JP5189825B2 - Magnetic signal measuring device and magnetic signal measuring method - Google Patents

Description

  The present invention relates to a magnetic signal measuring apparatus and a magnetic signal measuring method for detecting, for example, various antibodies, proteins, immunoglobulins, hormones, tumor markers, viruses, pathogens, and the like using magnetic particles and a magnetic sensor.

  Utilizing specific binding reactions such as antigen-antibody reactions, various biological substances such as hormones, antibodies, antigens, tumor markers, pathogens, viruses, cancer cells, DNA, environmentally hazardous substances, etc. Biological substance etc. ") can be detected. In recent years, there has been an increasing demand for highly sensitive and rapid detection of biological substances and the like, and apparatus development for that purpose has been actively conducted.

  For example, as a general method of immunoassay, a method is known that uses an optical marker in which a detection antibody that selectively binds to an antigen to be detected is labeled with a fluorescent enzyme or the like. In this method, the antigen-antibody binding reaction is detected as an optical signal generated from an optical marker, and the type and amount of the antigen are detected. However, such an optical method has problems such as insufficient detection sensitivity and a need for a pretreatment for purifying a sample and a washing step for washing away unbound optical markers.

  Therefore, in recent years, a magnetic method for detecting an antigen-antibody reaction using magnetic particles and a magnetic sensor has been proposed. In this magnetic method, an antibody labeled with magnetic particles (hereinafter referred to as a “magnetic marker”) is bound to a detection target substance, and a magnetic signal from the bound magnetic marker is detected using a magnetic sensor. To do. Here, by using a SQUID (Superconducting Quantum Interference Device) magnetic sensor which is a highly sensitive magnetic sensor, a higher detection sensitivity than the optical method is obtained.

  Various methods have been proposed for such a magnetic method. For example, a substance to be detected is fixed in a hole, and after the fixed substance to be detected reacts with a magnetic marker, unbound magnetic markers are washed away, and a magnetic signal from the magnetic marker combined with the substance to be detected is received. A method of measuring with a SQUID magnetic sensor is known (for example, see Patent Document 1).

  Also, a solution containing the substance to be detected and a magnetic marker are mixed to prepare a sample solution containing an aggregate formed by combining the substance to be detected and the magnetic marker, and an unbound magnetic marker is formed in the sample solution. There is a known method of measuring the magnetic signal from the sample solution by applying a magnetic field to the sample in the state of the presence of the magnetic marker and aligning the direction of the magnetic moment of the magnetic marker, and then blocking the magnetic field (for example, Patent Document 2).

  This method uses the fact that unbonded magnetic markers floating in the sample solution and the formed aggregates have different Brownian motion speeds. That is, even if the magnetic moment directions of all the magnetic markers in the sample solution are aligned in one direction by the magnetic field, if the magnetic field is interrupted, the magnetic moment directions of the uncoupled magnetic markers are quickly randomized by the Brownian motion. The magnetic signal from the uncoupled magnetic marker is quickly attenuated. On the other hand, when the magnetic marker is combined with the substance to be detected and aggregated, rotation due to Brownian motion is less likely to occur due to the increase in volume, so that the attenuation of the magnetic signal from the aggregate is delayed. By utilizing such a difference in attenuation characteristics of the magnetic signal, it is possible to measure the magnetic signal from the magnetic marker bound to the substance to be detected without removing the unbound marker. Other similar methods have been reported (for example, see Non-Patent Documents 1 to 3 and Patent Document 3).

  In addition, after the substance to be detected is fixed in the hole and the fixed substance to be detected reacts with the magnetic marker, the signal from the magnetic marker coupled to the substance to be detected is present in the presence of an unbound magnetic marker. Is known by a SQUID magnetic sensor (see, for example, Patent Document 4 and Non-Patent Document 4). Even in this method, the direction of the magnetic moment of the uncoupled magnetic marker is quickly randomized by the Brownian motion, so that the magnetic signal from the uncoupled magnetic marker is quickly attenuated. However, since the substance to be detected is fixed, the magnetic signal from the magnetic marker coupled to the substance to be detected is difficult to attenuate. Therefore, it is possible to measure the magnetic signal from the magnetic marker combined with the substance to be detected without removing the unbound marker. Other similar methods have been reported (for example, see Non-Patent Document 5).

  In addition, methods using magnetic susceptibility measurement have also been reported (see, for example, Patent Documents 5 and 6 and Non-Patent Document 6). In the method disclosed in Patent Document 5, a DC magnetic field that magnetizes the magnetic marker is applied from a direction perpendicular to the magnetic flux detection direction of the SQUID magnetic sensor, and is generated by the magnetic marker that moves within the magnetic flux detection region of the SQUID magnetic sensor. Changes in the magnetic field are detected. In the method disclosed in Patent Document 6, an alternating magnetic field is applied to a magnetic marker, and a magnetic signal from the magnetized magnetic marker is measured by a SQUID magnetic sensor. Further, in Non-Patent Document 6, AC susceptibility measurement is performed on an uncoupled magnetic marker, and the fact that the intensity of the magnetic signal from the uncoupled magnetic marker is attenuated due to the coupling with the substance to be detected is utilized. The amount of the substance to be detected is evaluated.

  As described above, various magnetic methods for detecting biological substances and the like have been proposed, and the magnetic method is superior to the optical method in terms of detection sensitivity. However, there are various problems with the magnetic method from the practical point of view of simply and accurately measuring a magnetic signal by collecting a large number of samples.

  For example, as a specific example of densely arranging a large number of samples, there is an example of sample arrangement in a 96-well microplate that is widely used in the current examination of biological materials and the like. The 96-hole microplate has bottomed holes for accommodating samples in 8 rows × 12 columns at intervals of about 9 mm. When such a sample container is used, the running cost of the sample container can be reduced. Moreover, since the sample container becomes medical waste, its disposal cost can be reduced. Furthermore, since many samples are inspected collectively, the time for exchanging sample containers and the like can be reduced, so that the inspection efficiency is improved. In addition, the arrangement of the holes in the 96-hole microplate is a standard specification, and various instruments and devices that match the arrangement of the holes are sold, so that these can be used effectively. it can. Therefore, if a sample arranged in accordance with a standard such as a 96-hole microplate can be inspected by a magnetic method, such various effects can be enjoyed.

However, although there are proposals for inspecting a large number of samples using magnetic signals (see, for example, Patent Documents 7 and 8), the lines of magnetic force generated from the magnetic particles are closed loops from one pole to the other, so they go straight. Poor nature and easily leaks to the surroundings. For this reason, when a large number of samples are densely arranged as in the case of using a 96-hole microplate, the magnetic sensor also measures a leakage magnetic signal from a sample adjacent thereto when measuring a magnetic signal from a predetermined sample. Therefore, it is difficult to accurately measure the magnetic signal from each sample.
JP-A-63-90765 JP-A-3-220442 Japanese National Patent Publication No. 10-513551 JP 2005-257425 A JP 2001-33455 A JP 2001-133458 A JP 2001-524675 A JP 2005-188950 A YR Chemla et al., “Proc. National Acad. Sciences of USA”, 97, 14268 (2000) A. Haller, et al, “IEEE Trans. Appl. Supercond.”, 11, 1371 (2001) HLGrossman et al., “Proc. National Acad. Sciences of USA”, 101, 129 (2004) K. Enpuku et al., “IEEE Trans. Appl. Supercond.”, 13, 371 (2003) R. Kotitz et al., “IEEE Trans. Appl. Supercond.”, 7, 3678 (1997) CYHong et al., “Appl. Phys. Lett.”, 88, 212512 (2006).

  The present invention has been made in view of such circumstances, and when a large number of samples are densely arranged, a magnetic signal from a predetermined sample is excluded, and a magnetic signal from a sample adjacent to the sample is excluded with high accuracy. An object of the present invention is to provide a magnetic signal measuring device and a magnetic signal measuring method capable of measuring.

  In the present invention, first, a plurality of samples including a magnetic material are arranged at predetermined intervals, and an inspection sample and one or more adjacent samples adjacent to the inspection sample are selected from the samples, and a magnetizing mechanism such as an electromagnet is used. Then, a magnetic field having a constant strength is applied to the inspection sample and the adjacent sample in the same direction to magnetize the magnetic particles contained in each sample, and then the magnetic signal from each sample is measured using a magnetic sensor. Thus, the first signal waveform is obtained. Next, only the direction of the magnetic field applied to the test sample is changed, and a magnetic field of a certain strength is applied to the test sample and the adjacent sample to magnetize the magnetic particles contained in each sample, and then the magnetic signal from each sample is detected by the magnetic sensor Measure using A second signal waveform is thus obtained. A difference signal waveform is obtained by subtracting the second signal waveform from the obtained first signal waveform, and a substance to be detected contained in the test sample is detected from the difference signal waveform. By sequentially changing the selection of the inspection sample and performing the same process, all the samples can be inspected.

  According to the magnetic signal measuring device and the magnetic signal measuring method of the present invention, when a large number of samples are arranged densely, a magnetic signal from a predetermined sample is excluded from a magnetic signal from a sample adjacent thereto. It can measure with high accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an example of a sample that can be inspected by the magnetic signal measuring method according to the present invention, a manufacturing method thereof, and a principle of measuring a magnetic signal from the manufactured sample will be described. Here, a sample for performing an immunological test using an antigen-antibody reaction and a sample for detecting pathogenic bacteria are taken up.

