By
alternating the flow of fluid through tiny plastic pipes,
a team of mechanical engineers at New Jersey Institute
of Technology (NJIT) has discovered a new and speedier
way to mix liquids, which in turn will someday produce
better and safer medications.
"Everybody looks at creating turbulence in three
dimensions to mix liquids," said team leader Nadine
Aubry, PhD, Jacobus distinguished professor and chair
of the mechanical engineering department at NJIT. "We
traded space for time, which is a much simpler way to
handle this problem when space is at a premium."
A
paper by Aubry and her team, "Electro osmotic
Mixing in Microchannels," published in the Nov.
29, 2004 issue of Lab on a Chip, showed that mixing
could be accomplished by changing the flow rates by
simply varying the voltage applied to the electrodes
that commonly pump the fluid through a micro-channel.
This publication follows other journal articles about
similar research using other types of pumping: the
Aug. 15, 2004 issue of Analytical Chemistry as well
as the May 19, 2003 issue of Lab on a Chip.
More
recognition for Aubry's work has come from professional
colleagues, who appointed her last month vice chair
of the U.S. National Committee for Theoretical and
Applied Mechanics. The Committee serves as a national
forum for discussions on research, technology and
education of mechanics, as well as represents the
U.S. in international scientific activities related
to mechanics.
"Normally
when two pipes in a micro-scale chemical reactor meet,
the two liquids fail to mix," said Aubry. But
by switching the flow many times per second, the scientists
were able to create - in just a second - a pseudo-turbulent
flow that completely blended the two liquids. To demonstrate
the method, Aubry used a "T" channel intersection
whose segments were 200 microns wide by 120 microns
deep – about twice the circumference of a human hair.
The
method caused the interface between the two liquids
to stretch, fold, and sweep through, allowing the
liquids to mix quickly after traveling only two millimeters
down the channel. Aubry expects the new methods to
have many useful applications, especially in the pharmaceutical
industry.
"The
process will be useful in the preliminary phases of
drug discovery," she said, "where reagents
need to be well-mixed to produce purer test drugs
with fewer unwanted by-products." Her process
will also help engineers design smaller, more sensitive
detectors for nerve gases and pollutants. And on the
domestic front, inexpensive lab-on-a-chip devices
could be used to make sensors that will detect rotting
food in kitchen refrigerators.
Aubry
is the co-director of NJIT's Keck Laboratory, a biotechnology
lab whose world-class technology can help identify
and manipulate bacteria, viruses and cancer cells.
She received her bachelor's degree in mechanical engineering
from the National Polytechnic Institute in Grenoble,
France, her master's degree in mechanical engineering
from the Scientific University of Grenoble and her
doctorate in mechanical and aerospace engineering
from Cornell University, N.Y.
She
has served as a member of the National Aeronautics
and Space Engineering Board's Air Force Office of
Scientific Research (AFOSR) Panel and as a member
of the National Research Council Panel for the NASA
Administrator's Fellowship Program. She is a recipient
of the Presidential Young Investigator Award from
the National Science Foundation and the Ralph R. Teetor
Award from the Society of Automotive Engineers.
Aubry
is looking forward to continuing her micro-fluidic
investigations. "Fluid mechanics has always been
at the forefront of engineering and science,"
she said. "The prominent role that it now plays
in emerging areas such as nanotechnology and biomedicine
makes it a particularly exciting field."
###
New Jersey Institute of Technology, the state's public
technological research university, enrolls more than
8,200 students in bachelor's, master's and doctoral
degrees in 100 degree programs offered by six colleges:
Newark College of Engineering, New Jersey School of
Architecture, College of Science and Liberal Arts,
School of Management, Albert Dorman Honors College
and College of Computing Sciences. NJIT is renowned
for expertise in architecture, applied mathematics,
wireless communications and networking, solar physics,
advanced engineered particulate materials, nanotechnology,
neural engineering and eLearning.
|