Coarse-Graining the Fluid Flow around a Human Sperm

Ishimoto, Kenta; Gadêlha, Hermes; Gaffney, Eamonn A.; Smith, D. J.; Kirkman-Brown, Jackson

doi:10.1103/physrevlett.118.124501

Cited by 78 publications

(134 citation statements)

References 22 publications

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“…We investigate the hydrodynamic impact of a nearby coverslip on the beating symmetry, given the uneven influence of hydrodynamic forces due to the presence of solid boundary, i.e. non-slip surface [22,23,26]. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This is further augmented by external sources of asymmetry, such as the hydrodynamic influence of solid surfaces during for sperm boundary accumulation near to the coverslip [21][22][23]. This raises a fundamental question: given this multilayered hierarchy of distinct asymmetries that are intrinsically present, how does the human sperm flagellum achieve symmetric beating and straight-line swimming trajectories typically observed under the microscope [10,[24][25][26][27][28]?…”

mentioning

confidence: 99%

“…Indeed, our understanding of the human sperm flagellum beating is centred on the dogma of symmetric beating [29][30][31]. This have been postulated based on the wealth of observations thus far showing straightline swimming trajectories for sperm beating symmetrically, as well as symmetric travelling waves of curvature of the waveform [10,24,[26][27][28]32]. As such, beating symmetry is the cornerstone of any comparative study on flagellar undulation [24,29,32], especially so while assessing symmetry-breaking events, such as in sperm capacitation, hyperactivation and buckling phenomena [18,19,[32][33][34].…”

mentioning

confidence: 99%

“…As such, beating symmetry is the cornerstone of any comparative study on flagellar undulation [24,29,32], especially so while assessing symmetry-breaking events, such as in sperm capacitation, hyperactivation and buckling phenomena [18,19,[32][33][34]. Theoretical and computational models equally, and ubiquitously, invoke symmetry, ranging from flagellar kinematic models to structural mechanics and even motor control hypothesis [5,10,12,26,[35][36][37][38][39].…”

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confidence: 99%

“…How to even reconcile symmetric swimming observations with the umbrella of asymmetries that are present at the molecular level in the human spermatozoa, is still open to debate. This scenario is aggravated by the fact that the literature to date has been predominately limited to planar projections of the flagella beat [10,[24][25][26][27][28][29][30][31], albeit the human sperm flagellum beats intrinsically in threedimensions. Despite numerous efforts to capture the flagellar beat in 3D [34,[40][41][42][43][44][45][46][47][48][49][50][51][52], the importance of threedimensional component of the beat is yet to be fully recognised at the human fertility realm [53].…”

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confidence: 99%

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The human sperm beats anisotropically and asymmetrically in 3D

Gadêlha¹,

Hernández‐Herrera

Montoya

et al. 2019

Preprint

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The canonical beating of the human sperm flagellum is postulated to be symmetric. This is despite the reported asymmetries inherent to the flagellar axonemal structure, from distribution and activation of molecular motors to, even, the localisation of regulatory ion channels. This raises a fundamental question: how symmetric beating is possible within such intrinsically asymmetric flagellar complex? Here, we employ high-speed 3D imaging with mathematical analysis capable of resolving the flagellar movement in 4D (3D+time). This reveals that the human sperm beating is both anisotropic and asymmetric, and composed by a superposition of two transversal waves: an asymmetric travelling wave and a symmetric standing wave. This novel anisotropic travellingpulsation mechanism induces sperm rolling self-organisation and causes a flagellar kinematic illusion, so that the beat appears to be symmetric if observed with 2D microscopy. The 3D beating anisotropy thus regularises the intrinsic flagellar asymmetry to achieve symmetric side-to-side movement and straight-line swimming.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The human sperm beats anisotropically and asymmetrically in 3D

Gadêlha¹,

Hernández‐Herrera

Montoya

et al. 2019

Preprint

Self Cite

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Bidirectional Propulsion of Arc‐Shaped Microswimmers Driven by Precessing Magnetic Fields

Mohanty

Jin

Furtado

et al. 2020

Advanced Intelligent Systems

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The development of magnetically powered microswimmers that mimic the swimming mechanisms of microorganisms is important for lab‐on‐a‐chip devices, robotics, and next‐generation minimally invasive surgical interventions. Governed by their design, most previously described untethered swimmers can be maneuvered only by varying the direction of applied rotational magnetic fields. This constraint makes even state‐of‐the‐art swimmers incapable of reversing their direction of motion without a prior change in the direction of field rotation, which limits their autonomy and ability to adapt to their environments. Also, due to constant magnetization profiles, swarms of magnetic swimmers respond in the same manner, which limits multiagent control only to parallel formations. Herein, a new class of microswimmers are presented which are capable of reversing their direction of swimming without requiring a reversal in direction of field rotation. These swimmers exploit heterogeneity in their design and composition to exhibit reversible bidirectional motion determined by the field precession angle. Thus, the precession angle is used as an independent control input for bidirectional swimming. Design variability is explored in the systematic study of two swimmer designs with different constructions. Two different precession angles are observed for motion reversal, which is exploited to demonstrate independent control of the two swimmer designs.

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A Multiscale Numerical Simulation of Quasi-Two-Dimensional Bacterial Turbulence Using a Regularized Stokeslet Representation

Ishimoto

2023

Springer Proceedings in Mathematics &Amp; Statistics

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Self-propelled particles in low-Reynolds-number flow interact through the surrounding fluid. This study examined the collective dynamics of model bacterial swimmers in which a collection of regularized Stokeslets and rotlets captured their surrounding near-field flow. With the hydrodynamic and steric repulsive interactions, the numerical simulation of the swimming cells in a two-dimensional plane reproduced well-known turbulence-like dynamics, characterized by coherent collective vortex dynamics, agreeing with the previous. Furthermore, we incorporated two parallel free-slip boundaries to consider the impact of geometrical confinement. We observed that the size of the vortices of bacterial turbulence attained its maximal value when the width of the two boundaries was of the same order as the swimmer length. The rotlet term induces chiral swimming trajectories in the presence of confines for a dilute suspension. In a dense turbulence suspension, however, we observed that the chiral dynamics are subdued.

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Coarse-Graining the Fluid Flow around a Human Sperm

Cited by 78 publications

References 22 publications

The human sperm beats anisotropically and asymmetrically in 3D

The human sperm beats anisotropically and asymmetrically in 3D

Bidirectional Propulsion of Arc‐Shaped Microswimmers Driven by Precessing Magnetic Fields

A Multiscale Numerical Simulation of Quasi-Two-Dimensional Bacterial Turbulence Using a Regularized Stokeslet Representation

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