A new approach to microfluidics

A team of University of Arkansas researchers has discovered an effective way to move small amounts of fluid around miniscule channels.

Their work may eventually lead to the creation of a lab on a chip, or a hand-held device, which could be used in medicine, research and industry to provide on-the-spot diagnosis, experimentation and monitoring.

Ingrid Fritsch, associate professor of chemistry and biochemistry, reported her team’s findings at a symposium on recent advances in microfluidics at the 221st meeting of the American Chemical Society in San Diego, CA.

Moving small fluid volumes down hair-width channels is a difficult problem. Current methods include electrokinetic pumping, mechanical pumping, and centrifugal force, which all have drawbacks, including moving parts and the need for high voltage systems.

Fritsch’s system, based around the principle of magnetohydrodynamics (MHD), has low voltage requirements, no moving parts or valves, and can be used with a variety of channel materials and aqueous and non-aqueous solvents.

‘We expect that this method will also allow mixing and stirring in ultra-small volumes of solution,’ Fritsch said.

The phenomenon has already been used to understand plasmas in astrophysics, control plasmas in nuclear fusion, generate electrical power, pump liquid metal coolants, and control the quality of electroplating, but only recently has been applied to microfluidics.

Using MHD, researchers could design a device with electrodes and magnets in different geometries to control the flow of fluids. The fields’ respective strengths would determine fluid flow rate. And if one of the fields is reversed, the flow would reverse, without need of mechanical manipulation. The researchers could also create a vortex and control the mixing of compounds they want to study.

‘The currents and magnetic fields are all at appropriate magnitudes suitable for a chip-based system,’ Fritsch said, ‘so it could potentially be (used in the development of) a hand-held device.’