细菌活性物质时空有序的粘弹性控制
Viscoelastic control of spatiotemporal order in bacterial active matter
摘要：
活性物质由通过消耗能量产生机械功的单元组成。实例包括生命系统，例如细菌和生物组织的组装体、由分子马达驱动的生物聚合物以及合成自推进颗粒的悬浮液。该领域的一个中心问题是理解和控制空间和时间中活动集合体的自组织。大多数主动系统表现出空间秩序介导的相互作用，协调的空间结构和运动的活性剂或个人振荡动力学的时间同步。同时控制空间和时间组织更具挑战性，通常需要复杂的相互作用，如反应扩散层次或基因工程细胞电路。在这里，我们报告了一种新的和简单的手段，同时控制空间和时间的自组织细菌活性物质。通过限制活性细菌悬浮液和操纵一个宏观参数，即悬浮流体的粘弹性，我们发现细菌流体首先在空间中自组织成毫米级的旋转涡旋;然后显示时间组织作为巨大的涡旋切换其全球手性周期性与可调频率，让人想起扭摆-一个自驱动的。结合实验与活性物质模型，我们解释了这一惊人的行为之间的相互作用，积极迫使和粘弹性应力松弛。我们的研究结果推进了对复杂流体中细菌行为的理解，并首次通过实验证明流变学特性可以用来控制活性物质流动。与驱动相结合，我们的可调自振荡细菌涡旋可以用作软机器人运动和微流体泵送的“时钟”。
英文摘要：
Active matter consists of units that generate mechanical work by consuming energy. Examples include living systems, such as assemblies of bacteria and biological tissues, biopolymers driven by molecular motors, and suspensions of synthetic self-propelled particles. A central question in the field is to understand and control the self-organization of active assemblies in space and time. Most active systems exhibit either spatial order mediated by interactions that coordinate the spatial structure and the motion of active agents or the temporal synchronization of individual oscillatory dynamics. The simultaneous control of spatial and temporal organization is more challenging and generally requires complex interactions, such as reaction-diffusion hierarchies or genetically engineered cellular circuits. Here, we report a novel and simple means to simultaneously control the spatial and temporal self-organization of bacterial active matter. By confining an active bacterial suspension and manipulating a single macroscopic parameter, namely the viscoelasticity of the suspending fluid, we have found that the bacterial fluid first self-organizes in space into a millimeter-scale rotating vortex; then displays temporal organization as the giant vortex switches its global chirality periodically with tunable frequency, reminiscent of a torsional pendulum - a self-driven one. Combining experiments with an active matter model, we explain this striking behavior in terms of the interplay between active forcing and viscoelastic stress relaxation. Our findings advance the understanding of bacterial behavior in complex fluids, and demonstrate experimentally for the first time that rheological properties can be harnessed to control active matter flows. Coupled with actuation, our tunable self-oscillating bacterial vortex may be used as a "clock" for locomotion of soft robots and microfluidic pumping.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
