Linear and non-linear behavior of mechanical resonators for optimized inertial electromagnetic microgenerators

In this work, the design, fabrication and characterization of an electromagnetic inertial microgenerator compatible with Si micro-systems technology is presented. The device includes a fixed micromachined coil and a movable magnet mounted on a resonant polymeric structure. The characterization of the fabricated prototypes has allowed to observe the presence of non-linear effects that lead to the appearance of hysteretic vibrational phenomenon and strongly affect the output of the microgenerator. These effects are likely related to the mechanical characteristics of the polymeric membrane, and determine an additional dependence of vibration frequency on the excitation amplitude. Under such non-linear conditions, power densities up to 40 mu W/cm(3) are obtained for devices working with low level excitation conditions similar to those present in domestic and office environment.