Moisture Content Evaluation Using Improved High-Tc SQUID-Based Rotating-Sample Magnetometer

Moisture content evaluated by magnetic signal change measured by rotating-sample magnetometer using high-temperature superconductor superconducting quantum interference device (HTS-SQUID) was investigated. To realize highly sensitive measurement of moisture content, an improvement in signal-to-noise (S/N) ratio of the previously developed magnetometer was examined. To increase the S/N ratio, the sample case with short width along the sample's movement direction was employed. By reducing the sample case width, the obtained magnetic signal intensity increased, and the frequency component of magnetic signal shifted toward high frequencies, leading to the low magnetic field noise range measurements. Using the improved magnetometer, the moisture content of silica gel was measured, and the magnetic signal intensity increased as the amount of water in the silica gel increased. Therefore, we propose a high-sensitivity, noncontact, and nondestructive method for moisture content evaluation using rotating-sample magnetometer.