The persistent motility of individual constituents in microbial suspensions represents a prime example of the so-called active matter systems. Cells consume energy, exert forces and move, overall releasing the constraints of equilibrium statistical mechanics of passive elements and allowing for complex spatio-temporal patterns to emerge. Moreover, when subject to physico-chemical stimuli their collective behaviour often drives large-scale instabilities of a hydrodynamic nature, with implications for biomixing in natural environments and incipient industrial applications. In turn, our ability to exert external control of these driving stimuli could be used to govern the emerging patterns. Light, being easily manipulable and, at the same time, an important stimulus for a wide variety of microorganisms, is particularly well suited to this end. In this paper, we will discuss the current state, developments and some of the emerging advances in the fundamentals and applications of light-induced bioconvection with a focus on recent experimental realizations and modelling efforts. This article is part of the theme issue ‘Stokes at 200 (part 2)’.

中文翻译：

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光生物对流：对活性悬浮液中的流动进行光控制

微生物悬浮液中单个成分的持久运动是所谓活性物质系统的一个主要例子。细胞消耗能量、施力和移动，整体释放被动元素的平衡统计力学约束，允许出现复杂的时空模式。此外，当受到物理化学刺激时，它们的集体行为通常会导致水动力性质的大规模不稳定性，对自然环境中的生物混合和初期工业应用产生影响。反过来，我们对这些驱动刺激施加外部控制的能力可用于控制新兴模式。光易于操作，同时也是对多种微生物的重要刺激，特别适合于这一目的。在本文中，我们将讨论光诱导生物对流的基本原理和应用的当前状态、发展和一些新进展，重点是最近的实验实现和建模工作。本文是主题问题“斯托克斯 200（第 2 部分）”的一部分。