Stacked planar micro coils for single-sided NMR applications.

Area of Science:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• Materials Science
• Microfabrication

Background:

• Single-sided NMR requires specialized coil designs for localized measurements.
• Existing coils have limitations in sensitivity and sample volume for certain applications.
• Tailoring coil parameters is crucial for optimizing performance.

Purpose of the Study:

• To design and fabricate advanced planar micro structured coils for single-sided NMR.
• To enhance coil sensitivity and signal-to-noise ratio (SNR) for small sample volumes.
• To enable high-resolution depth profiling and analysis of materials with short relaxation times.

Main Methods:

• Development of a novel multilayer assembly for planar micro coils.
• Implementation of an optimization algorithm using finite element method (FEM) simulations.
• Fabrication using thin-film technology and microstructuring techniques.
• Adaptation of coils to a Profile NMR-MOUSE® magnet.

Main Results:

• A 4x4 mm² coil design with 20 turns in four layers achieved comparable SNR to a larger state-of-the-art coil.
• The new coil measures sample volumes five times smaller.
• Minimal dead time of 4 μs achieved, facilitating echo adding techniques.
• Successful characterization of solid polymers (PE, PP) with short T2 relaxation times (200 μs).
• Demonstrated depth profiling with microscopic resolution.

Conclusions:

• The novel multilayer micro coils significantly improve SNR and enable measurements in smaller volumes for single-sided NMR.
• These coils are suitable for analyzing challenging samples, including those with short T2 relaxation times.
• The technology facilitates advanced applications like microscopic depth profiling and volume-limited analyses.