Continuous, rapid concentration of foodborne bacteria (Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes) using magnetophoresis-based microfluidic device

Abstract

Most biosensors use small amounts (a few tens of microliters) of a sample to detect bacteria. However, it is necessary to detect bacteria with at least a few milliliters of the sample to obtain statistically significant results. Therefore, the bacteria concentration process is critical for the rapid and accurate detection of bacteria. In addition, most bacteria concentration devices have a low throughput (200 mu L/h-3.6 mL/h), and it takes several hours to process a few milliliters of a sample. To significantly improve the throughput, a magnetophoresis-based bacteria concentration device is developed using a commercial polyethylene tube. The device is fabricated in three dimensions by wrapping the tube around the magnet. The channel length of the proposed device can be easily adjusted by adopting different tube lengths. Thus, particles can be concentrated even under high flow rates. The optimum channel length is calculated using the particle velocity engendered by the magnet and experimentally evaluated under various channel lengths and flow rate conditions. Moreover, the performance of the proposed device is evaluated using two different food samples, milk and homogenized cabbage, into which bacteria are spiked. The separation efficiency and concentration factor are higher than 92% and 110 times, respectively, at a flow rate of 40 mL/h. These results confirm that the proposed device has a considerably high throughput in comparison with that presented in previous studies.