MSE Seminar Series: Eva Campo
Friday, September 9, 2011
Room 2108 Chemical and Nuclear Engineering Bldg.
301 405 5240
Conversion of Optical Excitation into Motion: Photoconductivity in GaN and Photoactuation in Polymer-CNT Composites
University of Pennsylvania
In the last few decades, a myriad of one-dimensional nanostructures have been produced. From Carbon nanotubes (CNTs) to SnO, novel properties at the quantum mechanics frontier and tailored chemistries hold the promise of improved devices; with higher expectancy than their thin-film counterparts. This is the case of GaN nanofibers. The recent development by our group of GaN fibers by polymer-derived-ceramic (PDC) techniques hints at the possibility of affordable mass manufacturing. PDC fibers are polycrystalline, wurtzite-polymorph, and UV-photo-sensing has been recently demonstrated. However, mechanisms to control grain size and crystallinity of PDC-GaN are unknown. Our ongoing efforts aim at improving fabrication and characterization. To this purpose, high resolution electron microscopy and highly defect-sensitive spectroscopic techniques, such as cathodoluminescence, are being used to study defect distribution and luminescence with the ultimate purpose of correlating deep level emissions and point defects.
Adding to potentially surpass thin film performance, one-dimensional nanostructures could also demonstrate radically new functionalities. Indeed, photoactuation properties rest among the untapped physical properties of CNTs. In this scheme, light sources promote mechanical actuation producing a variety of nanooptical mechanical systems (NOMS) such as artificial muscles for robotic applications or tactile displays for the visually impaired. These smart materials present a unique opportunity in a variety of fields, as sensors or actuators, from robotics to microfluidics; as well as energy scavenging and vibration control. Challenges in this incipient field span from CNT dispersion and alignment in polymer matrices, to scalability and integration in Microsystems. In addition, fundamentals of photoactuation are not well understood. To provide a mechanistic description, the standing linear elastic model aiming at correlating nano and macro actuation in composites will be reviewed, and variations in the treatment such as compressibility and non-linearity will be discussed.
About the Speaker
Dr. Eva M. Campo is the current Associate Director of Education at the MRSEC in the Laboratory for Research on the Structure of Matter at the University of Pennsylvania. She holds Research Faculty positions within the PREM program at the University of Puerto Rico (Humacao) and is the PIs assistant at the Nano-Opto-Mechanical Systems NOMS FP7-funded European Project. She completed her M.S. in Theoretical Physics at Complutense University in Madrid (Spain), her Ph.D. in Materials Science and Engineering at Lehigh University, Bethlehem (PA) and her post-doctoral work at the Center for Optical Technologies in collaboration with the US Army Research Labs (ARL). After serving as senior scientist at the University of Pennsylvanias Nanotechnology Facility, she joined the National Center for Microelectronics (CNM-IMB) in Barcelona (Spain) as Assistant Professor; becoming the leading PI during the solicitation phase of NOMS. NOMS is a highly-ranked multidisciplinary project, awarded 2.5M euro within the nano-bio-info-cogni nanotechnology call (EU NMP-FP7) in 2008. During the execution phase, Dr. Campo is the assistant-PI; responsible for both managerial and scientific deliverables that are performed in cooperation with the CNM-IMB, the University of Puerto Rico, and the University of Pennsylvania. Her research interests include development, characterization, and integration of polymer-derived ceramics and photoactive composites in Microsystems; elasticity theory of photoactive composites; and Microtechnology-inspired tools for cellular studies. Her education efforts aim at increasing the participation of minorities in STEM. She serves on the SCANNING SPIE committee and is the organizing chair of the NOMS Session at the 2011 Optics+Photonics SPIE meeting.