Electrochemically activated adaptive liquid lens

Manipulating the shape of liquids using surface tension is an important and useful strategy in designing small-scale fluidic devices. Here we present an example of such a device, a millimeter-scale variable focal length liquid lens consisting of two capillary surfaces. Surface tension is made to change on one capillary surface relative to the other by means of an electric voltage that works in conjunction with a redox surfactant. The change in curvature of the capillary surfaces induces a change in focal length in a process that is shown to be reversible. Focal length values are between 0.5mm and infinity depending on the volume, and electrochemical activation can change the focal length of the liquid lens by 50% or more.