Orbiting magnetic microbeads enable rapid microfluidic mixing

Ballard, Matthew; Owen, Drew; Mills, Zachary; Hesketh, Peter J.; Alexeev, Alexander

doi:10.1007/s10404-016-1750-1

Cited by 31 publications

(21 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This paper demonstrates and quantifies the mixing effectiveness of a periodic array of rotating magnetic microbeads that actively perturb the fluid in a continuous-flow microfluidic system, such as we have previously proposed and investigated through numerical simulations [18][19][20][21]. We demonstrate that this mixing device, actuated simply by a rotating external magnetic field, can produce rapid and controllable mixing over a short distance in a microfluidic channel.…”

Section: Introductionmentioning

confidence: 94%

“…In our experiments, the linear velocity of the beads varied from 20 µm/s to 1400 µm/s. Since our system operates at a low Reynolds number, the ratio of the flow and bead velocities U/V b is more pertinent to system behavior than the actual magnitude of either velocity [21]. This is provided that the flow rate and channel length are such that diffusion alone does not lead to a noticeable mixing over the length of the mixing region, which was the case for our system.…”

Section: Mixing Under Flowmentioning

confidence: 99%

“…Indeed we have recently showed that the mixing effectiveness of orbiting magnetic microbeads increases monotonically with increasing bead coverage density leading to reduced distances between adjacent beads [21]. When there is a net flow down the channel, some of the fluid left in the wake of orbiting beads is pulled downstream out of the path of oncoming beads, and thus the streamlines turn downstream rather than crossing the channel and linking transverse cells, thereby reducing the mixing efficiency [21].…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…Surfaces of the solid superparamagnetic beads were triangulated to impose no-slip and no-penetration boundary conditions with surrounding viscous fluid [26,28,29]. Trajectories of the superparamagnetic beads were determined as described previously [18,21]. This model was coupled to a stochastic Brownian dynamics (BD) model [30,31] that calculates the trajectories of 15 million diffusive particles and calculates the particle concentration field, so as to solve the convection-diffusion equation and model microfluidic mixing.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…Thus, this device can best be used with beads orbiting at a sufficient rate such that U/V b < 0.1. For an in-depth numerical study on the effect of various geometrical alterations to this system over a large range of velocity ratios, we refer the reader to the recent work of Ballard et al [21].…”

Section: Numerical Simulationsmentioning

confidence: 99%

See 4 more Smart Citations

Rapid microfluidic mixing via rotating magnetic microbeads

Owen

Ballard

Alexeev

et al. 2016

Sensors and Actuators A: Physical

Self Cite

View full text Add to dashboard Cite

Presented here is a novel method for mixing in a microfluidic channel via an array of rotating magnetic microbeads. The microbeads rotate around circular permalloy (NiFe) features magnetized by a rotating external magnetic field. This system demonstrates rapid mixing in short channel lengths. The effectiveness of this system is quantified by analyzing the degree of mixing of two streams, one with fluorescence and one without. Our experiments and numerical simulations reveal that beads orbiting at a high velocity as compared to flow down the channel cause the fluid to form circular coronae that stretch across the microchannel leading to fluid mixing. Under these conditions, rotating magnetic microbeads were able to fully mix the streams in a 270 μm mixing region.

show abstract

Section: Introductionmentioning

confidence: 94%

Section: Mixing Under Flowmentioning

confidence: 99%

Section: Numerical Simulationsmentioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

Section: Numerical Simulationsmentioning

confidence: 99%

See 3 more Smart Citations

Rapid microfluidic mixing via rotating magnetic microbeads

Owen

Ballard

Alexeev

et al. 2016

Sensors and Actuators A: Physical

Self Cite

View full text Add to dashboard Cite

show abstract

Magnetic Lateral Ladder for Unidirectional Transport of Microrobots: Design Principles and Potential Applications of Cells‐on‐Chip

Ali,

Kim,

Torati

et al. 2023

Small

View full text Add to dashboard Cite

Functionalized microrobots, which are directionally manipulated in a controlled and precise manner for specific tasks, face challenges. However, magnetic field‐based controls constrain all microrobots to move in a coordinated manner, limiting their functions and independent behaviors. This article presents a design principle for achieving unidirectional microrobot transport using an asymmetric magnetic texture in the shape of a lateral ladder, which the authors call the “railway track.” An asymmetric magnetic energy distribution along the axis allows for the continuous movement of microrobots in a fixed direction regardless of the direction of the magnetic field rotation. The authors demonstrated precise control and simple utilization of this method. Specifically, by placing magnetic textures with different directionalities, an integrated cell/particle collector can collect microrobots distributed in a large area and move them along a complex trajectory to a predetermined location. The authors can leverage the versatile capabilities offered by this texture concept, including hierarchical isolation, switchable collection, programmable pairing, selective drug‐response test, and local fluid mixing for target objects. The results demonstrate the importance of microrobot directionality in achieving complex individual control. This novel concept represents significant advancement over conventional magnetic field‐based control technology and paves the way for further research in biofunctionalized microrobotics.

show abstract