Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy (NMR spectroscopy), or magnetic resonance spectroscopy (MRS), is a research technique that exploits the magnetic properties of certain atomic nuclei.
NMR used in many areas from materials sciences to medicine, for detailed molecule-specific investigations. Scientists now succeeded in enhancing the sensitivity of NMR measurements. The scientists used Lenz lenses that focus magnetic flux.
Specimens located in a high constant magnetic field and irradiated with a high-frequency alternating magnetic field. However, researchers seek to improve the unfavorable signal-noise ratio and increase the sensitivity of NMR measurements.
A high sensitivity is indispensable when applying mass and volume-limited methods or when a high spatial resolution is required, says Professor Jan Gerrit Korvink from Karlsruhe Institute of Technology, Germany. In NMR measurements on small samples, miniaturized high-frequency coils proved effective for the generation and reception of the alternating magnetic field.
For mobile applications and miniaturization, researchers developed a new method to enhance sensitivity. They used magnetic lenses, called Lenz lenses, to focus the magnetic flux of a macroscopic high-frequency coil on a smaller volume and to locally enhance sensitivity.
With these lenses, magnetic flux of the alternating field cannot focus also diverted or transformed. In this respect, the effect of these lenses can compare with that of optical lenses on light beams.
Change of the magnetic field induces current in the Lenz lenses, which made of metal plates or wires in symmetric or asymmetric arrangement. The shape of the lenses guides the induced currents such that the magnetic field focused.
With Lenz lenses, sensitivity of measurements in very small spaces. In which conventional NMR systems do not fit, can increase significantly. Moreover, the lenses work at any field strength. Medical applications can benefit from the use of Lenz lenses.
Korvink says, Lenz lenses are not wired, they are particularly suited for implants. An application might be possible with brain implants to observe healing of the tissue over longer terms with high resolution or on plasters for the observation of skin cancer. Currently, scientists exploring further applications, among others in electrical engineering.
More information: [PLOS ONE]