer dispersion is dropped on a substrate and water is evaporated to self-assemble three-dimensionally, or particles are observed one by one under an electron microscope. There is a method of manipulating and stacking up to three dimensions. However, it is known that the advection integration method cannot control the array state freely and has many defects. Further, the method of manipulating particles one by one has the advantage that a freely arranged state can be constructed, but the operation is extremely difficult and lacks in simplicity.

[0008]

As described above, there is a demand for providing means for easily arranging fine particles for producing a periodic structure of the order of micrometers, and the object of the present invention is to solve the problems. It is to provide such a means.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a large amount of particles can be moved at a time by using a specific electric field as an arranging means. The present inventors have completed the present invention by finding that the arrangement can be controlled in a solution and that the arrangement can reversibly control the arrangement.

That is, the present invention provides a method for forming a fine particle film characterized by aligning fine particles in a hyperbolic quadrupole electrode by applying an electric field varying at a high frequency.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, the term “fine particle” refers to a particle having a uniform shape of approximately 10 nm to several mm.
Means particles having a particle size in the range of. Here, the “uniform shape” means that the particles used have a regular structure when arranged, and the shape is not particularly limited, but the size is not limited. Is important, and spherical, rod-shaped, or plate-shaped particles are used. The material of the fine particles is not particularly limited, organic fine particles or inorganic fine particles are used, for example, polystyrene latex particles, polyacrylate particles, polymethylmethacrylate particles,
It is preferable to use polymer resin particles such as polyurethane particles and silica fine particles.

In order to carry out the method of the present invention, it is necessary to apply an electric field that fluctuates at a high frequency in the above-mentioned hyperbolic quadrupole electrode.

The hyperbolic quadrupole electrode used in the present invention has already been disclosed in the literature (Wataray et al., “Langmuir”, Vol. 13,
2417-2420, 1997), the electrode has a shape as shown in FIG. An electric field is applied to this electrode so that the counter electrode has the same polarity, and the electric field becomes weaker toward the center of the electrode. Then, the part to which the electric field is applied is a substantially diamond-shaped part surrounded by four electrodes,
The distance between the electrodes of the counter electrode is not particularly limited, but 5
It is about 0 to 2000 μm.

In this electrode, the fine particles to be arranged are preferably suspended in a solvent such as distilled water or deionized water. If necessary, an electrolyte medium such as potassium chloride may be added to the solvent. It can also be added. When an electrolyte medium is used, its concentration is preferably up to about 1 mM.

This hyperbolic quadrupole electrode is provided with, for example, 800
When a simple AC electric field that fluctuates at a high frequency of about 10 MHz from 10 Hz is applied, the microparticles migrate in a weak electric field direction by induction migration and are arranged in a monomolecular film shape. The time required for this arrangement depends on the type of fine particles, particle size, and concentration in liquid, but a monomolecular film is formed in about several minutes to several tens of minutes.

A monolayer is formed by the above method,
In order to form a multi-layered film, the hyperbolic quadrupole electrode on which the monomolecular film is formed as described above is superposed on a direct current,
For example, an alternating current varying at a high frequency of about 800 Hz to 10 MHz may be applied. Then, the electrostatic repulsive force between the fine particles and the negative electrode due to the direct current and the negative dielectrophoretic force due to the alternating current act to collect the fine particles from the outside of the electrode and arrange them in multiple layers. The time required for this arrangement depends on the type of the fine particles, the particle size, and the concentration in the liquid, but is about several minutes to several tens of minutes. It is desirable that the above-mentioned direct current alternates between positive and negative at intervals of about 5 to 30 seconds.

Further, the fine particles multilayered as described above become a multilayered film arranged three-dimensionally by applying a high frequency alternating current again. The time until the multilayered film is obtained is, depending on the type of fine particles and the like, a few minutes to a dozen minutes, as described above.

As described above, the dispersed fine particles can be arranged with regularity. And using an electrode with a certain height as a hyperbolic quadrupole electrode,
By repeating the above-mentioned operation, it becomes possible to obtain a multi-layered fine particle film in which three or more layers are three-dimensionally arranged.

The monomolecular film of the fine particles and the multilayered film arranged three-dimensionally obtained in this way can be used as various optical devices etc. by forming colloidal crystals in that state. . Further, the present invention is not limited to this, and can be advantageously used for producing various devices in the so-called nanotechnology field.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Reference Example 1 Preparation of hyperbolic quadrupole electrode: A device shown in FIG. 2 was prepared for applying an electric field. In addition, as a hyperbolic quadrupole electrode,
An electrode made of ruthenium was arranged in a shape as shown in FIG. 1 on a slide glass of 40 mm × 100 mm. The minimum distance between the counter electrodes was 0.4 mm, and the minimum distance between adjacent electrodes was 80 μm. The counter electrode was always the same.

