We report on a light-actuated, droplet based microfluidic platform enabling two-dimensional (2D) droplet manipulation on an open chamber with a single-side, featureless photoconductive surface. The droplet actuation mechanism is based on recently demonstrated floating electrode optoelectronic tweezers (FEOET), which enable light-induced dielectrophoretic forces to manipulate aqueous droplets im...

In this work we have investigated the integrated diaphragm micropump as an active fluidic control approach for the on-demand generation of droplets with precisely defined size, frequency and timing. In contrast to valve-actuated devices that only modulate the flow of the dispersed phase being continuously injected, this integrated micropump allows the combination of fluidic transport and modula...

Understanding the phenomenon of droplet coalescence in nanoparticle suspensions is extremely important for the preparation of Pickering emulsions. A microfluidic platform, which can provide compulsive droplet collisions, was developed to imitate the droplet coalescence process in the early stages of emulsification. Microscope videos showed the variations in the droplet coalescence percentage, d...

We experimentally investigate the effects of high electric field on living cells inside a charged droplet under electrophoretic actuation. When an aqueous droplet suspended in a dielectric liquid contacts with electrified electrode, the droplet acquires charge. This charged droplet undergoes electrophoretic motion under strong electric field (1-3 kV/cm), which can be used as a droplet manipulat...

Controlled metal transfer in gas metal arc welding (GMAW) implies controllable weld quality. To understand, analyse and control the metal transfer process, the droplet should be monitored and tracked. To process the metal transfer images in double-electrode GMAW (DE-GMAW), a novel modification of GMAW, a brightness-based algorithm is proposed to locate the droplet and compute the droplet size a...

In this work, the nanoscale footprints of self-driven liquid gallium droplet movement on a GaAs (001) surface will be presented and analyzed. The nanoscale footprints of a primary droplet trail and ordered secondary droplets along primary droplet trails are observed on the GaAs surface. A well ordered nanoterrace from the trail is left behind by a running droplet. In addition, collision events ...

The kinetics of wicking of liquid droplets into yarns was studied by a computerized imaging system. A new method is suggested for characterization of the yarn structure by monitoring the droplet absorption. The method is based on the comparative analysis of the time needed for the droplet disappearance as a function of the droplet volume for various yarns. A mathematical model is developed for ...

Electrowetting (EW) involves the actuation of liquid droplets using electric fields and has been demonstrated as a powerful tool for initiating and controlling droplet-based microfluidic operations such as droplet transport, generation, splitting, merging and mixing. The heat transfer resulting from EW-induced droplet actuation has, however, remained largely unexplored owing to several challeng...

Using the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)], we numerically investigate the hydrodynamics of Leidenfrost droplets under gravity in two dimensions. Some recent theoretical predictions and experimental observations are confirmed in our simulations. A Leidenfrost droplet larger than a critical size is shown to be unstable and break up into smaller droplets due to the Ra...

This paper describes a concept of concentration and binary separation of particles and its experimental confirmations for digital microfluidics where droplets are driven by the mechanism of electrowetting-on-dielectric (EWOD). As a fundamental separation unit, a binary separation scheme is developed, separating two different types of particles in one droplet into two droplets, one type each. Th...