Micro-bubbles generated by a single focused optoacoustic wave

Acoustically generated micro-bubble at solid surface is of paramount importance in applications such as selective surface treatment and controlled permeation of biological samples. However, surface heterogeneity (e.g., micro-sized nucleation sites) poses some challenges in controlling bubble, leading to uncontrolled heterogeneous bubbles. Here, we demonstrate controlled single micro-bubble rather insensitive to surface quality as a result of small focused acoustic spot (∼200 µm) and high-amplitude negative pressure (∼50 MPa) due to acoustic interference.