Development of Metallic Contaminant Detection System Using RF High-Tc SQUIDs for Food Inspection

摘要

In this study, we developed a practical magnetic metallic contaminant detector using three high-Tc RF superconducting quantum interference devices (SQUIDs) for food inspection. Finding small metallic contaminants is important for food safety. When contamination occurs, the manufacturer of the product suffers a great loss to recall the tainted products. Therefore we developed a practical food contaminant detection system based on high-Tc RF SQUIDs. The system was covered with waterproof stainless steel plates, and the outer dimensions of the system were 2450 mm (W) 714 mm (D) 1555 mm (H). An acceptable inspected object size was 150 mm (W) 100 mm (H), which is sufficiently large for practical food inspection. A digital filtering technique has been newly introduced to reduce noise. As a result, the signal-to-noise ratio (SNR) was dramatically improved, and we were able to robustly detect a steel ball as small as 0.3 mm in diameter.