Seminar - Probing Size-Dependent Mechanical Properties of Metallic Nanomaterials and Biological Structures by In Situ Nanomechanical Characterization by Dr. Yang Lu
Date: 09 April 2013 (Tuesday)
Time: 4:00 pm – 5:00 pm
Venue: EF305, The Hong Kong Polytechnic University
Mechanical properties of materials deviate largely from their bulk counterparts when characteristic dimensions become sufficiently small. Size-dependent mechanical behavior of metallic materials and biological structures at micro- and nano-scales have recently generated great interests because of their importance on assembly, performance, and reliability of functional nanoelectronics devices and nano-electro-mechanical systems (NEMS), as well as tissue engineering scaffolds. Hence, by design and development of a series of in situ nanomechanical testing platforms, which enable both scanning electron microscopy and transmission electron microscopy (SEM & TEM) imaging of sample structure evolution as well as real-time measurement of their mechanical properties at unprecedented high resolution, we were able to characterize individual metallic (gold and nickel) nanowires and Ubx protein fibers with a wide range of diameters, from nano to micro, and made significant progresses toward deeper understanding of their size-dependent mechanical properties and deformation mechanisms. In particular, we successfully performed the first quantitative in situ TEM characterization of “ultrathin metallic nanowires”, a new kind of 1-D nanomaterials with diameters down to sub-10 nanometers, and observed interesting new properties which were never expected at larger length scales, including the “cold welding” and “brittle fracture” of ultrathin gold nanowires. These discoveries may open new paths for researchers looking at next-generation nanoscale electronics. Finally, recent research on in situ nanomechanics study of nanotwinned copper, bones and red blood cells will be briefly talked about and discussed with their potential applications in advanced materials design and disease diagnostics.
Dr. Yang Lu is currently an Assistant Professor in the Department of Mechanical and Biomedical Engineering (MBE) at City University of Hong Kong. In 2011, He received his Ph.D. degree in Materials Science from Rice University with the highest student honor "Franz R. & Frances Brotzen Fellowship" award. Before joining CityU, he was a Postdoctoral Associate in the Nanomechanics Lab (former Suresh research group) at MIT. Dr. Lu's research interests focus on "nanomechanics and biomechanics", with particular emphasis on in situ nanomechanical characterization of metallic nanostructures and biological systems as well as their applications in nanofabrication, nanoelectronics and nano-electromechanical systems (NEMS), energy harvesting/storage, disease diagnostics/treatment, advanced materials processing and bio-inspired materials design. He has published more than 15 papers in a number of top journals, including "Nature Nanotechnology", "Advanced Functional Materials", "ACS Nano", and “Applied Physics Letters”, and serves as a reviewer for multiple international journals such as "Journal of Materials Research", “Scripta Materialia” and "Experimental Mechanics". (More information: http://www.cityu.edu.hk/mbe/yanglu/)