Abstract
The paper discusses wettability of micro-scale structure on surface. The micro-scale structures are manufactured in the following processes: (1) machining of the structure tools in FIB sputtering, (2) incremental forming for structured molds and (3) plastic molding. The micro-scale structures promote hydrophobicity on the polyethylene surface. Then, the structured surfaces are treated to change the wettability in plasma irradiation. The plasma treatment changes hydrophobic structured surfaces to hydrophilic ones. The wettability of the treated surface reaches the steady state after 120 hours. The contact angle decreases with the solid fraction on the hydrophilic structured surface. However, the most hydrophilic surface appears on the flat surface treated by the plasma irradiation. The droplet tests were performed to verify the edge effect of the micro pillars with measuring the change in the contact angle with the amount of the liquid.
