A novel viscoelastic-based ferrofluid for continuous sheathless microfluidic separation of nonmagnetic microparticles

Abstract

Separation of microparticles has found broad applications in biomedicine, industry and clinical diagnosis. In a conventional aqueous ferrofluid, separation of microparticles usually employs a sheath flow or two offset magnets to confine particle streams for downstream particle sorting. This complicates the fluid control, device fabrication, and dilutes the particle sample. In this work, we propose and develop a novel viscoelastic ferrofluid by replacing the Newtonian base medium of the conventional ferrofluid with non-Newtonian poly(ethylene oxide) (PEO) aqueous solution. The properties of both viscoelastic 3D focusing and negative magnetophoresis of the viscoelastic ferrofluid were verified and investigated. By employing the both properties in a serial manner, continuous and sheathless separation of nonmagnetic particles based on particle size has been demonstrated. This novel viscoelastic ferrofluid is expected to bring more flexibility and versatility to the design and functionality in microfluidic devices. Disciplines Engineering | Science and Technology Studies Abstract:Separation of microparticles has found broad applications in biomedicine, industry and clinical diagnosis. In a conventional aqueous ferrofluid, separation of microparticles usually employs a sheath flow or two offset magnets to confine particle streams for downstream particle sorting. This complicates the fluid control, device fabrication, and dilutes particle sample. In this work, we propose and develop a novel viscoelastic-based ferrofluid by replacing the Newtonian base medium of the conventional ferrofluid with non-Newtonian poly(ethylene oxide) (PEO) aqueous solution. The properties of both viscoelastic 3D focusing and negative magnetophoresis of the viscoelastic-based ferrofluid were verified and investigated. By employing the both properties in a serial manner, continuous and sheathless separation of non-magnetic particles based on particle size has been demonstrated. This novel viscoelastic ferrofluid is expected to bring more flexibility and versatility to the design and functionality in microfluidic devices.

Particle manipulations in non-Newtonian microfluidics: A review

“…A similar two-stage microfluidic sorter was later developed by Zhang et al (Fig. 12c), who demonstrated the benefit of using PEO-based ferrofluid by comparing the separation of 5 mm and 13 mm diameter diamagnetic particles therein with that in a conventional aqueous ferrofluid [134]. Table 2 summarizes the above-reviewed various particle separation methods in non-Newtonian microfluidic devices with the details of the important experimental conditions.…”

Manipulation of micro‐ and nanoparticles in viscoelastic fluid flows within microfluid systems

“…(b) The interaction between electrokinetic and viscoelastic forces in the constriction (Lu et al, ). (c) Particle/cell separation and sorting with the aid of magnetophoresis effect (Kim et al, ; Zhang et al, ). VEF, viscoelastic fluid [Color figure can be viewed at wileyonlinelibrary.com]…”

Microfluidics Based Magnetophoresis: A Review

“…The device is also investigated for the separation of two different‐sized biological entities, specifically Chlorella vulgaris and Synechococcus sp . Later Zhang et al . developed a two‐stage microfluidic sorter that employed PEO/ferrofluid solution for size‐based separation of diamagnetic microparticles; experiments were done to separate 5 μm and 13 μm diameter diamagnetic.…”

“…developed a two‐stage microfluidic sorter that employed PEO/ferrofluid solution for size‐based separation of diamagnetic microparticles; experiments were done to separate 5 μm and 13 μm diameter diamagnetic. Furthermore, they compare the results with that in a conventional aqueous ferrofluid …”