Linear and Non Linear Behaviour of Mechanical Resonators for Optimized Inertial Electromagnetic Microgenerators

The need for wearable or abandoned microsystems, as well as the trend to a lower power consumption of electronic devices, make miniaturized renewable energy generators a viable alternative to batteries. Among the different alternatives, an interesting option is the use of inertial microgenerators for energy scavenging from vibrations present in the environment. These devices constitute perpetual energy sources without the need for refilling, thus being well suited for abandoned sensors, wireless systems or microsystems which must be embedded within the structure, without outside physical connections. Different electromagnetic energy scavenging devices have been described in the literature [1,2,3], based on the use of a velocity damped resonator, which is well suited for harvesting of vibrational energy induced by the operation of machines. These vibrations are characterized by a well defined frequency (in the range between few Hz's and few kHz's) and low displacement amplitudes. Adjusting the resonant frequency of the system to that of the vibrations allows amplification of these low amplitude displacements. Moreover, for these applications, the use of an electromagnetic device has the potential advantages of a good level of compatibility with Si Microsystem technology, as well as the possibility of relatively high electromechanical coupling with simple designs.