425623 Measuring Concentration Fields in Microfluidic Channels in Situ with a Fabry–Perot Interferometer

Tuesday, November 10, 2015: 1:06 PM
155F (Salt Palace Convention Center)
Douglas R. Vogus1, Vincent Mansard1, Michael Rapp1 and Todd M. Squires2, (1)Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, (2)UCSB Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA

Spatio-temporal concentration profiles arise in a variety of physical systems; for example, those in which materials precipitate, dissolve, react, or equilibrate. While many of these systems can be studied in a microfluidic environment, there are few general techniques which can measure spatio-temporal concentration profiles without fluorescent labeling. Here we describe a Fabry-Perot interferometric technique, capable of measuring concentration profiles in situ, without any chemical label, by tracking Fringes of Equal Chromatic Order (FECO). The technique has a sensitivity of 10-5 RIU, which can be used to track local solute changes of ~0.05% (w/w). The technique is spatially resolved (1 mm) and easily measures evolving concentration fields with ~20 Hz rate. Here, we demonstrate by measuring the transport of various solutes and solvents through polyethylene glycol diacrylate (PEG-DA) hydrogels with and without embedded oil droplets. We anticipate that our technique will prove useful for directly measuring evolving concentration profiles, opening new possibilities for the direct interrogation of dynamic, material systems.

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See more of this Session: Fundamental Research in Transport Processes
See more of this Group/Topical: Engineering Sciences and Fundamentals