Abstract
When the size of object is shuck down to micro scale, some physical characteristics can be applied to biotechnology because of scale effects. This thesis has put forward two brand-new conceptions, one utilizes evaporating force and structural design to separate particles naturally, another one use the porous silicon dioxide membrane to fabricate microchannel. In this thesis, we use laminar flow characteristics of microfluid to separate particles. The principle to drive liquid in microfluidic system is evaporating-conception from plants. The evaporating region similar to vents of plants was designed at the end of microchannel to drive liquid spontaneously. The flows 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, will move with streamline cross theirs center to different branches. Thus, different size of particles will separate spontaneously. Furthermore, a novel fabrication process of microchannel has been developed in this thesis. The material of sacrificing layer of microchannel has replaced by photoresistance. It uses the silicon dioxide membrane, was deposited by E-gun vapor, as main structure of microchannel. This fabrication process only need a short period, and integrates with other fabrication process easily. The silicon dioxide also has other benefits like chemical inertia, hydrophilic, optically clean, and cheap. Therefore, it is a high economic technology to be applied on commercial products.