Particle–wall interactions have broad biological and technological applications. In particular, some artificial microswimmers capitalize on their translation–rotation coupling near a wall to generate directed propulsion. Emerging biomedical applications of these microswimmers in complex biological fluids prompt questions on the impact of non-Newtonian rheology on their propulsion. In this work, we report some intriguing effects of shear-thinning rheology, a ubiquitous non-Newtonian behaviour of biological fluids, on the translation–rotation coupling of a particle near a wall. One particularly interesting feature revealed here is that the wall-induced translation by rotation can occur in a direction opposite to what might be intuitively expected for an object rolling on a solid substrate. We elucidate the underlying physical mechanism and discuss its implications on the design of micromachines and bacterial motion near walls in complex fluids.

中文翻译：

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剪切稀化流体中旋转粒子的壁诱导平移

粒子-壁相互作用具有广泛的生物学和技术应用。特别是，一些人造微型游泳者利用它们靠近墙壁的平移-旋转耦合来产生定向推进力。这些微型游泳器在复杂生物流体中的新兴生物医学应用引发了关于非牛顿流变学对其推进的影响的问题。在这项工作中，我们报告了剪切稀化流变学（一种普遍存在的生物流体的非牛顿行为）对壁附近粒子的平移-旋转耦合的一些有趣影响。这里揭示的一个特别有趣的特征是，壁面引起的旋转平移可以发生在与物体在固体基板上滚动的直观预期相反的方向上。