News link: Body heat-powered computers a step closer ...Scientists have turned heat to their advantage by creating devices that run on heat instead of electricity. The advance could lead to thermal computers that run off of body heat or other waste heat from our surroundings. The breakthrough of the new research is to tailor composite materials so that their thermal conduction is not just side to side or top to bottom, but in a direction that changes throughout. The findings are due to be published in Physical Review Letters. "This is an interesting subject," says Alex Zettl, a physicist at the University of California, Berkeley. "The manipulation of heat currents has not been studied much or exploited. Nevertheless, there are likely situations where heat currents can be successfully harnessed for computation and other applications."This technology isn't about to appear in consumer products anytime soon, but it's clever, promising, and environmentally friendly because it's about using waste heat in the environment, including heat from us, to run our increasingly power-hungry gadgets. Perhaps someday our iPhones won't rely on bulky batteries because they will be solar-powered during the day and human-powered in the evening. And when you are sick and run down with a fever, your gadgets will have extra power and be less likely to run down!