JP3007921B2 - Probe for magnetic particle fixed type magnetic sensor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for collecting magnetic fine particles for measuring a magnetic field localized in a minute area with high resolution, a probe for a magnetic sensor, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Probes used in conventional magnetic force microscopes are manufactured by depositing a thin film of a magnetic material such as a cobalt alloy on a silicon cantilever and magnetizing the thin film with a strong magnet. I've been. The tip of this magnetized probe is scanned over the sample surface, and the probe displacement due to the attractive and repulsive forces due to magnetic interaction,
A micro magnetic field image of the sample is obtained by optically detecting an amplitude change, a phase change, and a frequency change at the resonance frequency and forming a two-dimensional image. The ideal case of such a probe is when the magnetization (magnetic dipole) is localized only at the tip of the probe, in which case the interaction with the sample is most localized and the resolution is increased. I knew that in principle.

Further, a conventional read head for magnetic recording of another type has a small gap formed in a ring-shaped soft magnetic core wound with a coil, and the resolution is limited by the width of the gap. The current gap width is typically several hundred nm from the viewpoint of manufacturing.

[0004]

However, in practice, in the previous example, the magnetic thin film is uniformly deposited on the entire probe, and the magnetization of the thin film other than the tip interacts with the magnetic field of the sample, so that the resolution is poor. This has been supported by the research results that the resolution is degraded as the thickness of the magnetic thin film increases. Also, it is essentially difficult to create a local magnetic dipole in a magnetic thin film, which has led to a decrease in the resolution of the probe in a magnetic force microscope.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned conventional drawbacks, and a culture solution containing magnetic bacteria is dropped on a non-magnetic substrate mounted on a magnet. The operation of immersing in an alkali / organic solvent for destroying the cell membrane of magnetic bacteria and washing with distilled water is repeated several times, and by removing the magnet, a magnetic particle array is collected on the substrate. It provides a method.

The present invention provides a method for collecting magnetic fine particles in which the alkali / organic solvent is sodium hydroxide-saturated ethanol.

Further, according to the present invention, a magnetic fine particle collected from a magnetic bacterium is fixed to the tip of a pointed probe made of a non-magnetic material so that the magnetic dipole direction is constant. An object of the present invention is to provide a method of manufacturing a probe for a magnetic particle fixed type magnetic sensor in which a body is configured as a probe of a magnetic sensor.

Further, the present invention provides a method in which magnetic fine particles collected from a magnetic bacterium are fixed to the tip of a pointed probe made of a non-magnetic material so that the magnetic dipole direction is constant. An object of the present invention is to provide a probe of a magnetic particle fixed magnetic sensor which is used as a probe of a magnetic sensor including a body.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First, the magnetic bacteria used in the present invention will be described below. Magnetic bacteria, also called magnetotactic bacteria, are bacteria that inhabit sediments at the bottom of seas, ponds, and lakes, and have a body length of several μm. Magnetic bacteria in the body 1
It has one to several magnetic fine particle rows composed of 0 to 20 magnetic fine particles. The magnetic moment of the row of magnetic microparticles generates torque by a magnetic field applied from the outside, such as geomagnetism, and the magnetic microparticle row, that is, the magnetic bacteria, is directed in a direction parallel to the magnetic force lines.

Due to the direction of the magnetic bacterium caused by the magnetic field and the movement of the bacterium itself, the magnetic bacterium generates movement in the direction along the magnetic field lines. This is the origin of the magnetotacticity of magnetic bacteria. The magnetic fine particles have a size of 50 to 100 nm.
The size of magnetite (F
e ₃ O ₄ ), which are magnetic.

A magnetic microparticle synthesized by the magnetic bacterium in the cell is taken out and fixed to the tip of a sharp probe (for example, a cantilever for an atomic force microscope made of silicon or silicon nitride) to produce a probe. The magnetic field is detected using the magnetic dipole of the magnetic fine particles. The magnetic microparticles produced by the magnetic bacteria are microparticles having a size of about 100 nm, are mainly composed of magnetite, and independently constitute a magnetic dipole of a single magnetic domain.

That is, the fixing of the magnetic fine particles to the tip of the probe is realized based on the flowchart shown in FIG. (a) A culture solution containing magnetic bacteria is dropped on a flat substrate (for example, a cover glass) having a magnet fixed to the back surface, and the cells are fixed by a magnetic field. (b) Immerse it in an alkali / organic solvent solution (eg, sodium hydroxide / ethanol solution) for a certain period of time to destroy bacterial cell membranes. (c) Thereafter, the residue is rinsed again with distilled water or the like, and the remaining material other than the magnetic substance is washed. (d) Repeat after repeating this operation several times. (e) Finally, remove the magnet on the back of the board. According to this procedure, the magnetic fine particles present in the magnetic bacteria on the substrate can be taken out on the substrate without aggregating.

