Cover Article in JMR: Gradient-Free Microfluidic Flow Labeling Using Thin Magnetic Films and Remotely Detected MRI

Gradient-free microfluidic flow labeling using thin magnetic films and remotely detected MRI

Nicholas W. Halpern-Manners, Daniel J. Kennedy, David R. Trease, Thomas Z. Teisseyre, Nicolas S. Malecek, Alexander Pines, Vikram S. Bajaj

JMR_Microgradient_Cover

Magnetic barcoding and remote detection of fluid flowing in a microfluidic device.

JMR_Microgradient_Phantom

Microfluidic flow phantom used in this experiment.

Abstract

Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) may be employed as noninvasive measurements yielding detailed information about the chemical and physical parameters that define microscale flows. Despite these advantages, magnetic resonance has been difficult to combine withmicrofluidics, largely due to its low sensitivity when detecting small sample volumes and the difficulty of efficiently addressing individual flow pathways for parallel measurements without utilizing large electric currents to create pulsed magnetic field gradients. Here, we demonstrate that remotely-detected MRI (RD-MRI) employing static magnetic field gradients produced by thin magnetic films can be used to encode flow and overcome some of these limitations. We show how flow path and history can be selected through the use of these thin film labels and through the application of synchronized, frequency-selective pulses. This obviates the need for large electric currents to produce pulsed magnetic field gradients and may allow for further application of NMR and MRI experiments on microscale devices.

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