  FIG. 1 schematically shows a preparation procedure of a sample used for an immunoassay using an antigen-antibody reaction and a measurement principle of a magnetic signal from the sample. As shown in FIG. 1 (a), a container 101 is prepared in which an immobilizing antibody 102 is immobilized on a bottom surface 101a and the inner wall surface is covered with a blocking agent 103 in order to prevent nonspecific adsorption to the inner wall surface. In addition, a liquid specimen 105 containing an antigen 106 as a substance to be detected and a solution 108 containing a magnetic marker 107 (an antibody labeled with magnetic particles) that binds to the antigen 106 are prepared.

  The container 101 is made of a nonmagnetic material such as resin. The magnetic particles used in the magnetic marker 107 are magnetized in the direction of the magnetic field when a magnetic field is applied, and after the magnetic field is cut off, residual magnetism remains, and a magnetic signal caused by the residual magnetism (hereinafter simply referred to as “magnetic signal”). ) Must be generated.

  As shown in FIG. 1B, when the specimen 105 is injected into the container 101, a part of the antigen 106 contained in the specimen 105 binds to the fixing antibody 102 by an antigen-antibody reaction. The antigen thus bound to the fixing antibody 102 is represented by reference numeral 106a, and the floating antigen is represented by reference numeral 106b.

  Next, as shown in FIG. 1C, when the solution 108 is injected into the container 101, a part of the magnetic marker 107 contained in the solution 108 reacts with the antigen 106 a bound to the fixing antibody 102 by an antigen-antibody reaction. Join. In addition, a part of the magnetic marker 107 binds to the antigen 106 b that is not bound to the fixing antibody 102. Thus, the magnetic marker coupled to the antigen 106a is represented by reference numeral 107a, the magnetic marker coupled to the antigen 106b is represented by reference numeral 107b, and the magnetic marker not coupled to either of the antigens 106a and 106b is represented by reference numeral 107c. A sample solution is thus prepared.

  The magnetic markers 107b and 107c move randomly in the sample solution by Brownian motion, but the movement of the magnetic marker 107a is restricted. In this state, as shown in FIG. 1D, when a magnetic field in the direction indicated by the arrow R is applied to the sample solution, all the magnetic markers 107a to 107c are magnetized in the direction of the magnetic field. In FIG. 1D, the direction of magnetization of the magnetic markers 107a to 107c (that is, the direction of the magnetic moment) is indicated by an arrow r. Note that the direction of the magnetic field applied to the sample solution is not limited to the direction of the arrow R, and may be, for example, the reverse direction of the arrow R or a direction orthogonal to the arrow R, and the magnetic markers 107a to 107c are applied. Magnetized in the direction of the magnetic field.

  Thereafter, when the magnetic field is removed as shown in FIG. 1 (e), the magnetic markers 107b and 107c move randomly in the sample solution by Brownian motion. For this reason, the magnetic signals from the magnetic markers 107b and 107c are canceled when the direction of the magnetic moment becomes random, and no net magnetic signal is generated. On the other hand, since the magnetic marker 107a does not cause Brownian motion and the direction of the magnetic moment does not change even when the magnetic field is removed, a magnetic signal proportional to the amount of the antigen 106a bound to the fixing antibody 102 is generated. .

  Therefore, measuring the magnetic signal from the sample solution is substantially the same as measuring only the magnetic signal from the magnetic marker 107a. Therefore, when measuring the magnetic signal from the magnetic marker 107a, it is not necessary to perform operations such as cleaning for removing the magnetic markers 107b and 107c from the container 101. Thus, in contrast to the inspection using an optical marker that requires a cleaning process, the inspection that does not require a cleaning process has the advantage that the labor of the sample preparation process can be saved and the inspection time can be shortened.

  Since the amount of the antigen 106a bound to the fixing antibody 102 depends on the amount of the antigen 106 contained in the specimen 105, the magnetic signal from the magnetic marker 107a is converted into a magnetic sensor 109 such as a highly sensitive SQUID magnetic sensor. The antigen 106a can be quantified by detecting with. For example, when the quantitative relationship among the fixing antibody 102, the antigen 106, and the magnetic marker 107 is magnetic marker 107> fixing antibody 102> antigen 106, the total amount of the antigen 106 is ideally quantified.

  As described above, when the Brownian motion of the magnetic markers 107b and 107c is sufficient, the magnetic signals from these are canceled out, and thus it is not necessary to remove them by washing or the like. If the movement is not sufficient, the magnetic signal from the magnetic markers 107b and 107c may be detected as noise. For example, when there is a residual magnetic field due to insufficient magnetic shielding against the geomagnetism, the magnetic markers 107b and 107c perform Brownian motion while receiving a force in the direction of the residual magnetic field, so that the orientation is not completely random. Also, when the magnetic markers 107b and 107c are aggregated or precipitated in the solution, the Brownian motion becomes incomplete and magnetic signals from the magnetic markers 107b and 107c are generated.

  Therefore, when the Brownian motion of the magnetic markers 107b and 107c is not sufficient, a solution 108 containing the magnetic marker 107 is injected into the container 101 as shown in FIG. As shown in FIG. 1 (d ′), a cleaning operation for removing the sample solution is performed, and then a magnetic field indicated by an arrow R is applied to the magnetic marker 107 a remaining in the container 101. When the magnetic marker 107 is magnetized in this way, as shown in FIG. 1 (e '), even after the magnetic field is removed, a magnetic signal is generated from the magnetic marker 107a. By measuring with the sensor 109, the antigen 106a can be quantified.

  Next, FIG. 2 schematically shows a sample used for detection of pathogenic bacteria and a measurement principle of a magnetic signal from the sample. As shown in FIG. 2A, the sample solution 114 accommodated in the container 111 includes a pathogen 112 that is a substance to be detected, a magnetic marker 113a that is coupled to the pathogen 112, and a magnetism that floats in the sample solution 114. A marker 113b is included. Such a sample solution 114 is prepared by, for example, mixing a solution containing a magnetic marker with a solution such as serum containing the pathogenic bacteria 112, and a part of the magnetic marker is combined with the pathogenic bacteria 112 and indicated by reference numeral 113a. The remaining magnetic marker is indicated by reference numeral 113b.

  The sample solution 114 shown in FIG. 2A is prepared by combining a magnetic marker in which magnetic particles are pre-magnetized with the pathogen 112. The arrow r shown in FIG. 2A indicates the direction of the magnetic moment of the magnetic marker. Needless to say, the magnetic moment of the magnetic marker 113b floating on the sample solution 114, the magnetic marker 113a bound to the pathogen 112. The magnetic moments are also not aligned in one direction.

  As shown in FIG. 2B, when a magnetic field is applied to the sample solution 114 shown in FIG. 2A using the magnet 115 in the direction indicated by the arrow R, the magnetic markers 113a and 113b are magnetized. The magnetization direction (arrow r) of the magnetic marker 113a combined with the pathogen 112 can be aligned with the magnetic field direction (arrow R). At this time, the magnetic marker 113b floating in the sample solution 114 is also magnetized in the direction of this magnetic field.

  As shown in FIG. 2C, when the magnet 115 is removed, the magnetic signal from the sample solution is attenuated by the Brownian motion of the pathogen 112 and the magnetic marker 113b, but the relaxation time of the rotational motion in the Brownian motion is Since the pathogen 112 has a volume sufficiently larger than the magnetic marker 113b in proportion to the volume, the component derived from the magnetic marker 113b of the magnetic signal from the sample solution 114 is quickly attenuated. Thus, the component derived from the magnetic marker 113a attenuates gently. Therefore, by using such a difference in relaxation time, the magnetic signal from the magnetic marker 113b is greatly attenuated, but the magnetic signal from the sample solution is received at a timing when the magnetic signal from the magnetic marker 113a remains sufficiently. Measurement is performed by a magnetic sensor 116 such as a SQUID magnetic sensor. Thus, the magnetic signal from the magnetic marker 113a can be selectively measured.

  Here, the magnetic signal is measured in a state where the pathogenic bacteria 112 is floating in the sample solution 114 without fixing the pathogenic bacteria 112. However, if the pathogenic bacteria and cells are fixed by a method using a solid phase antibody. The magnetic signal from the sample solution can be measured by the method described above with reference to FIG. The target of detection is not limited to the above-mentioned antibodies and pathogenic bacteria, but also includes biological substances such as hormones and proteins, substances detectable by binding assays such as DNA, leukocytes, lymphocytes, and cancer cells. It is done.

  Next, an embodiment of an apparatus and method for measuring magnetic signals from a plurality of samples arranged at predetermined intervals will be described.

<< First Embodiment >>
FIG. 3 shows the configuration of a simple magnetic signal measuring apparatus according to the first embodiment and its operation mode. 3A to 3F, the directions X, Y, and Z of the three-dimensional orthogonal coordinate system are determined as shown in FIG.

  The magnetic signal measuring apparatus 10 includes a stage 4, a moving mechanism 2 that can move linearly on the stage 4 in the X direction, a support plate 3 attached to the moving mechanism 2, and a support plate 3 at a constant interval in the X direction. The electromagnet 5a on the extended line of the line connecting the six containers 1a to 1f arranged in one row, the three electromagnets 5a to 5c installed in one row at regular intervals in the X direction, and the electromagnets 5a to 5c. ˜5c, and a magnetic sensor 6 installed at a position a certain distance away. Here, the containers 1a to 1f are arranged on the support plate 3, but instead of this, a sample container having a rectangular plate shape with holes for receiving samples at regular intervals in the length direction is used. It may be used.

