JPH03110448A - Detection of magnetic fine particle in liquid and device - Google Patents

Abstract

PURPOSE:To rapidly and efficiently perform detection of a foreign matter and measurement thereof by attracting the foreign matter to magnetic fine particles by gradient of a magnetic field impressed on the downstream side of a laminar flow and changing the proceeding direc tion of these magnetic fine particles to separate them and measuring the number of the separated magnetic fine particles. CONSTITUTION:When magnetic gradient is imparted from the outside of a capillary 4 with one set of magnets 6, 7, magnetic fine particles 1a with a foreign matter attracted thereto and magnetic fine particles 1b free from attraction of the foreign matter receive force propor tional to the magnetic moment incorporated in the magnetic fine particles 1a, 1b. The direction of force due to the magnetic gradient is regulated to the direction orthogonal to the direction of a laminar flow 3 and therefore acceleration is imparted to this direction. As a result, the processing directions of the magnetic fine particles 1a, 1b are curved. At this time, the particles 1a with the foreign matter attracted thereto are large in mass and therefore accelera tion is made small. The particles 1b free from attraction of the foreign matter are small in mass and therefore acceleration is made great. Accordingly, in the bending amount of the particles 1a, 1b in the direction orthogonal to the direction of laminar flow after lapse of a constant time, the bending amount of the particles 1a is made smaller than the bending amount of the particles 1b. Therein when a partition plate 8 is provided in the laminar flow 3, the particles 1a are separated from the particles 1b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention utilizes magnetic fine particles to selectively remove foreign substances from a liquid, and also separates magnetic fine particles into predetermined groups according to particle size and magnetic moment. The present invention relates to a method and apparatus for detecting magnetic fine particles in a liquid, in which the number of magnetic particles is measured by separating the particles into two.

[Prior art 1] In recent years, technology using magnetic fine particles has come to be widely applied industrially. In particular, the applications of magnetic tape and flexible disks in the field of magnetic media are remarkable. It is important to match the characteristics of the magnetic fine particles used in these materials in order to match the magnetic properties of the magnetic medium, and for this reason, it is important to first match the particle sizes. Industrially, it is common practice to uniformize the particle size by precisely controlling the production method.
Conventionally, this method has been considered desirable from the viewpoint of productivity.

However, due to side reactions in this method, magnetic fine particles can only be obtained as a highly dispersed group, and therefore, the magnetic properties cannot be avoided from deterioration. A common method for obtaining magnetic fine particles with uniform particle size is to perform low-pressure evaporation in an inert gas chamber. This makes it difficult to obtain magnetic particles of uniform particle size because uniformity occurs and because it is difficult to maintain a constant gas pressure within the chamber as a whole.

Therefore, in order to prevent this, by enlarging the boat shape, the area of uniform temperature is increased, and as a result, the particle size distribution is improved, and magnetic fine particles with uniform particle sizes are obtained.

In addition, in the past, after performing some kind of treatment on the surface of magnetic fine particles, they were placed in a liquid to selectively adsorb and remove unnecessary foreign substances on the surface, or to selectively adsorb necessary foreign substances. It has been put into practical use to measure these numbers. This method is relatively effective when there are a large number of foreign substances, but for example when inspecting the state of contamination of lakes, rivers, seawater, etc., in other words, the concentration of foreign substances contained in water such as lakes, etc. When the amount of foreign matter is low and high accuracy is required for detecting foreign matter, there are few suitable methods, and the following methods are used.

That is, a method is adopted in which magnetic fine particles having a magnetic moment are placed in a place where there is a magnetic gradient, and the magnetic fine particles are subjected to a force in a certain direction. This method detects antibodies in blood by applying a non-transferring magnetic field to a sample in a container, applying a magnetic gradient to magnetic particles, and moving them in a certain direction to reach the liquid surface. The number of foreign objects is measured by collecting foreign objects and detecting changes in the shape of the liquid surface such as swelling of the liquid surface.

FIG. 3 is a diagram showing an example of a conventional method, in which reference numeral 21 denotes magnetic fine particles to which foreign matter is adsorbed, 22 denotes a container containing an aqueous solution containing the magnetic fine particles 21, and 23 and 24 refer to the entire aqueous solution in the container 22. This is a set of magnets that provide a magnetic gradient. Then, when a magnetic gradient is applied to the aqueous solution by the magnets 23 and 24, as time passes, the magnetic fine particles 21 in the aqueous solution subjected to the force of the magnetic field gradient rise above the water surface, forming a raised portion 25. The conventional method is to measure the size of the raised portion 25 to determine the size of the magnetic fine particles 2.
This is to detect the number of foreign substances adsorbed on one.

