Continuous-Flow Separation of Magnetic Particles from Biofluids: How Does the Microdevice Geometry Determine the Separation Performance?

Abstract

The use of functionalized magnetic particles for the detection or separation of multiple chemicals and biomolecules from biofluids continues to attract significant attention. After their incubation with the targeted substances, the beads can be magnetically recovered to perform analysis or diagnostic tests. Particle recovery with permanent magnets in continuous-flow microdevices has gathered great attention in the last decade due to the multiple advantages of microfluidics. As such, great efforts have been made to determine the magnetic and fluidic conditions for achieving complete particle capture; however, less attention has been paid to the effect of the channel geometry on the system performance, although it is key for designing systems that simultaneously provide high particle recovery and flow rates. Herein, we address the optimization of Y-Y-shaped microchannels, where magnetic beads are separated from blood and collected into a buffer stream by applying an external magnetic field. The influence of several geometrical features (namely cross section shape, thickness, length, and volume) on both bead recovery and system throughput is studied. For that purpose, we employ an experimentally validated Computational Fluid Dynamics (CFD) numerical model that considers the dominant forces acting on the beads during separation. Our results indicate that rectangular, long devices display the best performance as they deliver high particle recovery and high throughput. Thus, this methodology could be applied to the rational design of lab-on-a-chip devices for any magnetically driven purification, enrichment or isolation.

Design and Synthesis of Multi-Functional Superparamagnetic Core-Gold Shell Nanoparticles Coated with Chitosan and Folate for Targeted Antitumor Therapy

“…Small particles in the tumor can pass easily through the capillary wall but can also be pushed out of the tumor by blood flow. Given that the magnetic force acting on the magnetic particles is proportional to the particle volume, the fluidic drag force may overcome the magnetic force experienced by the small particles [ 44 ].…”

Recovery of Magnetic Catalysts: Advanced Design for Process Intensification

“…Furthermore, the laminar flow developed in microstructures allows for a precise control of the fluid flow. 5 , 14 − 16 On the other hand, the small dimensions of microchannels also involve low-sample consumptions, thus reducing the risk of managing hazardous materials and the use of expensive reagents; accordingly, the decrease of the amount of waste that is generated and a considerable cost saving are accomplished. The use of small volumes also facilitates the control of process parameters, such as temperature, pressure, and residence time, etc.…”

“…To this end, taking advantage of the outstanding features of microfluidics, a second stage after the catalytic microreactor can be included in order to perform the continuous isolation of MMCs, since microfluidics enables the integration of several steps within the same device. 4 , 5 …”

“…The design of continuous-flow microfluidic-magnetophoretic devices to perform the recovery of the magnetic materials has been addressed both experimentally and theoretically. 5 , 25 − 27 In this regard, the effect of numerous variables, such as fluid flow rates, fluid rheological properties, particles size, magnet dimensions and positions, etc. on the performance of magnetophoretic-microrecovery systems has been elucidated.…”

“… 26 , 28 − 31 On the other hand, there is huge interest in optimizing the performance of such systems (i.e., obtaining complete recoveries when processing relatively high flow rates) so they could be effectively employed; to this end, the impact of the channel geometry on the particle recovery has also been investigated. 5 , 32 , 33 In our previous work, 5 we demonstrated the effect of the cross-section shape and thickness, which depend on the method used for the channel fabrication, as well as of the channel length and volume on the performance of these systems. Besides, we identified from the vast number of studied geometries the one that exhibits the best performance; thereby, we found that long microchannels with rectangular cross sections enable the processing of flow rates up to 2 orders of magnitude higher than other geometrical configurations while entirely capturing the beads.…”