Bioanalytical separations using electric field gradient techniques

Abstract

The field of separations science will be strongly impacted by new electric-field-gradient-based strategies. Many new capabilities are being developed with analytical targets ranging from particles to small molecules, and soot to living cells. Here we review the emerging area of electric field gradient techniques, dividing the large variety of techniques by the target of separation. In doing so, we have contributions using dielectrophoresis, electric field gradient focusing (including dynamic, true moving bed, and pulsed field), electrocapture and electrophoretic focusing, temperature gradient focusing, and focusing with centrifugal force. We cover the literature from the start of 2007 to June 2008, along with some introductory discussions. Even with the relatively short time frame, this young and dynamic field of inquiry produced some 100 contributions describing new and unique techniques and several new applications.

Dielectrophoretic Field-Flow Microchamber for Separation of Biological Cells Based on Their Electrical Properties

“…Still, even for cells with substantially different membrane properties, the efficiency of this method can be hampered if the cells within one or both classes have a broad distribution of sizes. Namely, as (1)- (3) in Section II-B show, the magnitude of is roughly proportional to ; in (1) the term features directly, while in (3) the two fractions containing have values close to 1 (as ). In the systems based on different magnitudes of , dielectrophoresis is combined with a flow of the medium in which the cells are suspended (the buffer).…”

“…Common uses of dielectrophoresis are in selective cell manipulation, separation of particles, ranging from DNA fragments to eukaryotic cells [3], [4], and cell properties characterization [5], [6]. Separation of cells by dielectrophoresis is possible if the cells in the mixture belong to two (or more) classes, each with either a different geometry or different dielectric permittivity and/or electric conductivity [7], [8].…”

Label-free isolation of circulating tumor cells in microfluidic devices: Current research and perspectives

“…[70][71][72][73][74][75][76][77][78][79] Dielectrophoresis is defined as the movement of a neutral but polarizable particle in a nonuniform electric field due to the interaction of the particle's dipole and spatial gradient of the electric field. DEP can be generated using alternative current (AC), direct current (DC) 80,81 or DC-biased alternative current (AC) electric fields.…”

Application of capillary electrophoresis to predict crossover frequency of polystyrene particles in dielectrophoresis

“…Although DEP can result from either AC or DC electric fields, the majority of DEP studies have been performed using AC fields as AC fields reduce electrophoretic transport. A number of reports demonstrate the use of DEP for spatial segregation of particles, such as magnetite [3], cells [4], or liposomes [5], by changing the field frequency to manipulate DEP response [6][7][8]. The crossover between positive and negative DEP response is dependent on the properties of the particle and the DEP medium.…”