Detection and confirmation of Salmonella Typhimurium by smartphone-enabled optomechanical platform

<i>Salmonella</i> ser. Typhimurium is notorious for causing serious foodborne illnesses and presenting considerable public health risks. The study introduces an innovative system based on a quartz crystal microbalance, designed to detect the target pathogen by integrating the system around a smartphone. The system operates through a dual-mode approach, relying on two distinct mechanisms: measuring frequency changes due to variations in bacterial mass and quantifying fluorescence intensities resulting from bacteria captured by FITC-labeled antibodies. Incorporating FITC-labeled antibodies not only enhances the resonance frequency shift but also offers visual confirmation through the fluorescence signal. The integration of the quartz crystal microbalance system with a smartphone enables real-time monitoring. This system displays both frequency and temperature data, while also capturing fluorescence intensities to estimate the concentration of the target analyte. The smartphone-based system successfully detected <i>Salmonella </i>Typhimurium within a concentration range of 10⁵ CFU/mL after the application of FITC-labeled antibodies. This portable QCM system represents a promising advancement in pathogen detection, holding significant potential to improve food safety protocols and strengthen public health safeguards.