The Field-Cycling NMR technique is a technique that changes the magnetic fields of the sample during the experiment. This method can be conducted on the applications that require NMR parameters measurements at different magnetic fields, for instance, MRI contrast agent studies or protein dynamics or material science.
To measure NMR parameters at a wide magnetic field range meanwhile with high-resolution spectra, we designed a high-speed sample shuttling device working on a superconducting magnet (high-field NMR spectrometer). This design uses the advantage of high field spectrometers, which has a high-magnetic field and large magnetic field range in the stray field. The field switch is controlled by the speed of sample shuttling. This combination is called "High-Field Field-Cycling NMR".
However, this implementation in high-field NMR brought significant challenges of hardware design:
narrow selection of material due to high-magnetic field environment:
because working environments are in the magnetic field from ultra-low to high magnetic field, such as 9Tesla even higher up to 20Tesla, installed rail must be non-magnetic metal and the moving components must be totally non-metal to prevent eddy current.
imited space in the magnetic bore of high-field NMR spectrometer:
the bore-size of a standard bore NMR spectrometer is only 54mm in diameter. The working space is only a narrow and long cylinder inside the magnet bore.
little margin between the sample tube and the probehead:
the margin between the 5mm sample tube and 5mm liquid-state probehead is only 0.1mm. Therefore, the shuttling action must be precisely to prevent any hitting on the probehead.
narrow material selection of high wear-out due to high-speed and frequent shuttling:
since we would like to shuttle the sample rapidly, a high-wearing out material is requisite. Meanwhile, the selected material cannot be metal at all.
Our device, called "High-Field Field-Cycler" (HFFC), has successfully overcome these difficulties and reached stable and precise sample shuttling along the stray field. Nowadays "High-Field Field-Cycler" (HFFC) is available commercially.