Real-Time Ultralow Bacterial Detection With A Gap-Method Microcantilever Biosensor

Detecting ultralow concentrations of pathogenic bacteria is important for public health, environmental monitoring, and therapeutic research. This study presents the development and testing of a microcantilever biosensor based on the gap-method for the detection of E. coli and P. aeruginosa bacteria in water. The biosensor utilizes dielectrophoresis (DEP) force to attract bacteria to the gap area for real-time detection of extremely low bacteria concentrations (10 cells/mL) within a 7-min timeframe. This design demonstrates excellent performance with a low limit of detection (LoD) (< 10 cells/mL), high sensitivity (minimum sensitivity of 2.59 pg/Hz), and a high signal-to-noise ratio (SNR) (minimum SNR of 23.38). In addition, the surface of the biosensor was functionalized with pyoverdine (PVD), a siderophore of pseudomonas bacteria. The test results show that the surface functionalization was effective and that the frequency shift of the functionalized microcantilever was much higher when testing P. aeruginosa compared to the testing with E. coli bacteria.