The present invention provides a microfluidic devices and methods of use thereof for the concentration and capture of cells. A pulsed non Faradaic electric field is applied relative to a sample under laminar flow, which results to the concentration and capture of charged analyte. Advantageously, pulse timing is selected to avoid problems associated with ionic screening within the channel. At least one of the electrodes within the channel is coated with an insulating layer to prevent a Faradaic current from flowing in the channel. Under pulsed application of a unipolar voltage to the electrodes, charged analyte within the sample is moved towards one of the electrodes via a transient electrophoretic force.