Surface modification of PDMS microfluidic devices with polyelectrolyte multilayers

PDMS has become the material of choice for making microfluidic devices, due to its ease of use and low cost in fabrication. However, PDMS’s high hydrophobicity can limit its applicability in studies of two-phase flows and drop formation, where the relative wetting of the microchannel walls by each phase becomes important. One way to control the surface chemistry of the microchannels, and so more fully exploit the devices’ potential, is to coat the channels with polyelectrolyte multilayers (PEMs). We use pressure-driven flow to form the PEM coatings, alternately exposing the channels to solutions of polycations and polyanions. Selectively coating channels has allowed for a study of emulsions in PDMS microfluidic devices. We hope to expand our studies to double emulsions and the coating of drops with PEMs.

Microchannel rendered hydrophilic with PEMs. An oil drop in water is shown.

Collaborators:

Juhyun Park, Marianne Terrot, Paula Hammond, Department of Chemical Engineering, MIT

Thomas Ward, Howard Stone, Dept of Engineering and Applied Sciences, Harvard University

Contact info:

Melissa Wessels
wessels@physics.harvard.edu
Department of Physics
Harvard University
Mckay Laboratories
9 Oxford Street
Cambridge, MA 02138