Experimental study on band dispersion in channels structured with micropillars.
The band dispersion in channels with an orderly pillar structure with a pressure-driven liquid flow was determined. Several channels with different geometries were etched in a silicon wafer and enclosed by a glass wafer. The microchannels obtained had the same depth, pillar disposition, and overall porosity, but different pillar diameters and channel widths. The broadening of narrow bands of a fluorescent sample solution flowing through the channels was measured using a fluorescence microscope. It was shown that the peak dispersion occurring in the channels can be much lower than in conventional packed columns, as a consequence of the higher degree of order of the solid structure. Reduced plate heights of approximately 0.2 could be obtained for (nonretained) bands. No correlation was found between the aspect ratio (the ratio of the channel width and the pillar diameter) and band dispersion. The geometrical construction of the sidewall region was shown to play a critical role for channel performance. A good agreement was found with predictions for the optimal sidewall geometry obtained previously with simulation studies.
De Pra
M
M
van 't Hoff Institute for Molecular Sciences (HIMS), Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV, Amsterdam, The Netherlands.
Kok
W Th
WT
Gardeniers
J G E
JG
Desmet
G
G
Eeltink
S
S
van Nieuwkasteele
J W
JW
Schoenmakers
P J
PJ
D019793:Fluorescein / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D012825:Silicon / Q000737:chemistry
D019793:Fluorescein; D012825:Silicon