Example 1 Formation of Microparticle Film (1) Colloidal particles having a diameter of 5 μm and a ζ potential of −64 m
V polystyrene latex (manufactured by Duke Scientific Co .; hereinafter referred to as "PSL") was used and suspended in distilled water for injection at 0.5 w%,
A sample suspension was obtained.

This sample suspension was placed in the hyperbolic quadrupole electrode of Reference Example 1 (FIG. 3). Then, an alternating current having a frequency of 1 MHz and a voltage of 1.5 Vrms was applied, and the behavior of the particles under application of an electric field was observed with a differential interference optical microscope. At first, it was observed that the dispersed polystyrene latex dielectrophores toward the center of the electrode, and in about 15 minutes PSL
Was formed (Fig. 4).

Example 2 Formation of Fine Particle Film (2) For the PSL monomolecular film formed as in Example 1, a direct current superposed with a high frequency alternating current was applied.
The direct current was set to 1.5 V, and positive and negative alternating every 15 seconds.
The alternating current to be superimposed has a frequency of 1 MHz and a voltage of 1.5.
Vrms. By this application, PSL was collected from outside the electrode, and after about 15 minutes, a PSL multilayer film was formed (FIG. 5).

Example 3 Formation of Fine Particle Film (3) Further, alternating current having a frequency of 1 MHz and a voltage of 1.5 Vrms was applied again to the multilayer film formed as in Example 2. After about 3 minutes, a three-dimensionally arranged multilayer film was obtained (FIG. 6).

[0026]

According to the present invention, it is possible to form particles into a monomolecular film, a multilayer film, and a three-dimensional packing arrangement by only operating an electric field.

By forming the hyperbolic quadrupole electrode to a certain degree of thickness, it is possible to form a considerably multi-layered fine particle film, and further control the number of layers to be stacked by controlling the electric field application time. It will be possible.

Furthermore, by combining with the method for bonding fine particles that the present inventors have invented separately, it becomes possible to fix a monomolecular film or a multilayer film, which is extremely useful as a method for developing a new device. It is something.

[Brief description of drawings]

FIG. 1 is a drawing showing the shape of a hyperbolic quadrupole electrode.

FIG. 2 is a drawing showing a block diagram of an electric field applying device.

FIG. 3 is a drawing showing a state of a sample suspension before applying an electric field.

FIG. 4 is a drawing showing a state of a sample suspension after application of an alternating electric field.

FIG. 5 is a drawing showing a state of a sample suspension after applying a DC electric field on which AC is superimposed.

FIG. 6 Above a drawing showing the state of the sample suspension after the AC electric field is applied again.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaki Oda             1-20-5 Bessho, Saitama City, Saitama Prefecture Kashimaso             No. 105 (72) Inventor Shinya Tsukamoto             6-9-10 Chiyono Nishi, Matsuto City, Ishikawa Prefecture (72) Inventor Toshiro Sakai             5103 Nishiharu, Ina City, Nagano Prefecture (72) Inventor Ariomo Yamaguchi             2-12-32 Katsuradai, Aoba-ku, Yokohama-shi, Kanagawa (72) Inventor Hideki Sakai             2-17-30 Tamawa, Kamakura City, Kanagawa Prefecture (72) Inventor Nobuyuki Momozawa             4-191 Edogawadainishi, Nagareyama City, Chiba Prefecture F term (reference) 2H047 KA03 KA12 PA00 TA43                 4G075 AA24 CA14 CA25 DA02 DA18                       EC21

Claims (10)

[Claims] 1. A method for forming a fine particle film, which comprises aligning fine particles in a hyperbolic quadrupole electrode by applying an electric field varying at a high frequency. 2. The method for forming a fine particle film according to claim 1, wherein the electric field fluctuating at a high frequency is given by an alternating current having a high frequency, and the fine particle film formed is a monomolecular film. 3. An electric field fluctuating at a high frequency is obtained by (1) applying a high frequency alternating current (2) applying a direct current superposed with a high frequency alternating current in this order,
The method for forming a fine particle film according to claim 1, wherein the formed fine particle film is a multilayer film. 4. An electric field fluctuating at a high frequency is obtained by (1) applying a high-frequency alternating current (2) applying a high-frequency alternating current (3) high-frequency alternating current in this order. ,
The method for forming a fine particle film according to claim 1, wherein the fine particle film to be formed is a multi-layered film having a three-dimensional regular array. 5. The electric field fluctuating at high frequency is 800 Hz.
5. The method for forming a fine particle film according to any one of claims 1 to 4, wherein the fine particle film is from 10 MHz to 10 MHz. 6. The method for forming a fine particle film according to claim 1, wherein the fine particles are suspended in an electrolyte solution. 7. The method for forming a fine particle film according to claim 1, wherein the fine particles are polymer resin particles. 8. The microparticles are substantially spherical.
9. The method for forming a fine particle film according to claim 7. 9. The method for forming a fine particle film according to claim 3, wherein direct current is alternating. 10. The method for forming a fine particle film according to claim 9, wherein the alternating period is 5 to 30 seconds.