  Samples 8a to 8f are accommodated in the containers 1a to 1f, respectively. The containers 1a to 1f are, for example, the container 101 described above with reference to FIG. 1, and the samples 8a to 8f are sample solutions (see FIG. 1C) accommodated in the container 101. The support plate 3 is made of a nonmagnetic material such as resin.

  The arrangement interval of the containers 1a to 1f and the installation interval of the electromagnets 5a to 5c are set to the same interval L. The moving mechanism 2 and the electromagnets 5a to 5c are installed with their positions shifted in the Y direction, and the moving mechanism 2 does not collide with the electromagnets 5a to 5c when the moving mechanism 2 is linearly moved in the X direction. . When the containers 1a to 1f are linearly moved in the X direction by linearly moving the moving mechanism 2 in the X direction, the containers 1a to 1f pass directly above the electromagnets 5a to 5c and the magnetic sensor 6 (Z direction side). .

  A pulse current is applied to the electromagnets 5a to 5c from a power supply circuit (not shown), whereby a pulse magnetic field is generated simultaneously. The direction of the pulse current applied to the electromagnets 5a and 5c is constant, but the direction of the pulse current applied to the electromagnet 5b can be reversed by operating a switch built in the power supply circuit. . That is, the direction of the pulse magnetic field generated from the electromagnets 5a and 5c is constant, but the direction of the pulse magnetic field generated from the electromagnet 5b can be reversed.

  Samples 8a to 8f contain magnetic particles. For example, if the samples 8a to 8f are sample solutions stored in the container 101 shown in FIG. 1C, the magnetic particles are magnetic particles constituting the magnetic markers 107a to 107c. The magnetic particles are magnetized in the direction of the pulse magnetic field by application of the pulse magnetic field by the electromagnets 5a to 5c, and the residual magnetism remains after the pulse magnetic field is cut off, and the property that the magnetic signal is generated is required. Needless to say, after applying a pulse magnetic field with the same strength again in a state of having residual magnetism or being demagnetized after that, after applying a pulse magnetic field using electromagnets 5a to 5c. It is preferable that the residual magnetism has a property of substantially the same.

  The magnetic sensor 6 is, for example, a SQUID magnetic sensor. The magnetic sensor 6 measures a magnetic signal for each of the samples 8a to 8f when the containers 1a to 1f pass immediately above.

  Next, a method for measuring magnetic signals from the samples 8a to 8f by the magnetic signal measuring device 10 will be described. Needless to say, all of the samples 8a to 8f are to be inspected. Here, first, the samples 8b and 8e are selected as the inspection samples, and the magnetism from the samples 8a and 8c adjacent to the sample 8b is selected. The measurement of the magnetic signal from the sample 8b from which the signal is excluded and the measurement of the magnetic signal from the sample 8e from which the magnetic signals from the samples 8d and 8f adjacent to the sample 8e are excluded are performed. Thereafter, the inspection sample is changed to samples 8c and 8f, and the same measurement as in the case of samples 8b and 8e is performed. Further, the inspection sample is changed to samples 8a and 8d, and the same measurement as in the case of samples 8b and 8e is performed. I will do it.

  When the moving mechanism 2 is moved in the X direction at a constant speed from the state shown in FIG. 3A, the support plate 3 and the containers 1a to 1f, that is, the samples 8a to 8f move in the X direction. As shown in FIG. 3B, when the sample 8a passes immediately above the electromagnet 5a, the sample 8b passes immediately above the electromagnet 5b, and the sample 8c passes immediately above the electromagnet 5c, the pulse current from the power supply circuit is electromagnetized. Apply to 5a-5c. Thereby, the pulse magnetic field generated simultaneously from the electromagnets 5a to 5c is applied to the samples 8a to 8c, and the magnetic particles contained therein are magnetized (magnetized).

  At this time, the directions of the pulse magnetic fields generated from the electromagnets 5a to 5c are aligned in the Z direction as indicated by an arrow P in FIG. As a result, the magnetic particles contained in the samples 8a to 8c are magnetized in the direction of the arrow P. Hereinafter, this magnetization direction is referred to as “forward direction”. Note that the magnetic field strength of the pulse magnetic field can be about one hundred to several thousand gausses.

  After the pulse magnetic field is applied to the samples 8a to 8c, the moving mechanism 2 continues to move linearly in the X direction, whereby the sample 8b passes over the electromagnet 5a, and the sample 8c passes over the electromagnet 5b and further the electromagnet 5a. Pass over. During this time, no pulse magnetic field is generated from the electromagnets 5a to 5c. Thus, when the moving mechanism 2 is continuously linearly moved in the X direction, the moving speed of the moving mechanism 2 is such that substantially only one pulse magnetic field is applied to one sample. And the generation time of the pulse magnetic field are adjusted.

  Then, as shown in FIG. 3C, when the sample 8d passes immediately above the electromagnet 5a, the sample 8e passes immediately above the electromagnet 5b, and the sample 8f passes immediately above the electromagnet 5c, the electromagnets 5a to 5c The generated pulse magnetic field is applied to the samples 8d to 8f, and the magnetic particles contained therein are magnetized. The direction of the pulse magnetic field at this time is also assumed to be the forward direction.

  When the samples 8a to 8c reach just above the electromagnets 5a to 5c, the moving mechanism 2 is temporarily stopped, a pulse magnetic field is generated from the electromagnets 5a to 5c, and applied to the samples 8a to 8c. When the samples 8d to 8f reach directly above the electromagnets 5a to 5c, the moving mechanism 2 is temporarily stopped, a pulse magnetic field is generated from the electromagnets 5a to 5c, and applied to the samples 8d to 8f. The driving of the moving mechanism 2 may be resumed.

  After the magnetic particles contained in the samples 8a to 8f are magnetized in this way, as shown in FIG. 3D, when the moving mechanism 2 is further moved in the X direction, the samples 8a to 8f are magnetic sensors. Pass directly above 6. At that time, magnetic signals from the samples 8a to 8f are detected by the magnetic sensor 6 for each of the samples 8a to 8f. Hereinafter, a magnetic signal waveform obtained by measuring a magnetic signal from each sample after applying a magnetic field in the same direction to the test sample and an adjacent sample adjacent to the test sample in this way is referred to as a “first signal waveform”. I will call it.

  FIG. 4A shows the first signal waveforms measured for the samples 8a to 8f. When the arrangement interval L between the corresponding containers 1a to 1f is narrow, the magnetic sensor 6 detects the magnetic signal from the adjacent sample as noise when measuring the magnetic signal of the predetermined sample. . That is, the first signal waveform includes a lot of noise, and it is extremely difficult to accurately detect the net magnetic signals from the samples 8a to 8f using only the first signal waveform.

For example, in the magnetic signal (M _8b ) detected when the sample 8 b passes over the magnetic sensor 6, the magnetic signal from the adjacent samples 8 a and 8 c is added to the magnetic signal (S _{8 b} ) from the sample 8 b. It is included as noise (N _8a , N _8c ). Here, assuming that the influence of the magnetic signals from the samples 8d to 8f located farther from the sample 8b than the samples 8a and 8c can be ignored.
M _8b = S _8b + N _8a + N _8c (1st formula)
The relationship holds. Therefore, the noise (N _8a , N _8c ) is removed from the first equation to obtain a magnetic signal including only the magnetic signal derived from the sample 8b. Similarly, the noise (N _8d , N _8f from the samples 8d, 8f is obtained. ) And the magnetic signal including only the magnetic signal derived from the sample 8e needs to be obtained.

  Therefore, next, magnetic fields in the direction opposite to the forward direction are applied to the samples 8b and 8e that are inspection samples, and the samples 8a and 8c that are samples adjacent to the sample 8b and the samples 8d and 8f that are samples adjacent to the sample 8e. Are each applied with a forward magnetic field to measure magnetic signals from the samples 8a to 8f.

  Specifically, after the containers 1a to 1f are returned to the positions shown in FIG. 3A, the moving mechanism 2 is moved again in the X direction at a constant speed. Thus, as shown in FIG. 3E, when the sample 8a passes immediately above the electromagnet 5a, the sample 8b passes immediately above the electromagnet 5b, and the sample 8c passes immediately above the electromagnet 5c, the electromagnets 5a and 5c Generates a forward pulse magnetic field and applies it to each of the samples 8a and 8c. From the electromagnet 5b, a pulse magnetic field in the direction of arrow Q (hereinafter referred to as "reverse direction") in which the forward arrow P is reversed. Is generated and applied to the sample 8b. Thus, the magnetic particles contained in the samples 8a and 8c are magnetized in the forward direction, and the magnetic particles contained in the sample 8b are magnetized in the reverse direction. The magnetization state of the samples 8a and 8c at this time is substantially the same as the magnetization state after the pulse magnetic field is applied in the process shown in FIG.

  After the pulse magnetic field is thus applied to the samples 8a to 8c, the moving mechanism 2 continues to move linearly in the X direction, the sample 8b passes over the electromagnet 5a, and the sample 8c passes over the electromagnet 5b and further passes over the electromagnet 5a. To do. During this time, no pulse magnetic field is generated from the electromagnets 5a to 5c.

