Acoustofluidics: A Versatile Tool for Micro/Nano Separation at the Cellular, Subcellular, and Biomolecular Levels

Abstract

Separation of micro/nanoparticles, such as cellular, subcellular and biomolecular, has attracted increasing attention because of their remarkable potential applications in various fields, including chemistry, physics, medicine, etc. Among different micro/nanoparticle separation methods, acoustofluidics, which combines acoustics and microfluidics, has drawn the interest of researchers due to its biocompatibility, high efficiency and free labeling. In this review, the basic constitutions, mechanisms, and materials of acoustofluidics are described. Subsequently, sorts of delicately designed acoustofluidic devices, including diverse bulk acoustic wave (BAW) microfluidics and surface acoustic wave (SAW) microfluidics, are discussed, covering principles, advantages, limitations and applications in separation. Besides the introduction of advances of micro/nanoparticle separation in the BAW microfluidics, the SAW microfluidics are elaborated in detail with a focus on various configurations of interdigital transducers (IDTs), comprising straight IDT, slanted‐finger IDT, chirped IDT and focused IDT. Microfluidic systems of the acoustofluidics involve the forms of straight channels, serpentine channels, and droplets. Additionally, besides simply structured acoustofluidics, acoustofluidics integrated with other structures are also mentioned. Finally, the prospects and limitations of acoustofluidics in micro/nanoparticle separation are also discussed. The acoustofluidics reviewed here is envisioned as a versatile tool for micro/nanoparticle separation at the cellular, sub‐cellular, and biomolecular levels.

High-Density Microporous Drainage-Integrating Sheath Flow Generator for Streamlining Microfluidic Cell Sorting Systems

“…In general, continuous particle/cell sorting techniques using microfluidics exploit differences in particle mobility in the lateral direction in laminar flow systems. Some of these techniques exert physical forces on cells as the driving forces for cell migration, as represented by dielectrophoresis, − acoustophoresis, − magnetophoresis, − and particle inertia raised by the flow, including Dean flow fractionation, inertial sorting, multiorifice fractionation, and centrifugation-assisted methods. , Purely hydrodynamic sorting techniques have also been studied, include pinched flow fractionation (PFF), , deterministic lateral displacement (DLD), , hydrodynamic filtration (HDF), , hydrodynamic migration-based separation, , and lattice-channel-based sorting. − These hydrodynamic mechanisms utilize branching channels or periodically arranged obstacles to selectively separate large and/or less deformable particles from the original flow of the particle suspension. A crucial requirement common to most of these methods for effective particle sorting is the introduction of sheath flow.…”