An NMR-compatible microfluidic platform enabling in situ electrochemistry

Area of Science:

• Analytical Chemistry
• Microfluidics
• Nuclear Magnetic Resonance Spectroscopy

Background:

• Integrating microfluidic devices with nuclear magnetic resonance (NMR) offers advanced sample handling and analysis capabilities.
• Conductive structures, such as metallic electrodes, pose challenges in microfluidic NMR due to potential spectral and signal-to-noise ratio (SNR) degradation.
• These challenges are amplified at the micro-scale, where electrode-induced distortions occupy a larger sample volume ratio.

Purpose of the Study:

• To identify and validate an optimal electrode geometry for microfluidic devices that minimizes NMR spectral degradation.
• To investigate the impact of electrode placement on NMR radiofrequency (RF) excitation performance and magnetic field homogeneity (B0).
• To demonstrate the feasibility of using this integrated system for in situ NMR characterization of electrochemical processes.

Main Methods:

• Utilized a combination of computational simulations and experimental validation to assess various electrode designs.
• Developed microfluidic channels with metallic electrodes strategically placed in the side-walls.
• Performed in situ monitoring of chitosan deposition using NMR spectroscopy within the microfluidic platform.

Main Results:

• Identified a specific side-wall electrode geometry that performs comparably to systems without electrodes, preserving NMR spectral parameters.
• Observed enhanced NMR RF excitation performance without compromising B0 homogeneity with the optimized electrode design.
• Successfully demonstrated proof-of-concept for NMR characterization of in situ chitosan deposition, an electrochemical process.

Conclusions:

• Optimized electrode placement in microfluidic channels can overcome NMR signal degradation issues.
• Side-wall electrode integration enhances NMR performance and enables detailed analysis of microfluidic electrochemical processes.
• This technology provides a powerful tool for real-time characterization of microscale electrochemical reactions.