Digital dielectrophoretic levitation

Abstract

In this article we describe a computer‐controlled active feedback dielectrophoretic (DEP) levitator and its measurement capabilities for characterizing single particles and particle chains (20–500 μm in length). Edge detection using a linear array of photodiodes is employed and an adaptive controller updates the voltage required for stable levitation at a rate of 4.7 kHz. Rms voltage fluctuations are typically less than 0.2% of the levitation voltage. The most precise data to date for the effective dipole moment of conducting particle chains up to four in length are presented along with experimental measurements of the effective dipole moment of two particle chains of unequal size as tests of accuracy and precision of the apparatus.