Low-Dimensional Nanomaterials: from Mechanics to Stretchable Electronics
Recent advance in nanotechnology has brought about a host of nanomaterials, such as nanoparticles, nanowires, nanotubes and graphene that exhibit ultrahigh strength (e.g., sample-wide stress > 1/10 of their ideal strengths). Such nanomaterials are not only an ideal platform to study fundamental mechanics, but also important building blocks for a broad spectrum of nanotechnology applications. Here I present three related examples. The first example is on in-situ scanning and transmission electron microscopy (SEM/TEM) mechanical testing of crystalline nanowires. I will highlight metallic nanowires with Ag as an example. Ag nanowires exhibit strong size dependent elastic modulus and yield strength. Its unique five-fold twinned structure gives rise to the strain hardening behavior. The second example is on the interface mechanics between graphene and polymer substrates. Two interfacial failure mechanisms, shear sliding under tension and buckling under compression, are identified for monolayer graphene on plastic substrate using in-situ Raman and atomic force microscopy measurements. A nonlinear shear-lag model is used to relate the measurements to the interfacial properties including the shear strength and efficiency for stress transfer. I will conclude my talk with the third example, which is stretchable electronics based on 1D nanomaterials. I will discuss a particular type of device, highly conductive and stretchable electrodes based on Ag nanowires.
Biography: Yong Zhu received his B.S. degree in Mechanics and Mechanical Engineering from the University of Science and Technology of China, China (1999), and his M.S. (2001) and Ph.D. (2005) degrees in Mechanical Engineering from Northwestern University. After a postdoctoral fellow at the University of Texas at Austin, he joined the Department of Mechanical and Aerospace Engineering at North Carolina State University in 2007, where he is currently an Associate Professor. Dr. Zhu’s research interests lie at the interface between solid mechanics and micro/nano-technology, including mechanical properties and multiphysical coupling of nanostructures, micro/nano-electromechanical systems, flexible/stretchable devices for healthcare applications, and adhesion/friction of nanostructures. He has received several awards including Best Poster Award in the Gordon Research Conference on Thin Film & Small Scale Mechanical Behavior (2006), Sigma Xi Faculty Research Award (2012) and Society of Experimental Mechanics Young Investigator Award (2013).