A microfluidic device for bacteria immobilization in a microporous carrier by dielectrophoresis

In this paper, the immobilization of bacteria in micropores is demonstrated using positive dielectrophoresis (DEP) in a microfluidic device. The device uses a hot melt sheet in which a microfluidic channel is formed, sandwiched between upper and lower electrodes. The sheet was patterned using a cutting machine with a precision of 5 μm and was successfully bonded to ITO electrodes at 100 °C. During experiments that took place over the course of 2 days, no erosion of the sheet was observed. The ultimate goal is to characterize bacteria while precisely controlling their number and reaction conditions. By effective screening of such bacteria, it is hoped that useful chemicals such as organic acids, antibiotic drugs, and foodstuffs can be efficiently produced by fermentation. Corynebacterium glutamicum was chosen as the sample bacterium in this study. An optimum DEP frequency of 10 MHz was first experimentally determined for preferentially driving live bacteria to areas with stronger electric fields. The proposed device was then used to immobilize the bacteria in micropores with diameters of 5 and 10 μm. An average of 7. 5 and 24. 4 bacteria were successfully immobilized in the 5- and 10-μm pores, respectively, with a live/dead ratio of greater than 10. The proposed microfluidic device allowed the lactic acid productivity of C. glutamicum to be evaluated while immobilizing them in the microporous carrier. It is thus readily applicable as an efficient bacteria screening platform.