Microfluidic devices have attracted increasing attention in the fields of biomedical diagnostics, food safety control, environmental protection, and animal epidemic prevention. Micromixing has a considerable impact on the efficiency and sensitivity of microfluidic devices. This work reviews recent advances on the passive and active micromixers for the development of various microfluidic chips. Recently reported active micromixers driven by pressure fields, electrical fields, sound fields, magnetic fields, and thermal fields, etc. and passive micromixers, which owned two-dimensional obstacles, unbalanced collisions, spiral and convergence-divergence structures or three-dimensional lamination and spiral structures, were summarized and discussed. The future trends for micromixers to combine with 3D printing and paper channel were brought forth as well.

A Review on Micromixers

The present review (with 205 refs.) addresses the need for microdevices, presents the basic microfluidic equations and describes the relevant numerical and experimental approaches. Various types and designs of passive and active micromixers are presented. In addition, the relevant effective dimensionless or dimensional parameters and the fabrication technology for different micromixer types are introduced. Different general configurations of lamination, obstacle, convergence-divergence and curved-channel are discussed for passive micromixers. The active micromixers are categorized and described as pressure field driven, acoustic field driven, magnetic field driven, electric field driven and thermal field driven.

Active and passive micromixers: A comprehensive review

Acoustic actuation of fluids at small scales may finally enable a comprehensive lab-on-a-chip revolution in microfluidics, overcoming long-standing difficulties in fluid and particle manipulation on-chip. In this comprehensive review, we examine the fundamentals of piezoelectricity, piezoelectric materials, and transducers; revisit the basics of acoustofluidics; and give the reader a detailed look at recent technological advances and current scientific discussions in the discipline. Recent achievements are placed in the context of classic reports for the actuation of fluid and particles via acoustic waves, both within sessile drops and closed channels. Other aspects of micro/nano acoustofluidics are examined: atomization, translation, mixing, jetting, and particle manipulation in the context of sessile drops and fluid mixing and pumping, particle manipulation, and formation of droplets in the context of closed channels, plus the most recent results at the nanoscale. These achievements will enable applications across the disciplines of chemistry, biology, medicine, energy, manufacturing, and we suspect a number of others yet unimagined. Basic design concepts and illustrative applications are highlighted in each section, with an emphasis on lab-on-a-chip applications.

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Micro/nano acoustofluidics: materials, phenomena, design, devices, and applications

Advances in microfluidics for lipid nanoparticles and extracellular vesicles and applications in drug delivery systems.

Liposomes : advancements and innovation in the manufacturing process

Passive mixers in microfluidic systems: A review

A novel micropump is proposed comprising a PMMA-based rotor, a circular PDMS micro-chamber, and a semi-circular PDMS microchannel connecting the inlet and outlet reservoirs as the rotor spins, a plug of sample fluid is trapped within the microchannel between neighboring blades of the rotor and is driven through the channel toward the outlet. Meanwhile, the rotors periodically compress and release the inlet and outlet regions of the microchannel. Thus, as the rotor turns, one plug of sample fluid is drawn into the microchannel as another is ejected into the outlet reservoir. In other words, a peristaltic pumping effect is achieved. It is shown that the flow rate in the proposed device can be controlled simply by adjusting the rotational velocity of the rotor. A maximum flow rate of 1.22 ml/min is obtained given de-ionized water as the working fluid and a rotational velocity of 232 rpm. Moreover, given the same rotational velocity, flow rates of 0.724 ml/min and 0.336 ml/min are obtained for salad oil and engine oil, respectively.

Wen Teng Wang

Papers

Passive mixers in microfluidic systems: A review

Design and Fabrication of PDMS/PMMA-Based Rotary Micropump