A surface-scanning coil detector for real-time, in-situ detection of bacteria on fresh food surfaces

Proof-in-principle of a new surface-scanning coil detector has been demonstrated. This new coil detector excites and measures the resonant frequency of free-standing magnetoelastic (ME) biosensors that may now be placed outside the coil boundaries. With this coil design, the biosensors are no longer required to be placed inside the coil before frequency measurement. Hence, this new coil enables bacterial pathogens to be detected on fresh food surfaces in real-time and in-situ. The new coil measurement technique was demonstrated using an E2 phage-coated ME biosensor to detect Salmonella typhimurium on tomato surfaces. Real-time, in-situ detection was achieved with a limit of detection (LOD) statistically determined to be lower than 1.5×103 CFU/mm2 with a confidence level of difference higher than 95% (p<0.05).