Wet and Sticky: Adhesion by Capillary Forces
Tian Tang
Associate Professor, Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada
Location：Meeting Room on the Fourth Floor of Mechanical Design Institute
Time: 9:30 AM, June 13, 2013
Abstract
Liquid surfaces or menisci create capillary forces, which become important in small-scaled systems. In nature, tree frogs and bugs inject wetting fluid between their pads and the surface they attach to. The formation of liquid bridges results in attractive forces that help them adhere to the surface. In industry, capillary force-induced adhesion can lead to problems in the functioning of devices in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS), causing deformation or even collapse of the structures. In this talk, I will take the example of a double cantilever beam and address the modeling of capillary adhesion in this structure. Several issues not correctly treated in the past will be emphasized, and the interesting coupling between capillary loading and deformation will be demonstrated. Some discussions on contact angle hysteresis will be given at the end, which can be used to modulate capillary adhesion.
Bio Sketch
Dr. Tian Tang received her Bachelor’s degree in Engineering Mechanics from Tsinghua University (2001) and PhD in Theoretical and Applied Mechanics from Cornell University (2005). She worked as a Visiting Research Scientist in the Chemical Engineering Department at Lehigh University before she joined the University of Alberta (2007). Dr. Tang’s research interests lie in the modeling and simulation of materials, especially materials and structures at micro- to nano- scales and in biological systems. She has published over forty papers in international journals in the areas of modeling polycation-based gene delivery carriers, polyelectrolyte, carbon nanotube, biomechanics and biomimetic adhesion. She is a reviewer for over twenty international journals including Science, Biomacromolecules, Journal of Royal Society Interface and Langmuir. Dr. Tang has received many awards, including Alberta Ingenuity New Faculty Award (2009), Early Accomplishment Award by the Association of Professional Engineers and Geoscientists in Alberta (2011), Tier II Canada Research Chair (2007 and renewed in 2013), as well as the Adhesion Society’s Distinguished Paper Award (2006) and Outstanding Young Adhesion Scientist Award (2009).