Magnetic resonance detection: spectroscopy and imaging of lab-on-a-chip.

This mini-review is focused on the use of nuclear magnetic resonance (NMR) spectroscopy and imaging to study processes on lab-on-a-chip devices. NMR as an analytical tool is unmatched in its impact across nearly every area of science, from biochemistry and medicine to fundamental chemistry and physics. The controls available to the NMR spectroscopist or imager are vast, allowing for everything from high level structural determination of proteins in solution to detailed contrast imaging of organs in-vivo. Unfortunately, the weak nuclear magnetic moment of the nucleus requires that a very large number of spins be present for an inductively detectable signal, making the use of magnetic resonance as a detection modality for microfluidic devices especially challenging. Here we present recent efforts to combat the inherent sensitivity limitation of magnetic resonance for lab-on-a-chip applications. Principles and examples of different approaches are presented that highlight the flexibility and advantages of this type of detection modality.