Nuclear magnetic resonance (NMR) devices, which analyze the molecular structure and physical properties of materials, are used across various fields such as life science, food, and materials science. Larger magnetic fields provide higher measurement performance, and global research and development have become even more intense since the development of NMR systems with frequencies exceeding one gigahertz (Giga = billion; GHz) in 2015. However, the magnets required to generate these magnetic fields are large and expensive and consume large amounts of liquid helium, a rare resource. These limitations mean only a limited number of institutions have been able to introduce this technology.
Yoshinori Yanagisawa, Unit Leader at the RIKEN Center for Biosystems Dynamics Research, and his colleagues have succeeded in developing the world's lightest and most compact NMR system. It provides frequencies that exceed 1 GHz with a weight one-tenth that of conventional systems. Specifically, the team has succeeded in increasing the current density of the high-temperature superconducting coils inside the magnet by a factor of 1.5 and the magnetic field sharing by more than 50% to concentrate a large current in a small space. These conditions would mean electromagnetic forces equivalent to a total weight of more than 100 tons are applied to the center of the high-temperature superconducting coil, which would normally cause it to break. The team, therefore, developed a new technology for winding high-temperature superconducting wires reinforced with high-strength metal in a closely aligned manner. It also confirmed that no additional liquid helium was needed during two months of operations.
The team aims to develop an NMR system with the world's highest magnetic field of 1.3 GHz by combining technologies such as high-temperature superconducting joints and persistent currents, which it is also developing in parallel. It is also working on the structural analysis of ultra-microscale samples related to Alzheimer's disease using the NMR system it has developed, hoping to make progress with these kinds of advanced research projects.