Magnetic Microtweezers: A Tool for High‐Throughput Bioseparation in Sub‐Nanoliter Droplets

Abstract

for his support in photolithography and sputtering and Bertrand Cinquin for EDX spectrometry. They also thank Koceila Aizel for support with electroplating, and Fanny Tabarin and Aude Battistella for training them on cell and molecular biology (Institut Curie, UMR168), David Hrabovsky (MPBT platform, Sorbonne University) for magnetometry measurements, and Olivier Lefebvre (C2N, Univ. Paris-Saclay) for helpful advice on electroplating. This work was supported by the Institut Pierre-Gilles de Gennes (équipement d'excellence and LABEX, "Investissement d'avenir," program ANR-10-EQPX-34).

A continuum model for magnetic particle flows in microfluidics applicable from dilute to packed suspensions

“…To demonstrate the applicability of the model, we performed the simulations on three different cases, corresponding to relevant applications of magnetic particles in microfluidics: (i) a simple magnetophoresis system in the dilute regime, 33,34 (ii) a magnetic fluidized bed in 2D, 11 and (iii) a magnetic microtweezer system in 3D. 19…”

“…To validate the model for plug formation in a 3D case, we tested the model on a different experimental case of our group: the magnetic microtweezers. 19 In this device, two microfabricated NiFe tips are facing each other on each side of a microfluidic channel (Fig. 6A).…”

“…After being trapped between the tips, the particles are extracted from the droplets as a compact cluster, enabling high-throughput purification from nanoliter droplets. This device has been extensively described by Dumas et al , 19 and used to extract mRNA from single-cells at high throughput.…”

“…This dependency of the capture efficiency with droplet velocity has been observed experimentally and described in our previous work. 19 Fig. 6G shows the capture efficiency, corresponding to the above mentioned plateau, for different droplet velocities and tweezer shapes.…”

“…[9][10][11] External permanent magnets are most commonly used for the actuation of magnetic particles, [2][3][4][5][6][7][8]10 but other approaches have been reported, which rely on external 12,13 or integrated 14,15 electromagnets, or on integrated soft magnetic elements. [16][17][18][19] The magnetic particles show a wide variety of behaviors and spatial arrangements, which depend on the chosen actuation method, the particles' physical properties, and their initial spatial distribution. In particular, the particles arrange differently depending on their concentration, and we can distinguish them between three main regimes, each of them being often encountered in microfluidics applications.…”