Abstract Suspended colloidal particles assemble into “bands” when subject to shear flow and a DC electric field over a range of conditions in combined Poiseuille and electroosmotic counterflow through microchannels. The initial stage in this process appears to be an accumulation stage, where particles are attracted to and concentrated near the channel wall. Spatially averaged grayscales and their standard deviation were calculated from evanescent-wave visualization images of band assembly to estimate the near-wall particle concentration and its local variations, respectively. The timescale for the accumulation stage was estimated from the standard deviation and used to scale physical time. The average grayscale appears to grow exponentially during the accumulation stage and exhibits self-similar exponential growth when normalized by its maximum value over a range of experimental parameters. Graphic abstract

中文翻译：

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确定通过剪切流和电场将粒子定向组装成带的时间尺度

摘要 悬浮的胶体颗粒在经过微通道的泊肃叶和电渗逆流的组合中，在一系列条件下受到剪切流和直流电场时，会聚集成“带”。该过程的初始阶段似乎是一个积累阶段，其中颗粒被吸引并集中在通道壁附近。空间平均灰度及其标准偏差是从带组件的倏逝波可视化图像中计算出来的，以分别估计近壁粒子浓度及其局部变化。积累阶段的时间尺度是根据标准偏差估计的，并用于衡量物理时间。平均灰度在积累阶段似乎呈指数增长，并且在通过一系列实验参数对其最大值进行归一化时表现出自相似指数增长。图形摘要