New Miniaturized Device for Lab-on-a-Chip Separations

Jan 19, 2007
New Miniaturized Device for Lab-on-a-Chip Separations
Core of the new NIST miniature GEMBE chemical separation device (above left) is a machined acrylic block, shown with a quarter for scale. Eight sample resevoirs for multiplexed separations form a ring around the central buffer solution port. (Smaller holes are for assembly screws.) At right: prototype in use. Credit: NIST

Researchers at the National Institute of Standards and Technology have developed an elegantly simple, miniaturized technique for rapidly separating minute samples of proteins, amino acids and other chemical mixtures. A low-cost prototype device described in a recent paper can run up to eight separations simultaneously in a space about the size of a quarter, highlighting the technique's potential for use in microfluidic "lab-on-a-chip" systems.

New Miniaturized Device for Lab-on-a-Chip Separations

Conventional electrophoresis instruments separate mixtures of electrically charged species--DNA fragments, for example--by injecting a discrete sample of the mixture at one end of a chemical race track, such as a capillary tube filled with a buffer solution, and applying a high voltage between the sample and the other end of the track.

Depending on their size, charge and chemical "mobility," the individual components of the mixture move down the track at different rates, gradually separating into individual bands. If two of the components move at very similar rates, it will require a relatively long channel--up to 50 centimeters or longer--to separate them effectively.

The new NIST technique, "gradient elution moving boundary electrophoresis" (GEMBE), works instead by opposing the movement of the mixture's components with a stream of buffering solution flowing at a variable rate. Like salmon swimming upstream, only the most mobile components can move up the channel against the highest buffer flow rates, but as that flow is reduced gradually, lesser mobility components begin to move. A sensor placed over the channel detects each new component as it arrives,

GEMBE is ideally suited for use in microfluidic "lab-on-a-chip" devices. Components are selected by buffer flow-rate rather than distance, so the channel can be very short--less than a centimeter in NIST prototypes. It doesn't require injection of a discrete sample, which greatly simplifies chip plumbing. By precisely controlling the flow rate, a particular component can be "parked" under the detector as long as desired to get a good signal, and the device can be adjusted easily to accommodate different separations. The device is easy to build with simple machining or molding techniques and low-cost polymers, enabling inexpensive mass production.

The technique has been validated at NIST with separations ranging from small dye molecules and amino acids to larger biomolecules, such as DNA. A prototype eight-channel GEMBE device built at NIST can produce a complete immunoassay calibration curve for insulin in a single run. NIST is applying for a patent on the method.

Citation: J.G. Shackman, M.S. Munson and D. Ross. "Gradient elution moving boundary electrophoresis for high-throughput multiplexed microfluidic devices." Anal. Chem., 79 (2), 565 -571, 2007. 10.1021/ac061759h S0003-2700(06)01759-8 on line at… 2/abs/ac061759h.html

Source: National Institute of Standards and Technology

Explore further: Liquid helium offers a fascinating new way to make charged molecules

add to favorites email to friend print save as pdf

Related Stories

NIST helps develop new standard for microsensor technology

Sep 10, 2014

The National Institute of Standards and Technology (NIST) has contributed to the development of a new standard for defining the performance of micromechanical sensors—a field that is expected to expand rapidly in coming ...

EUV calibrations for satellite sensors

Aug 26, 2014

Thanks to precision calibration measurements recently performed at NIST, satellites may soon be looking at sunlight with new and improved vision.

Ion duet offers tunable module for quantum simulator

Aug 06, 2014

Physicists at the National Institute of Standards and Technology (NIST) have demonstrated a pas de deux of atomic ions that combines the fine choreography of dance with precise individual control.

Recommended for you

Amino acids key to new gold leaching process

Oct 24, 2014

Curtin University scientists have developed a gold and copper extraction process using an amino acid–hydrogen peroxide system, which could provide an environmentally friendly and cheaper alternative to ...

Researchers create designer 'barrel' proteins

Oct 23, 2014

Proteins are long linear molecules that fold up to form well-defined 3D shapes. These 3D molecular architectures are essential for biological functions such as the elasticity of skin, the digestion of food, ...

User comments : 0