Spermatozoa scattering by a microchannel feature: an elastohydrodynamic model

Sperm traverse their microenvironment through viscous fluid by propagating flagellar waves; the waveform emerges as a consequence of elastic structure, internal active moments and low Reynolds number fluid dynamics. Engineered microchannels have recently been proposed as a method of sorting and manipulating motile cells; the interaction of cells with these artificial environments therefore warrants investigation. A numerical method is presented for large-amplitude elastohydrodynamic interaction of active swimmers with domain features. This method is employed to examine hydrodynamic scattering by a model microchannel backstep feature. Scattering is shown to depend on backstep height and the relative strength of viscous and elastic forces in the flagellum. In a ‘high viscosity’ parameter regime corresponding to human sperm in cervical mucus analogue, this hydrodynamic contribution to scattering is comparable in magnitude to recent data on contact effects, being of the order of 5°–10°. Sca...

精子借助鞭毛（flagellum）波动在粘性流体中穿行于自身的微环境；其波动波形源于弹性结构、内部主动力矩以及低雷诺数流体动力学的共同作用。近年来，工程化微通道被提出可作为分选和操控活动细胞的手段，因此细胞与这类人工微环境的相互作用值得深入研究。本文提出一种数值方法，用于研究主动游动体与微域结构间的大振幅弹性流体动力学相互作用。利用该方法，我们针对模型微通道的阶跃（backstep）结构开展流体动力学散射特性分析。研究表明，散射特性取决于阶跃结构的高度，以及鞭毛内粘性力与弹性力的相对强度。在对应人类精子于宫颈粘液类似物中的‘高粘度’参数区间内，流体动力学对散射的贡献量级与近期报道的接触效应数据相当，约为5°至10°。Sca...