Collecting the vibration energy existing in the surrounding environment and its transformation to a useful electrical energy in order to supply ultra-low power systems remains an emerging and promising technology. During the last decades, most of research efforts dealt with energy-harvesting technology using piezoelectric ceramics. However, those materials are stiff and limited in mechanical strain abilities. In addition, they lose their stiffness and piezoelectricity at high levels of mechanical strain. Thus, they are unsuitable for many applications in which low frequency and high strain level are required. However, electrostrictive polymers are lightweight, very flexible, have low manufacturing costs and are easy to mould into any desired shapes. These special properties led to them being considered as potential actuators. However, it is not well known that these materials also can be used for mechanical-to-electrical energy harvesting. In this research paper, electromechanical characterization of polymer/lead zirconate titanate composites was extended. The first part develops the analytical model predicting the energy harvested by polyurethane/PZT composites from electrical and mechanical properties of their constituent materials. Indeed, this model was based on the approach of representing the experimental setup with an equivalent electrical scheme. The second part focuses on the assessment of model performance by comparison between predicted and observed values. As a result, good agreements were observed between the two sets of data; in addition, the model could be used to optimize the choice of constituent materials. The last part concerns the contribution of both the electrostrictive effect and piezoelectric effect in electrical powers harvested by PU/PZT composites.

Electrostrictive polymers have been investigated as electroactive materials for electromechanical energy harvesting. This kind of material is isotope, i.e. there is no permanent polarization compared with piezoelectric material, so in order to ensure its polarization and scavenging energy, the electrostrictive polymers need necessarily an application of a static field. To avoid this problem, we used the hybridization of electrostrictive polymer with electret. The present work aims an analytical modeling for predicting the power convert when the material was mechanically excited. The study was carried out on polyurethane and terpolymer [P(VDF-TrFE-CFE)] films, either without filler or filled with carbon nanopowder. Experimental measurements of the harvested power showed a good agreement with the theoretical behavior predicted by the proposed model. It was also shown that the incorporation of nanofillers increased the power harvested from 5.22 · 10 À2 to 1.498 · 10 À1 μW cm À3 and from 6.87 · 10 À1 to 1.76 μW cm À3 in polyurethane and in the terpolymer, respectively.

The microelectromechanical systems invade gradually the market with applications in many sectors of activity. Developing these micro-systems allows deploying wireless sensor networks that are useful to collect, process and transmit information from their environments without human intervention. In order to keep these micro-devices energetically autonomous without using batteries because they have a limited lifespan, an energy harvesting from ambient vibrations using electrostrictive polymers can be used. These polymers present best features against inorganic materials, as flexibility and low cost. The aims of this paper are manifold. First of all, we made elaboration of the polyurethane/lead zirconate titanate films of 100 µm thickness using a lead zirconate titanate–volume fraction of 50%. Therefore, we did an observation of the lead zirconate titanate grains dispersion and the electrical characterization of the polyurethane–50 vol% lead zirconate titanate composites. Finally, a detailed study of the electromechanical transduction, for the polyurethane–50 vol% lead zirconate titanate unpolarized and polarized composites sustained to the sinusoidal mechanical strain with amplitude of 1.5% and at very low frequencies (f = 2 [Hz] and f = 4 [Hz]) and static electric field (Edc = 10 [V/µm]) or without it (Edc = 0 [V/µm]) has been presented.

This paper investigates energy harvesting performances of porous piezoelectric polymer films to collect electrical energy from vibrations and power various sensors. The influence of void content on the elastic matrix, dielectric, electrical, and mechanical properties of porous piezoelectric polymer films produced from available commercial poly(ethylene-co-vinyl acetate) using an industrially applicable melt-state extrusion method (EVA) were examined and discussed. Electrical and mechanical characterization showed an increase in the harvested current and a decrease in Young’s modulus with the increasing ratio of voids. Thermal analysis revealed a decrease in piezoelectric constant of the porous materials. The authors present a mathematical model that is able to predict harvested current as a function of matrix characteristics, mechanical excitation and porosity percentage. The output current is directly proportional to the porosity percentage. The harvested power significantly increases with increasing strain or porosity, achieving a power value up to 0.23, 1.55, and 3.87 mW/m3 for three EVA compositions: EVA 0%, EVA 37% and EVA 65%, respectively. In conclusion, porous piezoelectric EVA films has great potential from an energy density viewpoint and could represent interesting candidates for energy harvesting applications. Our work contributes to the development of smart materials, with potential uses as innovative harvester systems of energy generated by different vibration sources such as roads, machines and oceans.

More recently, the ferroelectric ceramic/polymer composites have been progressively replacing ferroelectric ceramics and polymers as they combine their interesting properties. Such as high compliance of polymers and high electromechanical coupling of ferroelectric ceramics those are required for piezoelectric transducer applications. At the same time, the ferroelectric ceramic/polymer composites formalism for predicting their energy-conversion capabilities is of both academic and industrial interest. The novelty of this paper is that the electrical power harvested by the PZT/PU polarized composite has been expressed in terms of the effective longitudinal piezoelectric coefficient (d33) of the composite via a parameter p related to the poling ratio. Besides, the parameter p, that is characterizing the PZT/PU composites with different longitudinal piezoelectric coefficients (d33), was evaluated. The other parameters of the electrical power expression were calculated using the Yamada model for the dielectric, piezoelectric and elastic constants. Finally, a good agreement was found between experience and model.