Insulator‐based dielectrophoresis for the selective concentration and separation of live bacteria in water

Abstract

Insulator-based dielectrophoresis (iDEP) was utilized to separate and concentrate selectively mixtures of two species of live bacteria simultaneously. Four species of bacteria were studied: the Gram-negative Escherichia coli and the Gram-positive Bacillus subtilis, B. cereus, and B. megaterium. Under an applied direct current (DC) electric field all the bacterial species exhibited negative dielectrophoretic behavior. The dielectrophoretic separations were carried out in a glass microchannel containing an array of insulating posts. The insulating posts in the microchannel produced nonuniformities in the electric field applied along the channel. Mixtures of two species of bacteria were introduced into the microchannel and the electric field was applied. The bacterial species exhibited different dielectrophoretic mobilities under the influence of the nonuniform field. From these experiments a trapping order was established with E. coli trapping at the weakest applied electric field, while the Bacillus species were trapped at different characteristic threshold fields. At stronger applied electric fields, the two different species of bacteria in the microchannel were dielectrophoretically trapped into two spatially distinct bands. The results showed that iDEP has the potential to selectively concentrate and separate different species of bacteria.

Single cell dielectric spectroscopy

“…For a typical cell the momentum relaxation time is of the order of tens of microseconds. The practical application of DEP for manipulation, separation and selection of cells, beads, bacteria and viruses has been reported by a number of authors [44][45][46][47][48][49].…”

Extraction and Purification of Bioproducts and Nanoparticles using Aqueous Two‐Phase Systems Strategies

“…DEP is the movement of particles in a nonuniform electric field, and it can occur in AC or DC electric fields. DEP has been successfully applied for the manipulation of a wide range of particles: biomolecules [34][35][36][37][38], virus [39][40][41], bacteria [42][43][44][45][46][47][48][49], spores [50,51], mammalian cells [52][53][54] and parasites [55][56][57]. DEP offers the possibility of sample concentration and separation in a single step.…”

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

“…In insulator-based dielectrophoresis (iDEP), both DC and AC voltages (of any frequency) can be applied to the remote electrodes positioned in end-channel reservoirs for transporting and manipulating particles. The electric field gradients are caused by the blockage of electric current due to in-channel hurdles, posts, and ridges [18][19][20][21][22][23][24][25][26][27].…”