Bacteria concentration using a membrane type insulator‐based dielectrophoresis in a plastic chip

Abstract

We report an insulator-based (or, electrodeless) dielectrophoresis utilizing microfabricated plastic membranes. The membranes with honeycomb-type pores have been fabricated by patterning the SU-8 layer on a substrate which was pretreated with self-assembled monolayer of octadecyltrichlorosilane for the easy release. The fabricated membrane was positioned between two electrodes and alternating current field was applied for the particle trap experiments. The particle could be trapped due to the dielectrophoresis force generated by the non-uniformities of the electric fields applied through the membranes with pores. Simulations using CFD-ACE+(CFD Research, Huntsville, Alabama) suggested that the dielectrophoresis force is stronger in the edge of the pores where the field gradient is highest. The bacteria could be captured on the near edge of the pores when the electric field was turned on and the trapped bacteria could be released when the field was turned off with the release efficiency of more than 93+/-7%. The maximal trapping efficiency of 66+/-7% was obtained under the electric fields (E=128 V/mm and f=300 kHz) when the dilute bacteria solution (Escherichia coli: 9.3 x 10(3) cell/mL, 0.5 mS/m) flowed with a flow rate of 100 microL/min.

Dielectrophoretic monitoring of microorganisms in environmental applications

“…Recent studies by Cho et al propose iDEP for bacteria concentration involving a plastic membrane as an insulating material [51]. By positioning a membrane between two electrodes and applying AC fields across it, the dielectrophoretic force is generated by the nonuniformities of the electric fields through the membrane with hexagonalshaped pores.…”

“…Many different approaches have been employed to apply DEP forces on particles, the most traditional manner is to use arrays of microelectrodes of a variety of geometries [34] and locations within a microchannel, from lateral electrodes [35] to threedimensional (3-D) cages [36,37] and 3-D electrodes [38]. Other novel approaches include: insulator-based DEP (iDEP) with 3-D columns or posts [39][40][41][42], oil menisci [43], glass spheres [44], microchannel with a geometry gradient [45,46], insulating hurdles [1,47], nanopipettes [19,48], spiral microchannels [49,50], and conical-pore membranes [51].…”

Microfluidic dielectrophoretic sorter using gel vertical electrodes

“…Thus, the design presented herein provides additional advantages over previously proposed iDEP designs to improve lateral DEP sorting. 71,72 …”

A new approach to design an efficient micropost array for enhanced direct-current insulator-based dielectrophoretic trapping

“…These devices are more appropriate for metal-sensitive organic samples. The iDEP microdevices including two separated electrodes in inlet and outlet have been successfully employed for different applications: separation and concentration of live and dead bacteria [13][14] separation of white blood cells [15], red blood cells (RBC) [16] or blood cell separation in a sawtooth microchannel [17] (see the review [18]). …”