Issue 10, 2012

Spinning magnetic trap for automated microfluidic assay systems

Abstract

While sophisticated analyses have been performed using lab-on-chip devices, in most cases the sample preparation is still performed off chip. The global need for easy-to-use, disposable testing devices necessitates that sample processing is automated and that transport complexity between the processing and analytical components is minimal. We describe a complete sample manipulation unit for performing automated target capture, efficient mixing with reagents, and controlled target release in a microfluidic channel, using an array of spinning magnets. The “MagTrap” device consists of 6 pairs of magnets in a rotating wheel, situated immediately beneath the microchannel. Rotation of the wheel in the direction opposite to the continuous flow entraps and concentrates the bead-target complexes and separates them from the original sample matrix. As the wheel rotates and the active pair of magnets moves away from the microchannel, the beads are released and briefly flow downstream before being trapped and pulled upstream by the next pair of magnets. This dynamic and continuous movement of the beads ensures that the full surface area of each bead is exposed to reagents and prevents aggregation. The release of the target-bead complexes for further analysis is facilitated by reversing the rotational direction of the wheel to sweep the beads downstream. Sample processing with the MagTrap was demonstrated for the detection of E. coli in a range of concentrations (1 × 103, 1 × 104 and 1 × 106 cells ml−1). Results show that sample processing with the MagTrap outperformed the standard manual protocols, improving the detection capability while simultaneously reducing the processing time.

Graphical abstract: Spinning magnetic trap for automated microfluidic assay systems

Supplementary files

Article information

Article type
Paper
Submitted
01 Dec 2011
Accepted
03 Feb 2012
First published
06 Feb 2012

Lab Chip, 2012,12, 1793-1799

Spinning magnetic trap for automated microfluidic assay systems

J. Verbarg, K. Kamgar-Parsi, A. R. Shields, P. B. Howell and F. S. Ligler, Lab Chip, 2012, 12, 1793 DOI: 10.1039/C2LC21189K

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