Useful Energy Harvesting Links

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Energy Harvesting Book
Energy Harvesting Survey paper
Energy Harvesting Kit
Piezo harvesting video

Ultra Low Power Harvester Power Management IC with Boost Charger, and Nanopower Buck Converter

This is pretty interesting!

ThermoGen

AltaDevices




One possible solution for powering these wearable devices without a battery is to harvest energy from human body to generate electricity using a thermoelectric generator. A thermoelectric generator (TEG) is a solid-state device that can convert heat into electricity. When a TEG is attached directly onto the skin, heat from the human body flows through the TEG due to the temperature difference between the skin and the ambient. This heat flow, or the temperature gradient, creates a voltage in the TEG by the Seebeck effect, which performs useful work when connected to an external circuit.

Heat dissipation from a human body largely vary depending on the body location and surrounding conditions, typically heat flow available from the skin under indoor sedentary conditions is 1 ~ 10 mW/cm2 on the average at 22 °C ambient temperature, and a higher heat flow of 10 ~ 20 mW/cm2 is possible on the wrist, where the heat-carrying radial artery is located near the skin.

According to our calculations, a power output on the order of hundreds microWatts can be achieved using a wearable TEG of wrist-band type made of the existing polymeric or paste-type inorganic materials. Read our recent paper published in J. Mater. Chem. C for more information and complete review of the state-of-the-art flexible thermoelectric materials and devices.

• J.-H. Bahk, H. Fang, K. Yazawa, and A. Shakouri, “Flexible thermoelectric materials and device optimization for wearable energy harvesting,” J. Mater. Chem. C, accepted manuscript (2015). DOI: 10.1039/C5TC01644D

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http://nanotechweb.org/cws/article/tech/55664

Flexible TEG breaks new power record

Researchers at the Integrated Nanotechnology Lab at KAUST in Saudi Arabia are the first to have made a thermoelectric generator on flexible silicon. The device, which is capable of generating 30 times more power than previous such generators, might find use in a host of application areas – including mobile phones, laptops, biomedical sensors and other portable devices.
Thermoelectric generators (TEGs) convert heat directly into electricity. The devices are good at conducting electricity but poor at conducting heat, and they have a large thermopower (the ratio of the voltage to temperature difference across the device to its temperature difference).
Thermoelectric generators (TEGs) convert heat directly into electricity. The devices are good at conducting electricity but poor at conducting heat, and they have a large thermopower (the ratio of the voltage to temperature difference across the device to its temperature difference).
The researchers, led by Muhammad Mustafa Hussain, began by fabricating their TEGs from the 2D layered materials bismuth telluride and antimony telluride on low-cost bulk mono-crystalline silicon. Next, they transformed the devices and the host silicon into flexible and transparent systems using state-of-the-art CMOS-compatible processes. The silicon layer is just 18 µm thick and contains 63 thermopiles.
“The TEGs we made generate 0.15 µW of power, which is 30 times more than previously-made devices of this kind,” Hussain told nanotechweb.org. “The thin silicon contains trenches that serve to minimize heat loss from the hot end of the device to the cold end. The power generated by the finished device is enough to run ultralow power CMOS circuitry in sensors, including some in vivo biomedical devices.”
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An intensive study of the performance of TEGs developed at IMEC and the Holst Centre allowed predicting the average limits for power production on man. At normal indoor conditions, the upper level is equal to about 30 µW per square centimeter occupying on the skin, on 24-hour average. It should be stressed that this is the acceptance-related limit [2, 3]. Taking into account the requirement of 50-100 µW necessary for the data processing and radio transmission, the self-powered wireless sensor nodes typically occupy an area of several square centimeters like a watch.

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As a result of decreasing the leg cross section by a factor of two, the TEG dimensions were successfully halved to the size of a man’s watch, thereby significantly improving its acceptance by the users. At typical indoor temperatures, it generated a daytime power of 0.2-0.3 mW. 
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http://www.hindawi.com/journals/ijdsn/2015/438695/
International Journal of Distributed Sensor Networks
Volume 2015 (2015), Article ID 438695, 17 pages
http://dx.doi.org/10.1155/2015/438695
Review Article

A Survey on Energy Harvesting and Integrated Data Sharing in Wireless Body Area Networks

A vibration energy harvester system using ME transducer can produce an output power density of 0.472 mW/cm3 at the acceleration of 1 g at 51 Hz [26].  

Terfenol/PZT/Terfenol sensor can produce more than 10 mW of electrical power with an acceleration of 0.5 g. The piezoelectric array within the midsole of the shoe can extract energy [42], but this shoe contains the generator; the prototype is big and heavy. Power output is measured for four subjects in three gait patterns. Walking experiments produces an average power of  mW/kg body weight, and jogging provides a higher average power level of  mW/kg.

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