A planar microfluidic mixer based on logarithmic spirals

Thomas Scherr*, Christian Quitadamo, Preston Tesvich, Daniel Sang Won Park, Terrence Tiersch, Daniel Hayes, Jin Woo Choi, Krishnaswamy Nandakumar, W. Todd Monroe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


A passive, planar micromixer design based on logarithmic spirals is presented. The device was fabricated using polydimethylsiloxane soft photolithography techniques, and mixing performance was characterized via numerical simulation and fluorescent microscopy. Mixing efficiency initially declined as the Reynolds number increased, and this trend continued until a Reynolds number of 15 where a minimum was reached at 53%. Mixing efficiency then began to increase reaching a maximum mixing efficiency of 86% at Re = 67. Three-dimensional (3D) simulations of fluid mixing in this design were compared to other planar geometries such as the Archimedes spiral and Meandering-S mixers. The implementation of logarithmic curvature offers several unique advantages that enhance mixing, namely a variable cross-sectional area and a logarithmically varying radius of curvature that creates 3D Dean vortices. These flow phenomena were observed in simulations with multilayered fluid folding and validated with confocal microscopy. This design provides improved mixing performance over a broader range of Reynolds numbers than other reported planar mixers, all while avoiding external force fields, more complicated fabrication processes and the introduction of flow obstructions or cavities that may unintentionally affect sensitive or particulate-containing samples. Due to the planar design requiring only single-step lithographic features, this compact geometry could be easily implemented into existing micro-total analysis systems requiring effective rapid mixing.

Original languageEnglish
Article number055019
JournalJournal of Micromechanics and Microengineering
Issue number5
StatePublished - May 2012
Externally publishedYes


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