الفهرس 
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Abstract
Electrowetting is defined as spreading of small liquid droplets on hydrophobic
surfaces by biasing the potential of the droplet with respect to an insulated electrode
located beneath the droplet. Electrowetting is the basic physical phenomenon behind
the Digital Microfluidics (DMF) technology which permits manipulation of
microdroplets on arrays of insulated electrodes. Electrowetting also has many other
useful applications such as adjustable focal distance liquid lenses, micromirrors,
micropumps, and electronic displays. The main challenge facing implementation of
electrowetting technology in many applications is the Contact Angle Saturation
(CAS) phenomenon in which the contact angle of the droplet ceases to decrease no
matter how much the applied voltage is increased. CAS phenomenon prevents liquid
droplets from spreading completely on the insulated electrode, and thus limiting the
actuation range at high applied voltages in many electrowetting applications.
In the present work, new approaches were introduced to interpret CAS
phenomenon in electrowetting systems, such as the effect of line tension of Three-phase Contact Line (TCL) where three phases solid (dielectric layer)-liquid (droplet)-vapor (surrounding medium of the droplet) meet together, the effect of the energy
stored in the mutual field of the accumulated charges at the TCL, and the repulsion
between the accumulated charges on the droplet surfaces at the TCL. The repulsion-based model was the best approach for modeling CAS phenomenon where the
repulsion model describes CAS phenomenon behavior completely in good
agreement with experimental results.
The repulsion model depends on considering the repulsion between trapped .