A Continuous Flow Dielectrophoresis (DEP) Device for the Separation/Concentration of Escherichia coli K12 and Bacteriophage MS-2 from Contaminated Tap Water
University of Hawaii, USA
Dr. Soojin Jun
Motivated by the lack of innovative water treatment technology and the absence of DEP food applications, this study examined the viability of using dielectrophoresis as a substitute for filtration by removing Escherichia coli K12 and bacteriophage MS-2 from tap water. A continuous flow, millimeter-sized, single-stage DEP device was constructed using polydimethylsiloxane (PDMS) as foundation, coupled with titanium electrodes. A frequency generator attached to an amplifier controlled the voltage and frequency applied to the electrodes, and a continuous flow was created using a syringe pump that ensured a steady flow rate of the sample into the device. Different combinations of the factors affecting separation, which included voltage, flow rate, and frequency, were also studied. The optimized parameters for successful E. coli K12 and bacteriophage MS-2 removal via DEP were determined using the response surface method. The highest separation efficiency obtained for E. coli K12 was found to be 47% and 42% under the experimental parameters of 40 V, 100 μl/min, and 1 MHz; and 60 V, 1 ml/min, and 1 MHz, respectively. In addition, the highest separation yield for MS-2 was found to be 82% at the conditions of 20 V, 100 μl/min, and 100 kHz. This micro-scale device is the first step in the application of DEP for cell separation and concentration, prior to future macro-scale water flow applications.