Ultra-low field (ULF) MRI
MRI systems are widely used for clinical diagnostics where imaging is typically done in high-field magnets ranging from 1.5 T to 7 T to achieve a manageable signal-to-noise ratio needed for short imaging times (few minutes) and high resolution (1 mm or less). Ultra-low field (ULF) MRI (100 µT) has several potential advantages: (a) narrower instrumentation line widths; (b) greater T1 contrast; (c) minimal susceptibility artifacts due to metallic implants or the presence of air; (d) air core B0, B1, Gx, Gy and Gz coils with relaxed uniformity and power requirements (100 ppm versus 0.1 ppm, less than1 kW versus 10 kW or more).
Dynamic Nuclear Polarization (DNP) enhanced MRI at low fields
Since its discovery in 1953, dynamic nuclear polarization (DNP) has provided a powerful means for enhancing the proton resonance signal. The majority of recent research effort has focused on high magnetic fields, leading to many transformative experiments. Initial research into solution DNP in low magnetic fields has also been very exciting, especially in light of models predicting the magnitude of DNP enhancement at very low magnetic fields could be an order of magnitude greater than γe/γH = 658x theoretical limit at high magnetic fields.
Portable low-field NMR
There are many instances where use of high magnetic field NMR is either unnecessary or impractical due to cost and large instrument footprint. Low magnetic field NMR instruments are considerably less expensive to build or purchase, and can be made portable for application to a greater variety of materials in a wide variety of environments. In many cases, simple electromagnets or small permanent magnets are sufficient to generate the required fields. Magnetic fields less than 100 mT (4.26 MHz) are optimally suited for extremely heterogeneous mixtures containing both liquids and solids. Internal gradients created by differences in liquid/solid susceptibility scale with main field strength, and are smaller in the low field regime.
Magnetic Particle Imaging (MPI)
We are developing compact AC susceptometers for real‐time monitoring of the conversion of precursors to magnetic nanoparticles in batch or continuous flow reactors. The goal is to rapidly assess specific magnetic performance parameters that are relevant to the final intended use of the magnetic particle solution. Ideally measurements on small sample aliquots (less than 1 μL) that are broadband and take a short time to perform (less than 1 s) are needed. Also, the physics package should be easily adaptable to the reactor as well as typical micro pumps or syringes for fluid control.