In the energy harvesting process, electrical conditioning circuits are nearly the last stage, before the actual load. Nonetheless, such circuits are as critical as the other stages (material, structure and so on), especially when considering the typical bidirectional coupling which yields a modification of the previous blocks (structural behavior, entering energy…) when varying the electrical parameters. Hence, optimization of electrical energy extraction and storage stage remains crucial.

In particular, in the case of vibrational energy harvesters based on active elements such as piezoelectric transducers, nonlinear processes induced by electrical circuits have been shown to be particularly attractive in order to artificially increase the converted energy of the microgenerator, yielding a significant harvested power gain up to a decade especially in the case of low-coupled, highly damped structures.

This talk will expose the progresses made since the first contemporary proposal of nonlinear circuits 20 years ago. In particular, issues such as the control of the trade-off between entering energy and converted one will be emphasized for the choice and design of proper interfaces according to the microgenerator characteristics and operating conditions. Recent trends in terms of bandwidth enhancement as well as multi-effect hybrid devices will be exposed as well.

Finally, microgenerators and associated wireless autonomous systems being above all intended to be applied in real environments and conditions, discussions regarding the realistic implementation (i.e., self-powering) of such interface will be discussed. Associated with this challenge, examples of truly self-powered sensors using such nonlinear circuits will be devised.