ABSTRACT
A well-defined hole was placed on a stainless steel sheet by a laser, and the surface of the stainless steel sheet was coated with a plasma polymer of (TMSþO2) by the cathodic polymerization using the stainless steel sheet as the cathode [1]. Changing the ratio of TMS to O2 yields surfaces with varying contact angles of water. Figure 27.3 depicts the correlation between cosine of water sessile droplet contact angle and the oxygen mole fraction, which indicates that a desired surface tension can be obtained by changing the mole ratio of O2 in a mixture of O2 and TMS [2]. Two size of holes, 0.25mm and 0.5mm, were used. The bubble formation was recorded by a video camera for a predetermined period, and all bubbles were collected in a graduated cylinder. From the number of bubbles and the total volume, the average bubble diameter of a spherical bulb was calculated.
