A microfluidic device for continuous capture and concentration of microorganisms from potable water

Abstract

A microfluidic device based on electrophoretic transport and electrostatic trapping of charged particles has been developed for continuous capture and concentration of microorganisms from water. Reclaimed and bottled water samples at pH values ranging from 5.2–6.5 were seeded with bacteria (E. coli, Salmonella, and Pseudomonas) and viruses (MS-2 and Echovirus). Negative control and capture experiments were performed simultaneously using two identical devices. Culture based methods were utilized to characterize the capture efficiency as a function of the species type, time, flow rate, and applied electric field. Based on differences between the capture and negative control data, capture efficiencies of 90% to 99% are reported for E. coli, Salmonella, Pseudomonas, and MS-2, while the capture efficiency for Echovirus was between 70% and 80%. Overall, the device exhibits a 16.67 fold sample volume reduction within an hour at 6 mL h⁻¹ flow rate, resulting in a concentration factor of 14.2 at 85.2% capture efficiency. The device can function either as a filter or a sample concentrator without using any chemical additives. It can function as an integral component of a continuous, microbial capture and concentration system from large volumes of potable water.