The complicated and/or tedious sample preparation procedures are one of problems for using developed numerous rapid detection methods as on-site applicable detection method. This study constructed a surface-scanning detection system consisting of phage-immobilized magnetoelastic (ME) sensor and miniatured square-type detector for the direct and automatic detection of Salmonella Typhimurium. ME sensor was fabricated by dicing and deposition methods. Detector was fabricated with microelectronic methods. The detector surrounded by magnetic boards was connected with movable food stand for the automatic movement. After dividing the zone of detector, a sensor was placed. A sensor was also placed on an apple and the signal amplitude of sensor was measured by moving the detector for the determination of optimal distance between sensor and detector. S. Typhimurium-specific phage was immobilized on the ME sensor directly prior measuring the resonant frequency (RF). The measured ME sensor was placed on the surface of apple inoculated previously with S. Typhimurium and measured its RF again for comparison. The ME sensor and detector was successfully fabricated, and the detection system was constructed for detecting the RF change of sensor. The signal was represented when placing the sensor on zone of B and D. As the distance between sensor and detector increased, the signal amplitude of sensor decreased with the ratio of -21.07 Hz/mm. Their maximum distance was determined to be 1.3 mm. The RF shift of phage-immobilized sensor was measured directly and automatically without any movement of sensor. In addition, the RF of sensor increased significantly depending on the increasing of Salmonella concentration. LOD and sensitivity were determined to be 2.17 ± 0.31 log CFU/mL and 531.00 ± 68.84 Hz/log CFU, respectively. Finally, the detection system constructed was optimized and its performance was demonstrated with easy and simple manner for S. Typhimurium detection.

Su-Hyeon Kim

Kyungpook National University

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