We report in this paper the design, the optimization and the fabrication of
an electret-based cantilever energy harvester. We develop the mechanical and
the electrostatic equations of such a device and its implementation using
Finite Elements (FEM) and Matlab in order to get an accurate model. This model
is then used in an optimization process. A macroscopic prototype (3.2cm^{2})
was built with a silicon cantilever and a Teflon\textregistered electret.
Thanks to this prototype, we manage to harvest 17\muW with ambient-type
vibrations of 0.2g on a load of 210M{\Omega}. The experimental results are
consistent with simulation results