Mechanical and Aerospace Engineering
Department Seminar Series
Anderson Ho Cheung Shum
Department of Mechanical Engineering
University of Hong Kong
In this talk, I will discuss our efforts to understand, characterize and manipulate droplets and jets that are electrically charged in microfluidic devices. By charging microdroplets in a microfluidic devices, novel dynamics between microdroplets are observed, as a result of a delicate balance between electric stress and interfaces forces. In the presence of stabilizers, such as surfactants, the strength of the applied electrical charging can be used to quantify the effectiveness of the stabilizers in one step. This fast and versatile technique represents a potent tool for assessing emulsion stability. The understanding can be extended to millimeter-sized droplets stabilized by a layer of particles, sometimes known as liquid marbles. We demonstrate how the stability of the liquid marbles, as well as mixing of components encapsulated in them can be controlled by a modified electro-fluidic platform. We also illustrate the potential of the modified platform for detection using a chemiluminescence reaction. Besides charging droplets, liquid jets can also be directed electrically. In particular, the concepts of electro-fluidics can be implemented to nozzles that dispense highly viscous liquid jets, which are typically difficult to manipulate with high precision. Through an electrical control of a coiling instability, we outline the potential of electrically charging viscous liquids for the printing industries.
Dr. Anderson Ho Cheung Shum received his B.S.E. degree, summa cum laude, in Chemical engineering from Princeton University in 2005, S.M. and Ph.D. in applied Physics from Harvard University in 2007 and in 2010. He joined the Department of Mechanical Engineering in the University of Hong Kong as an Assistant Professor in December 2010.
His research interests include emulsions, microfluidics, emulsion-templated materials and soft matter. He received the Early Career Award by the Research Grants Council of Hong Kong in 2012, Graduate Student Silver Award from the Materials Research Society in Spring 2010, Robert L. Wallace Prize Fellowship from Harvard School of Engineering and Applied Sciences in 2006-2007, as well as Notable mention in Art of Competition, Award for Overall Excellence in Chemical Engineering, Proctor & Gamble (P&G) Award for Outstanding Design Project, and Ticona Award for Outstanding Student Thesis from Princeton University in 2005.