Abstract: The disclosed magnetic immunoassay device, which performs magnetic immunoassays using antigen-antibody reactions, can perform speedy immunoassays without bound/free separation in the test samples. The device is also practical, being capable of stable magnetism measurement without magnetic shielding. The disclosed magnetic immunoassay device is provided with: an excitation coil that uses an AC magnetic field to magnetize a test sample containing a magnetic marker; a magnetism sensor that measures magnetism in the test sample and outputs a magnetism signal; and a displacement sensor for detecting changes in the distance between the test sample and the magnetism sensor.

Abstract: A base is provided with a concave and three leads, and the central lead is bent to the side opposite to the concave, and the other leads are bent to the side of the concave. A central electrode of a sensor element is attached to the central lead and the bottom of the concave and a coil serving as both a heater and an electrode is attached to the other leads to support the sensor element on a small base at four points.

Abstract: A central electrode 12 is arranged in a coiled heater electrode 10. They are buried in a SnO2-based inner area 6, and the entirety is covered by a filter 8. The volume of the inner area 6 is set at from 1×10−3 mm3 to 16×10−3 mm3, the total volume of the bead 4 is set at from 15×10−3 mm3 to 70×10−3 mm3, and the ratio of the total volume of the bead 4 to the volume of the inner area 6 is set at from four to twenty to bring the sensor resistance in CO and that in methane closer to each other and increase the selectivity from hydrogen.

Abstract: A central electrode 12 is arranged in a coiled heater electrode 10. They are buried in a SnO2-based inner area 6, and the entirety is covered by a filter 8. The volume of the inner area 6 is set at from 1×10−3 mm3 to 16×10−3 mm3, the total volume of the bead 4 is set at from 15×10−3 mm3 to 70×10−3 mm3, and the ratio of the total volume of the bead 4 to the volume of the inner area 6 is set at from 4 to 20 to bring the sensor resistance in CO and that in methane closer to each other and increase the selectivity from hydrogen.