Deriving energy from body heat and vibrations – energy harvesting makes it possible

July 13, 2015 2:52 PM by Heiko Wörrlein

In the early morning hours when it's still dark, many joggers, cyclists and hikers strap portable lamps on their foreheads to make sure they can see - and be seen by vehicle drivers - without restricting their own mobility. It's not uncommon however for the LED lamps to suddenly grow dim and eventually stop functioning because the battery is empty. Apart from the inconvenience, this can occasionally lead to dangerous traffic situations.

Experts at Fraunhofer IIS developed a technology based on so-called energy harvesting that makes it possible to detect changes in body heat and the person's surrounding and use these differences to generate energy to power the LED headlamp without batteries.


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Energy harvesting involves capturing very small amounts of ambient energy to power small consumer electronic devices. With this technology, our goal is to develop maintenance- and cable-free systems featuring an unlimited service life and continuous operation without the need for an external power source. Even minor temperature changes of 2 to 3 degrees can be exploited to generate electricity in the milliwatt range.


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By relying on energy harvesting, we have succeeded in supplying thermoelectric power to a Bluetooth low-energy wristband for the first time. Referred to as BlueTEG, this sensor wristband uses sensors to measure ambient temperature or acceleration rates and sends the data via Bluetooth to a smart phone or tablet PC. The BlueTEG technology, which is integrated in the wristband, uses the temperature differences between the skin and the surrounding air to generate electrical energy to power the electronic systems. It also features a conventional thermoelectric generator and a special voltage converter developed by Fraunhofer IIS. Unlike conventional devices, BlueTEG does not require a battery that needs to be recharged or exchanged. It is suitable for all types of wearable body sensors or wireless sensor systems and can also be integrated in multifunctional or GPS watches, for example.


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Apart from temperature differences, the technology can also produce electricity from vibrations. We have already managed to generate usable energy from shock impacts and mechanical shaking, such as those that occur with vehicles, motors or machines.

Are you interested in learning more about energy harvesting or do you have an idea for a special application? Our experts are more than happy to help.

Further information is available on our website: www.iis.fraunhofer.de/energyharvesting