Self-assembled synthesis and characterization of microchannels in polymeric membranes
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Date
2012-07-19Author
Iqbal, Samir M.
Kahsai, Wintana T.
Pham, Uyen H. T.
Sankaran, Jeyantt S.
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This article describes a novel self-assembly approach to create microchannels in polydimethylsiloxane
(PDMS) membranes using poly(ethylene oxide) (PEO) and polyurethane (PU). The interactions
between hydrophilic PEO/PU and hydrophobic PDMS, as it cross-links, result into PEO/PU
pushed out of the bulk PDMS. As this occurs, PEO/PU particles leave behind their tracks. PEO
depicts ease of handling, better inherent alignment, and excellent repeatability. Fourier transform
infrared spectroscopy, optical/confocal laser scanning microscopy, and fluid flow measurements
are done to characterize the microfluidic channels. These channels have a circular cross-section
and are parallel to each other. PEO generates smaller channels compared to PU. The diameter,
arrangement, and height of these channels are seen to depend on temperature; for example, channel
length increases linearly with temperature. An interdependent relationship between temperature,
pore size, and number of pores is also exhibited. During phase separation of hydrophilic and
hydrophobic materials, interface shows concentric circular arrangements of hydrophilic molten
polymer. The circular pattern shows almost similar radial change in size. The flow behavior of
colored ink solutions shows higher velocity at the entrance of microchannels which decreases to
sustained lower velocity as fluid travels farther in the microchannels. The fabrication of membrane
does not need lithography or etching, and channels are self-assembled from bottom-up
interactions. These microchannel membranes can have applications in drug delivery, cell culture
studies, mixing of solutions, separation of mixtures, lab-on-a-chip, etc.