Abstract
We studied the effect of aspect ratio and contact angle on formation process of gas-liquid interface in a microchannel having hydrophobic cavity-shaped microstructures. The microstructures were fabricated on a test wall by wire electric discharge machining, and the test wall was coated with triazine thiol to induce hydrophobicity. We experimented with 5 different microstructures and 7 different concentrations of aqueous ethanol solutions in order to investigate the effect of the aspect ratio n/l_s and contact angle θ_ε. As a result, it was found that formation of gas-liquid interface was not observed in n/l_s < 1 and θ_ε < 50°. When n/l_s > 1 and θ_ε > 50°, formation of gas-liquid interface was observed. In this condition, the form of gas-liquid interface has changed on θ_ε = 70°.