[Problem to be Solved by the Invention 1] The conventional method and apparatus for detecting magnetic fine particles in a liquid described above cannot efficiently collect magnetic fine particles of uniform particle size when obtaining magnetic fine particles according to an industrially strict WA manufacturing method. The problem was that I couldn't get it.

In addition, when the concentration of foreign matter contained in water such as lakes and marshes, that is, the concentration of foreign matter contained in the liquid is low and high accuracy is required to detect this foreign matter, it is possible to detect only the foreign matter in the liquid, and furthermore, it is possible to detect the foreign matter and its detection. There was a problem in that measurement required a large amount of time.

[Means for Solving the Problems] In order to solve these problems, the method of detecting magnetic particles in a liquid of the present invention detects foreign particles in a capillary in which a laminar flow state of a liquid such as water or alcohol is formed. A solution containing magnetic fine particles that adsorbed foreign matter and magnetic fine particles that did not attract foreign matter was gradually poured into the solution, creating a state with almost no turbulence, and the foreign matter was adsorbed by a magnetic field gradient applied in a perpendicular direction downstream of this laminar flow. This separation is performed by changing the traveling direction of the magnetic particles, and the number of separated magnetic particles is measured by irradiating a laser beam in a direction perpendicular to the laminar flow of the liquid and detecting the amount of scattered light of the laser beam. A method for detecting magnetic particles in a liquid is characterized by:

Further, a large number of magnetic fine particles each having a different particle size and having a wide particle size range are introduced into the laminar flow of the liquid,
This is a method for detecting magnetic fine particles in a liquid that makes it possible to measure or collect the number of magnetic fine particles in each group within a predetermined particle size range.

In addition, in order to realize this detection method, a thin tube through which a liquid such as water or alcohol flows in a laminar flow state, a solution inlet provided in a part of this thin tube, and a solution inlet provided downstream of this solution inlet are required. A set of magnets for applying a magnetic field gradient to magnetic particles in a solution containing magnetic particles that adsorb foreign substances and magnetic particles that do not adsorb foreign particles that are poured in from the solution inlet, and a foreign substance that is separated by the magnetic field gradient. A partition plate for separating magnetic particles that have adsorbed foreign substances from magnetic particles that do not attract foreign substances, and a measuring means installed downstream of this partition plate to measure the number of separated magnetic particles based on the amount of scattered laser light. It is equipped with the following.

In addition, in order to realize this detection method, a thin tube through which liquid such as water or alcohol flows in a laminar flow state, a solution inlet provided in a part of this thin tube, and particles poured from this solution inlet are required. A set of magnets for applying a magnetic field gradient to magnetic particles in a solution containing magnetic particles of different diameters, and multiple partitions for separating the magnetic particles separated into groups within a predetermined particle size range by the magnetic field gradient. a plate, a measuring means provided downstream of the partition plate for measuring the number of magnetic fine particles separated by the amount of scattered laser light, and a collection means provided downstream of the measuring means for collecting the separated magnetic fine particles. It is equipped with the following. [Effect] When a solution containing magnetic fine particles that have adsorbed foreign matter and magnetic fine particles that do not adsorb foreign matter is gradually poured in, the magnetic field gradient applied downstream of this laminar flow causes the magnetic fine particles that have attracted foreign matter to move in the direction of movement. These separations are performed by changing the particle size, and as a result, the number of separated magnetic particles is measured.Also, in the laminar flow, a large number of magnetic particles each having a different particle size and having a wide range of particle sizes When the particles are added, the number of magnetic particles in each group within a predetermined particle size range is counted and collected.

[Implementation N] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the method and apparatus for detecting magnetic particles in a liquid according to the present invention. In the same figure, 1
a is a magnetic particle that has adsorbed a foreign object, 1b is a magnetic particle that has not adsorbed a foreign object, 3 is a laminar flow, 4 is a thin tube made of glass or the like in which the laminar flow 3 flows in the direction of the arrow, and 5 is a tube that has adsorbed a foreign object. An inlet for slowly flowing a solution containing a mixture of magnetic fine particles 1 and magnetic fine particles 2 that do not adsorb foreign matter; 6 and 7 are a set of magnets for generating a magnetic field gradient; 8 is a laminar flow 3; a partition plate, 9.10 a layer waterfall section partitioned by the partition plate 8, 12 a measuring means for measuring the number of magnetic fine particles 1 and 2, 1
3 is a collection means for collecting the magnetic fine particles 1.2.

