ST and Micropelt Develop Autonomous Wireless Sensor Evaluation Kit

An autonomous wireless sensor based evaluation system has been developed by Micropelt GmbH and STMicroelectronics (STM) jointly.

ST Evaluation Boards

The evaluation system, also known as ‘TE-Power NODE evaluation kit,’ integrates the thermogenerator of Micropelt and the solid state type of thin film battery of STM as a energy storing system for pulse current and power backup. Charge monitoring and power management circuitry connects up to the graphic user interface software through a wireless link that operates on 2.4 GHz.

The product will be showcased at the Sensor and Test 2010 held on May 18 to 20, 2010 at Nuremberg, Germany.

The kit has a thermoelectric generator (TEG) that leverages the Seebeck Effect phenomenon wherein heat flux generated due to a difference in temperatures over a thermoelectric micro-structured layer results in generation of electric power. The TEG is able to generate 1.4V from an effective 10 degrees C gradient. The customized power conditioner of Micropelt transforms this voltage into adequate power for charging a battery via excess thermal energy, besides driving the wireless sensor node.

Energy harvesting results in generation of useful electrical energy through freely existing sources like heat, light or vibration. It is an essential component of self powered wireless sensors in buildings, which do not need battery maintenance. Currently the trend is for increased utilization of wireless sensors, more so in applications like smart buildings, conditioning monitoring and process automation. The wireless sensor networks can generate advantages immediately, including easy installation in earlier inaccessible locations and avoiding expensive sensor wiring. An intelligent environment technique, on the other hand, involves mounting a large quantity of sensors at every useful point of measurement. Parameters like vibration, pressure and temperature sensed by these sensors are transmitted wirelessly to a monitoring and control system.

STM has designed the battery board that incorporates the electronic circuitry and the EnFilm battery. This circuitry monitors and controls the energy balance and the battery charge level. A BiCMOS linear regulator that is designed particularly for functioning in low power consumption constrained environments and a battery management chip that tracks battery temperature, current and voltage are also included in the board. A Coulomb counter in the circuitry monitors the charge/discharge status.

The evaluation kit’s wireless sensor module was designed by Micropelt for establishing a low power, versatile link to the TE-Power SCOPE, a graphical user interface. The software helps to display and log the essential electrical and thermal parameters, besides a continually recorded power balance between the EnFilm battery and the TEG. The user will be able to evaluate the EnFilm-buffered thermoharvestor through the software for the required application, resulting in system design and faster time to market.


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