JP2007108164A - Magnetic substance sensor and magnetic substance sensor unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic substance sensor capable of detecting even minute amounts of magnetic substance particles as objects held planarly and not magnetized, and easy to be manufactured and regulated, and a magnetic substance sensor unit provided therewith. <P>SOLUTION: This magnetic substance sensor is provided with a magnetic circuit 11 comprising a material of high permeability and having a detecting gap G in its one part, a magnetic field generation means 12 for supplying magnetism to the magnetic circuit 11, and a detecting coil 13 wound around the magnetic circuit 11 to detect a change of magnetic resistance within the detecting gap G. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic sensor and a magnetic sensor device, and more particularly to a magnetic sensor and a magnetic sensor device suitable for use as a biosensor for analyzing a measurement object by detecting magnetic particles.

  Conventionally, as a magnetic sensor device for detecting magnetic particles, as shown in FIG. 8 (a), the support (51) holding the magnetic particles (1) in a planar shape is moved into a magnetic field, As a result, it is known that the magnetic particles (1) are magnetized, and their magnetism is detected by a magnetic sensor (52) including a Hall element or a magnetoresistive element arranged outside the magnetic field.

In the magnetic sensor device, the magnetic sensor (52) is arranged outside the magnetic field, so there is a problem that it is not suitable for detection of magnetic particles (1) with a short magnetic residual time, which is solved. As shown, in Patent Documents 1 and 2, as shown in FIG. 8 (b), a magnetic particle (1) in which a magnetic sensor (53) is disposed in a magnetic field and held on a support (51) is shown. A magnetic sensor (53) has been proposed that detects a change in the magnetic field associated with the movement of the magnetic field.
JP 2001-524675 A JP-T-2004-519666

  In the above-mentioned Patent Document 1, a pair of detection elements are arranged in an alternating magnetic field so as to be equal to the magnetic flux (so that the output signals cancel each other), and the magnetic field around the detection elements is approached by the approach of the magnetic particles. In order to achieve high-sensitivity detection of magnetic particles with this device, it is necessary to arrange a uniform magnetic field and a highly symmetrical detection element. There was a problem that accompanied the difficulty.

  Moreover, the thing of the said patent document 2 is different from the thing of patent document 1 by the point which uses the DC magnetic field for excitation, and in order to implement | achieve highly sensitive detection of a magnetic particle with this apparatus, it is strong. There was a problem that it was necessary to separately develop a high-performance sensor that worked in a magnetic field (wide dynamic range and high resolution).

  In view of the above-mentioned problems of the prior art, the present invention is intended for magnetic particles that are held flat and do not have magnetism, and can be detected even in trace amounts, and is easy to manufacture and adjust. It is an object of the present invention to provide a sensitive magnetic sensor and a magnetic sensor device including the same.

  A magnetic sensor according to the present invention includes a magnetic circuit made of a highly permeable material and partially having a detection gap, a magnetic field generating means for supplying magnetism to the magnetic circuit, and a magnetic resistance wound around the magnetic circuit. It comprises at least one detection coil for detecting a change.

  As the highly magnetically permeable material, electromagnetic soft iron, permalloy (Fe—Ni alloy) and the like are suitable, but are not limited thereto.

  The magnetic circuit is, for example, rectangular, and a detection gap is formed at the center of one of the sides. The magnetic circuit may be circular (the portion excluding the detection gap is C-shaped). In addition, the cross section of the high magnetic permeability material forming the magnetic circuit may be a square or a circle.

  An electromagnet or a permanent magnet is used as the magnetic field generating means.

  The detection coil is preferably wound a plurality of times and detects a change in magnetic resistance caused by the magnetic particles passing through the detection gap as a potential difference between both ends of the coil. The signals detected by the detection coil are preferably integrated, and the number of integrations is preferably 10 to 500 times.

