  In this work, Electrowetting on Dielectric (EWOD) and electrostatic induction
(ESI) are employed to manipulate droplet on the PDMS-ITO substrate. Firstly, we
report large vertical vibrations of the droplet, induced by EWOD, within a
voltage range of 40 to 260 V. The droplet's transition from a vibrating state
to a static equilibrium state are investigated in detail. It is indicated that
the contact angle changes synchronously with voltage during the vibration. The
electric signal in the circuit is measured to analyze the vibration state that
varies with time. By studying the influence of driving voltage on the contact
angle and the amplitude in the vibration, it is shown that the saturation
voltage of both contact angle and amplitude is about 120 V. The intrinsic
connection between contact angle saturation and amplitude saturation is
clarified by studying the surface energy of the droplet. A theoretical model is
constructed to numerically simulate the vibration morphology and amplitude of
the droplet. Secondly, we realize the horizontal motion of droplets by ESI at
the voltage less than 1000 V. The charge and electric force on the droplet are
numerically calculated. The frictional resistance coefficients of the droplet
are determined by the deceleration of the droplet. Under consideration of
frictional resistance of the substrate and viscous resistance of the liquid,
the motion of the droplet is calculated at 400 V and 1000 V, respectively. This
work introduces a new method for manipulating various forms of droplet motion
using the single apparatus.
