Self-organizing microfluidic crystals

Uspal, William E.; Doyle, Patrick S.

doi:10.1039/c4sm00664j

Cited by 29 publications

(25 citation statements)

References 41 publications

(63 reference statements)

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“…While drag forces in complex media are important for microrheological applications, the out-of-equilibrium interactions between particles are also of interest for their potential to produce self-assembly [10]. The equilibrium interactions between colloidal particles are well understood, particularly in dilute suspensions; these include effects such as the wellcharacterized "depletion" interaction, and associated selfassembly phenomena [11,12].…”

Section: Introductionmentioning

confidence: 99%

Two spheres translating in tandem through a colloidal suspension

Sriram

Furst

2015

Phys. Rev. E

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Using laser tweezers, two colloidal particles are held parallel to a uniformly flowing suspension of similarly sized bath particles at an effective volume fraction φ eff = 0.41. The local deformation in the bath suspension is imaged by confocal microscopy, and, concurrently, the drag forces exerted on both the leading and the trailing probe particles are measured as a function of probe separation and velocity. The bath structure changes in response to the velocity and separation of the probes. A depleted region between probes is observed at sufficiently high velocities. Both probes experience the same drag force and the drag force increases with probe separation. The results indicate that bath-probe and probe-probe hydrodynamic interactions contribute microstructure and drag force and that drag exerted by direct bath-probe collisions is reduced compared to an isolated probe.

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Section: Introductionmentioning

confidence: 99%

Two spheres translating in tandem through a colloidal suspension

Sriram

Furst

2015

Phys. Rev. E

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“…Among them, the most widely used are rod-shaped particles, including gold nanorods (Gu et al, 2012, 2011; Neupane et al, 2016; Chaudhari and Pradeep, 2014; Xiao et al, 2011a), colloidal ellipsoids (Han et al, 2006; Mukhija and Solomon, 2007), quantum rods (Tsay et al, 2006; Ohmachi et al, 2012), filamentous viruses (Lettinga et al, 2005), and dumbbell particles (Uspal et al, 2013; Uspal and Doyle, 2014), Typically, the rotation of rod-shaped imaging probes can be measured along two of the three possible rotational axes: in-plane rotational angle φ and out-of-plane rotational angle θ (Fig. 1a) (Anthony and Yu, 2015).…”

Section: General Methods For Probing Rotational Dynamicsmentioning

confidence: 99%

“…The three-dimensional orientation and position of the μm-sized rods suspended in viscous solutions was directly visualized by using conventional confocal fluorescence microscopy. Uspal et al (2013) and Uspal and Doyle (2014) synthesized dumbbell-shaped particles using continuous flow lithography and studied how the orientation of these particles affected their translational motion in microfluidic flows. They observed that tadpole-shaped particles with one large lobe and one small lobe quickly rotate to align with the direction of flow, whereas symmetric particles orient at random and oscillate transversely in the flow.…”

Section: General Methods For Probing Rotational Dynamicsmentioning

confidence: 99%

Seeing the unseen: Imaging rotation in cells with designer anisotropic particles

Gao

Sanchez

2017

Micron

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Cellular functions are enabled by cascades of transient biological events. Imaging and tracking the dynamics of these events have proven to be a powerful means of understanding the principles of cellular processes. These studies have typically focused on translational dynamics. By contrast, investigations of rotational dynamics have been scarce, despite emerging evidence that rotational dynamics are an inherent feature of many cellular processes and may also provide valuable clues to understanding those cell functions. Such studies have been impeded by the limited availability of suitable rotational imaging probes. This has recently changed thanks to the advances in the development of anisotropic particles for rotational imaging. In this review, we will summarize current techniques for imaging rotation using particle probes that are anisotropic in shape or optical properties. We will highlight two studies that demonstrate how these techniques can be applied to explore important facets of cellular functions.

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“…[18] identified ring-shaped particles which do not tumble in shear flow, in contrast to the tumbling behavior of axisymmetric particles reported by numerous earlier works; the particle shapes were derived as perturbations to a circular shape to obtain zero torques on the particle. Recent advances [19] have established self-aligning and centreline-focusing characteristics of asymmetric particles in Hele-Shaw flow -specifically, "dumbbell" and "trumbbell" shapes. Furthermore, modern fabrication techniques [20,21,22] allow for scalable fabrication of arbitrary-shaped microparticles, presenting an abundant landscape for the design of customized application-specific microparticles.…”

Section: Introductionmentioning

confidence: 99%

Shape design for stabilizing microparticles in inertial microfluidic flows

et al. 2020

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Design of microparticles which stabilize at the centerline of a channel flow when part of a dilute suspension is examined numerically for moderate Reynolds numbers (10 ≤ Re ≤ 80). This problem is motivated by the need for design of shaped particle carriers for use in next generation cell cytometry devices. Stability metrics for particles with arbitrary shapes are formulated based on linear-stability theory. Particle shape is parametrized by a compact, Non-Uniform Rational B-Spline (NURBS)-based representation. Shape-design is posed as an optimization problem and solved using adaptive Bayesian optimization. We focus on designing particles for maximal stability at the channel-centerline robust to perturbations. Our results indicate that centerline-focusing particles are families of characteristic "fish"/"bottle"/"dumbbell"-like shapes, exhibiting fore-aft asymmetry. A parametric exploration is then performed to identify stable particle-designs at different k's (particle chord-to-channel width ratio) and Re's (0.1 ≤ k ≤ 0.4, 10 ≤ Re ≤ 80). Particles at high-k's and Re's are highly stabilized when compared to those at low-k's and Re's. A comparison of the modified dumbbell designs from the current framework also shows better performance to perturbations in Fluid-Structure Interaction (FSI) when compared to the rod-disk model-dumbbell reported previously (Uspal & Doyle, 2014) for low-Re Hele-Shaw flow. We identify a basin of attraction around the centerline, within which any arbitrary release results in rotationally stable centerline-focusing. We find that this basin spans larger release-angle-ranges and lateral locations (tending to the channel width) for narrower channels. This effectively standardizes the notion of global focusing using the current stability-paradigm in narrow channels, which eliminates the need for an independent design for global-focusing in such configurations. The framework detailed in this work is illustrated for 2D cases and is generalizable to stability in 3D flow-fields. The current formulation is agnostic to Re and particle/channel geometry which indicates substantial potential for integration with imaging flow-cytometry tools and microfluidic biosensing-assays.

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Self-organizing microfluidic crystals

Cited by 29 publications

References 41 publications

Two spheres translating in tandem through a colloidal suspension

Two spheres translating in tandem through a colloidal suspension

Seeing the unseen: Imaging rotation in cells with designer anisotropic particles

Shape design for stabilizing microparticles in inertial microfluidic flows

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