  Then, as shown in FIG. 3 (f), when the sample 8d passes immediately above the electromagnet 5a, the sample 8e passes immediately above the electromagnet 5b, and the sample 8f passes immediately above the electromagnet 5c, the electromagnets 5a and 5c Generates a pulse magnetic field in the forward direction and applies it to the samples 8d and 8f, and generates a pulse magnetic field in the reverse direction from the electromagnet 5b and applies it to the sample 8e. Thus, the magnetic particles contained in the samples 8d and 8f are magnetized in the forward direction, and the magnetic particles contained in the sample 8e are magnetized in the reverse direction. The magnetization states of the samples 8d and 8f at this time are substantially the same as the magnetization states after the pulse magnetic field is applied in the process shown in FIG.

  After the magnetic particles contained in the samples 8a to 8f are magnetized in this way, the moving mechanism 2 is further moved in the X direction to pass immediately above the magnetic sensor 6. At that time, magnetic signals from the samples 8a to 8f are detected by the magnetic sensor 6 for each of the samples 8a to 8f. Hereinafter, after changing the direction of the magnetic field applied to the adjacent sample and changing only the direction of the magnetic field applied to the inspection sample, the magnetic field is applied to the inspection sample and the adjacent sample, respectively. A magnetic signal waveform obtained by measuring the magnetic signal is referred to as a “second signal waveform”.

FIG. 4B shows second signal waveforms measured for the samples 8a to 8f. In this second signal waveform, for example, the magnetic signal (m _8b ) detected when the sample 8 b passes over the magnetic sensor 6 is added to the adjacent sample 8 a in addition to the magnetic signal (s _{8 b} ) from the sample 8 b. , 8c are included as noise (N _8a , N _8c ). In addition, since the magnetization direction of the magnetic particles contained in the sample 8b is opposite between the measurement of the first signal waveform and the measurement of the second signal waveform, the magnetic signal (s _8b) measured for the sample _8b. ) And the magnetic signal (S _8b ) are reversed in polarity.

Therefore, the magnetic signal from the sample 8b is expressed as -s _8b, and it is assumed that the influence of the magnetic signals from the samples 8d to 8f located further away from the sample 8b than the samples 8a and 8c can be ignored.
m _8b = −s _8b + N _8a + N _8c (2nd formula)
The relationship holds.

Next, a differential signal waveform obtained by subtracting the second signal waveform shown in FIG. 4B from the first signal waveform shown in FIG. FIG. 4C schematically shows the difference signal waveform. For the portion related to the sample 8b in this differential signal waveform, from the above first and second equations,
_{M 8b -m 8b = S 8b +} N 8a + N 8c - (- s 8b + N 8a + N 8c) = S 8b + s 8b
As shown, the noise (N _8a , N _8c ) from the samples 8a, 8c can be removed, and only the magnetic signals (S _8b , s _8b ) from the sample 8b can be extracted. Similarly, for the sample 8e, it is possible to remove noise from the samples 8d and 8f and extract only the magnetic signal from the sample 8e.

For example, the magnetic signal (M _8c ) detected when the sample 8c passes over the magnetic sensor 6 when obtaining the first signal waveform is adjacent to the magnetic signal (S _8c ) from the sample 8c. The magnetic signals from the samples 8b and 8d are included as noise (N _8b and N _8d ), and the magnetic signal (m _8c) detected when the sample 8c passes over the magnetic sensor 6 when obtaining the second signal waveform. ) Includes magnetic signals from adjacent samples 8b and 8d as noise (n _8b and N _8d ) in addition to magnetic signals from sample 8c (S _8c ). Here, since N _8b and n _8b have opposite signs, S _8c and N _8d are canceled in the region for the sample 8c in the differential signal waveform, but noise (N _8b + n _8b ) derived from the sample 8b. Remains.

  Similarly, in the differential signal waveform, noise derived from the sample 8b remains in the region for the sample 8a, and noise derived from the sample 8e remains in each region for the samples 8d and 8f. However, these noises remaining in the differential signal waveform are derived from the samples 8b and 8e selected as the inspection samples, and do not substantially adversely affect the portions showing the magnetic signals from the samples 8b and 8e.

  After obtaining the magnetic signals from the samples 8b and 8e in this way, the container 1b is directly above the electromagnet 5a, the sample 8c is directly above the electromagnet 5b, and the sample 8d is an electromagnet in accordance with the procedure for obtaining the second signal waveform described above. When passing directly above 5c, a forward pulse magnetic field is generated from the electromagnets 5a and 5c and applied to the samples 8b and 8d, and a reverse pulse magnetic field is generated from the electromagnet 5b and applied to the sample 8c. Apply. Next, when the sample 8e passes immediately above the electromagnet 5a and the sample 8f passes immediately above the electromagnet 5b, a forward pulse magnetic field is generated from the electromagnets 5a and 5c and applied to the sample 8e. Generates a pulse magnetic field in the reverse direction and applies it to the sample 8f. Note that no pulse magnetic field is applied to the sample 8a, and the second generation of the pulse magnetic field by the electromagnet 5c is blanked.

  Thereafter, the magnetic signals from the samples 8a to 8f are measured by the magnetic sensor 6, a new second signal waveform is obtained, and a difference signal waveform from the previously obtained first signal waveform is obtained, whereby the sample 8c, The magnetic signal from 8f can be extracted.

  Further, according to the procedure for obtaining the second signal waveform described above, when the sample 8a passes immediately above the electromagnet 5b and the sample 8c passes immediately above the electromagnet 5c, the forward pulses from the electromagnets 5a and 5c. A magnetic field is generated and applied to the sample 8c, and a pulse magnetic field in the reverse direction is generated from the electromagnet 5b and applied to the sample 8a. Next, when the sample 8c passes immediately above the electromagnet 5a, the sample 8d passes immediately above the electromagnet 5b, and the sample 8e passes immediately above the electromagnet 5c, a forward pulse magnetic field is generated from the electromagnets 5a and 5c. Applied to the samples 8c and 8e, a pulse magnetic field in the reverse direction is generated from the electromagnet 5b and applied to the sample 8d. Note that no pulsed magnetic field is applied to the sample 8f, and the first pulsed magnetic field generated by the electromagnet 5a is blanked.

  Thereafter, the magnetic signal from the samples 8a to 8f is measured by the magnetic sensor 6, a new second signal waveform is obtained, and a difference signal waveform from the previously obtained first signal waveform is obtained, thereby obtaining the sample 8a. , 8d can be extracted.

<< Second Embodiment >>
FIG. 5 shows a schematic configuration of a magnetic signal measuring apparatus according to the second embodiment. The magnetic signal measuring apparatus 100A includes a first-order differential planar SQUID gradiometer 28 (hereinafter referred to as “SQUID 28”), a sapphire rod 25 and a copper rod 26 for holding the SQUID 28, and a cooling container for cooling the SQUID 28. 21, a magnetic shield 30 that houses the SQUID 28 and the cooling container 21, a sample table 32 that holds a sample container 71 for placing the sample 16, a shaft member 35 that supports the sample table 32, and the shaft member 35 A rotating mechanism 34 for rotating, a vertical moving mechanism 36 for moving the rotating mechanism 34 vertically, a horizontal moving mechanism 37 for moving the vertical moving mechanism 36 horizontally, and a magnet 16 for magnetizing the sample 16 disposed in the sample container 71. Magnetization mechanism 40, electromagnetic shield 29 and magnetic shield 3 that house these members and mechanisms And a control unit 20 that controls the operation of the entire magnetic signal measuring apparatus 100A, calculates the first signal waveform and the second signal waveform by calculating the magnetic signal measured by the SQUID 28, and obtains the difference signal waveform of these signals. I have.

  The cooling vessel 21 has a double structure composed of an outer layer 22 and an inner tank 23, and a vacuum heat insulating layer is formed between them. The outer tank 22 and the inner tank 23 are made of a nonmagnetic material such as SUS or FRP. The inner tank 23 is filled with liquid nitrogen 24, and the copper rod 26 is attached to the upper surface of the inner tank 23 so as to protrude from the upper surface of the inner tank 23 and to contact the liquid nitrogen filled in the inner tank 23. It has been. The sapphire rod 25 is attached to the upper surface of the copper rod 26, and the SQUID 28 is attached to the upper surface of the sapphire rod 25. Thus, the SQUID 28 is indirectly cooled by the liquid nitrogen 24 through the copper rod 26 and the sapphire rod 25 having high thermal conductivity. In addition, by arranging the sapphire rod 25 between the SQUID 28 and the copper rod 26, the influence of the magnetic noise generated from the copper rod 26 on the SQUID 28 can be reduced. The structure of SQUID 28 will be described in detail later.

  A cylindrical member 39 made of a nonmagnetic material is attached to the upper surface of the outer layer 22, and the upper surface of the cylindrical member 39 is sealed with a sapphire window 27. The SQUID 28 is disposed immediately below the sapphire window 27 in the heat insulating vacuum layer of the outer layer 22 and the inner tank 23. The cylindrical member 39 is movable in the vertical direction so that the position (height) of the sapphire window 27 can be adjusted. The magnetic shield 30 reduces the input of environmental magnetic noise to the SQUID 28, and is made of a high permeability material such as permalloy.

  FIG. 6A shows a plan view showing the schematic shape of the sample container (see FIG. 5 as appropriate), and FIG. 6B shows a plan view showing the detailed structure of the outer periphery of the sample container. The sample container 71 is made of a non-magnetic material such as a resin and has a disk shape. A hole 72 for fixing the sample container 71 to the shaft member 35 via the sample table 32 is provided at the center thereof. Yes. The sample container 71 is detachably attached to the sample table 32 and the shaft member 35 using a fixing screw 33 (see FIG. 5). In the vicinity of the outer periphery of the sample container 71, bottomed holes (hereinafter referred to as “holes”) 70 having a diameter of 5 mm for accommodating the sample 16 are provided at 49 locations at intervals of 10 mm. The sample stage 32 is also made of a nonmagnetic material such as resin.

