Coupled cantilever biosensor utilizing a novel approach to gap-method for real-time detection of E. coli in low concentrations

Abstract

Biosensors have become indispensable for rapid detection of pathogens and play a vital role in the monitoring of bioparticles in healthcare, environmental monitoring and food safety. This paper presents a novel microsensor consisting of a pair of coupled cantilevers. During testing, the cantilevers are immersed in a sample solution and one of the cantilevers is actively actuated to vibrate while the other is passively driven through the sample solution. To accelerate pathogen capture, dielectrophoresis (DEP) is used to concentrate the sparse bacteria in the sample solution to the gap region between the cantilevers. The captured bacteria cause frequency shifts for both cantilevers. The limit of detection (LOD) of the sensor is determined to be 15 cells/ml and signal-to-noise ratio (SNR) reaches to 12.8 and higher. For stagnant samples, high frequency shifts of up to 3.1 kHz are observed for 10⁵ cells/ml while even for a low concentration of 100 cells/ml a substantial frequency shift of 914 Hz is recorded. Performance is also characterized at different flowrates, and significant frequency shifts up to 1.7 kHz are observed for 10⁵ cells/ml concentration at 1 µl/min. These advancements establish the proposed biosensor as a highly sensitive, and versatile tool for detecting pathogens in diverse applications.