Collaborative Research: Generating Electricity from Deformation: Multiscale Modeling and Characterization of Flexoelectricity from Atoms to Devices

University Of Houston, Houston TX

Investigators

Abstract

Small sensors -- at the micro or nanoscale -- promise to extend human perception to extreme and previously inaccessible environments. How will these next-generation stand-alone sensor systems be powered? Many existing solutions use piezoelectric materials to convert mechanical vibration into electricity. However, only a small class of materials exhibits practically useful levels of this form of electromechanical coupling, and those typically lose their piezoelectricity at higher temperatures. This precludes their use in precisely the environments where the new classes of sensors are needed most. Furthermore, the highest performing piezoelectric materials contain lead, which creates manufacturing and disposal hazards. This project investigates generation of electricity by an entirely different phenomenon, called flexoelectricity. Unlike piezoelectricity, flexoelectricity is present in all dielectric solids, and thus offers an environmentally compatible alternative to piezoelectrics. This project combines complementary computational and experimental research studies to explore and understand flexoelectricity from atomistic scales to the device level. This work will enable a novel framework for the dramatically enhanced performance of energy harvesting devices. This collaborative research program combines atomistic and continuum electroelastic modeling, nonlinear dynamic phenomena, nanofabrication, multi-scale experiments, and device characterization to facilitate the establishment of a novel class of revolutionary self-powered sensors and sensing systems at small scales. By bridging the atomistic and continuum theories with rigorous experiments, a fully coupled flexoelectric energy harvester framework will be established to explore the scaling laws for conversion efficiency and power density. For high excitation levels, nonlinear elastic, electroelastic, and dissipative effects in flexoelectric energy harvesting will also be characterized. Based on this fundamentally transformative approach to electromechanical energy harvesting, atomistic modeling of flexoelectricity and continuum-based energy harvesting models will be synergistically coupled with experiments to establish next-generation energy harvesters. Both linear and nonlinear broadband architectures will be explored for harvesting deterministic and stochastic vibrational energy. This research will also establish a framework and thorough understanding of the electroelastic dynamics of nanostructures for use in a variety of other problems involving two-way electromechanical coupling (e.g. sensing, actuation, control) at submicron scales.