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International audience; In this work, a single-mode resonant microwave cavity (2.45 GHz) is loaded with spherical particles. A weakly coupled electromagnetic (EM)-thermal solver is used iteratively to determine how the microscopic geometry (local curvatures between the particles, grain size and neck size) modifies the EM field, and in turn the thermal field in the particles and also to quantify the microwave effect for an experimental process. The modelling is performed with the conformal finite element solver COMSOL Multiphysics. Moreover, this study will show that the electric field norm increases for one spherical particle of ceria with different sizes and consequently the temperature increases. In addition, the electric field and heating behaviour have been studied in the case of three particles with different neck sizes. Finally, the effect of the configuration versus the E-field direction has been studied for three particles and has a significant result.

We demonstrate a rapid generation of twin opposing microvortices (TOMVs) induced by non-uniform alternating current (AC) electric fields together with a laser beam on a patterned pair of indium tin oxide (ITO) electrodes. A fast and strong jet flow region between twin microvortices is also generated. Its pattern and direction, such as whether it is symmetric or asymmetric, are controlled mainly by the location of a single laser spot relative to the ITO electrodes. With two laser beams, two separate flows are superposed to give a new one. In situ generation and control of the TOMV flow are tested in suspensions of fluorescent polystyrene particles, as well as in milk emulsions. This technique has great potential for dynamically manipulating micro-fluid flows, functioning as a micro-pump or mixer.

We demonstrate an opto-electrokinetic technique for noninvasive particle manipulation on the surface of a parallel-plate indium tin oxide (ITO) electrode that is biased with an alternating current (AC) signal and illuminated with near-infrared (1064 nm) optical landscapes. This technique can generate strong microfluidic vortices at higher AC frequencies (> 100 kHz) and dynamically and rapidly aggregate and pattern particle groups at low frequencies (< 100 kHz).