Researchers Develop Low Power Memory

University of Illinois researchers have found a way to dramatically reduce the power consumption of flash memory used to store music, video, and other content in smartphones and other mobile devices, thereby lowering the impact of one of the biggest consumers of battery power.

The combination of the new technology with power-saving advancements under development in other components, particularly displays, could result in 10 times the battery life found in handheld devices today, says Eric Pop, assistant professor of electrical and computer engineering who led the research team.

"I think it's reasonable to say something like from a day of average use to maybe a week of average use," Pop said in an interview, "But, really, with the caveat that ultimately we have a lot of work cut out for us and other researchers who are working on improving the display technology."

Pop and his team have produced low-power memory by replacing the typical titanium or tungsten wiring used in memory today with nanotubes, microscopic carbon tubes that are 10,000 times thinner than human hair. The researchers also paired the nanotubes with "phase change materials," which are substances that change form when zapped with an electric charge.

In this case, the same shiny material found on a DVD for recording video and music was used. The chemical compound, called a chalcogenide, changes back and forth from being amorphous to crystalline when zapped with an electrical charge carried over the nanotube. These different states are used to represent the bits, or binary digits, used in storing data in flash memory used in handheld devices.

The invention uses far less power than flash because the latter stores bits as an electrical charge, which by definition would require much more power. Using a phase change material requires a tiny charge just to change the material, which stays in the converted state until zapped again, Pop says. Because a continuous charge isn't needed, there's no risk of erasing data by bringing a memory device to close to a magnet, for example.

"The only way to accidentally erase the phase change material is to stick it in the oven," Pop says. "Obviously, if you stick anything in the oven, things will melt."

Pop acknowledges that how much longer a smartphone battery will last in the real world using his team's invention will depend on a lot of factors, beyond just improvements in power efficiency of other components. If manufacturers get spare battery power, they are just as likely to add more features to use it up, rather than just give customers more time between charges.

"There's always a trade off like that, sadly. That's supply and demand. That's economics," Pop says. "You and I can talk about science and technology all day long but at the end of the day what really dictates these things are economics."

The research team's work will be published in an upcoming issue of Science magazine.