STMicroelectronics and Micropelt GmbH, a young German company specializing in novel thin-film thermoelectric devices, have jointly developed an autonomous wireless sensor evaluation kit. The TE-Power Node evaluation kit combines Micropelt’s thermogenerator and ST’s EnFilm solid-state thin-film battery to provide energy storage for power backup and pulse currents. A 2.4 GHz wireless link connects the power management and charge monitoring circuitry to the included GUI software.
The key component of the evaluation kit is a thermoelectric generator (TEG) that uses a physical phenomenon known as the Seebeck effect, which generates electricity from the heat flux resulting from a temperature gradient across a microstructured thermoelectric layer. The TEG generates a voltage of 1.4 V from an effective gradient of 10 °C. Micropelt’s custom power conditioning converts this into sufficient power to operate the wireless sensor node and charge a battery from the excess thermal energy.
In the TE-Power Node evaluation kit, the Micropelt TEG MPG-D751 is mounted between a solid aluminium base plate and a finned heat sink. The base is attached to a suitable heat source so the cooling effect of the heat sink can produce a temperature gradient across the embedded TEG.
The rechargeable battery used in the enhanced TE-Power NODE kit is ST’s EFL700A39 EnFilm thin film solid state battery, which has a capacity of 700 μAh and can deliver high peak currents up to 10 mA to power the wireless sensor node during communication with the network. When the base plate of the evaluation kit is in contact with a heat source, the Micropelt TEG provides power to the system and recharges the EnFilm battery. When the heat source is removed, the TEG stops and only the EnFilm battery provides power to the wireless sensor.
Image: Micropelt
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