chemical engineering research and design 9 3 ( 2 0 1 5 ) 1–11 Contents lists available at ScienceDirect Chemical Engineering Research and Design j ourna l h omepage: www.elsevier.com/locate/cherd An effective passive micromixer with shifted trapezoidal blades using wide Reynolds number range Hai Le The a,b,* , Hoa Le Thanh b , Tao Dong b , Bao Quoc Ta a , Nhut Tran-Minh b , Frank Karlsen b a Division of Computational Mathematics and Engineering (CME), Institute for Computational Science (INCOS), Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Viet Nam b Dept. of Micro and Nano Systems Technology, Buskerud and Vestfold University College, Postboks 235, 3603 Kongsberg, Norway a r t i c l e i n f o Article history: Received 12 August 2014 Received in revised form 30 November 2014 Accepted 1 December 2014 Published on line 6 December 2014 Keywords: Asymmetrical micromixer Low Reynolds number Shifted trapezoidal blades High mixing efficiency a b s t r a c t In this paper, a novel micromixer design, called the shifted trapezoidal blades (STB) micromixer, has been designed and fabricated to provide high mixing efficiency even at low Reynolds number (Re) based on the combination of several mixing principles, includ- ing vortices, transversal flows and chaotic advection. Although the STB micromixer has 3D geometrical structure, it can be easily fabricated by one-step photolithography technique, using only one mask and two inclined exposures and an aluminum base with 15 ◦ inclines. We conducted intensive numerical study to evaluate the performance of the proposed STB micromixer using COMSOL Multiphysics package with a wide range of Reynolds number from 0.5 to 100. We have fabricated STB micromixers for testing and verification. Both experiment and simulation results demonstrated that the STB micromixer had stable mix- ing efficiency of 80% or above for Reynolds number values in the range from 0.5 to 100. The most effective mixing performance was achieved at Re = 40 in which the STB micromixer had the highest mixing efficiency value (95%) and a moderate pressure drop P = 30.27 kPa. The proposed STB micromixer provided better mixing performance and smaller footprint com- pared to the previous micromixers presented in literatures. With a high mixing efficiency and the advantage of being easy to fabricate, the STB micromixer can be utilized in various microfluidic, point-of-care, point-of-need, central automatic diagnosis, and pre-treatment systems including sensor control systems. © 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction In the diagnosis based on RNA synthesis, sensitive biochem- ical detection, national screening of cancer, monitoring of water contamination, monitoring of molecular changes in the environment, PCR amplification, tissue engineering, enzyme reaction, and protein folding, the rapid well-mixed reagents ∗ Corresponding author at: Division of Computational Mathematics and Engineering (CME), Institute for Computational Science (INCOS), Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Viet Nam. Tel.: (+84-8) 37 755 024. E-mail address: lethehai@tdt.edu.vn (H. Le The). are vitally important in order to achieve fast and accurate anal- ysis under precise control of smallest reagents consumption. Micromixers thus play an important role in transforming the complex liquids such as heterogeneous fluids into homoge- nous liquids that can be easily used for further sample preparation, sample concentration/separation, extraction of active bio components and complex analyses (Giordano and http://dx.doi.org/10.1016/j.cherd.2014.12.003 0263-8762/© 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.