Abstract Run-and-tumble motility is widely used by swimming microorganisms including numerous prokaryotic and eukaryotic organisms. Here, we experimentally investigate the run-and-tumble dynamics of bacterium E. coli in polymeric solutions. We find that even small amounts polymer solution can drastically change dynamics: cells tumble less their velocity increases, leading to an enhancement cell translational diffusion a sharp decline rotational diffusion. show suppression tumbling due fluid...

The field of soft robotics has inspired recent mechanical engineering and materials science innovations to enable shape‐shifting systems be developed. This paper presents the design analysis a novel thermally tunable composite, namely, flexible open‐cell foam coated in wax that can achieve significant ranges stiffness, strength, volume. Experimental results were compared proposed model for predicting bulk compression modulus composites. Additionally, preliminary studies indicate composites...

We show that active, self-propelled particles are connected together to form a single chain is anchored at one end can produce the graceful beating motions of flagella. Changing boundary condition from clamp pivot anchor leads steadily rotating tight coils. Strong noise in system disrupts regularity oscillations. use combination detailed numerical simulations, mean-field scaling analysis and first passage time theory characterize phase diagram as function filament length, passive elasticity,...

We experimentally investigate the effect of particle size on motion passive polystyrene spheres in suspensions Escherichia coli. Using particles covering a range sizes from 0.6 to 39 microns, we probe dynamics at both short and long time scales. In all cases, exhibit super-diffusive ballistic behavior times before eventually transitioning diffusive behavior. Surprisingly, find regime which larger can diffuse faster than smaller particles: long-time effective diffusivity exhibits peak size,...

The adaptive mechanical properties of soft and fibrous biological materials are relevant to their functionality. emergence the macroscopic response these external stress intrinsic cell traction from local deformations structural components is not well understood. Here, we investigate nonlinear elastic behavior blood clots by combining microscopy, rheology, an network model that incorporates stretching, bending, buckling constituent fibrin fibers. By inhibiting cross-linking in clots, observe...

Abstract The motility of microorganisms is influenced greatly by their hydrodynamic interactions with the fluidic environment they inhabit. We show direct experimental observation bi-flagellated alga Chlamydomonas reinhardtii that fluid elasticity and viscosity strongly influence beating pattern - gait thereby control propulsion speed. frequency wave speed characterizing cyclical bending are both enhanced elasticity. Despite these enhancements, net swimming hindered for fluids sufficiently...

Polyacrylamide hydrogels (PAH gel) and polydimethylsiloxane (PDMS, an elastomer) are two soft materials often used in cell mechanics mechanobiology, manufacturing lab-on-a-chip applications, among others. This is partly due to the ability tune their elasticity with ease addition various chemical modifications. For affine polymeric networks, (of three) elastic constants, Young's modulus (

We study a continuum model of overdamped self-propelled particles with aligning interactions in two dimensions. Combining analytical theory and computations, we map out the phase diagram for parameter space covered by model. find that system self-organizes into robust structures different regions space: solitary waves composed ordered swarms moving through low density disordered background, stationary radially symmetric asters. The self-regulating nature flow yields separation, ubiquitous...

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 and alters entire motion. If the pushes cargo, friction on cargo can be enough deform filament, thus affecting transport properties of cargo. Motivated cytoskeletal motility assays, we study dynamic buckling instabilities two-dimensional slender elastic through dissipative medium in...

The ability of bacteria to colonize and grow on different surfaces is an essential process for biofilm development. Here, we report the use synthetic hydrogels with tunable stiffness porosity assess physical effects substrate Using time-lapse microscopy track growth expanding Serratia marcescens colonies, find that colony can increase increasing stiffness, unlike what found traditional agar substrates. traction force microscopy-based techniques, biofilms exert transient stresses correlated...

Surfaces covered by bristles, hairs, polymers and other filamentous structures arise in a variety of natural settings science such as the active lining many biological organs, e.g. lungs, reproductive tracts, etc., have increasingly begun to be used technological applications. We derive an effective field theory for elastohydrodynamics ordered brushes disordered carpets that are made large number elastic filaments grafted on substrate interspersed fluid. Our formulation elastohydrodynamic...

