A Portable Microfluidic Platform Based on Gravity-Mediated Magnetic Control for On-Site DNA Extraction and...

Rapid and accurate detection of foodborne pathogens in field settings remains challenging, as current methods typically rely on equipment-intensive and contamination-prone molecular steps. In this study, we propose a compact, fully integrated microfluidic system enabling automated magnetic bead-based DNA extraction and fluorescent loop-mediated isothermal amplification (LAMP) detection in raw samples. For efficient DNA extraction, a gravity-mediated magnetic microfluidic chip (GMMC) featuring a single flow channel was proposed. Reagents required for extraction were naturally settled at specific locations within the chamber via gravity, separated by mineral oil for liquid-phase partitioning. To enable magnetic bead transfer and execute the DNA extraction protocol, an automated control platform was designed with a single motor-driven magnet whose trajectory was constrained by a specially designed slot and two slide rails. Under the attraction of the magnet, the magnetic beads were driven along the preset trajectory. Therefore, DNA capture, washing, and elution can be completed sequentially. The DNA was amplified and detected using fluorescence-based qLAMP. Experiments confirmed that the system achieved highly sensitive detection of Salmonella enteritidis, Escherichia coli O157:H7, and Staphylococcus aureus in real food samples within 50 min, with detection limits as low as 10 copies. This self-contained, low-cost platform delivers an efficient solution for on-site food safety diagnostics, facilitating molecular detection in resource-limited settings and demonstrating potential for further development in point-of-care (POC) diagnostics.