Energy Harvesting from Crystalline and Conductive Polymer Composites

Modern electronic devices require less energy on-board and could be powered by energy harvested from the environment. Mechanical vibrations are attractive sources for energy harvesting due to their high availability in technical environments. Among the various mechanisms available to convert mechanical energy into electrical energy, piezoelectric transduction offers high power density at microenergy scales. In piezoelectric energy harvesters, the amount of electrical energy harvested directly depends on the strain undergone by the transducer. Commonly used piezoelectric transducers are made of perovskite ceramics such as PZT and are brittle. This limits the maximum allowable strain in the harvester and consequently the power harvested. In such cases, electroactive polymers act as viable alternatives due to their flexibility. Energy harvesting from conductive and crystalline electroactive polymers is explored in this chapter. Crystalline polymers such as polyurethane and semicrystalline polymers such as PVDF are commonly used in energy harvesting devices owing to their flexibility, affordability, and good electromechanical coupling properties. This chapter begins with a brief account on the material properties of PVDF and polyurethane. Subsequently, design of energy harvesters based on these materials is elucidated. A short note on energy harvesting from crystalline biopolymers such as cellulose nanocrystals is also included therein. Such harvesters are attractive as they are environment friendly and biocompatible. Among conductive polymer composites, harvesters based on polyaniline and carbon nanotubes are described. A comparison between the harvesting capabilities of different electroactive polymers and the challenges faced are discussed to draw an overall picture on energy harvesting from electroactive polymers.