By effective using interaction J integrals, the nanoscale planar field-projection methods (FPMs) can be an efficient way to analyze atomic defects by bridging scales from atoms to a continuum. The FPM results include cohesive traction-separation relations, which completely characterize the crack-tip cohesive zone or dislocation-core cohesive zone in continuum scale. To decrease the driving voltage of PVDF-based polymer actuators, multilayered relaxor ferroelectric polymer actuators were developed and successfully integrated onto a varifocal liquid-filled microlens. With an applied voltage of 40 V, the microlens was able to change the optical power by approximately 50 diopters. Flexible and transparent relaxor ferroelectric polymer film vibrators were also designed and fabricated to provide tactile feedback on flexible displays and touch screens.

 

Dr. Seung Tae CHOI

Dr. Seung Tae CHOI now is an Assistant Professor of Mechanical Engineering, University of Ulsan. His major research interests are in the fields of micro & nano mechanics of materials, focusing on scale bridging from atomic-scale phenomena to micro-scale description and experiments for mechanical characterization of small-features structures, especially, polymer films. Currently, he is also developing ferroelectric polymer actuators and sensors.