當物體尺寸縮小到微米尺度的時候，因為尺度效應的關係，有一些物理特性可以被應用到生物技術上，因此在本文研究中提出了一個全新的概念，利用自然蒸發力和結構設計來完成微粒分離。在本文中利用微流體在微米尺度穩定的層流特性，來達到粒子分離的效果。首先利用植物蒸發驅動液體的原理，製作類似植物氣孔的蒸發區，運用在微流體系統尾端，作為自發性驅動的來源；接著從入口端注入含微粒液體和不含微粒的流體到微流道中。由於層流的特性，所以它不會擴散到不含粒子的流體中，當粒子進入分支結構的時候，不同大小的粒子會隨著通過粒子中心的流線進入不同的分支流道，而達到粒子分離的效果。

When the size of object shrunk down to micro scale, some physical characteristics could be applied to biotechnology because of scale effects. This paper has put forward a brand-new conceptions, utilizes evaporating force and structural design to separate particles naturally. Laminar flow characteristics of microfluidic system is used to separate particles. The principle to drive liquid in microfluidic system is evaporation force which idea came from plants. The evaporating region similar to vents of plants was designed at the end of microchannel to drive liquid spontaneously. The samples with and without particles, were injected into fluidic system, and particles in the flow were fixed on each layer of laminar flow. The particles, flow into separating region, moved with streamline cross theirs center to different branches. Thus, different size of particles could be separated spontaneously.