Cell phones used to be just phones, but now they're organizers, Web browsers, cameras, and music players, too. As the power-hungry functions pile up, running phones on batteries gets trickier. Cell-phone makers have been hoping micro fuel cells -- tiny versions of the devices touted as a source of clean power for cars -- would be the answer. But problems with size and power have stalled early methanol-based versions in academic and industry labs. So Renew Power, a spinoff of the University of Illinois at Urbana-Champaign, is turning to formic acid, the chemical sprayed by black ants on the attack.

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