Abstract
In this study, we established a micro-channel detection system to detect characteristics of micro-flow. The testing micro-channel chips which were made by Micro-Electro-Mechanical Systems (MEMS) were used to find the relation between pressure drop and Reynolds number. We find that with hydraulic diameter decreasing to 100μm the water flowing in a micro-channel can be analyzed by classical hydrodynamics, meant that Reynolds number and pressure drop are direct proportion. Then, we used PDMS demolding fabrication to get a micro-channel with microstructures on its sidewall, and got hydrophobic surfaces by coating Teflon, attempted to decrease total liquid-solid contact area in the micro-channel. It results that flow resistant of the micro-channel is decreased. According to our measurement, flow resistant of a micro-channel at low flow rate and low width microstructures on its sidewall decreased clearly. In order to explain this phenomenon, we created a new theory: water won’t leak into gaps of microstructures because of hydrophobic surface and surface tension, resulting that total water-solid contact area decrease and flow resistant of the micro-channel decrease too. Finally, a method which can calculate size of microstructures to satisfy pressure drop decreasing condition with different kinds of micro-channels is proposed.