Hydrodynamic chromatography separations in micro- and nanopillar arrays produced using deep-UV lithography

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Micropillar array columns offer a novel geometry for chromatographic separations.
• Fabrication techniques like deep-UV lithography and reactive ion etching enable precise microscale structures.

Purpose of the Study:

• To investigate the efficacy of hydrodynamic chromatography in micropillar array columns.
• To assess the separation performance for nanoparticles of different sizes.
• To evaluate the impact of interpillar distance on separation resolution and efficiency.

Main Methods:

• Hydrodynamic chromatography (HDC) was performed using custom-fabricated micropillar array columns with varying interpillar distances (1.00, 0.70, and 0.47 μm).
• Columns were fabricated using deep-UV lithography and deep reactive ion etching.
• Separations involved fluorescein isothiocyanate (t(0) marker) and polystyrene beads (20- and 40-nm).
• Fluorescent signals were detected in a deep detection groove to enhance signal-to-noise ratio.

Main Results:

• Successful separation of fluorescein isothiocyanate and 20/40-nm polystyrene beads was achieved, despite fabrication limitations causing band broadening.
• A resolution of R(s) = 0.5 between 20- and 40-nm particles was obtained in 90 seconds with the smallest interpillar distance (0.47 μm).
• Selectivity in pillar array columns was comparable to traditional packed-bed columns.
• Signal-to-noise ratio was enhanced up to 150 times by using a deep detection groove.

Conclusions:

• Micropillar array columns are viable for hydrodynamic chromatography, enabling nanoparticle separation.
• Optimized interpillar spacing is crucial for achieving high resolution in particle separations.
• The integrated detection groove significantly improves signal quality, enhancing analytical capabilities.