Electrostatic fringe-field actuation for liquid-metal droplets

The paper reports an actuation mechanism for large displacement of liquid-metal (LM) droplets in air. The droplets are sandwiched between two substrates and are actuated by a fringe field based capacitive drive. In order to initiate motion, the driving force must overcome a critical force due to stiction. Electrowetting experiments showed significant variation from theory due to dielectric charging. A design modification to bias the LM droplet positively reduces charging effects and gives results in good agreement with theory. We demonstrated devices with actuation voltages of 80 V and actuation speed of more than 3.3 cm/s.