High-resolution nuclear magnetic resonance spectroscopy in microfluidic droplets

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Microfluidics

Background:

• Microfluidic Nuclear Magnetic Resonance (NMR) spectroscopy offers advanced analytical capabilities.
• Challenges in microfluidic NMR include magnetic susceptibility mismatches between chip materials, continuous phases, and droplet phases, causing broadened spectral lines and reduced resolution.

Purpose of the Study:

• To develop a generic approach for high-resolution NMR spectroscopy of water/oil droplet emulsions in microfluidic devices.
• To overcome spectral broadening caused by magnetic susceptibility differences.

Main Methods:

• Mitigated susceptibility differences between the oil phase and chip material using air-filled structures.
• Matched susceptibilities of continuous (oil) and droplet (aqueous) phases by doping the aqueous phase with a Europium(III) complex.

Main Results:

• Achieved proton line widths of approximately 3 Hz in the droplet phase.
• Demonstrated the capability for high-resolution NMR analysis in microfluidic systems.

Conclusions:

• The presented generic approach effectively enables high-resolution NMR spectroscopy of water/oil droplet emulsions.
• The method addresses key challenges in microfluidic NMR, paving the way for more detailed analyses of emulsion systems.