Efficiently harnessing low frequency vibrations as infinite power source for miniature electronic devices

Battery replacement may soon be a thing of the past. Researchers from A*STAR’s Institute of Microelectronics (IME) are tapping into low frequency vibrations, the most abundant and ubiquitous energy source in the surroundings, to power small-scale electronic devices indefinitely. IME’s energy harvester has the ability to continuously convert the vibrations — across a wide frequency range in different environments — into electricity. This breakthrough presents a green, economical and sustainable long-term solution to eliminate the manual re-charging or replacement of power sources in miniature devices.

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> “Our design strategy exploits the coupling effect between the Vortex shedding and Helmholtz resonating in order to enhance the Helmholtz resonating and lower the threshold input pressure. By transferring the low frequency input vibrational energy into a pressurised fluid, the fluid synchronizes the random input vibrations into pre-defined resonance frequencies, thus enabling the full utilization of vibrations from the complete low frequency spectrum.”

As a fluid dynamicist familiar with both Vortex shedding and Helmholtz resonance, this looks like rubbish. Sure, vortex shedding and Helmholtz resonators both produce fixed-frequency vibrations. For example, a flute is a Helmholtz resonator that produces fixed pitch vibrations. But in both cases the device converts uniform flow into vibrations – not random input vibrations into vibrations. And both are inherently lossy processes – the kinetic energy in the input stream exceeds the energy in the vibrations. Further, by the process of the vortex cascade, then energy converted into vibrations by vortex shedding are rapidly lost as heat.

And fluid vibrations have nothing to do with microelectonic devices. You’re better off just using a wind turbine.

Enough learning for one day, it’s making me dizzy.

http://en.wikipedia.org/wiki/Helmholtz_resonance

“Helmholtz resonance sometimes occurs when a slightly open single car window makes a very loud sound, also called “side window buffeting”.”

http://en.wikipedia.org/wiki/Vortex_shedding

“This vibration is the cause of the “singing” of overhead power line wires in a wind..”

http://en.wikipedia.org/wiki/Kadenacy_effect

“It is named after Michel Kadenacy who obtained a French patent for an engine utilizing the effect in 1933. There are also European and US patents. In simple terms, the momentum of the exhaust gas leaving the cylinder of an internal combustion engine creates a pressure-drop in the cylinder which assists the flow of a fresh charge of air, or fuel-air mixture, into the cylinder. The effect can be maximized by careful design of the inlet and exhaust passages”

I’d really need a reference suggesting that LFV are the most abundant.