The area of sensors is tightly intertwined with that of energy harvesting, since many sensors are in far-flung installations that are hard to power.
Early this year we looked at a self-sufficient energy harvester that fed itself on vibrations; it was able to generate up to 35.8 µW of power given vibrations of 1 G. Recently, imec announced at IEDM average generation of 42 µW, with a record of 489 µW under optimal conditions.
The installation? This is specifically for tires, using the shocks that the tires experience as the source of energy. Not a remote setting, but still, if you want to put sensors in your tire – for pressure, for example – you really want a wireless, self-sufficient way to do it. The average power generated is at a driving speed of 70 km/h; this, they say, is enough to power a wireless sensor node. I guess that would mean that, at some (unspecified) slower speed, the node would start to fail – depending on batteries or caps or whatever was done to manage and condition the power.
The peak value can be attained if the vibration frequency is near the resonant frequency of the cantilever in the MEMS unit, which is 1011 Hz. Probably hard to drive the car in a manner that exploits that, but then again, if the node is working, then more power won’t make it work more, so it doesn’t matter. For that application, anyway.
More info can be found in their release.