Data from: Symmetry-breaking phase transitions in highly concentrated semen

New experimental evidence of self-motion of a confined active suspension is presented. Depositing fresh semen sample in an annular shaped microfluidic chip leads to a spontaneous vortex state of the fluid at sufficiently large sperm concentration. The rotation occurs unpredictably clockwise or counterclockwise and is robust and stable. Furthermore, for highly active and concentrated semen, richer dynamics can occur such as self-sustained or damped rotation oscillations. Experimental results obtained with systematic dilution provide a clear evidence of a phase transition towards collective motion associated with local alignment of spermatozoa akin to the Vicsek model. A macroscopic theory based on previously derived self-organized hydrodynamics models is adapted to this context and provides predictions consistent with the observed stationary motion.

本研究呈现了受限活性悬浮体系自运动的全新实验证据。将新鲜精液样品注入环形微流控芯片后，当精子浓度足够高时，体系会自发形成流体涡旋态。该旋转方向不可预测，可呈顺时针或逆时针，且具备良好的鲁棒性与稳定性。此外，对于高活性、高浓度的精液体系，可观测到更为丰富的动力学行为，例如自维持旋转振荡或阻尼旋转振荡。通过系统稀释实验获得的结果，清晰证明了存在朝向集体运动的相变，该相变与精子的局部取向排列相关，类同于维切克模型（Vicsek model）。本研究基于此前已推导的自组织流体力学模型构建宏观理论，并将其适配于该研究场景，所得预测与观测到的稳态运动结果一致。