JPH05175Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is used in pharmacology and biochemistry for the purpose of researching intracellular enzymes in the brain, etc., by irradiating biological specimens with microwaves to instantly deactivate the enzymes in the specimen. This invention relates to a microwave heating device for biochemical tests.

When heating an object with microwaves, there are two possible methods: placing the object in an oven such as a microwave oven and heating it, and heating the object by placing it in a transmission line such as a waveguide. The latter method is especially effective for instantaneously heating an object, but if the object occupies a large proportion of the cross section of the waveguide, it will be affected by the waveguide's electric field distribution. The temperature difference in the heated part of the object becomes so large that it cannot be ignored.

Figure 1 shows a conventional microwave heating device using a transmission line. A waveguide is used as the transmission line, which generates an electric field in the direction of arrow E, that is, works as a TE ₁₀ mode. Short-circuit the ends to form applicator 1, and connect one long side to applicator 1.
The head of a biological specimen 2 such as a mouse is inserted through an insertion opening 1c formed at a predetermined distance from the shorting plate 1b in FIG. That is, the entire specimen 2 is pushed into the animal holder 3 by the pushing member 4, and its entire movement is fixed by inserting the locking plate 5 from the animal holder 3 into the pushing member 4. has been done. and,
This animal holder 3 is inserted into a chamber 6 attached to surround the outside of the insertion opening 1c of the applicator 1, so that the head of the specimen 2 enters the applicator 1. Note that the cylindrical portion 3a to which the head of the specimen 2 is fixed is made of plastic with good microwave transparency.

However, in this microwave heating device, when the microwave propagates in the direction of arrow A in the applicator 1 in the TE ₁₀ mode, the distribution of the electric field E in the applicator 1 is as shown in Figure 2a. The axial center a of the tube is the maximum, and the electric power (∝E ² ) is at the axial center a
becomes significantly stronger.

Therefore, if the volume and dimensions of the part of specimen 2 to be heated are very small compared to λg (tube wavelength) of the microwave used, the temperature difference inside the heated specimen 2 can be ignored. However, as the area to be heated becomes larger, it becomes more susceptible to the influence of the electric field distribution, and the temperature difference within the heated interior becomes so large that it cannot be ignored. Therefore, if the specimen 2 rotates even slightly in the direction of arrow B shown in FIG. When used as a research subject, one side may be overheated and the other side may be underheated, which may impede research aimed at uniformly heating parts of the brain 2a to investigate enzyme distribution in the brain.

The present invention was developed in view of this point, and its purpose is to scatter microwaves using a relatively thick, low-loss dielectric material, thereby expanding the range of areas where the electric field is strong within the applicator. Another object of the present invention is to provide a microwave heating device that can uniformly heat the inside of a specimen by expanding its heating range.

Hereinafter, the present invention will be described with reference to embodiments. Third
The figure shows one embodiment, and parts corresponding to those in FIG. 1 are given the same reference numerals. In this embodiment, the cylindrical portion 3a in the animal holder 3
A relatively thick cylinder 7 made of a low-loss dielectric material is attached to the inner wall of the long piece 1a of the applicator 1 with a set screw 8 so as to surround it with a gap in between. This cylinder 7 is attached so as to be coaxial with the axis of the insertion hole 1c of the applicator 1, so that the portion of the specimen 2 to be heated, for example, the brain 2a, is completely surrounded.

FIG. 4 shows the progress of microwaves. The direction of the microwaves traveling from above the applicator 1 is bent by the outer wall surface of the cylinder 7 made of a low-loss dielectric, but at this time, the microwaves are reflected. Waves are generated. Further, when this microwave exits into the air (inside the cylinder 7) from the inner wall surface of the cylinder 7, its traveling direction is bent and a reflected wave is generated, and these relationships follow Schunel's law. This situation also applies to the cylindrical portion 3a of the animal holder 3.

Therefore, the progress of the microwave inside the cylinder 7 is complicated, and the state is almost the same as the state of the microwave inside the oven of a microwave oven that stirs the microwave. Although this scattering is more pronounced due to the thicker cylinder 7 than due to the thinner cylinder 3a, the addition of both results in extremely good scattering within the cylinder 3a.

