Special Issue "Micromixers"

Guest Editor
Prof. Dr. Nam-Trung Nguyen
Nanyang Technological University, School of Mechanical and Aerospace Engineering, 50 Nanyang Avenue, 639798, Singapore
E-Mail:
Interests: development of micro technology; transport effects in microscale; microdevices; lab on a chip; diagnostic techniques

Dear Colleagues,

Micromixer is a key component in a number of microsystems, especially lab-on-a-chip. Micromixers are miniaturized mixing devices for at least two different phases that can be liquids, solids or gases. The structures of a micromixer are fabricated partially or in whole using microtechnology or precision engineering. The characteristic channel size of micromixers is in the sub-millimeter range. Common channel widths are on the order of 100 to 500 μm, while channel length could be a few millimeters or more. The channel height is on the order of the channel width or smaller. The overall volume defined by a micromixer is from microliters to milliliters. Compared with molecular size scale, the length scale and volume scale of micromixers are still very large. This fact leads to two key characteristics of micromixers. First, designing micromixers still relies on manipulating the flow using channel geometry or external disturbances. Secondly, while micromixers bring advantages and new features into chemical engineering, molecular level processes such as reaction kinetics remain almost unchanged. The laminar flow regime poses a challenge to designers of micromixers. New mixing concepts and the optimization of known concepts are the hot research topics in recent years. This special issue aims at attracting and publishing the latest works on micromixers.

Nam-Trung Nguyen, Ph.D.
Guest Editor

Submission

• micromixers
• microfluidics
• nanofluidics
• molecular diffusion
• chaotic advection

Typer of Paper: Review
Title: A Review on Mixing in Microfluidics
Authors: Yong Kweon Suh and Sangmo Kang
Affiliation: Department of Mechanical Engineering, Dong-A University 840 Hadan-dong, Saha-gu, Busan 604-714, Korea; E-Mail: yksuh@dau.ac.kr
Abstract: Mixing in small scales is uttermost important in the bio- and chemical analysis with micro TAS as well as in the enhancement of biochip operation. Many microfluidic applications involve chemical reaction and most often the fluid diffusivity is very low so that without the help of chaotic stirring the mixing time can be enormously large. In this article, we will review various kinds of mixers developed for use in microfluidic devices. Our review starts from the definition of terminologies necessary to understand the fundamental concept of mixing and also quantities evaluating the mixing performance, such as mixing index and residence time. In particular, we will review the concept of chaotic advection and the mathematical terms, Poincare section and Liapunov exponent. Being developed by the nonlinear dynamical systems, these concepts should play important role in devising microfluidic devices with enhanced mixing performance. Then we review the various designs of mixers employed in practical applications. We will classify the designs in terms of the driving forces including mechanical, electrical and magnetic forces used to control fluid flow upon mixing. The advantage and disadvantage of these will also be addressed for each design. Finally, we will briefly touch the expected future development as for the mixer design and related issues for the further enhancement of mixing performance.

Type of Paper: Review
Title: Rotational Micromixing
Author: Jens Ducrée
Affiliation: School of Physics, Dublin City University, Glasnevin, Dublin 9, Ireland; E-Mail: jens.ducree@dcu.ie
Abstract: Over the last two decades, centrifugal microfluidics has emerged as a powerful alternative to other lab-on-a-chip platforms, for instance pressure driven or electroosmotically pumped systems. This review surveys various batch-mode and continuous flow schemes exploiting the peculiar pseudo forces (centrifugal, Coriolis, Euler) arising from placing fluids the non-inertial, rotating frame of reference.