Dean of the College of Engineering and Applied Science
Biotechnology Program, Director
Google Scholar Profile
Davis Research Group
B.S., University of California at Davis (1978)
M.S., Ph.D., Stanford University (1979, 1982)
Biotechnology and Biofuels, Complex Fluids, Membrane Separations
The research program of my group is rooted in chemical engineering fundamentals of fluid mechanics, heat and mass transfer, and reaction engineering. However, many of our projects are motivated by practical applications from biotechnology, the environment, and materials processing. These projects are currently divided into three sub-groups:
Biotechnology and Biofluidics: Our efforts have included cell aggregation and sedimentation and the controlled influence of these phenomena on improved bioreactor performance, with applications ranging from beer brewing to protein overexpression by recombinant bacteria to continuous mammalian cell culture. We have also studied reaction kinetics and novel bioreactor design for the enzymatic transcription of ribonucleic acids which have pharmaceutical potential due to their catalytic and selective binding properties. A current focus is on biofluidics for polymeric lab-on-a-chip devices.
Complex Fluids: Suspensions of fine particles or emulsions of droplets dispersed in a fluid are found in many natural and industrial applications, including biological systems, raindrop growth, polymer processing, liquid-liquid extraction, mineral flotation, and the processing of composite materials. The physical mechanisms governing particle or droplet motion in suspensions include gravity, Brownian diffusion, van der Waals attraction, electrostatic repulsion, electrophoresis, thermocapillary and solutalcapillary migration, and convective motion due to stirring or imposed flow. Our analytical, computational and experimental research includes microphysical studies of the fundamental interactions between particles or droplets, and macrophysical studies of applications such as sedimentation, filtration, aggregation, coalescence, flotation, and phase separation.
Membrane Separations: Microporous membranes provide low-energy means for performing critical separations in water treatment, beverage processing, biotechnology, and other industries. Our research on membrane separations has included mathematical modeling of crossflow microfiltration and the development of a rapid backpulsing technique for overcoming the detrimental effects of membrane fouling. Application areas have focused on biological suspensions and waste waters.