Urbani Raphael, Westermeier Fabian, Banusch Benjamin, Sprung Michael, Pfohl Thomas
Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
Max Planck Institute for the Structure and Dynamics of Matter, CFEL, 22761 Hamburg, Germany.
J Synchrotron Radiat. 2016 Nov 1;23(Pt 6):1401-1408. doi: 10.1107/S1600577516012613. Epub 2016 Oct 6.
Combining microfluidics with coherent X-ray illumination offers the possibility to not only measure the structure but also the dynamics of flowing samples in a single-scattering experiment. Here, the power of this combination is demonstrated by studying the advective and Brownian dynamics of colloidal suspensions in microflow of different geometries. Using an experimental setup with a fast two-dimensional detector and performing X-ray correlation spectroscopy by calculating two-dimensional maps of the intensity auto-correlation functions, it was possible to evaluate the sample structure and furthermore to characterize the detailed flow behavior, including flow geometry, main flow directions, advective flow velocities and diffusive dynamics. By scanning a microfocused X-ray beam over a microfluidic device, the anisotropic auto-correlation functions of driven colloidal suspensions in straight, curved and constricted microchannels were mapped with the spatial resolution of the X-ray beam. This method has not only a huge potential for studying flow patterns in complex fluids but also to generally characterize anisotropic dynamics in materials.
将微流控技术与相干X射线照明相结合，不仅能够在单次散射实验中测量流动样品的结构，还能测量其动力学。在此，通过研究不同几何形状微流中胶体悬浮液的平流和布朗动力学，展示了这种组合的强大功能。使用配备快速二维探测器的实验装置，并通过计算强度自相关函数的二维图来进行X射线相关光谱分析，不仅可以评估样品结构，还能表征详细的流动行为，包括流动几何形状、主流方向、平流流速和扩散动力学。通过在微流控装置上扫描微聚焦X射线束，以X射线束的空间分辨率绘制了直的、弯曲的和收缩的微通道中驱动胶体悬浮液的各向异性自相关函数。这种方法不仅在研究复杂流体中的流动模式方面具有巨大潜力，而且在一般情况下能够表征材料中的各向异性动力学。
