Self-assembled permanent micro-magnets in a polymer-based microfluidic device for magnetic cell sorting

Lucie Descamps (1, 2, 3) , M.-C. Audry (2) , Jordyn Howard (2) , Samir Mekkaoui (2) , Clément Albin (4) , David Barthelemy (5, 6) , Léa Payen (7) , Jessica Garcia (8) , Emmanuelle Laurenceau (9) , Damien Le Roy (4) , A.-L. Deman (2)

1 CREAB - Chimie pour la Reconnaissance et l’Etude d’Assemblages Biologiques
2 INL - Institut des Nanotechnologies de Lyon
3 DIESE - Département Interfaces pour l'énergie, la Santé et l'Environnement
4 MAGNETIQUES - Nanostructures magnétiques
5 Laboratoire de Biochimie et Biologie Moléculaire
6 CHLS - Centre Hospitalier Lyon Sud [CHU - HCL]
7 UNICANCER/CRCL - Centre de Recherche en Cancérologie de Lyon
8 HCL - Hospices Civils de Lyon
9 INL - C&N - INL - Chimie et Nanobiotechnologies

Magnetophoresis-based microfluidic devices offer simple and reliable manipulation of micro-scale objects and provide a large panel of applications, from selective trapping to high-throughput sorting. However, the fabrication and integration of micro-scale magnets in microsystems involve complex and expensive processes. Here we report on an inexpensive and easy-to-handle fabrication process of micrometer-scale permanent magnets, based on the self-organization of NdFeB particles in a polymer matrix (polydimethylsiloxane, PDMS). A study of the inner structure by X-ray tomography revealed a chain-like organization of the particles leading to an array of hard magnetic microstructures with a mean diameter of 4 µm. The magnetic performance of the self-assembled micro-magnets was first estimated by COMSOL simulations. The micro-magnets were then integrated into a microfluidic device where they act as micro-traps. The magnetic forces exerted by the micro-magnets on superparamagnetic beads were measured by colloidal probe atomic force microscopy (AFM) and in operando in the microfluidic system. Forces as high as several nanonewtons were reached. Adding an external millimeter-sized magnet allowed target magnetization and the interaction range to be increased. Then, the integrated micro-magnets were used to study the magnetophoretic trapping efficiency of magnetic beads, providing efficiencies of 100% at 0.5 mL/h and 75% at 1 mL/h. Finally, the micro-magnets were implemented for cell sorting by performing white blood cell depletion.

Mots clés: magnetophoresis; micro-magnets; polymer composite; microfluidic devices; particle separation

Domaines: Micro et nanotechnologies/Microélectronique

Lucie Descamps, M.-C. Audry, Jordyn Howard, Samir Mekkaoui, Clément Albin, et al.. Self-assembled permanent micro-magnets in a polymer-based microfluidic device for magnetic cell sorting. Cells, 2021, 10, pp.1734. ⟨10.3390/cells10071734⟩. ⟨hal-03309148⟩