New Scientist

A fluid-filled lens that changes focus in response to an electrical current could provide cheaper optical systems for electronic gadgets like camera phones and DVD players.

Conventional optical systems change focus by altering the distance between two solid lenses, requiring moving parts. In contrast, the FluidFocus lens developed by Philips manipulates two fluids using current to bring objects into clearer view.

The new lens comprises of a short cylinder filled with two liquids – an electrically conducting aqueous solution and a non-conducting oil. The fluids are immiscible, forming two distinct layers, and also refract light differently.

When an electrical current is applied, the walls of cylinder becomes less water repellent. This process – called electrowetting – changes the distribution of the two fluids in the lens and causes the curve to flatten out, changing its focal length. The current can even reverse the curvature of the lens from convex to concave.

In principle, two lenses of this type could be used together to create an optical system that is also capable of zooming in and out.