Two degree-of-freedom micromirror actuation using thermocapillary effect in liquid droplets

A novel way to manipulate micro-objects using thermocapillary effect in a liquid droplet is presented for the application in optical scanning micromirror. Thermally induced, the surface tension gradients cause convection flows in a liquid droplet from high-temperature to low-temperature regions, changing the droplet shape. The contact angle hysteresis meanwhile is applied to keep the droplet from rolling away. The micro-object on top is therefore moved along the deformed droplet, which functions as a micromirror rotating around a liquid pivot. The device characterization is conducted and the two degree-of-freedom (2 DOF) scanning capability is demonstrated.