Integration of fully microfabricated, three-dimensionally sharp electrospray ionization tips with microfluidic glass...

Area of Science:

• Analytical Chemistry
• Microfluidics
• Materials Science

Background:

• Microfluidic systems are crucial for chemical analysis but integrating emitters remains challenging.
• Existing methods for fabricating electrospray ionization (ESI) emitters often require manual steps and lack robustness.
• Achieving stable and repeatable performance in micro-total chemical analysis systems is hindered by emitter design and integration.

Purpose of the Study:

• To develop a novel microfabrication process for parallel, three-dimensionally sharp glass ESI emitters.
• To demonstrate the integration of these emitters with microfluidic separation channels.
• To evaluate the performance, repeatability, and solvent compatibility of the fabricated glass ESI emitters.

Main Methods:

• Utilized standard microfabrication techniques including deposition, photolithography, and wet etching.
• Developed a method for direct integration of 3D-sharp emitter tips with microfluidic channels.
• Performed parallel fabrication of multiple glass ESI emitters.

Main Results:

• Achieved robust, repeatable performance with signal intensity RSD of 8.0% and migration time RSD of 6.2%.
• Demonstrated successful integration of emitters with microfluidic channels, overcoming a long-standing challenge.
• Obtained high separation efficiencies (up to 2.7 × 10^5 plates/m) and enabled stable ESI at low voltages (1.4-1.75 kV).
• Showcased the utility of the emitters with various solvent compositions, including aqueous conditions for protein analysis.

Conclusions:

• The developed microfabrication process offers a reliable and efficient method for producing high-performance glass ESI emitters.
• This approach simplifies the construction of micro-total chemical analysis systems, improving overall system robustness.
• The low-voltage operation and solvent flexibility make these emitters suitable for diverse analytical applications, including biological sample analysis.