了解微生物運動的機制相當重要，許多科學領域的研究也都與之息息相關；好譬生物學，醫藥科學和生醫工程。最近的實驗證實分子馬達在細胞運動和細胞內的傳輸作用有所貢獻，而細菌的鞭毛馬達正是我們所知最有強而有力的分子馬達；它可以推動整個細胞使之達到每秒數十倍身長的移動速率。所以我們可將這類細菌被視為自我推動粒子。另外，在細菌在高密度下還有許多有趣的成群移動的現象。
Vibrio alginolyticus 是海洋中的一種雙鞭毛系統細菌；系統分有單極與側向兩種鞭毛馬達。在生物學上，對於雙鞭毛馬達系統的優勢尚無法清楚解釋。所以我們的研究是對此雙鞭毛馬達系統做分析，測量單一細胞的速率和群體移動的現象。我們觀察對象為Vibrio alginolyticus的三種類型；138-2(有單極與側邊鞭毛)、VIO5(只有單極鞭毛)、 YM19(只有側邊鞭毛)。利用PIV粒子影像速度追蹤，可知細菌在高濃度時的速率。我們亦發展細菌的微流場量測技術。

The understanding of micro-organism is important in many scientific disciplines such as biology, medical science and engineer. Some recent experiments show that the microscopic molecular motors contribute to the cell locomotion and intracellular transportation. Bacterial flagellar motor is one of the most powerful molecular motor we have known. It can propel the cell up to the speed of tenth of the cell length per second. Therefore, the bacterial cells can be viewed as self-propelled particles. The collective motion of high density cells shows many interesting behaviors such as swarming.
Vibrio alginolyticus is a marine bacterium that has dual flagellar motor system, polar and lateral flagellar motors. The exact biological advantage of dual flagellar motor system is unknown. Here we present this investigation of the dual flagellar motor system including single cell speed and collective swarm measurements. We obtained three different strains of Vibrio alginolyticus, 138-2 (wild-type), VIO5 (polar+, lateral-), and YM19 (polar-, lateral+) for our investigation. We use Particle Imaging Velocimetry (PIV) to calculate the bacterial speed in high density. We also develop a micro-fluid flow-field measurement of bacteria.

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