  A notch hole 38 for inserting the sample container 71 is formed in a part of the magnetic shield 30. The vertical movement mechanism 36 and the horizontal movement mechanism 37 are driven in a state where the sample container 71 is fixed to the shaft member 35, and a part of the sample container 71 is inserted into the magnetic shield 30 through the cutout hole 38. The rotation mechanism 34 is positioned so that the bottom surface of the hole 70 is positioned directly above the sapphire window 27. In this state, by rotating the sample stage 32 and rotating the sample container 71, the 49 hole portions 70 provided in the sample container 71 sequentially pass immediately above the SQUID 28 at a constant speed. The magnetic signal of the sample 16 accommodated in the hole 70 is measured.

  Note that by positioning the sample container 71 so that the distance between the bottom surface of the hole 70 and the SQUID 28 is as short as possible, the detection sensitivity and spatial resolution of the magnetic signal from the sample 16 can be increased. The rotation speed of the sample container 71 can be normally set to 20 to 60 rpm, and a good signal-to-noise ratio can be obtained by measuring magnetic signals for 40 to 100 rotations for each of the 49 samples 16 and performing the averaging process. Is obtained.

  The magnetizing mechanism 40 and the SQUID 28 face each other across the center of rotation of the sample container 71 in a state in which the magnetic signals of the samples 16 respectively accommodated in the 49 holes 70 provided in the sample container 71 can be measured by the SQUID 28. Installed in position. FIG. 7A shows a side view of the magnetization mechanism, and FIG. 7B shows a plan view of the magnetization mechanism (see FIG. 5 as appropriate). The magnetizing mechanism 40 includes five electromagnets 41 having a diameter of 8 mm, and the five electromagnets 41 are installed on the fixed base 42 along a circular locus h drawn by the hole 70. The distance between the centers of the electromagnets 41 is set to 10 mm, which is the same as the distance between the hole portions 70. When a current of 120 mA is passed through one electromagnet 41, the strength of the magnetic field at a height at which the sample 16 accommodated in the hole 70 passes immediately above the electromagnet 41 is about 100 Gauss.

  The five electromagnets 41 are covered with a magnetic shield 43. In this magnetic signal measuring device 100A, while the SQUID 28 measures a magnetic signal from a predetermined sample among the 49 samples 16, another sample may be magnetized by the electromagnet 41. By providing the shield 43, it is possible to suppress the magnetic field generated by the electromagnet 41 from adversely affecting the detection of the magnetic signal of the SQUID 28. The magnetic shield 43 is made of a high permeability material such as permalloy.

  The electromagnetic shield 29 and the magnetic shield 31 reduce the input of environmental magnetic noise to the SQUID 28. The electromagnetic shield 29 is made of a metal material having a low electrical resistance such as aluminum. The magnetic shield 31 is made of permalloy or the like. It is composed of a high permeability material.

  Subsequently, the structure of the SQUID 28 will be described in detail. Here, a high-temperature superconducting SQUID gradiometer is used as the SQUID 28. FIG. 8A shows a schematic configuration of the entire high-temperature superconducting SQUID gradiometer, and FIG. 8B shows an enlarged view of the central portion thereof.

This high-temperature superconducting SQUID gradiometer is a high-temperature superconducting material such as YBa ₂ Cu ₃ O _x on a bicrystal substrate 60 having a structure in which single crystals such as SrTiO ₃ and MgO are bonded to each other at a bicrystal junction surface 61 while shifting the crystal orientation. A thin film of material is formed and processed to form a detection coil 62 and SQUID rings 64a and 64b.

  Each of the SQUID rings 64a and 64b crosses the bicrystal junction surface 61 formed on the bicrystal substrate 60, and grain boundary Josephson couplings 65a and 65b are formed in the high-temperature superconducting thin film formed on the bicrystal junction surface 61. Has been. As a result, two grain boundary Josephson bonds 65a are formed in the SQUID ring 64a, and two grain boundary Josephson bonds 65b are formed in the SQUID ring 64b. Since one bicrystal substrate 60 has two SQUID rings 64a and 64b coupled to one detection coil 62, one having better characteristics can be used for measuring a magnetic signal.

  The detection coil 62 constitutes an 8-shaped differential coil having two loops each having a side of 5 mm. When a magnetic flux is input to the detection coil 62, a difference amount between induced currents generated in the two loops flows through the central portion 66 of the detection coil 62 to the SQUID rings 64a and 64b, and this current is detected as a magnetic flux. The two feedback coils 67a and 67b are formed on the bicrystal substrate 60 in a pattern surrounding one loop of the detection coil 62, and one of these is used.

  The wiring pads 63 and 68 are formed on the high-temperature superconducting thin film with a predetermined pattern using gold (Au). Specifically, the wiring pads 63 are provided at four locations so as to be electrically connected to the SQUID rings 64a and 64b, and the wiring pads 68 are provided at four locations so as to be electrically connected to the feedback coils 67a and 67b. ing.

  An arrow 69 shown in FIG. 8A indicates the passing direction of the sample 16. When the sample 16 is magnetized in the direction perpendicular to the paper surface depicted in FIG. 8A and the sample 16 passes over the high-temperature superconducting SQUID gradiometer in the direction of the arrow 69, the sample 16 has two loops. Across a detection coil 62 having FIG. 8C schematically shows a magnetic signal waveform obtained at this time. Since the sample 16 passes over two loops having different polarities constituting the detection coil 62, a magnetic signal waveform having continuous peaks in the vertical direction is obtained.

A method for measuring a magnetic signal by the magnetic signal measuring apparatus 100A will be described below (see FIG. 5 as appropriate). As a sample 16 for generating a magnetic signal, polymer-magnetic composite particles in which fine particles of iron oxide (Fe ₃ O ₄ ) having a particle diameter of 10 to 25 nm are coated with a nonmagnetic polymer are dispersed at a concentration of 0.5 mg / ml. An aqueous solution (hereinafter, referred to as “composite particle dispersion”) was used, and each polymer-magnetic material composite particle contains a plurality of fine iron oxide particles, and the particle size of one polymer-magnetic material composite particle. Is about 100-200 nm and exhibits a remanence of 2-10 emu / g.

  First, about 500 ng of the composite particle dispersion was injected into each of the five adjacent holes 70 formed in the sample container 71. Even when a magnetic field is applied to the composite particle dispersion and the magnetic signal is measured after the magnetic field is cut off, the polymer-magnetic composite particles move freely in the composite particle dispersion, and the composite particle dispersion Therefore, the amount of the polymer-magnetic composite particles contained in the composite particle dispersion injected into the sample container 71 cannot be determined as it is. Therefore, the composite particle dispersion injected into each of the five hole portions 70 was sufficiently dried to fix the polymer-magnetic composite particles.

  In this way, five samples 16 are arranged in the sample container 71. Thereafter, the sample container 71 was fixed to the sample stage 32, and the sample 16 was arranged on the electromagnet 41 on a one-to-one basis. Subsequently, a current of 120 mA was simultaneously applied to the electromagnet 41 for 0.1 second, and the sample 16 was magnetized by the magnetic field generated thereby. Here, the directions of the magnetic fields generated by the five electromagnets 41 are all the same. After this magnetization process, the sample container 71 was rotated at a rotation speed of 20 rpm, and the magnetic signal from the sample 16 was measured a plurality of times, for example, 20 times with the SQUID 28, and the average was obtained.

  FIG. 9A shows the magnetic signal waveform thus obtained, that is, the first signal waveform. Here, the numerical value on the horizontal axis shown in FIG. 9A is converted into the interval between the samples 16, that is, the interval between the hole portions 70. In the first signal waveform, five peaks are detected at the top and bottom, and the interval between the upward peaks and the interval between the downward convex peaks coincide with 10 mm, which is the arrangement interval of the sample 16. It can be considered that the magnetic signals from the five samples 16 overlap.

  Next, the sample 16 was placed one-on-one directly above the electromagnet 41 again. Out of the five electromagnets 41, the direction of the current flowing through the four electromagnets excluding the electromagnet installed at the center is not changed, and the electromagnet installed at the center is opposite to the other four electromagnets. A current of 120 mA was simultaneously supplied to the five electromagnets 41 for 0.1 second so that a current in the direction flows. Accordingly, only the central electromagnet of the five electromagnets 41 generates a magnetic field in the opposite direction to the other four electromagnets, so that only the central sample of the five samples 16 is opposite to the other four samples. Magnetized in the direction.

  After this magnetization process, the sample container 71 was rotated at a rotation speed of 20 rpm, and the magnetic signal from each sample 16 was measured a plurality of times, for example, 20 times with the SQUID 28. FIG. 9B shows the magnetic signal waveform thus obtained, that is, the second signal waveform. When the second signal waveform is compared with the first signal waveform shown in FIG. 9A, it can be clearly seen that the magnetic signal from the central sample among the five samples 16 changes greatly.

