The goal of an integrated, miniaturized laboratory analysis system, also known as a "lab-on-a-chip," is simple: sample in, answer out. However, researchers wanting to use these microfluidic devices to analyze complex solutions containing particulates or other contaminating materials often find that the first part of the process isn't so easy. Effective sample preparation from these solutions can be laborious, expensive and time-consuming, involving complicated laboratory methods that must be performed by skilled technicians. This can significantly diminish the benefits associated with using miniaturized analytical techniques. Recent work at the National Institute of Standards and Technology (NIST) could help change that.
NIST researchers Elizabeth Strychalski and David Ross, in collaboration with Alyssa Henry of Applied Research Associates Inc. (Alexandria, Va.), have developed a novel and simple way to analyze samples that are complex mixtures, such as whole milk, blood serum and dirt in solution. In a paper published recently in Analytical Chemistry,* the team describes its latest enhancement to a NIST-developed separation technique called gradient elution moving boundary electrophoresis (GEMBE) (see "New Miniaturized Device for Lab-on-a-Chip Separations" in NIST Tech Beat, Jan. 19, 2007).
GEMBE relies on a combination of electrophoresis and variable pressure-driven flow through a microchannel. Electrophoresis uses electricity to push a mixture in solution through a channel, forcing the individual components to separate as they move at specific rates based on their individual properties, such as size and electrical charge. Complex samples can be difficult to separate cleanly because components in these samples (for example, the fat globules in milk or proteins in blood) can "foul" microfluidic channels in a way that prevents reliable detection of the desired sample components.
The new technique solves this problem by pumping
|Contact: Michael E. Newman|
National Institute of Standards and Technology (NIST)