Low-cost charge of electrostrictive polymers for efficient energy harvesting

Abstract

Energy harvesting has become a particularly hot topic over the last few years in order to replace batteries in autonomous devices. In particular, vibration energy scavenging has been the subject of many researches as such a source is widely available in many environments. While piezoelectric elements, electromagnetic devices or electrostatic systems have been studied since the beginning of such an interest, electrostrictive polymers that are flexible and lightweight have recently attracted the attention of the scientific community. However, in order to properly operate and convert energy efficiently, such materials require a relatively high electric field for polarization purposes and activation of the electromechanical activity. Hence, applying this electric field may lead to significant losses in the system that may compromise the operation of the microgenerator by a negative energy balance. The purpose of this paper is to investigate the application of such an electric field in an efficient manner in order to limit the losses in the system, showing that a ramp input may decrease the loss factor from more than 50% to a few per cent only. The energy balance of the global system as well as a realistic implementation of the charging system is also discussed.