NMR scanners become hand held

Palm sized NMR machines are capable of performing quality control in rubber and other organic materials as well as showing promise for some medical applications. While they lack the ability provided by car sized hospital scanners to study the human body in depth, their relative cheapness and smallness allow them to perform tasks for which a conventional NMR would be a drastic overkill. The NMR Mouse (Nuclear Magnetic Resonance-MObile Universal Surface Explorer) is the brainchild of Professor Bernhard Blumich in a venture spun out of the University of Aachen. It uses permanent magnets to produce a horizontal magnetic field across a gap. A surface coil within the gap produces a radio frequency modulated field in the range 12 to 25 MHz. Detection of suitable nuclei, usually hydrogen, as in all pulsed NMR machines, is by detecting the decaying radio frequency signal that arises from the relaxation of nuclei subsequent to their initial excitation. The first reported industrial application for the devices was to monitor elastomers. Relaxation measurements show a clear dependence on the type of polymer, the cross link density, and filler materials in the unvulcanised state. The molecular chain orientation in strained rubber can be investigated, as can the curing of adhesives. Since then the devices have become available with cylinder magnets as well as rectangular magnets, and research has come up with medical and other possible application areas. It is found, for example, that human and animal tendon has a low relaxation time, about 10ms, while soft skin has a relaxation time of around 40ms. Furthermore, tendon is an anisotropic material so that the NMR signals depend on the relative orientation of the tendon axis with respect to the magnetic field. The device thus shows promise for assessing skin disease and monitoring healing processes and the quality of tendon replacements before and following implantation. Another area being researched is the study of nanometre thick lipid films with potential applications in biosensors and membrane based chemical separation. By monitoring the take up of water in pores, it is possible to study the porosity of very fine pored materials. Developments for the rubber industry include the uses of up to five NMR sensors in parallel in a spectrometer. The new instrument has been developed by Intech Thuringen, which calls it the Intec Veri NMR spectrometer. It is found suitable for the monitoring of raw material, processed rubber and finished products, including valve gaskets. AixNMR Professor Bernhard Blumich Pointers * NMR sensor is palm sized instead of car sized, and requires no superconducting magnets * Measurements concerning the distribution and chemical state of hydrogen and some other nuclei can be made at depths of up to 10mm * First applications are in the rubber industry, but it is of quite general potential usefulness in process quality control, and may soon be found in some doctor's offices