Extending the number of functions and to improving the reliability of portable equipments is a current issue. Considering the recent progresses in ultralow-power electronics, powering complex systems on ambient energy is not chimerical anymore This paper addresses the problem of the mechanical to electrical energy conversion in electroactive materials (ferroelectrics and electrostrictive polymers) and underlines the similarities and differences between these two classes of materials in terms of energy conversion. These materials exhibit different conversion abilities and mechanical properties. The lightweight, flexible, conformable polymer properties are definitively a strong advantage for practical application like energy harvesters. The proposed energy conversion improvement is an extension, to polymer materials, of the so-called "SSHI "technique previously developed for ferroelectric materials. This non-linear voltage processing basically consists in switching the voltage, for a short period, when the voltage reaches a maximum or a minimum, resulting in a large enhancement of the conversion, up to 1000%, as well as the harvesting capability. Unlike ferroelectrics based energy harvesters, polymer harvesters require a bias electrical field to convert mechanical to electrical energy that forbids a direct extension of the SSHI technique. The needed adaptations will be discussed as well as the different trade-offs between the mechanical and electrical characteristics that the system must meet to maximize the converted energy. Increasing the polymer capacitance to enhance the conversion has been done by introducing nano-conductive particles in the polymer matrix. The paper will present and discuss experimental and theoretical data.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.