  FIG. 9 (c) shows a differential signal waveform obtained by subtracting the second signal waveform shown in FIG. 9 (b) from the first signal waveform shown in FIG. 9 (a). It can be seen that the magnetic signals are almost completely removed from the samples at both ends of the five samples 16. Two samples adjacent to the center sample among the five samples 16 include noise derived from the center sample whose magnetization direction is changed, as described in the measurement principle described above with reference to FIG. It is thought that this appears as some unevenness. It was confirmed that the magnetic signal from the central sample magnetized by changing the magnetization direction was clearly extracted.

  As described above, in the case of a high-density sample arrangement in which magnetic signals interfere with each other, not all the samples are inspected at the same time, but the inspection samples are sequentially selected and the magnetic signal is measured as described above. This eliminates the magnetic signal from the adjacent sample, measures the accurate magnetic signal for each sample, and quantifies the substance to be detected contained in each sample.

  Here, polymer-magnetic composite particles are used as a sample having residual magnetism, but the present invention is not limited thereto, and any sample having residual magnetism may be used. In addition, usable magnetic sensors are not limited to SQUID magnetic sensors. In addition, MR (Magnet Resistive) sensors, GMR (Giant Magnet Resistive) sensors, Hall elements, optical pumping magnetometers, fluxgate magnetometers, etc. Can be used.

<< Third Embodiment >>
FIG. 10 shows a schematic configuration of a magnetic signal measuring apparatus according to the third embodiment. The magnetic signal measuring device 100B is different from the magnetic signal measuring device 100A shown in FIG. 5 in that the reflection markers 51 and 56 for detecting the position of the sample 16 arranged in the sample container 71 are provided in the sample container 71. The reflection marker 51, 56 is detected by the position detection sensor 50, and a magnetizing mechanism 45 is provided instead of the magnetizing mechanism 40. Due to the difference in the configuration, the magnetic signal measuring device The magnetic signal from the sample 16 is measured in a manner different from 100A. Hereinafter, these points will be described.

  FIG. 11A is a plan view showing the positional relationship among the sample container, the SQUID, and the magnetization mechanism, and FIG. 11B is an enlarged view of the region surrounded by the square in FIG. 11A. The side view showing the structure of the electromagnet which comprises a magnetization mechanism is shown to c), respectively. As described above with reference to FIG. 6, the structure of the sample container 71 is described. The sample container 71 has a hole 70 for placing the sample 16. Therefore, the hole 70 is not shown in each drawing of FIG.

  Forty-nine samples 16 are arranged in the sample container 71 at equal intervals along a circumference 47 centered on the rotation center of the sample container 71. In order to specify the positions of these samples 16, a single-line reflection marker 51 is provided at one position along the circumference 48 concentric with the circumference 47 on the back surface of the sample container 71 at a single interval. Markers 56 are respectively attached at 48 locations. The position detection sensor 50 detects the position of the sample 16 by irradiating a laser beam toward the back surface of the sample container 71 and measuring the reflected signal. At this time, using the difference between the reflected signal from the reflective marker 51 and the reflected signal from the reflective marker 56, the position of the sample corresponding to the reflective marker 51 can be identified from among the 49 samples 16.

  The magnetizing mechanism 45 includes three electromagnets 46 a to 46 c, and the electromagnets 46 a to 46 c are arranged on the fixed base 42 at the same interval as the arrangement interval of the samples 16 along the circumference 47 that is also a movement locus of the sample 16. is set up. FIG. 11C shows the structure of the electromagnet 46b. The electromagnets 46a to 46c have the same structure, and have a structure in which a copper wire coil 53 is wound around a U-shaped iron core 52. doing. When a current is passed through the copper wire coil 53, the magnetic field lines 54 are generated in the vicinity of the opening of the iron core 52 as indicated by the arrows, thereby magnetizing the sample 16 passing near the opening of the iron core 52. As a result, the sample 16 is magnetized in a direction that connects the center of rotation and the sample 16 in parallel with the rotation surface (the surface including the circumference 47) of the sample container 71. That is, the sample 16 is magnetized in the normal direction of the circumference 47.

  The electromagnets 46a and 46c generate a magnetic field that magnetizes the sample 16 only in the direction toward this rotation center (this direction is referred to as “forward direction”), but the electromagnet 46b reverses the current flowing through the copper wire coil 53. Thus, a magnetic field for magnetizing the sample 16 can be generated not only in the forward direction but also in the opposite direction (this direction is referred to as “reverse direction”).

  Magnetization of the sample 16 is started immediately after the position detection sensor 50 detects the reflection marker 51 after the rotation of the sample container 71 is started and the rotation speed becomes constant. For example, the direction of the magnetic field generated from the electromagnets 46a to 46c is aligned in the forward direction, and a pulse magnetic field is applied from the electromagnets 46a to 46c when the sample 16 passes immediately above the electromagnets 46a to 46c. When the 49 samples 16 are magnetized three by three, the first, second, and third samples are magnetized, the sixteenth magnetization, the 46th, 47th, and 48th samples are magnetized. In the magnetization, the 49th, 1st, and 2nd samples are magnetized, in the 33rd magnetization, the 48th, 49th, and 1st samples are magnetized, and in the 49th magnetization, the 47th, 48th, and 49th samples are magnetized.

  Therefore, when the sample container 71 is rotated three times, all 49 samples 16 receive magnetization by the electromagnets 46a to 46c once. The SQUID 28 is magnetized by any of the electromagnets 46a to 46c, and measures a magnetic signal from the sample when the sample passes over the SQUID 28. Therefore, the first signal waveform is obtained by measuring the magnetic signal with 3 rotations (49 times of magnetization processing) of the sample container 71 as one batch, and repeating this for a predetermined number of times to obtain the average.

  Next, when the sample 16 passes directly above the electromagnets 46a to 46c, a forward pulse magnetic field is generated from the electromagnets 46a and 46c, and a reverse pulse magnetic field is generated from the electromagnet 46b and applied to the sample 16. To do. While the sample container 71 rotates three times, all 49 samples 16 are magnetized by the electromagnet 46b only once. In this case as well, the second signal waveform is obtained by measuring the magnetic signal with three rotations of the sample container 71 as one batch, and repeating the measurement a predetermined number of times to obtain the average. Thus, by subtracting the second signal waveform from the measured first signal waveform to obtain a differential signal waveform, accurate magnetic signals from which magnetic signals from adjacent samples are excluded are obtained for all 49 samples 16. It can be measured.

<< Fourth Embodiment >>
FIG. 12 shows a schematic configuration of a magnetic signal measuring apparatus according to the fourth embodiment. The magnetic signal measuring apparatus 100C includes a fixing base 81 for fixing a sample container 80 for arranging the sample 16, a triaxial moving mechanism 82 for moving the fixing base 81 in an arbitrary direction, and the position of the sample container 80. A position sensor 83 for measuring the position, a magnetization mechanism 84 for magnetizing the sample 16 disposed in the sample container 80, a magnetic sensor array 85 for measuring a magnetic signal from the sample 16, and a three-axis movement mechanism 82, a moving mechanism control circuit 87 for controlling 82, a power supply circuit 88 for driving the magnetization mechanism 84, a position sensor 83, a magnetic sensor array 85, a moving mechanism control circuit 87, and a computer 89 for controlling the power supply circuit 88. The components excluding the moving mechanism control circuit 87, the power supply circuit 88, and the computer 89 are installed inside the magnetic shield 86.

  FIG. 13A shows a sample arrangement in the sample container, and FIG. 13B schematically shows a positional relationship among the magnetization mechanism, the magnetic sensor array, and the sample container (see FIG. 12 as appropriate). Here, a 96-well microplate, which is a standard, is used as the sample container 80. Therefore, the hole 70 for accommodating the sample 16 is provided in the sample container 80 two-dimensionally (planarly) at intervals of 8 rows × 12 columns and 9 mm. The fixing position of the sample container 80 on the fixing base 81 is constant, and a marker (not shown) associated with the row position of the holes 70 in the sample container 80 is provided on the upper surface of the fixing base 81.

  The magnetizing mechanism 84 has a structure in which 140 electromagnets 90 having a diameter of 5 mm are two-dimensionally arranged in 10 rows × 14 columns at the same 9 mm intervals as the hole portions 70 provided in the sample container 80. The sample container 80 has a magnetization mechanism such that the 96 holes 70 provided in the sample container 80 are positioned on the 96 electromagnets excluding the electromagnets arranged on the outermost periphery among the 140 electromagnets 90. 84. An outer peripheral contour 91 of the sample container 80 at this time is shown in FIG. The electromagnet 90 generates a magnetic field in a direction perpendicular to the installation surface of the electromagnet 90. For example, a magnetic field of about 200 gauss is generated by applying a current of 200 mA, and the sample 16 on the electromagnet 90 is individually generated by the magnetic field. Is magnetized.

  By controlling the power supply circuit 88 by the computer 89, a magnetic field can be generated in any of the 140 electromagnets 90. For example, 96 samples 16 arranged in the sample container 80 are magnetized simultaneously. In this case, a magnetic field is generated simultaneously from all 140 electromagnets 90. Thereby, the magnetic field application environment equivalent to the sample arrange | positioned inside can be implement | achieved also with respect to the sample arrange | positioned outside the sample container 80. FIG.

  The magnetic sensor array 85 has a structure in which eight MR sensors 93 are arranged in a row at the same interval of 9 mm as the hole 70 provided in the sample container 80. The sample container 80 is movable between the magnetization mechanism 84 and the magnetic sensor array 85 by moving the fixed base 81. The eight MR sensors 93 measure magnetic signals simultaneously when the eight samples 16 arranged in a row on the MR sensor 93 pass in the row direction indicated by the arrow 92, and for each column that passes continuously. Measure magnetic signals. Therefore, one MR sensor 93 measures the magnetic signals of 12 samples 16 arranged in one row.

