CMDITR Review of Undergraduate Research - Pluto - University of ...

Future Work
The overall lesson learned was that the EOF
along the bottom had much more effect than the
EF on the microbeads. This is highly relevant to
microfluidics, because small channels have
higher surface area/volume ratios, increasing the
contribution of the EOF. Further work to
increase bead velocity in such a system should
therefore focus on maximizing EOF instead of
EF. In addition, one could use positively
charged beads, so that the effects of EF and EOF
would add, instead of opposing each other.
These effects are maximized at opposite ends of
the pH spectrum, but an optimum pH could be
found that produces the greatest net effect. On
the other hand, EF may become negligible
compared to EOF in smaller channels, so it may
be practical to use uncharged beads (they would
have the added benefit of not adhering to the
surface itself, which was a problem with the
charged beads). Others have designed
micropumps that work on the principle of
EOF—it may be practical to use such a pump to
pressurize the entire system and control motion
with valves, instead of spanning the channels
with voltage and using EOF to move beads
directly and selectively.
42 CMDITR Review of Undergraduate Research Vol. 1 No. 1 Summer 2004