Converting Body Heat Into Electricity

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IN PHOTO: Cellphones use 1 watt of energy. Reuters

Scientists have been fascinated by the concept of converting body heat into electricity. In theory, 100-120 watts of energy is generated by a male resting, which is enough to provide power to many electronics like Nintendo Wii, a cellphone and a laptop, that uses 14 watts, 1 watt and 45 watts of power, respectively. Excess heat is provided by eighty percent of body power. 

Currently, only a few milliwatts of body heat is converted to electricity that can be used for small devices like heart rate monitors and watches. Seiko's Thermic, which debuted in 1998 to mixed reviews, runs on 1 microwatt of body heat converted to electricity. 

Nanotechnology's recent developments promise to bring in more body-powered devices. A thermoelectric device, a thin material that creates the Seebeck effect(exploiting the temperature difference between the two sides of the material to generate electricity), is the basic technology used to capture body heat and convert it into electricity. A USB-powered drink chiller is a thermoelectric generator working in the reverse.

As long as the ambient air's temperature is lower than that of the body, a device kept on the skill will produce power. 30 microwatts of power can be captured by a patch of material that is in terms of area one square centimeter. Keeping these devices next to each other will multiply the amount of power being generated.

Researchers, at MIT, are working to improve the effectiveness of the circuitry which traps small amounts of power produced by standard thermoelectric generators. Scientist and director of Microsystem Technology Laboratories, Anantha Chandrakasan, and Yogesh Ramadass, his colleague have created efficient circuitry in an EKG sensor with a built-in processor and wireless radio. The U.S. Department of Energy and the University of California-Berkeley are researching on developing more efficient thermoelectric generators.

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