Optical force-driven and tip-enhanced plasmonic bubble generation

Plasmonic bubbles are promising for micro-/nanofabrication, energy conversion, and Raman-based sensing. However, conventional approaches typically require high nucleation power and confine bubble formation to solid interfaces, leading to collateral heating and limited spatial controllability. Here, we introduce a nanotip-Au nanoparticle (NP) hybrid strategy that can exploit nanoscale optical forces and the coupled local thermal-electromagnetic enhancement to enable bubble nucleation. Raman thermometry characterizes the photothermal enhancement of the hybrid nanotip and identifies the threshold temperature for bubble generation. Compared with the conventional plasmonic-bubble method, the tip-enhanced methodology reduces the nucleation power by 89.12% ± 0.58% and enables bubble formation at arbitrary locations within a suspension. Leveraging Marangoni convection and a shrinking surface-bubble deposition protocol, we achieve ultrasensitive microplastic detection, including polystyrene at ultralow concentrations (3 ng·mL −1 ) as well as analyses of environmental samples. This platform provides improved controllability for plasmonic bubble generation and practical opportunities in environmental sensing and beyond.