Therefore, the part of the specimen 2 located inside the applicator 1 is heated almost uniformly, and the uniform heating range can be greatly expanded compared to the conventional method. The rotation and movement of can also be sufficiently compensated for.

Figure 5 shows a cylinder 9 made of a low-loss dielectric material with the side opposite to the direction in which the microwaves travel (that is, the lower part) removed; in this case as well, the scattering state of the microwaves inside is the same as in Figure 4. They are almost the same, and similar effects can be obtained.

The heating distribution of the specimen 2 described above is determined by the dielectric constant, thickness, inner diameter, and axial length of the cylinders 7, 9 and 3a made of low-loss dielectrics, as well as the dimensions of the specimen 2 and the dielectric constant. Therefore, an appropriate heating distribution must be determined experimentally, taking these factors into account.

The present inventor assumes that the specimen 2 is a mouse, the brain 2a of its head is to be heated, and the cylinder 7 has a thickness of 5 mm and an inner diameter.
50mm, axial length 50mm, dielectric constant 2.2, tanδ=1/1
00, the thickness of the cylinder part 3a is 1 mm, the inner diameter is 38 mm, the dielectric constant is 2.5, the microwave tube wavelength λg is 148 mm, the microwave power is 5Kw, and the axis of the cylinder part 3a and cylinder 7 is Good results were obtained by setting the distance to the heart as λg.

6 to 8 show another example of a cylinder made of a low-loss dielectric. First, in FIG. 6, the inner wall is oriented in the axial direction so that the screwed part 10a side is thicker and the opposite side is thinner. Cylinder 10 with two steps formed
If the thickness is changed stepwise in this way, the state of microwave scattering will change stepwise in the axial direction, so the heating distribution of the specimen placed inside can be changed stepwise. I can do it.

FIG. 7 shows a cylinder 11 that can be used when inserting a specimen from the short side into the cylinder attached to the long side 1a of the applicator 1, and shows a hole for inserting the specimen. 11a is formed on the side surface, that is, on the side perpendicular to the axis. 11b is the long side 1a
This is the screwed part.

FIG. 8 shows a cutout 12a formed in a part as a relief when the specimen to be placed inside is large, and a flange 1 for attachment to the applicator 1.
2b shows the cylinder 12 formed with the cylinder 2b. 12
c is a screwed part.

Note that in the above, the head of the specimen 2 is fixed so as not to move by the cylindrical part 3a of the animal holder 3, but this fixation is performed directly with a relatively thick cylinder made of a low-loss dielectric material. You can also do that.

As described above, according to the present invention, traveling microwaves can be sufficiently scattered, so that the heating distribution, which was conventionally determined almost by the shape of the waveguide, can be changed and expanded. The heating range is expanded, and a desired region can be uniformly heated without being affected by the movement of the specimen.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional microwave heating device.
Figure 2a is a diagram showing the electric field and power distribution characteristics within the applicator, b is a cross-sectional view taken along the - line in Figure 1, and Figure 3 is a cross-section of a microwave heating device according to an embodiment of the present invention. Figure 4 is a diagram showing the progression of microwaves to a cylinder, Figure 5 is a diagram showing the progression of microwaves to a cylinder in another example, and Figure 6 is a diagram showing a cylinder in yet another example. a is a front view, b
7 is a cross-sectional view, and FIGS. 7 and 8 are views showing further examples of cylinders, in which a is a front view and b is a side view. DESCRIPTION OF SYMBOLS 1... Applicator made of a waveguide, 2... Test object, 3... Animal holder, 4... Pushing member,
5... Locking plate, 6... Chamber, 7, 9-12...
...Relatively thick cylinder made of low-loss dielectric material, 8...
Set screw.

Claims (1)

[Scope of utility model registration request] The head or other part of the specimen is projected into the waveguide through an insertion port formed on the wall of a waveguide for microwave transmission, and tissue cell enzymes such as brain oxygen of the specimen are removed by microwave irradiation. In a microwave heating device for biochemical tests which is configured to deactivate, at least the microwave entrance side of the space in which the specimen protruding from the insertion port is located is covered with a low-loss dielectric, and the low-loss dielectric is A microwave heating device characterized by scattering microwaves in a space surrounded by.