Many important biological functions depend on microorganisms' ability to move in viscoelastic fluids such as mucus and wet soil. The effects of fluid elasticity motility remain poorly understood, partly because the swimmer strokes properties medium, which obfuscates mechanisms responsible for observed behavioural changes. In this study, we use experimental data gaits Chlamydomonas reinhardtii swimming Newtonian inputs numerical simulations that decouple gait type order isolate effect...

Abstract Propagating interfaces are ubiquitous in nature, underlying instabilities and pattern formation biology material science. Physical principles governing interface growth well understood passive settings; however, our understanding of active systems is still its infancy. Here, we study the evolution an active-passive using a model matter system, bacterial swarms. We use ultra-violet light exposure to create compact domains bacteria within Serratia marcescens swarms, thereby creating...

We study spatio-temporal dynamics and pattern formation in ordered arrays of active semi-flexible filaments, each which is pinned at one end free the other. The filaments are...

The trajectories of 20 and 40 is the gas viscosity. Theory experiment show similar trends increasing critical Weber number with decreasing Ohnesorge Knudsen number. Theoretical results are also derived for coalescence–bounce transition coefficient restitution head-on collisions equal sized drops.

We consider the sticking of a fluid-immersed colloidal particle with substrate coated by polymeric tethers, model for soft, wet adhesion in many natural and artificial systems. Our theory accounts kinetics binding, elasticity hydrodynamics fluid drainage between colloid substrate, characterized three dimensionless parameters: ratio viscous time to elastic thermal energies, size relative height polymer brush. For typical experimental parameters discrete families we find that proceeds via...

Swarming colonies of the light-responsive bacteria Serratia marcescens grown on agar exhibit robust fluctuating large-scale flows that include arrayed vortices, jets and sinuous streamers. We study immobilization quenching these collective when moving swarm is exposed to intense wide-spectrum light with a substantial ultraviolet component. map emergent response in terms two parameters—light intensity duration exposure—and identify conditions under which motility impacted. For small exposure...

We study the head-on collision between two weakly deformable droplets, each of radius a (in range 10–150 μm), moving towards one another with characteristic impact speeds ± U ′ c . The liquid comprising drop has density ρ d and viscosity μ takes place in an incompressible continuum gas ambient g [Lt ] , pressure p ∞ gas–liquid interface is surfactant free interfacial tension σ. Weber number based on density, ≡ 2 /σ 1 capillary viscosity, Cag σ 1. Reynolds characterizing flow inside drops...

We report a simple route to form robust, inorganic, semi-permeable compartments composed of montmorillonite, natural plate-like clay mineral that occurs widely in the environment. Mechanical forces due shear narrow gap assemble nanoplates from an aqueous suspension onto air bubbles. Translucent vesicles suspended single-phase liquid are produced when clay-covered bubbles exposed variety water-miscible organic liquids and water-soluble surfactants. These mechanically robust stable water other...

Arrays of clamped active filaments, interacting <italic>via</italic> steric forces, display traveling waves and jammed clusters.

Elastic-driven slender filaments subjected to compressive follower forces provide a synthetic way mimic the oscillatory beating of biological flagella and cilia. Here, we use continuum model study dynamical, nonlinear buckling instabilities that arise due action nonconservative on prestressed rod clamped at both ends allowed move in fluid. Stable responses are observed as result interplay between structural elastic instability inextensible rod, geometric constraints control onset...

Mucus, composed significantly of glycosylated mucins, is a soft and rheologically complex material that lines respiratory, reproductive, gastrointestinal tracts in mammals. Mucus may present as gel, highly viscous fluid, or viscoelastic fluid. acts barrier to the transport harmful microbes inhaled atmospheric pollutants underlying cellular tissue. Studies on mucin gels have provided critical insights into chemistry gels, their swelling kinetics, diffusion permeability molecular constituents...