  The detection coil is not disposed in the detection gap, but is wound so as to be integrated with the magnetic circuit. The diameter of the detection coil is determined according to the diameter of the highly permeable material forming the magnetic circuit without being affected by the size of the detection target. The detection coils may be provided in any one of the magnetic circuits, but the present invention is not limited to this. For example, a pair of detection coils may be provided via a detection gap.

  The portion of the magnetic circuit (probe portion) in which the detection gap is formed is preferably tapered.

  The tapered shape is a quadrangular pyramid (including a quadrangular frustum) when the cross-sectional shape of the magnetic circuit is a square, and a cone (including a frustum) when the cross-sectional shape of the magnetic circuit is a circle. Can be obtained.

  The detection coil is preferably provided in the vicinity of the detection gap of the magnetic circuit.

  When the vicinity of the detection gap of the magnetic circuit is tapered, a detection coil may be provided so as not to include the tapered portion, and the detection coil is provided so as to include the tapered portion. It may be.

  It is preferable that a noise canceling gap is provided in a portion facing the detection gap of the magnetic circuit.

  If it does in this way, the influence of the noise accompanying an external magnetic field can be controlled.

  When the noise cancellation gap is provided, the detection coils may be provided at a total of four locations, two locations facing each other via the detection gap and two locations facing each other via the noise cancellation gap. preferable.

  In principle, the detection coil may be provided anywhere in the magnetic circuit. However, by providing a plurality of detection coils at symmetrical positions in this manner, magnetic noise can be canceled and the S / N ratio is greatly improved.

  Two detection coils facing each other through the detection gap are A and B, and two detection coils facing the noise canceling gap are on the same side as A with C and B. Each coil is connected (A → C → D → B) so that the coil current induced by the magnetic flux change in the magnetic circuit is added with D on the same side, and the common between C and D is common It is preferable that the difference between the potential difference P between the coil A and the coil C and the potential difference Q between the coil D and the coil B are obtained as a final output signal.

  In a signal detection circuit that obtains a final output signal from four coils, several coil connection methods can be considered, but the above addition and subtraction are performed using the symmetry (optimization of processing by software). Thus, the S / N can be improved without changing the hardware.

  A magnetic sensor device according to the present invention supports the above magnetic sensor, a support that holds magnetic particles that are not magnetized in a flat shape, and the magnetic particles pass through the detection gap of the magnetic circuit. And a support moving means for moving the body.

  The support moving means may move the support linearly or may rotate the support. The moving speed (gap passing speed) of the support is 50 mm / sec or more, preferably 100 mm / sec or more. The support body moving means preferably includes a rotating disk capable of holding the support body at a predetermined place in the circumferential direction and a rotating means for rotating the rotating disk.

  The magnetic sensor device further includes an amplifier that amplifies a potential difference generated at both ends of the detection coil when magnetic particles held in a planar shape pass through the detection gap, and a recording unit that records the amplified potential difference. It is preferable.

  According to this magnetic sensor device, when the magnetic particles held on the support pass through the detection gap, the magnetic resistance of the detection gap changes, and the magnetic flux density in the magnetic circuit changes. Thereby, an induced voltage is generated in the detection coil, and a potential difference of the induced voltage is detected as an output signal.

  This magnetic sensor device is suitably used as a biosensor for analyzing a measurement object by measuring the amount of magnetic particles in a sample containing magnetizable magnetic particles. Such a biosensor can measure, for example, the binding force acting between DNA-DNA, antibody-antigen, or ligand-receptor at the single molecule level.

  According to the magnetic sensor and the magnetic sensor device of the present invention, since the change in the magnetic resistance in the detection gap of the magnetic circuit is detected, it is possible to detect even a very small amount of magnetic particles, and it is expensive. Since a magnetic sensor is not required and the detection coil only needs to be wound around a magnetic circuit, the position adjustment is not required, and manufacturing and adjustment can be easily performed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a basic configuration (first embodiment) of a magnetic sensor and a magnetic sensor device according to the present invention. The magnetic sensor device (2) is magnetic and has a magnetic sensor (3). A support (4) that holds the magnetic particles (1) in a flat shape, a signal amplification means (5) that amplifies the output of the magnetic sensor (3), and a recording means (6) that records the amplified potential difference. ).

