David Carroll | Wake Forest University | “Power Harvesting in Organic Thermoelectric Piezotronics”
Event Date:
February 19, 2015 – 3:30 PM to February 20, 2015 – 4:59 PM
Location:
Burson 115
Event Date:
February 19, 2015 – 3:30 PM to February 20, 2015 – 4:59 PM
Location:
Burson 115
Ph.D Nanoscale Science
Seminar Series
Spring 2015
David Carroll
Wake Forest University
Center for Nanotechnology and Molecular Materials, and Department of Physics
“Power Harvesting in Organic Thermoelectric Piezotronics”
Abstract:
Power harvesting from ambient sources such as the human body, has proven to be technologically challenging. Of the two primary candidates for such tasks, thermoelectrics often do not make sufficient thermal contact with the skin as the body moves. Moreover, they are not very efficient typically capturing only a percent or so of the available heat at the contact area. The alternative, a piezo-scavenger, also has problems: when the body doesn’t move it makes no power and typically such scavengers are most efficient in some resonant condition of motion. Miniaturizing technologies and combining their use is unattractive since power scavenging is usually an extrinsic property. And a material that might combine such effects into a single technology would require a set of orthogonal properties making them also seem beyond reach. However, in this work we show that it is possible to combine dramatically different materials properties into a single monolith capable of simultaneous thermoelectric and piezoelectric functionalities. These organic meta-structures, based on layered heterogeneous blends of doped nanotubes and piezo-active PVDF, allow for flexibility and conformal applications. Surprisingly, however they give rise to an astonishing synergistic effect that enhances power scavenging beyond the simple addition of the components. In fact, we show that an enhancement factor to the Seebeck coefficient of more than 20% is possible through simple torsional motion in such architectures. These structures open a door to new physics and a variety of novel scavenging approaches to ambient power.
Bio:
Prof. David Carroll earned his PhD. in Physics at Wesleyan University in Connecticut (1993) working on the excited state dynamics of charged defects induced in complex metal oxides under electron beam irradiation. His postdoctoral work at the University of Pennsylvania in Philadelphia was under the direction of Prof. D. Bonnell and focused on the application of scanning probes to transition metal oxide surfaces. From UPENN, Dr. Carroll joined the group of Prof. M. Rühle at the Max-Planck-Institut für Metallforschung in Stuttgart, Germany where his work centered on the application of scanning probes to interface studies of supported nanostructures. It was at MPI that Dr. Carroll obtained a life-long fascination with dimensionality in solid-state physics. Following Stuttgart, Dr. Carroll became an assistant professor then associate professor at Clemson University in South Carolina where his work expanded to include organic devices and organic electronics. In 2003 Dr. Carroll and his research team moved to Wake Forest University in Winston-Salem NC, to establish a center dedicated to the research and development of electroactive, matrix nancomposites. His research continues to focus on the role of dimensionality in the thermal, electrical, and optical phenomena of nanoscale structures and their meso-assemblies. Dr. Carroll is currently a Professor of Physics at Wake Forest University, Director of the Center for Nanotechnology and Molecular Materials at Wake, and a Fellow of the American Physical Society.
Thursday, February 19, 2015 @ 3:30 PM in Burson 115
Coffee & soft drinks served at 3:15 PM