Additive manufacturing of 3D surface microstructures through repetitively nucleated plasmonic bubbles

Photothermally triggered bubbles have been widely used to fabricate various surface microstructures. So far, studies have mostly focused on the fabrication of planar microstructures. In this study, we present an approach to achieve three-dimensional (3D) fabrication of surface microstructures via plasmonic bubbles in an ethanol suspension of polystyrene (PS) microparticles. We will show that the dispersed PS microparticles will be guided by a thermal Marangoni convection flow around a plasmonic bubble and deposited at the three-phase contact line. Interestingly, we find that PS microparticles tend to deposit along the vertical direction driven by the repetitively nucleated plasmonic bubbles, resulting in the formation of a 3D hollow microcylinder. The detailed process and the mechanism of the microstructure formation were systematically investigated. Finally, microstructures of different sizes were readily fabricated, exhibiting good controllability. Our method paves the way for 3D microstructure manufacturing using photothermal microbubbles.