Development of Contaminant Detection System using HTS SQUIDs

Abstract

In terms of food safety,mixture of contaminants in food is a serious problem for not only consumers but also manufacturers. In general, the target size of the metallic contaminant to be removed is 0.5 mm. However, it is a difficult task for manufacturers to achieve this target, because of lower system sensitivity. Therefore, we developed a food contaminant detection system based on high-Tc RF superconducting quantum interference devices (SQUIDs), which are highly sensitive magnetic sensors. This study aims to improve the signal to noise ratio (SNR) of the system and detect a 0.5 mm diameter steel ball. Using a real time digital signal processing technique along with analog band-pass filters, we improved the SNR of the system. Owing to the improved SNR, a steel ball with a diameter as small as 0.3 mm, with stand-off distance of 117 mm was successfully detected. These results suggest that the proposed system is a promising candidate for the detection of metallic contaminants in food products.

Prototype of Multi-Channel High-Tc SQUID Metallic Contaminant Detector for Large Sized Packaged Food

“…Thus, in order to obtain a steeper decay and improve the SNR, introduction of a digital filter was considered. We used past finite data for our filter calculations and a finite impulse response (FIR) type LPF with a rectangular window with which the processing operation can be stabilized [8], [9]. The transfer function of the FIR filter is expressed by…”