Mirror Reflector Actuated by Liquid Droplet

In this letter, we demonstrate a mirror reflector actuated by a liquid droplet. Four rectangular polymethyl methacrylate substrates are stacked to form the device structure. Three ITO electrodes are fabricated on the bottom substrate. One droplet is placed on the middle of the substrate and is surrounded by silicone oil. One side of the mirror is adhered to a rotating axis and the other side is immersed in the droplet. When we apply a voltage to one side of the ITO electrode, the droplet stretches and moves toward this side of the substrate surface and pushes the mirror to rotate. When illuminated by a light beam, the mirror reflector can function as a beam steering and detecting device. Our experiments show that the mirror reflector can deflect and steer the light within an angle of 0 degrees-60 degrees (+/- 30 degrees) as the applied voltage is changing from 0 to 65 V. The proposed device has potential applications in many fields such as free-space optical communications and laser detections.