Good vibrations: tiny generator harnesses kinetic energy to power wireless electrical systems

Researchers at the University of Southampton have developed a kinetic energy generator which derives electrical energy from the vibrations and movements that occur within its environment. Developed by Dr Steve Beeby and his team at the University's School of Electronics & Computer Science (ECS), the tiny generator (less than 1 cubic cm in size) is 10 times more powerful than anything yet developed in the field and could form the basis of technology for self-powered pace makers and other embedded applications that require periodic replacement of batteries.

The generator produces electrical energy using an arrangement of four magnets on a cantilever with a wound coil located in the magnetic field. The magnet size and coil properties are designed to produce energy from low vibration levels and the device has been shown to convert 30% of the power supplied from the environment into useful electrical power.

The unit has been specifically designed to power wireless sensors that monitor the condition of industrial plant equipment and is to be installed within an air compressor unit supplying several laboratories. Beyond this, the potential applications are huge. For example it could be used in wireless, self-powered tyre sensors and with further development it could be applied to self-powered pace makers or to replace or augment batteries in any miniature embedded system where the periodic replacement of batteries is not feasible – particularly in wireless sensor networks containing many sensor nodes where battery replacement is problematic.

In addition to medical and industrial applications, the technology could also provide benefits for transportation through stand-alone systems that continuously monitor wheel bearings and provide feedback on potential problems with railway carriages or other large scale equipment. Similar safety monitoring systems currently used in aircraft could also become cheaper and more accessible due to advances in the field.

Vibrations from household items such as fridges, washing machines and microwave ovens as well as buildings and bridges are also suitable for the application of the model presented by Dr. Beeby.

The generator was developed as part of the EU-funded VIBES (Vibration Energy Scavenging) project.

“This is the most successful generator of its kind and generates energy much more efficiently than any similar device of its size,” said Dr Beeby. “Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes. The big advantage of wireless sensor systems is that by removing wires and batteries, there is the potential for embedding sensors in previously inaccessible locations.'

According to Dr Beeby, there has been a growing interest in the field of low power miniature sensors and wireless sensor networks, but an area that has received comparatively little attention is how to supply the required electrical power to such sensors, particularly if the sensor is completely embedded in the structure with no physical connection to the outside world. He believes that the VIBES generator could hold the solution.

A paper entitled A micro electromagnetic generator for vibration energy harvesting about this research has just been published on the Journal of Micromechanics and Microengineering website.

Dr Beeby and his team plan to exploit this application further through Perpetuum, the world-leading vibration energy-harvesting company which was formed in 2004 as a spin out from the University of Southampton.