Smartphone-based pathogen detection using concurrent monitoring of resonant frequency and optical fluorescence

Recently, the use of a Quartz Crystal Microbalance (QCM) as a biosensor for detecting foodborne pathogens by observing changes in resonant frequency has gained popularity. However, conventional detection methods are time-consuming and require expensive equipment and trained personnel. The current trend is toward detection approaches that are quick, portable, and easy to use. In order to address this need, a dual-modality QCM system combining a smartphone, an in-situ fluorescence imaging subsystem, and a flow injection component has been proposed. This system enables a smartphone to receive real-time frequency data via Bluetooth, while a camera detects the presence of bacteria on the quartz crystal surface using a fluorescence-tagged antibody. The fluorescence imaging subsystem utilizes a camera to capture the bacteria fluorescence signal, while the flow injection subsystem employs a mini peristaltic pump and controller to introduce biochemical solutions, antibodies, and bacteria. All components are contained in a 3D cartridge that is portable. FITC images were captured with 5 MHz quartz crystals when the prototype system was tested. The developed QCM biosensor has t