Characterizing Diffusion and Transport in Microfluidics Channels: A Combined Raman Microscopy and Band-Target Entropy Minimization Study

With the increasing use of microfluidics, there is a need for a rather general experimental approach in order to monitor and characterize transport effects. Indeed, micro-fabrication methods have allowed the inclusion of numerous new structures and devices within microfluidics channels, and such alterations in flow patterns should impact solute transport characteristics. In the present contribution, Raman microscopy is combined with band-target entropy minimization analysis (BTEM) in order to rapidly assess and map concentration profiles in various regions of a microfluidics device. Two isotopomers, CHCl3 and CDCl3, are contacted under laminar conditions. Special consideration is given to the point of contact between the two liquids, transport in straight sections, transport in curved sections, and wall effects. Break-through curves confirmed that stagnation of fluid at the wall is not occurring, despite substantial wall roughness. Since the methods used in the present study are quite general, they should be useful in rapidly accessing transport effects when fluids (also in conjunction with colloids, suspensions, and solids) are contacted in the presence of both simple as well as complex geometries.

[1]  Wee Chew,et al.  Band-target entropy minimization (BTEM): An advanced method for recovering unknown pure component spectra. Application to the FTIR spectra of unstable organometallic mixtures , 2002 .

[2]  Wee Chew,et al.  Rhodium tetracarbonyl hydride: the elusive metal carbonyl hydride. , 2002, Angewandte Chemie.

[3]  Bernhard H Weigl,et al.  Microfluidic technologies in clinical diagnostics. , 2002, Clinica chimica acta; international journal of clinical chemistry.

[4]  A. Lee,et al.  Droplet microfluidics. , 2008, Lab on a chip.

[5]  J. Leng,et al.  Microfluidic crystallization. , 2009, Lab on a chip.

[6]  E. Widjaja,et al.  Application of Raman microscopy and band-target entropy minimization to identify minor components in model pharmaceutical tablets. , 2008, Journal of pharmaceutical and biomedical analysis.

[7]  Xiaoju Tang,et al.  A PDMS viscometer for microliter Newtonian fluid , 2007 .

[8]  P. Seeberger,et al.  Safe, facile radical-based reduction and hydrosilylation reactions in a microreactor using tris(trimethylsilyl)silane. , 2008, Chemical communications.

[9]  L. Fan,et al.  Models for flow systems and chemical reactors , 1975 .

[10]  M. Schwarz,et al.  Recent developments in detection methods for microfabricated analytical devices. , 2001, Lab on a chip.

[11]  Amy K. Manocchi,et al.  Microfluidic fabrication of hydrogel microparticles containing functionalized viral nanotemplates. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[12]  Klavs F Jensen,et al.  Infrared spectroscopy for chemically specific sensing in silicon-based microreactors. , 2004, Analytical chemistry.

[13]  Helen Song,et al.  Reactions in Droplets in Microfluidic Channels , 2007 .

[14]  L A Sklar,et al.  Performance of in-line microfluidic mixers in laminar flow for high-throughput flow cytometry. , 2002, BioTechniques.

[15]  D. Talaga,et al.  Chemical reaction imaging within microfluidic devices using confocal raman spectroscopy: the case of water and deuterium oxide as a model system. , 2008, Analytical chemistry.

[16]  F. Regnier,et al.  Microfabricated filters for microfluidic analytical systems. , 1999, Analytical chemistry.

[17]  J. Salmon,et al.  Interdiffusion of liquids of different viscosities in a microchannel , 2009 .

[18]  M. Garland,et al.  Pure component Raman spectral reconstruction from glazed and unglazed Yuan, Ming, and Qing shards: a combined Raman microscopy and BTEM study , 2011 .

[19]  Marc Garland,et al.  The Rh4(CO)12-catalyzed hydroformylation of 3,3-dimethylbut-1-ene promoted with HMn(CO)5. Bimetallic catalytic binuclear elimination as an origin for synergism in homogeneous catalysis. , 2003, Journal of the American Chemical Society.

[20]  Anthony N. Michel,et al.  Algebra and Analysis for Engineers and Scientists , 2007 .

[21]  A. Helmicki,et al.  An integrated microfluidic biochemical detection system for protein analysis with magnetic bead-based sampling capabilities. , 2002, Lab on a chip.

[22]  J. Mecklenburgh,et al.  The theory of backmixing : the design of continuous flow chemical plant with backmixing , 1975 .

[23]  P. Tabeling,et al.  In situ Raman imaging of interdiffusion in a microchannel , 2005 .

[24]  Marc Garland,et al.  Semi-Batch Homogeneous Catalytic In-Situ Spectroscopic Data. FTIR Spectral Reconstructions Using Band-Target Entropy Minimization (BTEM) without Spectral Preconditioning , 2002 .

[25]  J. Ouellette.  A New Wave of Microfluidic Devices by , 2022 .

[26]  Wei Li,et al.  Multi-step microfluidic polymerization reactions conducted in droplets: the internal trigger approach. , 2008, Journal of the American Chemical Society.

[27]  Wee Chew,et al.  Band-target entropy minimization. A robust algorithm for pure component spectral recovery. Application to complex randomized mixtures of six components. , 2003, Analytical chemistry.

[28]  Shelly Gulati,et al.  Chemical imaging of microfluidic flows using ATR-FTIR spectroscopy. , 2009, Lab on a chip.

[29]  R. Ismagilov,et al.  Effects of viscosity on droplet formation and mixing in microfluidic channels , 2004 .