(340a) Assessment of the Particle-Particle Influence On the Dielectrophoretic Response of Microparticles

Hector Moncada-Hernandez¹, Adrienne R. Minerick²

¹BioMEMS Research Chair, Tecnológico de Monterrey, Monterrey, NL, México.

²MD-ERL, Michigan Technological University, Houghton, MI, USA.

Advances on microfabrication technologies allow for the development of more complex and specific devices for the characterization and manipulation of particles. Microsystems that probe biological particles for diagnostic, materials, and other applications varying in configuration, complexity, and operating conditions. One electrokinetic tool commonly utilized is dielectrophoresis (DEP) which is based on the polarization of particles in the presence of non-uniform electric fields. This technique has been increasingly employed for the manipulation of bioparticles in miniaturized systems due to the easily observable particle movements with slight differences in dielectric properties using very low potentials over small distances. Further, computational models are employed to simulate the behavior of particles under specific conditions and to optimize the performance of a specific microfluidic device. In order to properly simulate the electrokinetic behavior of biological particles, it is important to determine the particle’s dielectric properties, which are most commonly obtained by studying the dielectrophoretic response and electrorotation (ROT) spectra for that specific cell. However, the number of particles in the system or number density is important to consider because particle-particle interactions under a controlled external electric field play an important role on the observed dielectrophoretic response. This is largely overlooked in the dielectrophoresis literature, although the particle-particle interactions affect particle polarizations by changing the local electric field between the particles. This work reports experimentally obtained velocity and negative DEP/positive DEP response of chained particles under a characteristic suspending medium and AC signal. Polarization can be determined as a function of the number of particles interacting together in a pearl-chain formation. In the present work, the velocity of spherical polystyrene microparticles and red blood cells (RBC) due to DEP force are measured in a device with a modified quadruple electrodes configuration. The velocity is compared between a single particle, 2, 3 and 4 particles aligned together in a chain formation along the electric field for both polystyrene beads and cells independently and changing the frequency of the signal in a range of 1 kHz to 80 MHz. Results are tabulated by region in the devices. The results from this work will help to further understand how induced dipole polarizations with different concentrations of particles can affect electrokinetic systems.