  The position sensor 83 detects a marker (not shown) provided on the fixed base 81 in order to detect the row position of the hole 70 in the sample container 80, and which row of the sample container 80 is the MR of the magnetic sensor array 85. It is specified whether or not the sensor 93 is positioned. The position information of the sample 16 by the position sensor 83 and the magnetic detection output of the MR sensor 93 are recorded in the computer 89 and processed, and the intensity of the magnetic signal of each sample is calculated.

  In this magnetic signal measuring device 100C, first, sample containers 80 each containing a predetermined sample 16 in 96 holes 70 are fixed at fixed positions on a fixing base 81, and an outer contour 91 of the sample container 80 is illustrated. The sample container 80 is stationary on the magnetization mechanism 84 in accordance with the position shown in FIG. The first magnetization of the sample 16 is performed by generating a magnetic field in the same direction from all 140 electromagnets 90. Subsequently, the sample container 80 is reciprocated linearly on the magnetic sensor array 85, and magnetic signals are detected for all the samples 16 by the MR sensor 93. For example, the stroke of this reciprocating linear motion is 120 mm so that the 12 samples 16 arranged in one line can pass over the MR sensor 93. The sample container 80 is reciprocated 20 times, the change of the magnetic signal during that time is detected by the MR sensor 93, and the detection output is sent to the computer 89. The computer 89 obtains magnetic signal waveforms, that is, first signal waveforms for all 96 samples 16 by combining the position information of the sample containers 80 from the position sensor 83 with this.

  Subsequently, the sample container 80 was moved onto the magnetization mechanism 84. Also here, the outer peripheral contour 91 of the sample container 80 is matched with the position shown in FIG. 14A to 14D schematically show the magnetization directions of the samples from the second time to the fifth time. 14A to 14D, an electromagnet 90a indicated by a black circle generates a magnetic field opposite to the first magnetization direction to magnetize the sample, and an electromagnet 90b indicated by a white circle A magnetic field in the same direction as the direction of the second magnetization is generated to magnetize the sample.

  Focusing on the electromagnet located inside the outer peripheral contour 91 of the sample container 80, the upper left electromagnet in the outer peripheral contour 91 is the position of 1 row × 1 column, the lower left electromagnet is the position of 8 rows × 1 column, the upper right of the diagram. Is the position of 1 row × 12 columns, and the electromagnet in the lower right of the figure is the position of 8 rows × 12 columns, the electromagnet 90a is the position of the odd rows × odd columns in the second magnetization of the sample 16. It can be seen that the samples placed on these are magnetized in the opposite direction. After the second magnetization of the sample 16, the sample container 80 is reciprocated 20 times on the magnetic sensor array 85 and the change of the magnetic signal is detected by the MR sensor 93 in the same manner as the measurement of the first signal waveform. The computer 89 obtains the first second signal waveform from the detection output and the position information.

  Thereafter, similarly, in the third magnetization of the sample 16, the electromagnets at even row × odd column positions are used as the electromagnets 90 a, and the sample placed on these magnets is magnetized in the reverse direction, and the second second signal is obtained. A waveform is required. In the fourth magnetization of the sample 16, the electromagnets at odd-numbered rows and even-numbered columns are set as the electromagnets 90a, and the sample placed on these magnets is magnetized in the reverse direction to obtain the third second signal waveform. In the fifth magnetization of the sample 16, the electromagnets at even row × even column positions are used as the electromagnets 90a, and the sample placed thereon is magnetized in the reverse direction to obtain the fourth second signal waveform.

  The computer 89 obtains the first differential signal waveform by subtracting the first second signal waveform from the first signal waveform thus obtained, and subtracts the second second signal waveform from the first signal waveform. A signal waveform is obtained, a third differential signal waveform is obtained by subtracting the third second signal waveform from the first signal waveform, and a fourth differential signal waveform is obtained by subtracting the fourth second signal waveform from the first signal waveform. Ask for. Each of these four differential signal waveforms includes a magnetic signal from a sample to which a reverse magnetic field is applied as shown in FIGS. 14A to 14D, and a magnetic signal from a sample adjacent to the sample. Extracted in the excluded state. Therefore, accurate magnetic signals can be obtained for all 96 samples 16 from these differential signal waveforms.

  In the magnetic signal measuring device 100C, the sample container 80 is configured to be movable in the row direction of the holes 70. However, the sample container 80 may be configured to be movable in the column direction of the holes 70. In this case, it is necessary to use a magnetic sensor array in which twelve MR sensors are arranged in one row, and one MR sensor measures magnetic signals from eight samples arranged in one column. Become. Of the 140 electromagnets 90, the 44 electromagnets arranged on the outermost periphery always generate a forward magnetic field, but conform to the arrangement of the electromagnets 90a and 90b in the outer periphery 91 of the sample container 80. Then, every other electromagnet 90a may appear in the row direction and the column direction, respectively.

  As described above, according to the present invention, even when interference of magnetic signals from adjacent samples becomes a problem because a plurality of samples are arranged close to each other, magnetism from the sample to be inspected. The signal can be accurately measured by eliminating the magnetic signal from the adjacent sample, and the magnetic signal from all the samples can be measured by sequentially changing the sample to be inspected. it can.

  This makes it possible to densely arrange samples, which was not possible before, reducing the amount of sample containers used to place samples, reducing running costs and disposal costs, and reducing the number of sample container replacements. Inspection efficiency can be improved. Alternatively, the entire magnetic measuring device can be reduced in size by reducing the size of the sample container. Furthermore, since a 96 microplate or the like which is a standard specification can be used as a sample container, operations such as efficient sample preparation using existing instruments and apparatuses can be performed.

  The present invention is suitable for, for example, an immunological test apparatus used for testing biological materials such as various antibodies, proteins, immunoglobulins, hormones, tumor markers, blood culture apparatuses and bacterial test apparatuses for testing viruses, pathogenic bacteria, and the like. It is.

The figure which shows typically the preparation procedure of the sample used for the immunoassay using an antigen antibody reaction, and the measurement principle of the magnetic signal from this sample. The figure which shows typically the preparation procedure of the sample used for detection of a pathogenic microbe, and the measurement principle of the magnetic signal from this sample. The figure which shows typically the schematic structure of the magnetic signal measuring device which concerns on the 1st Embodiment of this invention, and its operation | movement aspect. (A), (b) is a figure which shows an example of the magnetic signal waveform measured by the magnetic signal measuring apparatus of FIG. 3, (c) is a figure which shows an example of a difference signal waveform. The figure which shows schematic structure of the magnetic signal measuring device which concerns on the 2nd Embodiment of this invention. (A) is a figure which shows schematic shape of the sample container used for the magnetic signal measuring device of FIG. 5, (b) is a top view which shows the detailed structure of the outer peripheral part of this sample container. (A) is a side view of the magnetization mechanism attached to the magnetic signal measuring device of FIG. 5, (b) is a plan view of this magnetization mechanism. (A) is a top view which shows schematic structure of a high-temperature superconducting SQUID gradiometer, (b) is the elements on larger scale of (a), (c) is a figure which shows the example of the magnetic signal waveform measured. (A), (b) is a figure which shows the measured magnetic signal waveform, (c) is a figure which shows a difference signal waveform. The figure which shows schematic structure of the magnetic signal measuring device which concerns on the 3rd Embodiment of this invention. (A) is a top view which shows the positional relationship of a sample container, SQUID, and a magnetization mechanism, (b) is the elements on larger scale of (a), (c) is a side view which shows the structure of an electromagnet. The figure which shows schematic structure of the magnetic signal measuring device which concerns on the 4th Embodiment of this invention. (A) is a figure which shows typically sample arrangement | positioning in a sample container, (b) is a figure which shows typically the positional relationship of a magnetization mechanism, a magnetic sensor array, and a sample container. The figure which shows typically the magnetization direction of the sample from the 2nd time to the 5th time by the magnetic signal measuring device of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a-1f ... Container, 2 ... Moving mechanism, 3 ... Support plate, 4 ... Stage, 5a-5c ... Electromagnet, 6 ... Magnetic sensor, 8a-8f ... Sample, 10 ... Magnetic signal measuring device, 16 ... Sample, 20 ... Control part, 21 ... Cooling container, 22 ... Outer tank, 23 ... Inner tank, 24 ... Liquid nitrogen, 25 ... Sapphire rod, 26 ... Copper rod, 27 ... Sapphire window, 28 ... SQUID, 29 ... Electromagnetic shield, 30, 31 ... Magnetic shield, 32 ... Sample stage, 33 ... Fixing screw, 34 ... Rotation mechanism, 35 ... Shaft member, 36 ... Vertical movement mechanism, 37 ... Horizontal movement mechanism, 38 ... Notch hole, 39 ... Cylindrical member, 40 ... Magnetization Mechanism: 41 ... Electromagnet, 42 ... Fixing base, 43 ... Magnetic shield, 45 ... Magnetization mechanism, 46a to 46c ... Electromagnet, 47 ... Circumference, 48 ... Circumference, 50 ... Position detection sensor, 51 ... Reflection marker, 52 ... Iron core, 5 DESCRIPTION OF SYMBOLS ... Copper wire coil, 54 ... Magnetic field line, 56 ... Reflection marker, 60 ... Bicrystal board | substrate, 61 ... Bicrystal joint surface, 62 ... Detection coil, 63 ... Wiring pad, 64a, 64b ... SQUID ring, 65a, 65b ... Grain boundary Josephson coupling, 66 ... central part of detection coil, 67a, 67b ... feedback coil, 68 ... wiring pad, 69 ... arrow indicating the passage direction of the sample, 70 ... hole, 71 ... sample container, 72 ... hole, 80 ... Sample container (96-well microplate), 81 ... fixed base, 82 ... triaxial moving mechanism, 83 ... position sensor, 84 ... magnetizing mechanism, 85 ... magnetic sensor array, 86 ... magnetic shield, 87 ... moving mechanism control circuit, 88 DESCRIPTION OF SYMBOLS ... Power supply circuit 89 ... Computer, 90, 90a, 90b ... Electromagnet, 91 ... Outer periphery outline of sample container, 92 ... Sample moving path, 93 ... MR , 101 ... container, 101 a ... bottom surface of the container, 102 ... antibody for immobilization, 103 ... blocking agent, 105 ... specimen, 106, 106 a, 106 b ... antigen (substance to be detected), 107, 107 a to 107 c ... magnetic marker, 108 DESCRIPTION OF SYMBOLS ... Solution 109 ... Magnetic sensor 111 ... Container 112 ... Pathogen (substance to be detected), 113a, 113b ... Magnetic marker, 114 ... Sample solution, 115 ... Magnet, 116 ... Magnetic sensor.

