Over the past decade, we and other groups have developed a number of RF probes which are based on very small (0.1-1 mm diameter) coils. These have high sensitivity, strong B1 fields, and are very useful where the sample is limited in mass (spectroscopy) or size (cellular). A number of different types of RF coils have been produced, and continue to be developed.
(a). Two hand-wound solenoidal coils with outer diameters 350 and 150 mm.
(b) Hydrogen fluoride etched bubble cell to increase the filling factor for NMR coupled separations.
(c) Micromachined square surface coil detector with inner diameter 60 mm.
(d) Micropatterned solenoidal coil
Some of the major applications and publications can be found under these links:
Proton NMR spectroscopy
Hyphenated chemical microseparations with NMR detection
Very high (>50 tesla) field spectroscopy