Rapid and Sensitive Detection of Salmonella Typhimurium on Plastic Food Processing Plates by Using Wireless Biosensors

Food products can be contaminated with bacteria, spores, viruses, toxins and other pathogens at any point in the farm-to-table continuum. This paper presents an investigation into rapid, sensitive detection of Salmonella Typhimurium on plastic food processing plates by using wireless magnetoelastic (ME) biosensors. In this research, a planar spiral coil was microfabricated and employed as a surface-scanning detector for real-time, in-situ measurement of the biosensors without sample preparation and/or enrichment in the testing process. The ME biosensor consists of an ME resonator, made from metallic glass (Metglas alloy 2826MB), as the signal transducer and E2 phage as the bio-molecular recognition element that is engineered to selectively bind with Salmonella Typhimurium. The ME biosensor is a type of mass-sensitive biosensors that can be wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field. Both measurement sensors (multiple E2 phage-coated biosensors) and control sensors (multiple biosensors without phage) were prepared and distributed on a food grade PET plate contaminated with S. Typhimurium with known volumes and concentrations. The resonant frequency changes of the measurement sensors due to specific binding of S. Typhimurium were found to be statistically different from those of the control sensors. The effects of sensor distribution and the surface roughness of PET plates (in the range of 0.25 to 1 um) on ME biosensor detection were also investigated.