Exploiting Particle Mutual Interactions To Enable Challenging Dielectrophoretic Processes.

Dielectrophoresis (DEP) is the motion of particles under the influence of a nonuniform electric field. In insulator-based dielectrophoresis (iDEP), the required nonuniform electric fields are generated with insulating structures embedded in a microchannel. These structures distort the electric field distribution when an electric potential is applied. This contribution presents an experimental characterization of the electrokinetic (EK) and DEP velocities of a set of target particles, under DC potentials, when additional innocuous particles are used as fillers. Streak-based particle velocimetry in a tapered channel was used to assess particle motion. Filler particles of various sizes were added at different volume fractions (ϕ) to suspending media containing the target particles/cells. The presence of the filler particles resulted in electric field distortions and dissimilar particle behaviors caused by particle-particle interactions. These particle mutual interactions were exploited to improve the enrichment of low-abundance yeast cells in an iDEP channel. It was shown that the smallest studied filler particles (500 nm) have the potential to aid the enrichment of low-abundance yeast cells when filler volume fractions ∼1 × 10-5 v/v are used. Enrichment factors of ∼115 were achieved by applying electric potentials as low as 500 V.