Magnetic Polymers for Magnetophoretic Separation in Microfluidic Devices

Abstract

Magnetophoresis offers many advantages for manipulating magnetic targets in microsystems. The integration of micro-flux concentrators and micro-magnets allows achieving large field gradients and therefore large reachable magnetic forces. However, the associated fabrication techniques are often complex and costly, and besides, they put specific constraints on the geometries. Magnetic composite polymers provide a promising alternative in terms of simplicity and fabrication costs, and they open new perspectives for the microstructuring, design, and integration of magnetic functions. In this review, we propose a state of the art of research works implementing magnetic polymers to trap or sort magnetic micro-beads or magnetically labeled cells in microfluidic devices.

MagPure chip: an immunomagnetic-based microfluidic device for high purification of circulating tumor cells from liquid biopsies

“…The composite approach has shown to be a powerful bottom-up method to fabricate magnetic sources with micrometric size and high density and integrate them into polymer-based microfluidic devices 30,31,34,35 . In particular, on-demand magnetic functions can be Please do not adjust margins Please do not adjust margins obtained using the magnetic composite approach by tailoring the magnetic powder composition (nature, size and morphology), the packing density and ordering (by applying a magnetic field pattern during the polymer reticulation), as well as the microfabrication technique 26 . Here, after tuning the concentration (4 wt%) and self-organization of the magnetic powder, we obtained NdFeB microstructures embedded in PDMS, averaging 5 μm in diameter, with a nearest-neighbor distance of 15 μm, and a density as high as 1500 microtraps/mm 2 .…”

“…30,31,34,35 In particular, on-demand magnetic functions can be obtained using the magnetic composite approach by tailoring the magnetic powder composition (nature, size and morphology), the packing density and ordering (by applying a magnetic field pattern during the polymer reticulation), as well as the microfabrication technique. 26 Here, after tuning the concentration (4 wt%) and self-organization of the magnetic powder, we obtained NdFeB microstructures embedded in PDMS, averaging 5 μm in diameter, with a nearest-neighbor distance of 15 μm, and a density as high as 1500 micro-traps per mm 2 . In particular, the fabricated micro-traps presented a high aspect ratio (>10) as it can be seen via the chain-like agglomeration of NdFeB particles (Fig.…”

“…Challenges remain regarding the complexity of microfabrication of such microscale magnetic sources, and their integration with polymer-based microfluidic devices. Recently, the magnetic composite polymer strategy has emerged as a real breakthrough for compatible and costeffective integration of magnetic materials into polymer-based microfluidic devices 26 . The composite strategy consists in doping the polymer matrix with magnetic particles or filaments, conferring magnetic properties to composite polymers.…”

Basic Principles and Recent Advances in Magnetic Cell Separation

“…Such composite materials featuring magnetic properties can be easily structured using simple, soft lithography processes, which facilitate the integration of magnetic sources very close to the microfluidic channel. They therefore provide a promising low-cost alternative to complex and costly microfabrication approaches, as recently reviewed [181].…”

Progress of Microfluidic Continuous Separation Techniques for Micro-/Nanoscale Bioparticles

“…However, continuous sample handling, minimization of run-by-run errors, and application to small sample volumes remain challenges. These limitations of conventional approaches have been effectively solved by combining microfluidic technology and magnetophoresis, which continuously separate or extract cells and biomaterials functionalized with magnetism in a microchannel [ 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 ]. This means that the degree of freedom in separation is higher because it is possible to give magnetic properties to each particle desired by the end users beyond the limitation of the conventional bioparticle separation, being simple size-based cell separation, resulting in less damage to the samples and excellent biocompatibility.…”