Companies prepare product that uses "perpetual energy" - from ST Micro web site

Giant chip company ST Microelectronics said that it and a German company Micropelt GmbH have jointly created an autonomous wireless sensor evaluation kit. That's a wireless sensor that won't need batteries changing.

The kit, called TE-Power NODE, uses a Micropelt thermogenerator coupled with ST Micro's Enfilm solid state thin film battery for power backup and pulse current.

The power management and charge monitoring circuitry is connected to the graphical user interface software over a 2.4GHz wireless link.

Energy harvesting, explained ST Micro, generates electrical energy from sources such as vibration, heat and light - that's used to power wireless sensors without the need for replaceable batteries.

The Thermoelectric Generator (TEG) in the evaluation kit uses a physical phenomenon called the Seebeck Effect.  Electric power is generated from a heat flux produced by temperature differentials over a thermoelectric micro layer.

The TEG can generate 1.4 volts and Micropelt's contribution is to convert this into enough power to drive a wireless sensor node and charge a battery.

Micropelt CEO Fritz Volkert explained: "Harvesting thermal energy holds enormous potential as a virtually infinite self sustaining energy source, exploiting free surplus heat that would otherwise be wasted."

The rechargeable battery in the kit is ST Microelectronics' thin film solid state battery using its Enfilm technology that will produce high pulsed peak current of up to 10mA to the wireless sensor as it communicates with the network.

The battery board contains the thin film battery and the electronic circuitry, a BiCMOS linear regulator, and a battery management chip as well as a Coulomb counter to check on the charge/discharge status.

Of course it is the energy that is perpetual - not the individual components. But it's an interesting concept as wireless sensors will become omnipresent and battery life was always the problem employing them pervasively.