Abstract
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 10(1) to 10(4) 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.