  Ambient energy harvesting has been in recent years the recurring object of a
number of research efforts aimed at providing an autonomous solution to the
powering of small-scale electronic mobile devices. Among the different
solutions, vibration energy harvesting has played a major role due to the
almost universal presence of mechanical vibrations: from ground shaking to
human movements, from ambient sound to thermal noise. Standard approaches are
mainly based on resonant linear oscillators that are acted on by ambient
vibrations. Here we propose a new method based on the exploitation of the
dynamical features of stochastic nonlinear oscillators. Such a method is shown
to outperform standard linear oscillators and to overcome some of the most
severe limitations of present approaches, like narrow bandwidth, need for
continuous frequency tuning and low efficiency. We demonstrate the superior
performances of this method by applying it to piezoelectric energy harvesting
from ambient vibration. Experimental results from a toy-model oscillator are
described in terms of nonlinear stochastic dynamics. We prove that the method
proposed here is quite general in principle and could be applied to a wide
class of nonlinear oscillators and different energy conversion principles.
There are also potentials for realizing micro/nano-scale power generators.
