Inside-out NMR with two concentric ring magnets.

Area of Science:

• Magnetic Resonance Imaging
• Sensor Technology
• Spectroscopy

Background:

• Traditional NMR sensors often have limited sensitive regions and require complex setups.
• Developing portable and cost-effective NMR solutions remains a challenge for broader applications.

Purpose of the Study:

• To design and implement a novel inside-out Nuclear Magnetic Resonance (NMR) sensor.
• To achieve a large sensitive region with a uniform magnetic field at a remote location.
• To demonstrate the sensor's capability for measuring samples with long relaxation times and high diffusivity.

Main Methods:

• Utilized a simple construction with a pair of ring magnets for the inside-out NMR sensor.
• Optimized the sensor geometry to create a 'sweet spot' with quasi-uniform B0 field.
• Integrated a coil printed circuit board (PCB) and housing for a palm-size device.

Main Results:

• Achieved a large sensitive region (approx. 4 mm width x 5 mm height) with a uniform magnetic field (0.16 T) at 5 mm above the magnet surface.
• Demonstrated high signal-to-noise ratio (SNR ~23 per two scans) with low radiofrequency (RF) power (~10 W peak).
• Successfully measured samples with T2 = 1.5 s and a 100 μs echo time, indicating suitability for long T2 and high diffusivity samples.

Conclusions:

• The developed inside-out NMR sensor offers a cost-effective and portable solution.
• Its design enables measurements in large sample volumes with enhanced sensitivity.
• The sensor shows promise for applications requiring precise NMR measurements of challenging samples.