Coupled electro-mechanical response of an electroactive polymer cantilever structure and its application in energy harvesting
Ionic polymer-metal composites (IPMC), piezoelectric polymer composites and nematic elastomer composites
are materials, which exhibit characteristics of both sensors and actuators. Large deformation and curvature are
observed in these systems when electric potential is applied. Effects of geometric non-linearity due to the chargeinduced
motion in these materials are poorly understood. In this paper, a coupled model for understanding the
behavior of an ionic polymer beam undergoing large deformation and large curvature is presented. Maxwell's
equations and charge transport equations are considered which couple the distribution of the ion concentration
and the pressure gradient along length of a cantilever beam with interdigital electrodes. A nonlinear constitutive
model is derived accounting for the visco-elasto-plastic behavior of these polymers and based on the hypothesis
that the presence of electrical charge stretches/contracts bonds, which give rise to electrical field dependent
softening/hardening. Polymer chain orientation in statistical sense plays a role on such softening or hardening.
Elementary beam kinematics with large curvature is considered. A model for understanding the deformation
due to electrostatic repulsion between asymmetrical charge distributions across the cross-sections is presented.
Experimental evidence that Silver(Ag) nanoparticle coated IPMCs can be used for energy harvesting is reported.
An IPMC strip is vibrated in different environments and the electric power against a resistive load is measured.
The electrical power generated was observed to vary with the environment with maximum power being generated
when the strip is in wet state. IPMC based energy harvesting systems have potential applications in tidal wave
energy harvesting, residual environmental energy harvesting to power MEMS and NEMS devices.
This paper was published in SPIE Proceedings Vol. 7287