In addition, (1) using a manipulator under an optical microscope,
A minute amount of adhesive resin is applied. As the adhesive resin, an ultraviolet-curable resin (for example, an ultraviolet-curable epoxy resin) that is cured by irradiation with ultraviolet light is used. (2) The probe is scanned over the magnetic fine particles taken out of the substrate, and a small number of magnetic fine particles are attached to the tip. (3) While aligning the direction of the magnetic fine particles in a strong magnetic field with the probe, the adhesive resin is cured and bonded by ultraviolet irradiation, and the magnetic fine particles are fixed on the probe. By using such an ultraviolet curable resin, magnetic fine particles are adhered to the tip of the probe in a state where the resin is not cured, and then irradiated with ultraviolet light in a desired environment (for example, the magnetization directions of the magnetic fine particles are aligned). The resin can be cured to fix the magnetic fine particles.

FIG. 2 shows the above steps in a diagram, so that the steps can be understood more specifically.

FIG. 3 (a) shows an example in which magnetic fine particles are bonded and fixed to the tip of a sharp probe portion of a silicon cantilever. FIG. 3B is an enlarged view of a main part of FIG. 3A, and the distribution of magnetic dipoles in a single magnetic domain of the magnetic fine particles can be easily understood. FIG. 3C is a perspective view of the silicon cantilever of this embodiment, which is used in this state in a magnetic force microscope (not shown), and the resolution is greatly improved from this figure. You can see that it is doing.

As described above, the present invention has been described based on the embodiments described in the drawings. However, the present invention is not limited to the above-described embodiments, but may be implemented in any manner unless the configuration described in the claims is changed. can do. For example,
When this embodiment is used for reading data from a magnetic recording medium such as a hard disk, high-density reproduction, which has not been obtained conventionally, can be performed.

[0017]

According to the present invention, a high-resolution magnetic force microscope image can be obtained from a probe using a conventional magnetic thin film, which is useful for studying magnetic materials. When used for reading data from a magnetic recording medium, the spatial resolution can be further enhanced by using a small magnetic dipole having a smaller size (nm size) without using a magnetic gap having a submicron size. And the density of the magnetic recording medium can be increased.

[Brief description of the drawings]

FIG. 1 is a flowchart according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating the flowchart of FIG. 1;

FIGS. 3 (a), (b), and (c) are diagrams illustrating the present embodiment, and FIG. 3 (a) shows magnetic fine particles adhered and fixed to the tip of a sharp probe portion of a silicon cantilever. (B) is an enlarged view of a main part of (a), and (c) is a perspective view of a silicon cantilever of the present embodiment.

──────────────────────────────────────────────────続 き Continuing from the front page (73) Patent holder 591033744 Isao Matsunaga 4-20-15, Honcho, Koganei-shi, Tokyo (72) Inventor Jin Suzuki 1-1-2-1-1, Migatadai, Nishi-ku, Kobe-shi, Hyogo Prefecture 1-1103 (72) Inventor Nobuo Mashiko 2-4-1-123 Shimizugaoka, Tarumizu-ku, Kobe-shi, Hyogo (72) Inventor Makoto Naganaga 2-40-B506, Sachimachi, Fuchu-shi, Tokyo (56) References JP-A-62-171677 (JP, A) JP-A-62-294089 (JP, A) JP 6-12994 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 33/00-33 / 18

Claims (4)

(57) [Claims] 1. A tip of a pointed tip made of a non-magnetic material
At the end, the magnetic particles obtained from the magnetic bacteria
The magnetic particles are fixed so that the direction is fixed.
Is configured as a magnetic sensor probe.
Of Probe for Fixed Magnetic Particle Fixed Magnetic Sensor
Method. 2. A method for collecting magnetic fine particles from a magnetic bacterium.
Magnetic bacteria on a non-magnetic substrate placed on a magnet
The cell membrane of the above-mentioned magnetic bacteria is destroyed by dropping the containing culture solution
Soak with alkaline or organic solvent and wash with distilled water
Repeat the cleaning process several times and remove the magnet
Sample on the substrate without breaking the array of magnetic particles
2. The magnetic microstructure according to claim 1, wherein
A method for manufacturing a probe for a particle-fixed magnetic sensor. 3. The tip of a pointed probe made of a nonmagnetic material.
At the end, the magnetic particles obtained from the magnetic bacteria
The magnetic particles are fixed so that the direction is fixed.
And a magnetic sensor probe including
Probe for magnetic particle fixed type magnetic sensor. 4. A non-magnetic substrate mounted on a magnet,
The culture medium containing the bacterium is dropped into the cells of the magnetic bacterium.
Soak in alkaline or organic solvent to break the film
Repeat the operation of washing with distilled water several times, and then remove the above magnet.
By removing, the magnetic fines taken out in a row on the substrate
The feature is that particles are fixed to the tip of the probe.
Of a magnetic particle fixed type magnetic sensor.