Abstract
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.