McDonnell Amarin G, Gopesh Tilvawala C, Lo Jennifer, O'Bryan Moira, Yeo Leslie Y, Friend James R, Prabhakar Ranganathan
Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Australia.
Soft Matter. 2015 Jun 21;11(23):4658-68. doi: 10.1039/c4sm02742f.
Suspensions of motile cells are model systems for understanding the unique mechanical properties of living materials which often consist of ensembles of self-propelled particles. We present here a quantitative comparison of theory against experiment for the rheology of such suspensions in extensional flows. The influence of motility on viscosities of cell suspensions is studied using a novel acoustically-driven microfluidic capillary-breakup extensional rheometer. Motility increases the extensional viscosity of suspensions of algal pullers, but decreases it in the case of bacterial or sperm pushers. A recent model [Saintillan, Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys., 2010, 81, 56307] for dilute active suspensions is extended to obtain predictions for higher concentrations, after independently obtaining parameters such as swimming speeds and diffusivities. We show that details of body and flagellar shape can significantly determine macroscale rheological behaviour.
活动细胞悬浮液是用于理解生物材料独特力学特性的模型系统，这些生物材料通常由自驱动粒子集合组成。我们在此展示了此类悬浮液在拉伸流动中流变学的理论与实验的定量比较。使用一种新型的声学驱动微流控毛细管破裂拉伸流变仪研究了运动性对细胞悬浮液粘度的影响。运动性增加了藻类拉动者悬浮液的拉伸粘度，但在细菌或精子推动者的情况下则降低了拉伸粘度。在独立获得诸如游动速度和扩散率等参数后，将最近一个关于稀活性悬浮液的模型[圣蒂兰，《物理评论E：统计、非线性、软物质物理》，2010年，81卷，56307期]进行扩展，以获得更高浓度下的预测结果。我们表明，物体和鞭毛形状的细节可以显著决定宏观尺度的流变行为。
