Cellphone cameras are packing more and more megapixels, but unless you want a DSLR that can make calls we also need all the other elements - autofocus mechanisms, lenses, etc. - to slim down as well. A team of engineers at Rensselaer Polytechnic Institute reckon they're on the way to that, with an autofocus system that can focus without traditional moving parts. They're calling the tech "liquid pistons", which use droplets of ferrofluid that deform liquid-based lenses.
Rather than the mechanical components of current lenses, the "liquid pistons" are saturated with metal nanoparticles which move when electrically charged. For compact cameras, the pistons themselves - which can be transparent - work as the lenses, tweaking the path of light through to the camera sensor depending on the charge applied.
"As the droplets vibrate, their shape is always changing. By passing light through these droplets, the device is transformed into a miniature camera lens. As the droplets move back and forth, the lens automatically changes its focal length, eliminating the usual chore of manually focusing a camera on a specific object. The images are captured electronically, so software can be used to edit out any unfocused frames, leaving the user with a stream of clear, focused video."
It's not just lenses, however; the movement of the liquid pistons can also be used for mechanical pumps small enough to fit a whole "lab" on a chip. The researchers have produced a chewing-gum stick sized pump consisting of two bubbles of ferrofluid that pulse in opposition: when submerged in water, they can use capillary force to move the liquid around. The study was partially funded by DARPA.