This device is a device for separating magnetic fine particles 18 that have adsorbed foreign matter from magnetic fine particles tb that have not adsorbed foreign matter and counting the number of each, which are dispersed in a liquid such as water or alcohol. . When fine particles are flowed into a laminar flow 3 at a certain speed or higher with almost no turbulence, the particles change their flow direction at a constant speed within the thin tube 4 without being affected by gravitational acceleration. move without When a magnetic gradient is applied here from the outside of the thin tube 4 using a pair of magnets 6 and 7, when the particles are magnetic fine particles 1a and lb, these magnetic fine particles 1a and Ib will absorb the magnetism possessed by these magnetic fine particles 1a and 1h. Receives a force proportional to the moment. and,
The force exerted on the magnetic particles 1a, lb is proportional to the magnetic moment and the strength of the magnetic field j2, and does not depend on their mass. Therefore, the magnetic particles 1a that have attracted foreign matter are similar to the magnetic particles 1b that have not attracted foreign matter. Receive power.

However, since the direction of the force due to the magnetic field gradient is perpendicular to the direction of the laminar flow 3, they are subjected to acceleration in this direction, and as a result, the magnetic particles 1a, Ib are bent in their traveling direction. At this time, the magnetic fine particles 1a that have attracted foreign matter have a large mass, so their acceleration becomes small, and conversely, the magnetic fine particles tb that have not attracted foreign matter have a small mass, so their acceleration increases. This acceleration is
By selecting the strength of the magnetic field, it can be easily set to several times the gravitational acceleration or more. Therefore, the amount by which the magnetic fine particles 1a adsorbing large-mass foreign objects are bent downward by gravitational acceleration can be almost ignored.

That is, since the amount of bending of the magnetic fine particles 1a, lb in the direction perpendicular to the laminar flow direction after a certain period of time is proportional to the acceleration, the amount of bending of the magnetic fine particles 1a that has adsorbed a foreign object with a large mass is not the same as that of the magnetic fine particles 1a that have adsorbed a foreign object with a large mass. The amount of bending is smaller than the amount of bending of the magnetic fine particles 1b. Therefore, by providing the partition plate 8 at an appropriate position in the laminar flow 3, it is possible to separate the magnetic fine particles 1a that have attracted foreign matter from the magnetic fine particles 1b that have not.

In the example shown in FIG. 1, the magnetic fine particles 1a that have adsorbed foreign matter are separated into a laminar flow section 9 in the laminar flow 3, and the magnetic fine particles tb that have not attracted foreign matter are separated into a laminar flow section 10.

In addition, the measuring means 12 for measuring the number of particles in the transparent medium based on the amount of scattered light of the laser is provided in the laminar flow section 9 and the laminar flow section 10.
The measuring means 12 measures the number of magnetic fine particles 1a that have attracted foreign matter and the number of magnetic fine particles 1b that have not attracted foreign matter.

Further, a collecting means 13 for collecting the magnetic fine particles 1a and lb is provided in a portion located further downstream of the measuring means 12, and the magnetic fine particles 1a and lb are collected by the collecting means 13.

Next, FIG. 2 is a block diagram showing another embodiment of the method and apparatus for detecting magnetic particles in a liquid according to the present invention. In this figure, the same parts as those in the configuration diagram of FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted. In Figure 2, lla, ll
b are magnetic fine particles having different particle sizes, among which lla is a large magnetic particle and llb is a small magnetic particle.

As mentioned above, the force that the magnetic particles 11a and llb receive is proportional to the magnetic moment and the strength of the magnetic field, and does not depend on their mass. Therefore, the magnetic particles 11a having a large particle size, that is, a large magnetic moment, The acceleration due to the gradient is large, and this acceleration can be easily set to several times the gravitational acceleration or more by selecting the strength of the magnetic field. Therefore, the amount by which the magnetic particles adsorbing foreign matter with a large mass, that is, the magnetic particles 11a having a large particle size, is bent downward by the gravitational acceleration is almost negligible, and the bending amount is only due to the magnetic field gradient. The amount of bending increases.

On the contrary, since the magnetic fine particles ttb having a small mass, that is, a small particle size have a small magnetic moment, the acceleration due to the magnetic field gradient is also small, and therefore the amount of bending in the laminar flow 3 is also small.

Therefore, in FIG. 2, small magnetic particles 11
b Above the partition plate 8, magnetic fine particles 1 with a large particle size are placed.
1a are separated below the partition plate 8. A measuring means 12 for measuring the number of particles in a transparent medium based on the amount of scattered light of the laser is provided in the downstream portion of the laminar flow of each thin tube separated by a plurality of partition plates 8, and this measuring means 12 is used to The number of magnetic fine particles in each group existing in the particle size range is measured.