  The magnetic sensor (3) includes a magnetic circuit (11) made of a highly permeable material and partially having a detection gap (G), and a magnetic field generating means (12) for supplying magnetism to the magnetic circuit (11), And a detection coil (13) for detecting a change in magnetic resistance in the detection gap (G).

  The magnetic field generating means (12) is a permanent magnet or an electromagnet, and when it is an electromagnet, it may be a DC magnetic field or an AC magnetic field.

  The principle of magnetic particle detection by the magnetic sensor device (2) is as follows.

1. When the magnetic particles (1) held on the support (4) pass through the detection gap (G), the magnetic resistance of the detection gap (G) changes (the magnetic substance in the detection gap (G) When the particle (1) is positioned, the magnetic resistance decreases).

2. The magnetic flux density in the magnetic circuit (11) changes due to the change in the magnetic resistance in the detection gap (G) (the magnetic flux density increases when the magnetic resistance decreases).

3. When the magnetic flux density inside the detection coil (13) wound around the magnetic circuit (11) changes, an induced voltage is generated in the detection coil (13).

4). The potential difference of the induced voltage is amplified by the signal amplification means (5) and detected as an output signal.

  The output signal obtained as described above is as shown in FIG. 2, and the amount of the magnetic particles (1) can be detected from the output signal.

  In the prior art, the magnetic flux of the magnetic circuit is intended for the magnetization of the magnetic particles, and the detection element is either directly above the detection element or regardless of whether it is a Hall element, a magnetoresistive element or a coil. It is output when it is located directly below, and it was necessary to make the size correspond to the size of the sample.In the present invention, the magnetic flux of the magnetic circuit (11) is within the detection gap (G). Because the magnetic circuit (11) and the detection coil (13) are integrated, there is little positional adjustment for high-sensitivity detection. The manufacturing process can be simplified.

  FIG. 3 shows a preferred embodiment (second embodiment) of the magnetic sensor (3) according to the present invention.

  In the figure, a magnetic circuit (11) is provided by detecting a U-shaped part (11a) having a U-shape when viewed from the front and a square cross section, and both ends of the U-shaped part (11a). And probe portions (11b) and (11c) that face each other with a gap (G) for use. The probe portions (the portions of the magnetic circuit (11) in which the detection gap (G) is formed) (11b) and the tip portions (11d) and (11e) of the 11c are tapered, that is, a quadrangular pyramid. . The magnetic field generation means (12) is a permanent magnet, whereby a direct-current magnetic field is supplied to the magnetic circuit. The detection coil (13) is provided in one probe portion (a portion near the detection gap (G) of the magnetic circuit (11)) (11c).

  FIG. 4 shows another preferred embodiment (third embodiment) of the magnetic sensor (3) according to the present invention.

  In the figure, a magnetic circuit (11) is provided by detecting a U-shaped part (11a) having a U-shape when viewed from the front and a square cross section, and both ends of the U-shaped part (11a). And probe portions (11b) and (11c) that face each other with a gap (G) for use. The probe portions (the portions of the magnetic circuit (11) where the detection gap (G) is formed) (11b) and the tip portions (11d) and (11e) of the 11c are tapered, that is, a quadrangular pyramid. . The magnetic field generating means (12) includes an electromagnet (21) and an AC power source (22) that supplies an AC current to the electromagnet (21), whereby an AC magnetic field is supplied to the magnetic circuit (11). The detection coil (13) is provided in one probe portion (a portion near the detection gap (G) of the magnetic circuit (11)) (11c).

