Electrokinetically Controlled Micro/nano Flows Applied for Miniature Fuel Cell Systems

1. 제 목 : Electrokinetically Controlled Micro/nano Flows Applied for
Miniature Fuel Cell Systems

2. 연 사 : Dr. Daejoong Kim
(Post Doctoral Fellow, University of Illinois, Urbana-Champaign)

3. 일 시 : 2007년 7월 27일 (금) 10:30 ~ 11:30

4. 장 소 : 301동 1512호

5. 내 용 :
The first part of this talk is on the development of high flow rate per power
electrokinetic pumps and their applications for miniature fuel cells. The pumps having
no moving part operate, based on linear electroosmosis, which refers to bulk liquid
motion linear with an electric field applied to charges accumulated near a solid surface
(in a so-called electric double layer). We designed electrokinetic pumps compatible with
diverse low ion density solvents, such as organic solvents without added ions, to
achieve high flow rate per power pumping. We demonstrated a novel air delivery method in
hydrogen fuel cells, using the developed pumps with AC biasing and two-fluid
configurations. We then proposed the extension of the same concept to drug delivery
applications. We also investigated the application of electrokinetic pumps for liquid
fuel delivery in direct methanol fuel cells. The second part is on on-going research
about nonlinear electrokinetics (a nonlinear response of liquid motion to an electric
field), applied for micro hydrogen generators. We are developing osmosis-actuated
nanofluidic devices to control liquid flows in chemical hydride-based hydrogen
generators, while minimizing parasitic power losses. With an electric field-effect (like
in a field-effect transistor), we can control ionic currents through nanochannels,
thereby osmotic liquid flows, and finally hydrogen generation. As an effort to further
understand these rather complex phenomena, we are studying so-called concentration
polarization and electroosmosis of the second kind in nanochannels and the feasibility
of their various applications. The last part is on molecular dynamics studies of
electrokinetic phenomena in two types of heterogeneous nanochannels. The results showed
significantly lowered electroosmotic flows in rough nanochannels and revealed the
existence of electroosmotic flows in uncharged nanochannels. We attributed these
unpredicted results partly to non-continuum effects, such as the structurization of
water molecules and the non-uniformity of transport and electric properties near the
nanochannel wall.

6. 연사약력 :
B.S., Mechanical and Aerospace Engineering, Seoul National University, 1999.
M.S., Mechanical and Aerospace Engineering, Seoul National University, 2001.
Ph.D., Mechanical Engineering, Stanford University, 2007.

7. 문 의 : 기계항공공학부 정석호 교수(☏ 880-7114)