Abstract

Passive Micro Mixers for Applications in the µTAS and Micro Reactor Field

Micro reactors and micro total analysis systems (µTAS) for chemical processing and bioanalytics require fast and efficient micro mixers allowing to mix the reagents used in specific processes or protocols. Owing to the mostly laminar flow patterns in microchannels, mixing can be notoriously slow, especially when liquid flows are considered. Hence, special methods have to be devised allowing to speed up mixing. Nowadays, a broad spectrum of micro mixers is available qualifying for specific flow regimes encountered in microfluidics. The focus of this presentation lies on passive micro mixers which are especially attractive since they do not require external actuators for fluid stirring.

Specifically, three different micro mixing principles are presented: Multilamination, split-andrecombine flow and chaotic advection. The specific advantages and disadvantages of these principles are discussed and mapped to requirements from practical applications. In each case, simulation and modeling techniques are presented allowing to predict the mixing performance. Furthermore, suitable experimental techniques allowing to measure mixing time-scales are discussed. Theoretical predictions are compared with experimental results, showing that methods of computational fluid dynamics and related techniques nowadays offer far reaching capabilities for mixer design. As a result, the different micro mixers developed at IMM in the past few years cover a broad range of possible applications in liquid, gas and multiphase mixing, corresponding to different volume flow and viscosity regimes.

Brief Bio

Dr. Hardt obtained his Ph.D. degree from the Institute of Tehoretical Physics from Unversität Giessen in 1996 on "Dirac-RPA theory of the nucleon and effective quark models." Currently he is the head of the simulation group at IMM, with research focus on contract research for industrial companies, mainly in the field of microfluidics systems.