本實驗利用團藻的趨光性當作主動粒子，藉此研究團藻在黏滯液體中移動與阻塞現象。為了解團藻的基本性質，我們以光源驅使團藻移動，藉此計算團藻大小、軌跡與速度關係，並在不同黏度的培養液環境測量對團藻移動的影響。實驗結果發現，液體黏滯度越低時團藻速度越快，且有無光刺激的影響對團藻移動速度並無明顯差異。團藻半徑小時70μm速度與半徑正相關，但當團藻半徑大時70μm速度開始下降。 在阻塞方面，我們改變玻璃針管管徑、不同濃度PVP混合培養液改變液體黏滯度，來研究主動粒子在管徑改變、不同流速所造成的阻塞現象。以PVP重量百分濃度4%為例：我們發現在管子頸部與顆粒尺寸比在4.6、6.0與8.0時阻塞的比例為100%、80%與15%。 在棘輪部分，我們給予團藻各種持續的光刺激(線性、次方與指數)並觀察團藻分布情況。結果發現團藻會依光刺激的類型大略排列出匹配圖形。團藻在線性及次方亮度變化下，穩定度會比指數棘輪高。 ;This thesis uses volvox, with its phototaxis ability, as a self-driven particle system to study the motions and the phenomena of jamming in a viscous fluid. In order to measure the basic self-driven properties of volvox, the volvox is driven by light so as to find the relations between the size and the speed of volvox particles. Besides, we use fluid with different viscosity to study the viscous effects on their movement. Our experiment shows that the speed of volvox is negatively correlation with the viscosity of the fluid and their speed is independent of the intensity of the light source. The speed will reach a maximum when the radii of volvox particle are approximately 70μm. To study the phenomenon of jamming , we shrink the central part of a glass tube (the neck) to different diameters, and use volvox suspended in medium with different viscosities produced by mixing with different PVP concentrations. We find that when the concentration of PVP is 4% , the jamming ratio are 100%、80% and 15% when the neck-to-particle size ratio is 4.6, 6 and 8 respectively. We also generate various background light simulations (linear, square and exponential) to observe the distribution of volvox under these backgrounds. We find that volvox would have a spatial distribution according to the intensity of the light. The stability of volvox is higher in the linear and square spatial light variations than an exponential one.
