Applied Physics Seminar

Abstract:

This talk chronicles the novel phenomena we have encountered in our decade-long journey in attempting to understand the behaviour of fluids and particles at microscale dimensions when they are subjected to excitation by high frequency (MHz order) surface vibration. While some of our observations can be explained by well-known classical theories such as those by Chladni, Rayleigh and Lighthill on vibration-induced particle patterning and acoustic streaming, a number of other peculiar phenomena also arise due to the highly nonlinear fluid-structural coupling that either have yet to be elucidated, or appear to defy longstanding conventional thought such as Faraday's theory on parametrically-excited waves. These include dynamic colloidal island patterning and erasure, broadband excitation of capillary waves, and double flow reversal and solitary wave formation in thin liquid films. Additionally, we also report the discovery of a new class of sound waves—the surface reflected bulk wave—and show how this rich and diverse sound toolbox can be exploited for microscale fluid actuation and bioparticle manipulation for a wide range of microfluidic applications. In particular, we demonstrate its versatility for a variety of low-cost and portable non-invasive microfluidic drug delivery technologies: (1) as an efficient intracellular cytosol delivery mechanism for ex vivo autologous cell therapeutics that retains high (>97%) cellular viability; (2) as a means for local transmucosal delivery in tissue for targeted vaccine administration; and, (3) as a powerful nebulisation technique for inhaled macromolecular delivery.

About the Speaker:

Leslie Yeo is a Professor of Chemical Engineering at RMIT University, Australia. He received his PhD from Imperial College London in 2002, for which he was awarded the Dudley Newitt prize for a computational/theoretical thesis of outstanding merit. Prior to joining RMIT, he was a postdoctoral research associate in the Department of Chemical & Biomolecular Engineering at the University of Notre Dame, USA, after which he held a faculty position at Monash University. He also held the Australian Research Fellowship and Australian Research Council Future Fellowship from 2009 to 2017. Dr Yeo was the recipient of the 2007 Young Tall Poppy Science Award from the Australian Institute for Policy & Science ‘in recognition of the achievements of outstanding young researchers in the sciences including physical, biomedical, applied sciences, engineering and technology', and several awards for excellence in research and innovation both at Monash and RMIT. Dr Yeo is co-author of the book Electrokinetically Driven Microfluidics & Nanofluidics (Cambridge University Press), and the author of over 200 research publications and 20 patent applications. He is also the Editor-in-Chief of the American Institute of Physics journal Biomicrofluidics and an editorial board member of Interfacial Phenomena & Heat Transfer and Scientific Reports.