Chandrakar Pooja, Varghese Minu, Aghvami S Ali, Baskaran Aparna, Dogic Zvonimir, Duclos Guillaume
Department of Physics, Brandeis University, Waltham, Massachusetts 02453, USA.
Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
Phys Rev Lett. 2020 Dec 18;125(25):257801. doi: 10.1103/PhysRevLett.125.257801.
Spontaneous growth of long-wavelength deformations is a defining feature of active liquid crystals. We investigate the effect of confinement on the instability of 3D active liquid crystals in the isotropic phase composed of extensile microtubule bundles and kinesin molecular motors. When shear aligned, such fluids exhibit finite-wavelength self-amplifying bend deformations. By systematically changing the channel size we elucidate how the instability wavelength and its growth rate depend on the channel dimensions. Experimental findings are qualitatively consistent with a minimal hydrodynamic model, where the fastest growing deformation is set by a balance of active driving and elastic relaxation. Our results demonstrate that confinement determines the structure and dynamics of active fluids on all experimentally accessible length scales.
长波长形变的自发增长是活性液晶的一个决定性特征。我们研究了约束对由伸展性微管束和驱动蛋白分子马达组成的各向同性相中三维活性液晶不稳定性的影响。当进行剪切排列时，此类流体呈现出有限波长的自放大弯曲形变。通过系统地改变通道尺寸，我们阐明了不稳定性波长及其增长率如何依赖于通道尺寸。实验结果在定性上与一个最小流体动力学模型相一致，在该模型中，增长最快的形变由活性驱动和弹性弛豫的平衡所决定。我们的结果表明，约束在所有实验可及的长度尺度上决定了活性流体的结构和动力学。
