Fraunhofer sensor converts fluids energy into electricity

Stuttgart, Germany - Researchers of the Fraunhofer Technology Development Group TEG have developed a transducer to convert this fluidic energy into electricity. The technology, they say, could enable sensors to supply themselves with energy in future.

Target applications for the transducers include sensors for air compression systems, which are required to constantly monitor the pressure in order to keep costly fault-related losses to a minimum. At present, these sensors are either battery-driven or connected up by complex technical wiring, making it very difficult or even impossible to install sensors in places that are hard to reach.

"Our system is eminently suitable for sensors in pneumatic plants, as we can convert the kinetic energy from air or water into electricity," explained José Israel Ramirez, who is doing research on this topic at the TEG. "The fluidic energy transducer generates electricity in the microwatt or milliwatt range. This is sufficient to supply cyclically operating sensors with enough energy to read out and transmit the relevant data."

The fluid-electricity conversion takes place in a fixed housing, through which the medium is fed on a course similar to that of blood circulating in the heart. The Coandã effect causes the constant stream of fluid to oscillate. This produces a periodic pressure fluctuation in the feedback branches, which are coupled to piezoceramics.

"The piezoceramics convert the fluidic energy into electricity," said group leader Axel Bindel. "This fluidic conversion is simple and cost-efficient. We have the advantage that both air and water can be used to generate energy. What¹s more, we don¹t have any movable parts in our system. The structure can be produced in simple processes, and that saves costs."

The new technique can be applied to any system in which a fluid or a gas is guided through a fixed geometry in supply networks or in medical engineering, for example.

"Our objective is to be able to provide currently battery-driven devices, such as water meters, with an autonomous supply of energy in the near future, resulting in completely independent systems," said Bindel.