Data from: 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°. Scattering can be positive or negative depending on the relative strength of viscous and elastic effects, emphasizing the importance of viscosity on the interaction of sperm with their microenvironment. The modulation of scattering angle by viscosity is associated with variations in flagellar asymmetry induced by the elastohydrodynamic interaction with the boundary feature.精子通过传播鞭毛波动，在粘性流体中穿行于自身所处的微环境；其鞭毛波形的形成源于弹性结构、内部主动力矩以及低雷诺数流体动力学（low Reynolds number fluid dynamics）的共同作用。近年来，工程化微通道（engineered microchannels）被提出作为分选与操控活动细胞的技术手段，因此细胞与这类人工环境的相互作用值得开展深入研究。本研究提出一种数值方法，用于研究主动游泳者（active swimmers）与流体域结构特征间的大振幅弹性流体动力学相互作用（elastohydrodynamic interaction）。借助该方法，本研究考察了微通道阶跃模型结构引发的流体动力学散射效应。结果表明，散射效应取决于阶跃高度以及鞭毛内粘性力与弹性力的相对强度。在对应宫颈粘液类似物（cervical mucus analogue）中人精子的“高粘性”参数区间内，这种流体动力学对散射的贡献量级与近期关于接触效应的研究数据相当，约为5°至10°。散射效应可正可负，具体取决于粘性与弹性效应的相对强度，这凸显了粘度在精子与其微环境相互作用中的重要性。粘度对散射角的调制作用，与边界特征引发的弹性流体动力学相互作用所诱导的鞭毛不对称性变化密切相关。