Milli, Micro and Nano Fluidics in Air-Lift Operated Tank for Culture of Animal Cell

为了进一步改进动物细胞封闭系统培养气泡驱动气举罐，研究了气泡的上升行为以及细胞和细胞外基质的转运现象。为了实现均匀的气泡流动，需要确定最优的气泡数密度，即气泡直径和气泡相互距离。由于表面活性剂的作用对气泡运动至关重要，我们观察了超纯水中的气泡运动。研究发现，上升气泡与自由表面的接触时间是恒定的，能量耗散很小。在超纯水中，一对并排的上升气泡的上升速度随着气泡合并后的气泡形状振荡而显著降低。采用光致变色染料硅油溶液，在紫外光片照射下活化，观察气泡上升的尾迹。研究发现一对上升气泡的尾迹在气泡的聚并和弹跳过程中起着重要的作用。我们还发现，在一对气泡重复碰撞的情况下，会形成与单上升气泡相似的双线型或马蹄形涡。我们还研究了细胞外基质（ECM）中细胞代谢与转运现象之间的关系。本研究利用琼脂糖凝胶对动物细胞进行细胞代谢，观察荧光标记糊精分子在细胞周围构建的ECM中的扩散情况，探讨细胞周围的转运现象。结果表明，体外电浆是由细胞代谢形成的，电效应在体外电浆的转运过程中起着重要作用。

For the further improvement of bubble-driven airlift-operated tank for closed-system culture of animal cell, we studied both rising bubble behavior, and transport phenomena of cell and extra cellular matrix.It is highly required for the realization of the homogeneous bubbly flow that the most optimized bubble number density, i.e., bubble diameter and bubble mutual distance, should be determined. We observed the bubble motion in super purified water since the surfactant effects are essential for the bubble motion.It was found that the contact time of rising bubble with free surface was constant, and energy dissipation was very small. It was also found that the rising velocities of a pair of rising bubbles side by side in super purified water significantly decreased with bubble shape oscillations after the coalescence of bubbles.Wakes of rising bubbles were visualized by using silicone oil solution of photochromic dye, which was activated by illumation of UV light sheet. It was found that wakes of a pair of rising bubbles are playing the most important roles in the bubble coalescence and bouncing. It was also found that either double thread type or horse shoe type vortices, which are similar to those observed in the case of single rising bubble, were developed in the case of repetitive collision of a pair of bubblesWe also studied the relations between cell metabolism and transport phenomena in the extra cellular matrix (ECM). We visualized the diffusion of fluorescent labeled dextrin molecules in ECM constructed around cells by cell metabolism of animal cells which were seeded in agarose gel, in order to investigate transport phenomena around cells. It was found that ECM was constructed by the cell metabolism and that electrical effects are significant in transport phenomena in ECM.