Chaotic mixing using source–sink microfluidic flows in a PDMS chip
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We present an active fixed-volume mixer based on the creation of multiple source–sink microfluidic flows in a polydimethylsiloxane (PDMS) chip without the need of external or internal pumps. To do so, four different pressure-controlled actuation chambers are arranged on top of the 5 μl volume of the mixing chamber. After the mixing volume is sealed/fixed by microfluidic valves made using ‘microplumbing technology’, a virtual source–sink pair is created by pressurizing one of the membranes and, at the same time, releasing the pressure of a neighboring one. The pressurized air deforms the thin membrane between the mixing and control chambers and creates microfluidic flows from the squeezed region (source) to the released region (sink) where the PDMS membrane is turned into the initial state. Several schemes of operation of virtual source–sink pairs are studied. In the optimized protocol, mixing is realized in just a sub-second time interval, thanks to the implementation of chaotic advection.
KeywordsFixed-volume mixer Valve Chaotic advection Source–sink flow PDMS Microfluidics
We would like to thank Meng Shen of the Laboratory of Microsystems of EPFL (Switzerland) and Dr. Bo Song of the Laboratory of Lanthanide Supramolecular Chemistry of EPFL for helpful discussions and suggestions, Di Jiang of the Laboratory of Microsystems of EPFL (Switzerland) for solving programming issues on the FPGA board and the staff of the EPFL Center of MicroNano Technology (CMI) for assistance in the chip fabrication issues.
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