Like other users of microfluidic systems, National
Institute of Standards and Technology (NIST) researcher Javier Atencia was
faced with an annoying engineering problem: how to simply, reliably and most
of all, tightly, connect his tiny devices to the external pumps and reservoirs
delivering liquids into the system. While pondering this one day, he randomly
picked up two magnets and began playing with them. As the magnets pulled apart
and then snapped back together, Atencia realized that he had his solution.
Photograph showing the use of the NIST magnetic connectors with a microfluidic device designed to generate liposomes. The microchip has five inlets and one outlet, all linked to tubing via the magnetic connectors. The inset at upper right shows the setup of the tube-magnet combination. Credit: G. Cooksey, NIST
In a paper recently published online in Lab on a Chip,* Atencia and colleagues
describe the result of that brainstorm: a new, inexpensive, reusable and highly
efficient microfluidic connector. The NIST connector employs a ring magnet with
a O-ring gasket on its bottom and a tube in its center set directly atop the
inlet or outlet port of a microfluidic channel embedded in a glass chip. A disc
magnet on the underside of the chip holds the first magnet—and its tubing—securely
Unlike traditional approaches to connectors—such as gluing the tubing
directly to the chip or mounting a male/female connection with the tubing attached
to the male portion—the NIST magnetic connector is reusable; can be positioned
anywhere on the chip; and eliminates any possibility of broken bonds that leak,
chips cracked during heat curing of the glue, or microfluidic devices turned
useless by excess glue entering the channels. Additionally, the reliability,
flexibility and fast assembly of the NIST connector compares favorably to a
recently developed press-fit system (where springs produce the sealing force)
but the magnetic connectors cost hundreds of dollars less to build and operate.
As reported in their paper, the NIST researchers demonstrated the viability
of their magnetic connector in a microfluidic device designed to generate liposomes
(tiny bubble-shaped membranes that can be used to transport drugs throughout
the body), a fairly port-intensive task. A solution of lipids suspended in isopropyl
alcohol is pumped at a high rate into a microchannel through one inlet and hit
with a buffer solution pumped in through four other ports. The convection and
diffusion that occurs as the liquid streams mix produces liposomes that exit
the microfluidic device through an outlet port. Magnetic connectors at the five
inlets and one outlet were removed and reseated numerous times without any visible
The NIST researchers state that their magnetic connector is suitable for most
microfluidic applications except those dealing with iron-containing (ferro)
fluids, superparamagnetic particles (particles so small that their magnetic
properties decrease with time and fluctuations in temperature), cells tagged
with magnetic particles, or high-temperatures (greater than 80 degrees Celsius).
NIST is seeking a patent for the magnetic microfluidic connector. Once the
patent application is filed, the technology will be available for licensing.
Interested parties should contact Terry Lynch, NIST Office of Technology Partnerships,
firstname.lastname@example.org, (301) 975-3084 (301) 975-3084 .
* J. Atencia, G. Cooksey, A. Jahn, J. Zook, W. Vreeland and L. Locascio. Magnetic
connectors for microfluidic applications. Lab on a Chip. Published online Nov.