Recently, a large variety of disease-model experimental animals, which are generated by gene modification or drug inducement, have become available for studying disease development and treatment. Biomagnetic measurement has been considered a powerful tool in the study of disease-model animals since it is a completely non-invasive and contact-free technique for the functional mapping of a living body. This paper reviews the biomagnetic studies of experimental animals for the purpose of elucidating the electrophysiological functions of the brain and heart, and introduces our newly developed magnetocardiogram (MCG) measurement system for mice. We have developed the system using a dc superconducting quantum interference device (SQUID) magnetometer to make comparative MCG studies of disease-model mice in order to clarify the mechanism of disease development in a living body. We measured the MCG of wild-type (control) and aconitine-induced arrhythmia model mice. The difference in the spatial distribution and time course of the MCG signals between regular sinus rhythm and arrhythmia was clearly evaluated. The results suggest that the system presented is capable of screening the cardiac excitation pathway of mice in good spatial and time resolution.
We have developed a system that uses a superconducting magnet to remove arsenic from geothermal water. The advantages of applying a high-field, high-gradient magnetic separator (HGMS) and a reciprocating high-gradient magnetic separator for practical use are presented. Finally, we demonstrate that the capture efficiency of the HGMS does not depend on dimensions, and show that properties of a large HGMS plant can be estimated from our experimental results.