(395b) Using Particle-Particle Interactions to Enable Challenging DEP Separations

Insulator-based dielectrophoresis (iDEP) is a powerful electrokinetic (EK) technique that is commonly used for the focusing, enrichment and isolation of biological and non-biological particles. In iDEP devices, arrays of insulating structures are used to create a non-uniform electric field. When dielectric particles are exposed a non-uniform electric field, a particle dipole moment is induced, generating a DEP force on the particles. This force dominates particle movement in highly diluted solutions, where particle-particle interactions are insignificant. However, the influence of particle mutual interactions increases along with particle concentration, since particles are more closely spaced and their dipoles can interact with each other. This contribution presents a systematic approach for the characterization of the EK and DEP velocities of a set of target particles, when additional innocuous particles are used as fillers. The characterization was performed by using the streak-based velocimetry technique in a tapered channel [1]. The dependence of the target EK/DEP velocities on the filler particle concentration, as well as on the filler particle size, was studied. Experiments were carried out to assess how the volume fraction and size of the filler particles can be exploited for the enrichment of target particles/cells. Experiments with a low concentration of yeast cells where performed to demonstrate the potential of this technique for enriching target cells- an essential step in sample preparation for many bioanalytical assessments.