Controlling the adhesion force for electrostatic actuation of microscale mercury drop by physical surface modification

Under electrostatic actuation, mercury droplet can act as a contact and moving part in a microswitch system. In order to reduce the actuation voltage while keeping the electrical advantages of liquid-solid contact, the contact properties of mercury droplet on structured surfaces are investigated in this paper. Forces to actuate a mercury droplet on different structured surfaces are theoretically analyzed and experimentally tested. Both results confirm our claim that the adhesion forces of liquid metal droplets on a solid surface can be designed by physical modification of the surface. The criteria for detaching a mercury droplet from solid surface was predicted and verified by experimental results.