Insulating Post Dielectrophoresis

Direct current dielectrophoresis (DC-DEP) Electrodeless dielectrophoresis Insulating post dielectrophoresis Insulator-based dielectrophoresis (iDEP) Streaming dielectrophoresis Trapping dielectrophoresis... 

Insulating post dielectrophoresis was adopted in 2004 to concentrate and sort live and dead E. coli [6]. The batch concentrator strategy was employed, and in 16 V/mm DC fields, live E. coli cells were concentrated between insulating posts. Bands of dead cells and then live cells were accomplished at 60 V/mm with the dead cells preferentially concentrating at the electric field... 

Cummings, E.B., Singh, A.K., Dielectrophoresis in microchips containing arrays of insulating posts Theoretical and experimental results. Anal. Chem. 2003, 75, 4724—4731. 

DC Dielectrophoresis in Lab-on-a-Chip Devices, Fig. 1 The diagram depicts chambers holding a reservoir of fluid (shaded) at either end of a lab-on-a-chip linear microchannel. The electrodes are immersed in the chamber liquid and deliver a DC electric field the field lines bend around insulating posts or protrusions of varying geometries (triangular posts, cylindricrd posts,... 

Conventionally, the nonuniform electric fields for dielectrophoresis applications are produced directly with an arrangement of conductive electrodes. However, a nonuniform electric field can be generated in microchannels without direct interaction with electrodes. For example, Cummings generated nonuniform electric fields using remote electrodes placed at the inlet and outlet of the microchannel [7]. The electric field is applied across the channel and is deformed by the variations in the channel geometry or by insulating structures or posts within the microchannel. 

A number of creative ways have been developed to create nonuniformities in an electric field using insulators. Initial efforts simply used prefabricated posts embedded in the channels [6] or rectangular [8], triangular [3], oil menisci [9], and other protrusions into the channels. The most common insulator materials are polymers utilized for photolithography or hot press microfahrication including polydimethylsiloxane PDMS and polymethyl methacrylate PMMA, or glass or silicone, which can be chemically etched or ablated [2]. A key attribute of direct current dielectrophoresis is that the electrodes supplying the electric field can be located more remotely on the lab-on-a-chip device. Electrodes can be immersed in fluid in chambers at either end of the test channel to avoid detrimental electrolysis reaction products [31]. Please see Pig. 1. 

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