On-Chip Impedance for Quantifying Parasitic Voltages During AC Electrokinetic Trapping.

Abstract

Assessing the effectiveness of microfluidic device structures for enabling electrokinetic or acoustic trapping requires imaging of model particles within each device under the requisite force fields. To avoid the need for extensive microscopy, the use of valuable biological samples, and reliance on a trained operator to assess efficacy of trapping, we explore electrical means to identify device geometry variations that are responsible for the poor trapping. Using the example of AC electrokinetic trapping over an insulated channel in a contact-less dielectrophoresis mode, we present an on-chip method to acquire impedance spectra on the microfluidic device for quantifying the parasitic voltage drops. Based on the parasitic voltage drops, device geometries can be designed to maximize fraction of the applied voltage that is available for dielectrophoretic manipulation and the measured on-chip impedance can rapidly inform downstream decisions on particle manipulation.