Further, a collecting means 13 for collecting magnetic fine particles is provided at the most downstream side of each capillary, and the collecting means 13 collects magnetic fine particles having a predetermined particle size range in a state where they are separated into groups.

As explained above, the method and apparatus for detecting magnetic particles in a liquid according to the present invention is intended to separate magnetic particles dispersed in a liquid such as water or alcohol. Forming a laminar flow state in the liquid, into which a solution containing magnetic fine particles 1a with foreign matter adsorbed is gradually poured into a state in which almost no turbulence occurs,
A magnetic field gradient applied in a direction perpendicular to the laminar flow 3 separates the magnetic fine particles 1a that have adsorbed foreign matter from the magnetic fine particles 1b that have not adsorbed foreign matter, and measures the number of each, and Magnetic particles are separated from a solution containing magnetic particles as groups in each predetermined particle size range, and the number of each is counted effectively in a short time.

[Effects of the Invention] As explained above, the method and apparatus for detecting magnetic fine particles in a liquid of the present invention is such that when a solution containing magnetic fine particles to which foreign substances are adsorbed and magnetic fine particles to which foreign substances are not adsorbed is gradually poured. The structure is configured so that the traveling direction of the magnetic fine particles with foreign matter adsorbed is changed by the magnetic field gradient applied downstream of this laminar flow, these particles are separated, and the number of separated magnetic fine particles is measured. When the concentration of foreign matter contained in the liquid is low and high precision is required for detection of this foreign matter, there is an effect that detection and measurement of the foreign matter can be performed quickly and efficiently.

In addition, when a large number of magnetic fine particles each having a different particle size and having a wide range of particle sizes are introduced into a laminar flow, the number of magnetic particles in each group within a predetermined particle size range is counted. Since the structure is configured such that magnetic fine particles having a uniform particle size can be efficiently obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the method and apparatus for detecting magnetic particles in a liquid according to the present invention, and FIG. 2 is a block diagram showing another embodiment of the apparatus for detecting magnetic particles in a liquid. FIG. 3 is a block diagram of a conventional magnetic particle detection device. Ia, lb, Ila, llb --- Magnetic fine particles, 3... Laminar flow, 4... Thin tube, 5... Inflow port, 6.7... Magnet, 8... Partition plate, 12・
... Measuring means 513 ... Collection means.

Claims (4)

[Claims] (1) Gradually pouring a solution containing magnetic fine particles that adsorb foreign matter and magnetic fine particles that do not adsorb foreign matter into a thin tube in which a laminar flow state of liquid such as water or alcohol is formed;
With almost no turbulence, this separation is performed by changing the traveling direction of the magnetic particles that have adsorbed foreign matter by a magnetic field gradient applied perpendicularly downstream of this laminar flow. 1. A method for detecting magnetic particles in a liquid, the method comprising: measuring the number of separated magnetic particles by irradiating a laser beam with a laser beam and detecting the amount of scattered laser light. (2) Injecting a large amount of magnetic fine particles each having a different particle size and having a wide range of particle sizes into the laminar flow of the liquid,
A method for detecting magnetic particles in a liquid that makes it possible to measure or collect the number of magnetic particles in each group within a predetermined particle size range. (3) A capillary through which the liquid such as water or alcohol flows in a laminar flow state, a solution inlet provided in a part of the capillary, and a solution inlet provided downstream of the solution inlet into which the solution flows. a set of magnets for applying a magnetic field gradient to magnetic particles in a solution containing magnetic particles that have adsorbed foreign substances and magnetic particles that do not adsorb foreign substances; and magnetic particles that have adsorbed foreign substances that have been separated by the magnetic field gradient. A liquid in a liquid comprising a partition plate for separating magnetic particles that do not attract foreign matter, and a measuring means provided downstream of the partition plate to measure the number of magnetic particles based on the amount of scattered laser light. Magnetic particle detection device. (4) A capillary through which the liquid such as water or alcohol flows in a laminar flow state, a solution inlet provided in a part of the capillary, and the magnetic fine particles having different particle sizes poured through the solution inlet. a set of magnets for applying a magnetic field gradient to the magnetic fine particles in the solution; a plurality of partition plates for separating the magnetic fine particles separated into groups within a predetermined particle size range by the magnetic field gradient; A measuring means provided downstream of the partition plate for measuring the number of separated magnetic fine particles by the amount of scattered laser light, and a collecting means provided downstream of the measuring means for collecting the separated magnetic fine particles. A device for detecting magnetic particles in liquid.