Modeling and experimentation on an electrostrictive polymer composite for energy harvesting

Abstract

The harvesting of energy from ambient environments is an emerging technology with potential for numerous applications, including portable electronic devices for renewable energy. Most of the current research activities refer to classical piezoelectric ceramic materials, but more recently the development of electrostrictive polymers has generated novel opportunities for high-strain actuators. At present, the investigation of using electrostrictive polymers for energy harvesting (a conversion of mechanical to electrical energy) is beginning to show potential for this application. This paper discusses the development of a model that is able to predict the energy harvesting capabilities of an electrostrictive polymer composite (EPC). An equivalent electrical scheme has been developed by using the model of current that was recently developed by our group. After the validation of the model on a macroscopic level, an empirical relationship was established to predict the value of power from the electrostriction coefficient, the dielectric permittivity, and the compliance of the material. Finally, results indicated that the dielectric permittivity was the crucial parameter for energy harvesting.

Electrostrictive Polymers for Vibration Energy Harvesting

“…In particular, this energy loss tends to zero as the frequency increases, meaning that pseudo-piezoelectric mode is very well adapted to relatively high frequency operations. As an example, it has been estimated in ( [18]) that, in the case of a polyurethane material with a bias electric field of 5 V.μm −1 for polarization purposes operating at a frequency of 20 Hz, the losses represent less than 0.5% of the harvested energy. Therefore, although electrostatic-based harvesting schemes seem to be the most appealing ones, the losses when using such charge/discharge approaches may compromise the realistic operations of the system, yielding a negative energy balance.…”

“…The main drawback concerns the need of applying high electrical fields to induce polarization when such materials are used as active materials for energy harvesting ( [17,18]). It is thus clear that the intrinsic dielectric properties of the polymer are of prior importance, and a trade-off must be found between stretchability and dielectric properties of the polymer.…”

Electrostrictive polymers for mechanical energy harvesting

“…9,[15][16][17] • Pseudo-piezoelectric cycles, consisting in applying a bias voltage on the material and working around this static regime. [18][19][20] Electrostatic-Derived Cycles As electrostrictive polymers feature dielectric behaviors, it is possible to consider harvesting schemes usually used in purely capacitive approaches. [10][11][12][13][14] Typically, there are two cycles that can be envisaged for such techniques:…”

“…[18][19][20] To do so, one solution consists of processing polymer-based composites by filling the polymer with high K fillers or conductive fillers. Currently, a variety of methods are available to increase the dielectric permittivity of polymer materials.…”

Ambient Energy Harvesting Using Electrostrictive Polymer Composite

“…The electric impedance of a polymer vibrating at a given frequency, could be modeled by an equivalent electrical circuit. Figure.8.b displays the most commonly adopted form of an electrical scheme [16], where C p is the capacitance of the clamped polymer and R p is a resistance representing the dielectric losses. The third branch is the motional branch, modeled by the current source I h (eq.…”