Two conventional configurations of EWOD: (a) parallel-plate configuration; (b) single-plate configuration.
Change in contact angle and minimization of free energy of system: (a) before applying a voltage; (b) just after voltage is applied; (c) in equilibrium state.
A droplet in contact with high voltage and grounded electrodes.
Switching methods. (a) Method A simultaneously applies high and low voltages to a pair of electrodes located in transverse direction to the direction of movement. (b) In method B, the electrode pair is parallel to the direction of movement. In methods (c) C and (d) D, an intermediate step is introduced to methods A and B, respectively. That is, after a droplet moves to the activated electrode pair, the activated electrodes are briefly grounded. (e) Method E is nonfloating switching method which applies a high voltage to a single electrode while grounding the rest of electrodes. Time sequence is from left to right.
Charge distribution in electrodes. Left is for initial step and right is for next step. (a) Conventional switching method; (b) nonfloating switching method.
Electrode connections: (a) with two switches; (b) with one switch and one resistor; (c) with single three-way switch.
Patterns of electrode arrays: (a) pattern 1; (b) pattern 2. electrode arrays are made; the dimension of an electrode is and the gap between two electrodes is in width.
Droplet oscillation on an electrode array.
Transport path: (a) for methods A and C; (b) for methods B, D, and E.
Maximum speed of transport for five switching methods: (a) at ; (b) at .
Equilibrium position obtained theoretically (up) and experimentally (down): (a) for methods A and C; (b) for methods B and D; (c) for method E.
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