A Continuum Modeling Approach to Nanoparticle Polarizability Characterization Using Fluorescence Intensity Profiles

The use of dielectrophoresis (DEP) for the manipulation of electrically polarizable particles has received a lot of interest in the past decades. Theories relying on the Clausius-Mossotti (CM) factor describe the DEP behavior of macroscale particles with great accuracy. However, under nanoscale conditions, these classical CM factor theories can break down. Therefore, experimental characterization of particle polarizabilities is of utmost importance. We present an integrated experimental-computational methodology that allows the quantification of effective particle polarizabilities from DEP experiments. The methodology is based on the comparison of experimental and simulated concentration profiles of fluorescent nanoparticles captured by a set of electrodes. We obtain effective particle polarizabilities for 52 and 105 nm particles that agree well with values predicted by CM theory. The considered particles hence serve as a calibration model for our approach, demonstrating that realistic particle polarizabilities can be obtained and paving the way for polarizability quantification for particles where existing theories are inadequate.