scholarly journals Propulsion and maneuvering of an artificial microswimmer by two closely spaced waving elastic filaments

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Roei Elfasi ◽  
Yossef Elimelech ◽  
Amir D. Gat
Keyword(s):  
Elastic Filaments

scholarly journals Propulsion by stiff elastic filaments in viscous fluids

2019 ◽  
Vol 99 (5) ◽  
Author(s):  
Panayiota Katsamba ◽  
Eric Lauga
Keyword(s):  
Viscous Fluids ◽  
Elastic Filaments

Using Actuated Cilia to Regulate Motion of Microscopic Particles

2010 ◽  
Author(s):  
Alexander Alexeev ◽  
Rajat Ghosh ◽  
Gavin A. Buxton ◽  
O. Berk Usta ◽  
Anna C. Balazs
Keyword(s):  
Reynolds Number ◽  
Respiratory Tract ◽  
Microfluidic Devices ◽  
Design Concept ◽  
Biological Cells ◽  
Marine Animals ◽  
Elastic Filaments ◽  
Food Particles ◽  
Polymeric Microcapsules ◽  
Surrounding Fluid

Marine animals use microscopic elastic filaments, or cilia, to capture food particles that are suspended in the surrounding solution [1, 2]. In the respiratory tract, active cilial layers facilitate the transport of particulates such as dust or mucous. These motile cilia experience the surrounding fluid as a highly viscous, low Reynolds number environment, where the effects of inertia are negligible [2]. Nevertheless, by oscillating in a periodic, time-irreversible manner, the elastic cilia can generate net currents within the fluid and thereby, effectively transport and direct microscopic particles. The behavior of these biological cilia provides a useful design concept for creating microfluidic devices where actuated “synthetic cilia” would regulate the movement of micrometer-sized particles, such as biological cells and polymeric microcapsules.

Effects of the intrinsic curvature of elastic filaments on the propulsion of a flagellated microrobot

2020 ◽  
Vol 32 (4) ◽  
pp. 041902
Author(s):  
Zhaorong Liu ◽  
Fenghua Qin ◽  
Lailai Zhu ◽  
Runhuai Yang ◽  
Xisheng Luo
Keyword(s):  
Intrinsic Curvature ◽  
Elastic Filaments

Elastic Filaments and Vortex Waves

1971 ◽  
Vol 4 (6) ◽  
pp. 2305-2308 ◽  
Author(s):  
Alexander L. Fetter ◽  
Kenneth Harvey
Keyword(s):  
Elastic Filaments

scholarly journals Filament extensibility and shear stiffening control persistence of strain and loss of coherence in cross-linked motor-filament assemblies

2018 ◽  
Author(s):  
Arvind Gopinath ◽  
Raghunath Chelakkot ◽  
L. Mahadevan
Keyword(s):  
Collective Behavior ◽  
Molecular Motors ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spatial Coordination ◽  
Elastic Filaments ◽  
Mechanical Information ◽  
Loss Of Coherence ◽  
Elastic Strains

AbstractCross-linked flexible filaments deformed by active molecular motors occur in many natural and synthetic settings including eukaryotic flagella, the cytoskeleton and in vitro motor assays. In these systems, an important quantity that controls spatial coordination and emergent collective behavior is the length scale over which elastic strains persist. We estimate this quantity in the context of ordered composites comprised of cross-linked elastic filaments sheared by active motors. Combining a mean-field theory valid for negligibly noisy systems with discrete simulations for noisy systems, we show that the effect of localized strains – be they steady or oscillatory – persist over distances determined by motor kinetics, motor elasticity and filament extensibility. The cut-off length that emerges from these effects controls the transmission of mechanical information and determines the criterion for spatially separated motor groups to stay synchronized. Our results generalize the notion of persistence in passive, Brownian filaments to active, cross-linked filaments.

scholarly journals Synchronized oscillations, metachronal waves, and jammed clusters in sterically interacting active filament arrays

2020 ◽  
Author(s):  
Raghunath Chelakkot ◽  
Michael F. Hagan ◽  
L. Mahadevan ◽  
Arvind Gopinath
Keyword(s):  
Surface Roughness ◽  
Brownian Dynamics ◽  
Locking Mechanism ◽  
Elastic Filaments ◽  
Filament Spacing ◽  
Dynamics Simulations ◽  
Parameter Ranges ◽  
Brownian Dynamics Simulations ◽  
Filament Surface ◽  
Metachronal Waves

