Self-Aligned Micro Bubble Arrays by Using Surface Tension

This paper describes the theory and experiments involve in the capture of bubbles onto a patterned surface. Guided by surface free energy, bubbles can automatically attach to the energetically favorable locations (bubble-traps) and align into bubble arrays. Bubble capturing potential φbc is proposed as the quantity to evaluate the surface’s “affinity” for bubbles. A bubble-trap can therefore be viewed as an area with locally maximum positive φbc. Two types of bubble-traps are proposed and evaluated. Type I bubble-traps are hydrophobic patterns on a hydrophilic flat surface. Type II bubble-traps are concave conic pits surrounded by a hydrophilic flat surface. Simulation of bubble capturing potential φbc explains the bubble-capturing behavior for both cases and predicts a better performance for type II bubble-traps. Experiments agree well with the theoretical prediction and suggest promising applications.