Axial electrokinetic trapping of single particles at kHz feedback rates

Anti-Brownian Electrokinetic (ABEL) trapping has proven to be a valuable novel tool for analysis at the single-nanoparticle level. In previous work, we explored axial (in the z-direction only) ABEL trapping with planar ITO electrodes based on video image analysis. In this work, we improved the method by using total-internal-reflection (TIR) in combination with a single-photon-counting module. This allows us to axially trap single nanoparticles with a homogeneous field at feedback rates of several kHz such that screening of the electric field becomes negligible.