Photoreactive coating for high-contrast spatial patterning of microfluidic device wettability
Authors: Adam R. Abate, Amber T. Krummel, Daeyeon Lee, Manuel Marquez, Christian Holtzed and
David A. Weitz
Lab Chip, 2008, 8, 2157–2160
Soft matter keywords
By Alex Epstein
Abstract from the original paper
For many applications in microfluidics, the wettability of the devices
must be spatially controlled. We introduce a photoreactive sol–gel
coating that enables high-contrast spatial patterning of microfluidic
SEM images of channel cross sections; scale bars denote 5 mm. (a) Uncoated PDMS channel cross-section and (b) magnified view of upper right corner. (c) Coated, PAA functionalized PDMS channel and (d) magnified view of upper right corner; the corner is rounded because the sol–gel wets the surface and collects in regions of high curvature.
Contact angle measurement of water droplets in air on (a) sol–gel coated substrate with contact angle 105 deg and (b) PAA grafted substrate with contact angle 22 deg. AFM images of (c) sol–gel coated and (d) PAA grafted microchannels. The images show a 10 deg 20 mm area at high resolution; the dark to light color scale maps to feature heights of -150 to 150 nm. (e) Surface concentrations of atoms on sol–gel coated and PAA functionalized substrates, measured with XPS; fluorine (F 1s), oxygen (O 1s), carbon (C 1s), and silicon (Si 2s).