Study and Development of New Passive Micromixers Based on Split and Recombination Principle

Abstract

Micromixers have been a major topic of research in the past decade and progress on recent development of micromixers has been reviewed by many researchers. Developing devices for microfluidic technology has been a major concern for industry and microfluidic devices offer many advantages over conventional techniques. Compared to conventional macroscopic methods, microfluidic devices have the advantages of reduced solvent, reagent and cell consumption, shorter reaction times, portability, low cost and low power consumption. Also, micromixers are key elements in microfluidic technology and have been addressed by a large body of research. Interestingly, the historical development of microfluidics and its preoccupation with micromixing are the main fields of microtechnology. Micromixers have a wide variety of potential applications in industry. In modern technology, micromixers are applied in microtechnologies such as biological systems, as microreactors for chemical reactions, and as MEMS and lab-on-a-chip devices. This means that the community of engineers and scientist now engaged in microfluidic devices and also mixing process in micro scales. Indeed, they have entered the field from a variety of different backgrounds and they would have been confronted by the problems of mixing processing and mass transport at the micro scales. According to the survey carried out in my research, the main driving forces for this investigation are applications in incompressible mixing processing at low Reynolds number range, 0.08<Re<4.16. As far as we know, the technology and science of microfluidics cover a wide spectrum ranging from fundamental studies to real applications in laboratories and industries. This research focuses on an important subject of microfluidics, namely mixing processing at the microscale. The science of such mixing has carried out on newly fabricated micro scale devices on an extensive collection of established knowledge. Due to its applied nature, my research discuss practical outcome in the design and characterization of micromixers. In this thesis, first and foremost, I describe the method that I've used for analyzing the experimental data. The laminar flow regime (0.08<Re<4.16) was considered during tests and image-based techniques are used to evaluate mixing efficiency. This study propose a novel generation of 3D splitting and recombination passive micromixers. Mixing characteristics of two species are elucidated via experimental and numerical studies associated with microchannels with various inlet flow rates (velocities) and results compared with the previous well-known micromixers. It was found that mixing performance is significantly affected by the split and recombination (SAR) flows and depends on Reynolds number (inlet velocities). As well as the efficiencies of my proposed mixer are almost quite the same with the well-known basic mixers at each desired region, the required pressure drop is approximately two times less than previous mixers. This is a good particular result that with higher efficiency the required pressure drop decreases. Hence, this new geometries satisfies both of targets in micromixer design which are higher mixing efficiency and lower pressure drop in comparison with previous well-known mixers. These results open the new operating windows for rapid mixing in the microchannel to overcome the fluid mixing which strongly limited to laminar regime with lower required pressure drop