A Microfluidic Platform Integrating Dielectrophoretic Concentration and Impedimetric Sensing for Rapid Salmonella...

Fast and sensitive detection of foodborne bacteria, such as Salmonella, is essential for food safety and public health control. This study constructed a microfluidic device integrating a top-bottom opposite electrode pair for performing positive dielectrophoresis (pDEP) and electrochemical impedance spectroscopy (EIS). The immunomagnetic beads (IMBs) modified with anti-Salmonella antibodies were spiked in Salmonella enterica serovar Choleraesuis (SC)-containing samples for 30 min to form IMBs@SC complexes, and they were separated by a magnet, which can prevent the sample matrix from contaminating the EIS detectors. After applying the 50 kHz/7.5 V_pp pDEP for 3 min to collect the IMBs@SC complexes in the microholes of the working electrodes, EIS was used to determine the SC concentration. The linear range and the calculated detection limit obtained from SC-spiked undiluted milk samples are 10¹ to 10⁴ and 2 cfu/mL. The total procedures from the IMBs immunoreaction to the sample-to-result on the device only take 50 min. The microfluidic device offers a promising platform for the rapid and ultrasensitive detection of pathogenic bacteria.