We utilize a simple parallel electrode setup on which intense holographic optical landscapes are shone. Intense optical
illumination creates high local gradients in the dielectric properties of the fluid, which in the presence of an electric field
results in a fluid body force. This leads to the creation of toroidal microvortices, which aid the particle concentration
process. Fluid drag aiding low frequency AC electrokinetic forces leads to an aggregation of particles on the illuminated
regions of the electrode surface. With a fine balance of these forces, we show that such optically driven electrokinetic
mechanisms can capture and aggregate nanoparticles (50nm and 100 nm). Particle aggregation is a function of the AC
frequency and by using fluorescent particles we characterize the technique as a function of the applied AC frequency.
Relatively low optical powers (~20 mW) are utilized in this technique.
We show an optically induced AC electrokinetic technique that rapidly and continuously accumulates colloids on an
electrode surface resulting in a crystalline-like monolayer aggregation. We demonstrate colloidal aggregation for
particles ranging from 100 nm to 3 μm. Electrothermal hydrodynamics produce a microfluidic vortex that carries
particles in suspension towards its center where they are trapped by low-frequency AC electrokinetic forces. We
characterize the rate of particle aggregation as a function of the applied AC voltage and hence characterize trapping
kinetics of this technique. We show that inter-particle distance varies with frequency and we explain this in the light of