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Soft Materials and Rheology Group Research There has been much research on generating drop flows in
microfluidic devices. Our own group has done research on this previously
(Fig. 1). We are now extending this research towards fabrication of microparticles. Microfluidic devices have been used for converting drops into microparticle. Typically drops of a monomer are generated
using a T-junction or a cross flow junction, and then crosslinked with UV
irradiation or thermally. The chief limitation of this approach is that one
can only fabricate particles out of monomers that can be crosslinked rapidly.
We seek to develop high-temperature microfluidic devices which can generate
controlled-size and shape drops from molten polymers; simply cooling them would
be adequate to make particles. The major advantage of this approach is that
one could make microparticles out of a vast variety
of polymers, or by combining them. The chief challenge is that the conventional devices made from
PDMS using soft lithography are not suitable for handling molten polymers. A
second problem – and a fundamental one – is that the high
viscosity and low interfacial tension makes it difficult to generate drops by
interfacial tension-driven breakup processes. We have developed a new
fluid-handling platform that uses laser-machined metal foil to make
microfluidic devices, and uses air pressure (rather than syringe pumps) to
drive flow. We have successfully demonstrated drop and bubble formation using
undiluted polymers of high viscosity and are now developing methods to
generate particles from thermoplastic polymers.
Fig. 1: Generation of drops at a T-junction in a microfluidic
device. Full details in Adzima and Velankar, J.
Micromechanics and Microeng., 16, 1504-1510, 2006. Download Questions, Suggestions,
Comments? Send e-mail to velankar@pitt.edu
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Current projects Interfacially-active
particles Natural and
synthetic papillae
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