A Silicon Microchip for Infrared Transmission Kinetics Studies of Rapid Homogeneous Liquid Reactions

Floyd, Tamara M.; Schmidt, M.A.; Jensen, Klavs F.

doi:10.1007/978-94-010-1015-3_115

Cited by 2 publications

(1 citation statement)

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“…[1][2][3] More specifically, on-chip microfluidic mixing devices have applications in microfluidic chemical synthesis experiments, 4 immunoassays, 5 and protein analysis, 6,7 and can offer benefits to other on-chip processes which demand fast, highly-uniform mixing of analytes and reagents such as in the study of chemical reaction kinetics. 8,9 Microfluidic mixing is typically limited to diffusion due to the laminar nature of microflows.…”

Section: Introductionmentioning

confidence: 99%

High-efficiency electrokinetic micromixing through symmetric sequential injection and expansion

2006

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Rapid electric field switching is an established microfluidic mixing strategy for electrokinetic flows. Many such microfluidic mixers are variations on the T- or Y-form channel geometry. In these configurations, rapid switching of the electric field can greatly improve initial mixing over that achieved with static-field mixing. Due to a fundamental lack of symmetry, however, these strategies produce lingering cross-channel concentration gradients which delay complete mixing of the fluid stream. In this paper, a field switching microfluidic mixing strategy which utilizes a symmetric sequential injection geometry with an expansion chamber to achieve high efficiency microfluidic mixing is demonstrated experimentally. A three-inlet injector sequentially interlaces two dissimilar incoming solutions. Downstream of the injector, the sequence enters an expansion chamber resulting in a dramatic (two orders of magnitude) decrease in Peclet number and rapid axial diffusive mixing. The outlet concentration may be accurately varied over the full spectrum by tuning the duty cycle of the field switching waveform. The chips are designed with input from a previous numerical study, manufactured in poly(dimethylsiloxane) using soft-lithography based microfabrication, and tested using fluorescence microscopy. In the context of on-chip chemical processing for analytical operations, the demonstrated mixing strategy has several features: high mixing efficiency (99%), compact axial length (2.3 mm), steady outflow velocity, and readily variable outlet concentration (0.15 < c* < 0.95).

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