  According to the embodiment shown in FIG. 3 and FIG. 4, the tip portions (11d) and (11e) of the probe portions (11b) and (11c) are tapered, so that the height of the probe portions (11b) and (11e) is increased in the detection gap (G). High-sensitivity detection is possible because a magnetic flux having a density is supplied and the detection coil (13) is provided in the vicinity of the detection gap (G). By providing the detection coil (13) to include the tapered tip (11d) (11e), the magnetic flux change of the magnetic circuit (11) when the magnetic particles (1) pass through can be more efficiently performed. Can be detected.

  The output signal of FIG. 2 uses the magnetic sensor (3) shown in FIG. 3 and is provided at three locations on the plane of the support (4) having a width of 6 mm and a length of 30 mm (the interval is 4 mm and the width is 1 mm) 3 shows the results of measuring the magnetic particles (1) held on the surface.

  Although not shown in the figure, the detection coil (13) is also provided in the other probe section (11b) to form a pair, and a signal from the pair of detection coils (13) is amplified using a differential amplifier. Thus, the noise for the coil (13) may be canceled.

  FIG. 5 shows another preferred embodiment (fourth embodiment) of the magnetic sensor (3) according to the present invention.

  In this figure, in addition to the detection gap (G) in the second embodiment (FIG. 3) and the third embodiment (FIG. 4), the magnetic circuit (11) includes another gap (noise cancel gap) ( H) is provided. The noise canceling gap (H) is provided at the center of the bottom of the U-shaped portion (11a) of the second and third embodiments. As a result, the magnetic circuit (11) is provided at a pair of pillars (21) and (22) parallel to each other and at one end of each pillar (21) and (22) via the detection gap (G). The noise canceling probe (23) (24) on the opposite side of the detection gap and the other end of each pillar (21) (22) are opposed to each other via the noise canceling gap (G). Thus, in each of the above embodiments, the magnetic circuit (11) is symmetrical only with respect to the left and right center lines in the figure (with respect to the upper and lower centers). Is symmetric with respect to the center line on the left and right of the figure and the center line on the top and bottom of the figure. The magnetic field generating means (permanent magnet shown in the figure) (12) is provided on one of the pillars (22), and the detection coil (13) is located at the same position as in the above embodiment, that is, the upper right probe part (24). Is provided.

  The magnetic circuit (11) includes not only the magnetic field generated by the magnetic field generating means (12) but also an external magnetic field (such as geomagnetism and magnetic noise derived from surrounding electrical equipment). And the influence is suppressed. That is, in the second embodiment or the like, the shape of the upper portion where the detection gap (G) is present is different from the lower portion where it is not present. Is generated in the magnetic circuit, and noise is generated. In this embodiment, the magnetic flux accompanying the influence of the external magnetic field is canceled by the symmetry, and the noise is reduced.

  FIG. 6 shows another preferred embodiment (fifth embodiment) of the magnetic sensor (3) according to the present invention.

  In the figure, the shape of the magnetic circuit (11) itself is the same as that of the fourth embodiment (the one shown in FIG. 5). The detection coil (13) is not provided only in the upper right probe part (24), but also in the upper left probe part (23) facing this via the detection gap (G). Furthermore, a total of four detection coils (13) are used, which are also provided on the probe portions (25) and (26) facing each other via the noise canceling gap (H).

  The signal detection circuit (27) for obtaining signals from these four detection coils (13) has two detection coils (13) facing each other through the detection gap (G) as A and B, and cancels noise. Of the two detection coils (13) facing each other via the gap (H), the coil on the same side as A is treated as C, and the coil on the same side as B is treated as D. .

  Each coil (13) is connected in the order of A → C → D → B, and the difference between the potential difference P between the coil A and the coil C and the potential difference Q between the coil D and the coil B between C and D is the difference. Ask for. As a result, the signal output level is increased, magnetic field noise for the coil (13) is canceled, and the S / N is greatly improved.

