Blink twice to zoom in. A new soft lens can be controlled by your eye movements, pivoting left and right as you look around and zooming in and out when you blink.
The human eyeball is electric聽鈥� there is a steady electrical potential between its front and back, even when your eyes are closed or in total darkness. When you move your eyes to look around or blink, the motion of the electrical potential can be measured. Shengqiang Cai at the University of California San Diego and his colleagues used these signals, called electro-oculograms, to control a soft lens.
Advertisement
The casing of the lens is made of polymers that expand when an electrical voltage is applied, and the lens itself is just salt water. The casing has two main parts that mimic the muscles of the eye: the polymer chamber that encloses the water can become more convex, in effect zooming out, and around that chamber a ring of polymers expands and contracts to move the lens back and forth.
It is controlled via five electrodes placed around a subject鈥檚 eyes. They sense the electrical potential in the eyeball, so that when the subject looks side to side or up and down, the lens moves accordingly. The team programmed it so that when the subject blinks twice, the lens zooms in. When they blink twice again, it zooms back out.
With some tweaks to the design, a machine like this could be used in eyeglasses or even a prosthetic eye, Cai says. 鈥淓ven if your eye cannot see anything, many people can still move their eyeball and generate this electro-oculographic signal,鈥� he says. It could also be used as an external lens so that a human could control a camera with their eyes.
鈥淭he soft machine can also be absolutely any soft machine,鈥� Cai says. 鈥淚t doesn鈥檛 have to be a lens.鈥� Eventually, the interface that the researchers designed to control their lens could be used to run other types of machines or maybe even whole robots.
Advanced Functional Materials
