"Towards NMR and MRI on a smaller and faster scale"
Song-I Han
University of California, Berkeley
Wednesday, February 25, 2004 -- 11 AM -12:00 Noon in 375 LeConte Hall
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy and magnetic resonance
imaging (MRI) are techniques that can provide rich and unique information, from molecular
structure and dynamics, to imaging of density, diffusion and flow properties.
However, these techniques are intrinsically insensitive compared to other
analytical and visualization methods. One goal of my postdoctoral reseach
is to find fundamental solutions that overcome this sensitivity limitation of NMR
and MRI. Spectroscopy and imaging of dilute spins located inside a solid or liquid
matrix - e.g. fine-porous media and dilute protein solutions - would be
facilitated or enabled by such methodologies. One approach is the hyperpolarization ofthe
NMR nuclei - typically noble gases - to obtain polarization that is orders of
magnitude larger than the parts per million (ppm) polarization at thermal equilibrium.
Another approach to increase sensitivity is the physical condensation of the
NMR sensor nuclei out of the sample matrix into a different location for sensitive
detection. This is first allowed by the new NMR and MRI remote detection
methodology being developed at Berkeley, which basic feature is the spatial
separation and individual optimization of the encoding Farraday coil and the
magnetization detector (1). Achieving the ultimate signal enhancement with
spin concentration and sensitive detection will allow e.g. the performance of NMR and
MRI on miniaturized microfluidic lab-on-a-chip devices. Online spectroscopic
monitoring of biochemical processes and flow characterization and visualization
in such miniaturized channels are part of my ongoing research, with the latter
(also known as NMR velocimetry) being an expertise gained during my Ph. D. research
in Aachen, Germany. Overcoming the sensitivity limitations of NMR and MRI allow
e.g. the access of spectral information in very small volumes and structures,
image information on micron scale, and furthermore dynamic information on a timescale
of milliseconds to seconds by obtaining a time series of single shot spectra.
(1) Alex Pines, Sunil Saxena, Adam Moule, Megan Spence, Juliette Seeley, Kimberly Pierce, Song-I Han, Joseph Granwehr. Remote NMR/MRI detection of laser polarized gases. CIP U.S. Patent Application, IB-1771PCT, filed October 9, 2002.
