Assistant Professor

Department of Mechanical Engineering

University of Houston, Houston, TX 77204

Email: dongliu@uh.edu

 

 

Integration of microelectrodes into microfluidic devices makes it possible to induce strong electromechanical effects into microscale flow fields, giving rise to dielectrophoresis (DEP) among others.  Dielectrophoresis results from the interaction of non-uniform electric fields and the induced dipole moment of small particles.  Dielectrophoretic effect has been primarily used in biomedical applications for manipulating cells and macromolecues.  However, its potential as a powerful tool for microfluidic flow actuation has not yet been explored.  In this talk, a novel DEP-based micropumping concept will be presented that capitalizes on the fact that micro/nanoparticle motion will exert an inverse drag force on the surrounding fluid and thus produce a net flow along its direction of motion, i.e., pumping action.  When this DEP-microactuation mechanism is used to pump nanofluids, the suspended nanoparticles will serve as both fluid mover and process enhancer of thermal transport, and therefore, an attractive self-contained microscale cooling scheme can be generated.

In this talk, the dielectric polarization mechanism and theoretical modeling of DEP in a traveling wave electrical field (twDEP) will be presented, followed by a brief discussion of particle dynamics in low Reynolds number flow field.  Numerical simulation of the flow field generated by DEP will then be described.  Experimental characterization of a prototype DEP-micropump and measurements of the fluid velocity using micro-particle velocimetry (mPIV) will also be presented.  Finally, the potential of utilizing DEP in directed fluidic self-assembly of nanoscale structures and the key challenges will be briefly discussed.

 

 

 

 

Dr. Dong Liu joined the faculty of Mechanical Engineering at the University of Houston in September, 2007.  Before that, he was a post-doctoral research associate in the School of Mechanical Engineering at Purdue University, where he received his Ph.D. in 2006.  Dr. Liu obtained both his B.S. (1996) and M.S. (1999) from Tsinghua University, China.  His research interests include electrokinetics in micro/nanofluidics, microscale thermal transport phenomena, boiling and two-phase flow and microscale flow diagnostics.