Fundamentals of Viscous Withdrawal, Flow-Focusing & Light-Driven Jetting

University Of Chicago, Chicago IL

Investigators

Abstract

PROPOSAL NO.: CBET-0730629 PRINCIPAL INVESTIGATOR: ZHANG, WENDY W. INSTITUTION: UNIVERSITY OF CHICAGO FUNDAMENTALS OF VISCOUS WITHDRAWAL, FLOW-FOCUSING & LIGHT-DRIVEN JETTING New engineering processes can manipulate small amounts of liquid with accuracy and speed. Such techniques make possible new materials whose textures are controlled on micron to sub-micron scales. A theoretical/numerical analysis will elucidate the interaction between bulk flow and interface deformation. Focus will be on three example problems: viscous entrainment, cell encapsulation and light-induced jetting. All three have direct technological relevance. The entrainment of a viscous liquid can be manipulated to create thin, stable micron-sized spouts. This is a crucial step in the manufacture of fibers and wires. Thin spouts can also coat irregularly-shaped solid particles uniformly. In particular, it currently encapsulates insulin-producing Islets in an effort to develop a transplant therapy for type I diabetes. Light-induced jetting offers a way to produce and transport small amounts of liquid using entirely light from a laser beam, without the need of pre-fabricated microchannels. The PI will analyze these questions within a common framework characterizing the interaction between viscous flow and surface deformation. Building on prior work successfully modeling the interface deformation produced by a converging flow will help develop simple, asymptotic models for the processes and also numerical models for quantitative comparisons to experiments. Broader impacts include quantitative analyses on the dynamics to determine the speed attained by a rising bubble in a liquid-lined tube has been instrumental in the development of medical treatments for airway closure, and in current development of microfluidic devices. Results obtained from this analysis are likely to be relevant to formation of compound fibers in electrical spinning, the manufacture of droplets, capsules and photonic band gap materials via flow-focusing in microfluidic channels. This research will also be incorporated into science education on several different levels. The analysis of simulation results, in particular the comparison between the simulation results and the experimental measurements, will be part of the summer undergraduate/high-school student research program sponsored by the Physics department at the University of Chicago. Some of the broader issues raised by this research, in particular the connection between fundamental fluid dynamics and technological challenges in bio-medical engineering and nanotechnology, will be explored in the graduate and undergraduate courses on fluid dynamics.