German scientists use body heat to generate electricity
Tuesday, 07 August 2007, 19:30 IST
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Erlangen: German scientists have developed a way of harnessing heat from the body to generate electricity. The method uses the difference between the body's surface temperature and that of the surrounding environment, the Fraunhofer Institute for Integrated Circuits said. Energy produced this way can be used to power medical equipment, such as sensors attached to the body of a patient in an intensive care ward, the institute said. The system works on the principle of thermoelectric generators - semiconductor elements that extract electrical energy from the temperature difference between a hot and cold environment. Normally, a difference of several tens of degrees would be required to generate enough power, but the divergence between the body's surface temperature and its environment is only a few degrees. "Only low voltages can be produced from differences like these," said Project leader Peter Spies. Conventional thermoelectric generators deliver roughly 200 millivolts but electronic devices require at least one or two volts. To get around the problem, Spies and his team combined a number of components in a completely new way to create circuits that can operate on 200 millivolts. "This has enabled us to build entire electronic systems that do not require an internal battery, but draw their energy from body heat alone," he said. The scientist believes that with further improvements to the system, a temperature difference of only 0.5 degrees will be sufficient to generate electricity. "Electricity can be generated from heat at any place where a temperature difference occurs," said Spies. That could be on the body, in air conditioning systems, on radiators to meter the heating costs or monitoring the cooling chain during the transport of refrigerated goods. Looking even further ahead, it might be possible one day to make a call from a cell phone with no battery, using just the warmth of your hand.
Source: IANS
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