  FIG. 7 shows a preferred embodiment (sixth embodiment) of the support moving means. When moving the support (4) that holds the magnetic particles (1) in a flat shape, the support (4) may of course be moved linearly.In this embodiment, the support (4) is rotated and moved. I am letting. In the figure, the support moving means (31) includes a rotating disk (32) capable of holding the support (4) at a predetermined location in the circumferential direction, and rotating means (not shown) for rotating the rotating disk. .

  The rotating disk (32) has an outer diameter of 300 to 500 mm and a rotating speed of 100 to 500 rpm. The rotating disk (32) is, for example, circular, but may be oval or other shapes.

  According to the support moving means (31) of this embodiment, the rotational movement is less likely to cause vibration of the support (4) than the linear movement, so that noise can be suppressed. The detection signals are preferably integrated for improving the S / N. However, the necessary number of integrations can be obtained in a short time by rotating the rotating disk (32) at a high speed.

FIG. 1 is a diagram showing a basic configuration (first embodiment) of a magnetic sensor and a magnetic sensor device according to the present invention. FIG. 2 is a diagram showing an example of an output obtained by the magnetic sensor according to the present invention. FIG. 3 is a front view showing a second embodiment of the magnetic sensor according to the present invention. FIG. 4 is a vertical sectional view showing a third embodiment of the magnetic sensor according to the present invention. FIG. 5 is a vertical sectional view showing a fourth embodiment of the magnetic sensor according to the present invention. FIG. 6 is a vertical sectional view showing a fifth embodiment of the magnetic sensor according to the present invention. FIG. 7 is a vertical sectional view showing a sixth embodiment of the magnetic sensor according to the present invention. 8A and 8B are diagrams showing a conventional magnetic sensor.

Explanation of symbols

(1): Magnetic particles
(2): Magnetic sensor device
(3): Magnetic sensor
(4): Support
(11): Magnetic circuit
(12): Magnetic field generation means
(13): Coil for detection
(G): Detection gap
(H): Noise canceling gap

Claims (9)

  Magnetic circuit made of a highly permeable material and partially having a detection gap, magnetic field generating means for supplying magnetism to the magnetic circuit, and at least one detection wound around the magnetic circuit to detect a change in magnetoresistance within the gap A magnetic sensor comprising a coil for use.   2. The magnetic sensor according to claim 1, wherein the detection coil detects a change in magnetic resistance caused by the magnetic material passing through the detection gap as a potential difference between both ends of the coil.   The magnetic sensor according to claim 1, wherein a portion of the magnetic circuit in which the detection gap is formed is tapered.   2. The magnetic sensor according to claim 1, wherein the detection coil is provided in the vicinity of the detection gap of the magnetic circuit.   2. The magnetic sensor according to claim 1, wherein a noise canceling gap is provided at a portion facing the detection gap of the magnetic circuit.   6. The magnetic sensor according to claim 5, wherein the detection coils are provided at a total of four locations, two locations facing each other via a detection gap and two locations facing each other via a noise canceling gap.   Two detection coils facing each other through the detection gap are A and B, and two detection coils facing the noise canceling gap are on the same side as A with C and B. Each coil is connected (A → C → D → B) so that the coil current induced by the magnetic flux change in the magnetic circuit is added with D on the same side, and the common between C and D is common 6. The magnetic sensor according to claim 5, wherein a difference between the potential difference P between the coil A and the coil C and the potential difference Q between the coil D and the coil B is obtained as a final output signal.   A magnetic body sensor according to any one of claims 1 to 7, a support body for holding magnetic particles that are not magnetized in a flat shape, and a support body so that the magnetic particles pass through a detection gap of a magnetic circuit. And a support body moving means for moving the magnetic sensor device.   9. The magnetic sensor device according to claim 8, wherein the support moving means includes a rotating disk capable of holding the support at a predetermined position in the circumferential direction and rotating means for rotating the rotating disk.

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