Surface-Directed Liquid Flow Inside Microchannels
Bin Zhao,1
Jeffrey S. Moore,1*
David J. Beebe2
Self-assembled monolayer chemistry was used in
combination with either multistream laminar flow or photolithography to
pattern surface free energies inside microchannel networks. Aqueous
liquids introduced into these patterned channels are confined to the
hydrophilic pathways, provided the pressure is maintained below a
critical value. The maximum pressure is determined by the surface free energy of the liquid, the advancing contact angle of the liquid on the
hydrophobic regions, and the channel depth. Surface-directed liquid
flow was used to create pressure-sensitive switches inside channel
networks. The ability to confine liquid flow inside microchannels with
only two physical walls is expected to be useful in applications where
a large gas-liquid interface is critical, as demonstrated here by a
gas-liquid reaction.
1 The Beckman Institute for Advanced Science
and Technology, University of Illinois at Urbana-Champaign, Urbana, IL
61801, USA.
2 Department of Biomedical Engineering,
University of Wisconsin-Madison, Madison, WI 53706, USA.
*
To whom correspondence should be addressed. E-mail:
moore{at}scs.uiuc.edu
