| 摘要 |
PROBLEM TO BE SOLVED: To exclude an influence of a magnetic field for magnetization or a magnetization of a substrate and to permit accurate immunoassay by utilizing high sensitivity of an original SQUID(superconducting quantum interference device) by squaring a magnetic field for magnetizing a label to a direction of a magnetic flux to be detected by the SQUID. SOLUTION: A specimen 2 supported onto a substrate 1 is magnetized, and then detected by a SQUID 3. A magnetic field for magnetizing the specimen 2 is parallel to a surface of the substrate 1 as indicated by an arrow A. The SQUID 3 is disposed so that a plane including its ring current circuit becomes parallel to the substrate 1, and the SQUID 3 detects the magnetic flux perpendicular to the plane formed with itself with high sensitivity. Meanwhile, the SQUID 3 has no sensitivity at the magnetic flux parallel to the surface formed with itself. Accordingly, the SQUID 3 is no affected by an influence of a magnetic field A for magnetizing the specimen 2. The substrate 1 is moved at a predetermined speed from left to right parallel to the field A. Then, if the substrate 1 is sufficiently large, the influence of the magnetization of the substrate 1 when measured can be removed.
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