by Joe Buffaloe
Daily Lobo
When something has to be mixed in a channel that is measured in micrometers, it's complicated.
Liquids in a microscopic channel can't be mixed by shaking them up like gin and vermouth in a martini, said Dimiter Petsev, assistant professor in chemical and nuclear engineering.
"When you reduce the size of the channel, you cannot use methods and approaches that engineers use in much wider channels or fluid tanks," Petsev said. "So, we have to look for other ways to do that."
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Petsev worked with collaborators from North Carolina State University and the University of Hull in the United Kingdom to develop a technique that can mix and separate fluids in channels less than half a millimeter wide.
The research could be applied to isolating and analyzing proteins and could help in the early detection of diseases, including several types of cancer, Petsev said.
The technology will also allow smaller samples to be used for diagnostics, he said.
"You don't need to drain a pint of blood or something - you can just take a very small sample and do the analysis," he said.
The process involves placing diodes - which are components that allow electricity to flow in one direction but block it in the other - along a channel.
As fluids pass through the diodes, they can be mixed or separated by electrical fields within the diodes.
While one electrical field pumps fluid through the channel, another field does the opposite, causing materials to swirl together or be pulled apart.
This process is an improvement over existing methods, Petsev said.
A common method is to make grooves in the channels that force the fluids to mix.
There are problems with such methods, he said. The features are difficult to make, and once they exist in a channel, they remain there forever, mixing any fluids that pass through, no matter what.
With the method Petsev helped develop, scientists can mix fluids in the diodes as long as they want, or stop mixing by turning off the electrical fields.
Details of the experiments were published in the February issue of the journal "Nature Materials."
Petsev has applied for a patent through UNM.
Research on the subject is ongoing, he said.
"We can flow two components together, mix them, let them react," he said. "Then we can separate the products. This is something we're looking at in the future."
