| dc.description.abstract | In recent years, microfluidics technology has been developed rapidly. Microfluidic can be operated complexly and exactly by microfluidic chips. It has many advantages such as lightweight, less reagent, etc. Therefore, the scope of application in biotechnology research is very extensive. Common microfluidic driving principle can be roughly classified into thermocapillary forces, surface roughness gradient, surface chemistry gradient, static electricity and electro-wetting etc. Compared with other methods, using thermocapillary force to drive liquid drop has some advantages like manufacturing process is simple, easy to control and so on. Because thermocapillary force can’t provide great driving force within a small range, the drop moving speed is not fast. To this end, we added column microstructure into silicon wafer to change wettability between squalane droplet and silicon chip, expect to increase the droplet migration speed.
This paper, mainly make column microstructure with different spacing on the silicon surface by dry etching, and drive liquid droplet by thermocapillary force on it to investigate the effect of microstructure on the droplet migration. On the smooth silicon surface, droplet will deform when moving. Resulting advancing contact angle is larger than receding contact angle, and the greater the temperature gradient, the droplet moving faster. Because of the microstructure, droplet exhibits hydrophilic on roughness solid surface. Thermocapillary force becomes larger, so the displacement and velocity of droplet is faster than it on smooth surface. But hampered by the microstructure, the moving speed of the droplet is declining. Finally, using Newton′s laws of motion to estimate the resistance caused by micro structure. From a point of the fixed surface roughness coefficient, find that the greater temperature gradient, the faster droplet moves and the greater the resistance. From the view of fixing temperature gradient, find that the smaller the surface roughness coefficient, because the contact area between liquid droplet and solid is fewer, the faster droplet moves, but the greater the resistance. | en_US |