Claims (18)

A magnetic field in a predetermined direction is applied to an inspection sample selected from a plurality of samples each including a magnetic material arranged at a predetermined interval and one or more adjacent samples adjacent to the inspection sample, and is included in each sample. A magnetization mechanism for magnetizing the magnetic material;
A magnetic sensor for measuring magnetic signals from the inspection sample and the adjacent sample;
A magnetic signal from each sample after applying a magnetic field in the same direction to the inspection sample and the adjacent sample is obtained to obtain a first signal waveform, and only the direction of the magnetic field applied to the inspection sample is changed to change the inspection sample. And measuring a magnetic signal from each sample after applying a magnetic field to the adjacent sample to obtain a second signal waveform, and the difference signal waveform between the first signal waveform and the second signal waveform is included in the inspection sample. And a control unit for detecting the amount of the magnetic material. A magnetic signal measuring device that detects a substance to be detected by binding a substance to be detected contained in a specimen and a reagent having magnetic particles and measuring a magnetic signal from the magnetic particles,
A sample container for arranging a plurality of samples including a conjugate of a reagent having magnetic particles and a substance to be detected at a predetermined interval;
A magnetization mechanism that magnetizes magnetic particles contained in each sample by applying a magnetic field having a predetermined strength to a test sample selected from the plurality of samples and one or more adjacent samples adjacent to the test sample in a predetermined direction; ,
A magnetic sensor for measuring magnetic signals from the inspection sample and the adjacent sample;
A moving mechanism for moving the sample container between the magnetization mechanism and the magnetic sensor;
A magnetic signal from each sample after applying a magnetic field in the same direction to the inspection sample and the adjacent sample is obtained to obtain a first signal waveform, and only the direction of the magnetic field applied to the inspection sample is changed to change the inspection sample. And measuring a magnetic signal from each sample after applying a magnetic field to the adjacent sample to obtain a second signal waveform, and the difference signal waveform between the first signal waveform and the second signal waveform is included in the inspection sample. A magnetic signal measuring device comprising: a control unit that detects a substance to be detected. The sample container has a plurality of holes arranged at equal intervals along a circumference to accommodate the plurality of samples.
The moving mechanism has a rotation mechanism that rotates the sample container around an axis that passes through the center of the circumference and is perpendicular to a plane including the circumference.
The magnetization mechanism has at least three electromagnets installed at the same interval as the arrangement interval of the hole portions along a circular locus drawn by the hole portion by rotation of the sample container,
The magnetic signal measuring apparatus according to claim 2, wherein the control unit has a function of changing a direction of a magnetic field generated from an electromagnet that applies a magnetic field to the test sample among the plurality of electromagnets.   The control unit rotates the sample container so that any sample of the group of samples magnetized by the magnetization mechanism at a predetermined timing is not continuously magnetized by the magnetization mechanism. The magnetic signal measuring apparatus according to claim 3, which has a function of sequentially changing the selection of the inspection sample.   The magnetic signal measuring device according to claim 3, wherein the plurality of electromagnets have a structure that applies a magnetic field in a direction perpendicular to a rotation surface of the sample container to the inspection sample and the adjacent sample. .   The plurality of electromagnets have a structure that applies a magnetic field in a direction parallel to the rotation surface of the sample container and connecting the rotation center of the sample container and each sample to the inspection sample and the adjacent sample. The magnetic signal measuring device according to claim 3. The sample container has a plurality of holes arranged at equal intervals on a straight line to accommodate a plurality of the samples,
The moving mechanism has a slide mechanism for sliding the sample container in the length direction of the straight line,
The magnetization mechanism has at least three electromagnets installed at the same interval as the arrangement interval of the hole portions along a line locus drawn by the hole portion by sliding the sample container,
The magnetic signal measuring apparatus according to claim 2, wherein the control unit has a function of changing a direction of a magnetic field generated from an electromagnet that applies a magnetic field to the test sample among the plurality of electromagnets. The sample container has a plurality of holes arranged at regular intervals in m rows × n columns, where m and n are integers of 2 or more, in order to accommodate a plurality of the samples,
The moving mechanism has a slide mechanism that slides the sample container in a row direction in which a plurality of the holes are arranged,
The magnetization mechanism has m × n electromagnets arranged in m rows × n columns at the same intervals as the arrangement intervals of the plurality of holes,
The controller has a function of changing the direction of a magnetic field generated from an electromagnet that applies a magnetic field to the test sample among the m × n electromagnets
The magnetic sensor has n magnetic sensor elements arranged in one row at the same interval as the arrangement interval of the plurality of hole portions in order to measure magnetic signals from the plurality of samples for each row. The magnetic signal measuring apparatus according to claim 2, wherein the apparatus is a magnetic signal measuring apparatus.   The magnetizing mechanism further includes 2m + 2n + 4 electromagnets arranged so as to surround the electromagnets of m rows × n columns so as to be (m + 2) rows × (n + 2) columns as a whole. The magnetic signal measuring device according to 8.   The magnetic signal measuring device according to claim 2, further comprising a magnetic shield for suppressing interference of the magnetism generated by the magnetization mechanism with the magnetic sensor. A magnetic signal measurement method for detecting a substance to be detected by binding a substance to be detected contained in a specimen and a reagent having magnetic particles and measuring a magnetic signal from the magnetic particles,
Arranging a plurality of samples including a conjugate of a reagent having magnetic particles and a substance to be detected at predetermined intervals;
A test sample and one or more adjacent samples adjacent to the test sample are selected from a plurality of the samples, and a magnetic field of a certain strength is applied to the test sample and the adjacent sample in the same direction to include magnetism contained in each sample. A first magnetization step for magnetizing the particles;
Measuring magnetic signals from the inspection sample and the adjacent sample that have undergone the first magnetization step to obtain a first signal waveform;
A second magnetization step of magnetizing the magnetic particles contained by applying a magnetic field of constant intensity in the test sample and the adjacent samples by changing only the direction of the magnetic field applied to the test sample to each sample,
Measuring a magnetic signal from the inspection sample and the adjacent sample that has undergone the second magnetization step to obtain a second signal waveform;
Subtracting the second signal waveform from the first signal waveform to obtain a differential signal waveform, and detecting a substance to be detected contained in the test sample from the differential signal waveform. Method.
  A plurality of the samples are arranged at equal intervals along one circumference and rotated around an axis that passes through the center of the circumference and is perpendicular to the plane including the circumference. The magnetic signal measurement method according to claim 11, wherein magnetization of the magnetic particles contained and measurement of a magnetic signal from each sample are performed. The selection of the inspection sample is sequentially changed so that any sample of the group of samples magnetized at a predetermined timing is not continuously magnetized by the first magnetization step . The magnetic signal measuring method according to claim 11 .   The magnetic signal measurement method according to claim 12, wherein a magnetic field in a direction perpendicular to a rotation surface of the plurality of samples is applied to the inspection sample and the adjacent sample.   The magnetic field according to claim 12, wherein a magnetic field is applied to the inspection sample and the adjacent sample in a direction parallel to a rotation surface of the plurality of samples and connecting the rotation center of the sample and each sample. Signal measurement method.   While arranging a plurality of samples on a straight line at equal intervals and sliding them in the length direction of the straight line, magnetization of magnetic particles contained in the test sample and the adjacent sample and measurement of magnetic signals from each sample The magnetic signal measurement method according to claim 11, wherein:   While the plurality of samples are arranged at regular intervals in m rows × n columns with m and n being integers of 2 or more and slid in the row direction, the magnetization of the magnetic particles contained in each of the inspection sample and the adjacent sample, The magnetic signal measurement method according to claim 11, wherein a magnetic signal from each sample is measured.   The test sample is selected so that the test sample and the adjacent sample are alternately positioned in each row and each column of the m rows × n columns, and these samples are magnetized at the same time, and then m arranged in one column. The magnetic signal measuring method according to claim 17, wherein magnetic signals from a single sample are continuously measured in the row direction.

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