Autonomous active, elastic filaments that interact with each other to achieve cooperation and synchrony underlie many critical functions in biology. A striking example is ciliary arrays in the mammalian respiratory tract; here individual filaments communicate through direct interactions and through the surrounding fluid to generate metachronal traveling waves crucial for mucociliary clearance. The mechanisms underlying this collective response and the essential ingredients for stable synchronization remain a mystery. In this article, we describe Brownian dynamics simulations of multi-filament arrays, demonstrating that short-range steric inter-filament interactions and surface-roughness are sufficient to generate a rich variety of collective spatiotemporal oscillatory, traveling and static patterns. Starting from results for the collective dynamics of two- and three-filament systems, we identify parameter ranges in which inter-filament interactions lead to synchronized oscillations. We then study how these results generalize to large one-dimensional arrays of many interacting filaments. The phase space characterizing the multi-filament array dynamics and deformations exhibits rich behaviors, including oscillations and traveling metachronal waves, depending on the interplay between geometric spacing between filaments, activity, and elasticity of the filaments. Interestingly, the existence of metachronal waves is nonmonotonic with respect to the inter-filament spacing. We also find that the degree of filament surface roughness significantly affects the dynamics — roughness on scales comparable to the filament thickness generates a locking-mechanism that transforms traveling wave patterns into statically stuck and jammed configurations. Our simulations suggest that short-ranged steric inter-filament interactions are sufficient and perhaps even critical for the development, stability and regulation of collective patterns.

scholarly journals Instabilities and Spatiotemporal Dynamics of Active Elastic Filaments

2019 ◽  
Author(s):  
Yaouen Fily ◽  
Priya Subramanian ◽  
Tobias M. Schneider ◽  
Raghunath Chelakkot ◽  
Arvind Gopinath
Keyword(s):  
Molecular Motors ◽  
Brownian Dynamics ◽  
Linear Stability Theory ◽  
Unified Framework ◽  
Cytoskeletal Filament ◽  
Elastic Filaments ◽  
Elastic Filament ◽  
Follower Forces ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

Biological filaments driven by molecular motors tend to experience tangential propulsive forces also known as active follower forces. When such a filament encounters an obstacle, it deforms, which reorients its follower forces and alters its entire motion. If the filament pushes a cargo, the friction on the cargo can be enough to deform the filament, thus affecting the transport properties of the cargo. Motivated by cytoskeletal filament motility assays, we study the dynamic buckling instabilities of a two-dimensional slender elastic filament driven through a dissipative medium by tangential propulsive forces in the presence of obstacles or cargo. We observe two distinct instabilities. When the filament’s head is pinned or experiences significant translational but little rotational drag from its cargo, it buckles into a steadily rotating coiled state. When it is clamped or experiences both significant translational and rotational drag from its cargo, it buckles into a periodically beating, overall translating state. Using minimal analytically tractable models, linear stability theory, and fully non-linear computations, we study the onset of each buckling instability, characterize each buckled state, and map out the phase diagram of the system. Finally, we use particle-based Brownian dynamics simulations to show our main results are robust to moderate noise and steric repulsion. Overall, our results provide a unified framework to understand the dynamics of tangentially propelled filaments and filament-cargo assemblies.

scholarly journals The Effect of Salts on the Anal Gills of the Mosquito Larva

1933 ◽  
Vol 10 (1) ◽  
pp. 1-14 ◽  
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Mosquito Larva ◽  
Divalent Cations ◽  
Complete Separation ◽  
Elastic Membrane ◽  
Hypertonic Solutions ◽  
Elastic Filaments ◽  
Granular Cytoplasm ◽  
Visible Effect ◽  
The Difference ◽  
Elastic Fibrils

The so-called anal gills of the mosquito larvae (Aedes argenteus) are delicate chitinous papillae lined by flattened cells and filled with haemolymph. Externally the cells rest directly upon the chitinous cuticle. Internally they are bounded by a continuous elastic membrane, apparently composed of some "scleroprotein." The faintly granular cytoplasm is crossed vertically by elastic fibrils or membranes. If the gills are cut off in various salt solutions, which can then come in contact with the cells on both their surfaces, the cells swell or contract like other tissues, depending on whether the solutions are hypo- or hypertonic. But if the same solutions are applied to the intact larva, so that they come in contact with the outer surface while the inner surface of the cells is still in contact with the haemolymph, the effects are altogether different: Hypotonic solutions have no visible effect. Hypertonic solutions of salts like NaCl, KBr, etc., in which both ions are monovalent, cause enormous swelling of the cells. This is probably because these salts diffuse through the outer membrane (the cuticle) of the gills into the cells, which then absorb water from the haemolymph by osmosis. If the larva so treated is soon restored to fresh water, the action is reversible; but after a time the elastic filaments in the cells are dissolved and these can no longer contract again. These effects occur equally in the presence of salts with divalent cations. Hypertonic solutions of salts like CaCl2, Na2SO4, etc., in which one or both ions are divalent, extract water from the larva but do not cause swelling of the cells. These salts do not dissolve the elastic filaments. In the presence of hypotonic NaCl, etc. (which by itself has no visible effect), they cause temporary swelling followed by contraction. The cause of the difference between these two groups of salts is discussed. Dilute alkalis (N/50 NaOH) applied to the isolated gill or the intact larva dissolve the cells and cause extreme swelling, but do not dissolve the cuticle or the inner membrane. This action is accentuated by NaCl, etc., and by Na2SO4, etc., but is partially inhibited by CaCl2. Dilute acids (N/100 HCl) cause precipitation of the nuclei, slight swelling of the cells, and complete separation from the cuticle. In the presence of hypertonic Na2SO4 or CaCl2 the separation does not occur. All these effects are peculiar to the gills; no other part of the surface of the larvae is affected by these reagents.1

Sign in / Sign up

Export Citation Format

Share Document