Zooming In on Microscopic Flow by Remotely Detected MRI

Abstract

Finely Tracking Flow Magnetic resonance imaging (MRI) is in principle well-suited for tracking flow dynamics in microfluidic channels. However, multiple channels tend to be arrayed on much larger substrates, and MRI coils large enough to enclose the whole assembly do not have the sensitivity required to resolve an intimate picture of any one channel. Bajaj et al. (p. 1078 , published online 7 October; see the Perspective by Utz and Landers ) present an imaging protocol in which the spins of the fluid molecules in a microfluidic chip are first tagged by a conventionally sized coil and then analyzed downstream using a more sensitive and smaller coil through which the fluid flows incrementally after leaving the microfluidic device.