Application of a microrheology technique to measure the viscosity of disodium cromoglycate liquid crystal

Although the science of rheology is well established, some important challenges still persist to measure the viscoelastic properties of complex fluids, such as biological solutions and liquid crystals (LC). In this work, we present a method, based on the calculation of the step length of Brownian particles, to measure the effective local viscosity sensed by microscopic objects in the LC host. This approach allowed us to quantify the anisotropy of the viscosity, and it could also be extended to measure the local viscosity in other nonhomogeneous media. We also present a new guided light dark-field microscopy technique that was used to track particles during our experiments.

尽管流变学（rheology）这门学科已发展成熟，但在测量复杂流体（complex fluids，如生物溶液与液晶（liquid crystals, LC））的粘弹性性质（viscoelastic properties）方面，仍存在若干关键挑战。本研究提出了一种基于布朗粒子步长计算的方法，用于测量液晶基质中微观物体所感知的有效局部粘度。该方法不仅实现了粘度各向异性的定量表征，还可推广应用于其他非均匀介质中的局部粘度测量。本研究同时提出了一种新型导光暗场显微镜（guided light dark-field microscopy）技术，用于实验过程中的粒子追踪。