Extending Battery Life for Mobile Devices

Friday, March 11 2011

Three parallel memory bits with carbon nanotube electrodes (false color image based on topographic profile from atomic force microscopy). The middle bit is in the “off” state, the other two are “on”. The silicon dioxide substrate is shown in blue. (University of Illinois/Eric Pop)

“I think anyone who is dealing with a lot of chargers and plugging things in every night can relate to wanting a cell phone or laptop whose batteries can last for weeks or months,” said electrical and computer engineering professor Eric Pop, who is also affiliated with the Beckman Institute for Advanced Science and Technology at Illinois.

The flash memory used in mobile devices today stores bits as charge, which requires high programming voltages and is relatively slow. Industry has been exploring faster, but higher power phase-change materials (PCM) as an alternative. In PCM memory a bit is stored in the resistance of the material, which is switchable.

Pop’s group lowered the power per bit to 100 times less than existing PCM memory by focusing on one simple, yet key factor - size. Rather than the metal wires standard in industry, the group used carbon nanotubes, tiny tubes only a few nanometers in diameter – 10,000 times smaller than a human hair.