Microdroplet cluster rotation based on the laser-induced thermal effect of optical fiber.

We propose and demonstrate a method for driving microdroplet cluster rotation by the laser-induced thermal effect of an optical fiber. The movement trend of microdroplets in the airflow is determined by the airflow characteristics. When an optical fiber taper is immersed in liquid and a 1480 nm laser is incident, the airflow at the liquid-air interface is altered due to light-liquid interactions. Under continuous heating by the laser, stable suspended micro-droplet rings are formed at the liquid interface. Adjusting the relative position between the fiber and the liquid-air interface changes the airflow direction at the interface. The rotation direction of the micro-droplet ring cluster is determined by the airflow direction. Furthermore, with the changes in laser power, the size and rotation speed of the micro-droplet ring cluster change accordingly. It realizes the integration of micro-droplet generation and manipulation, and manipulates the rotation of microdroplets by altering the airflow characteristics, expanding the research scheme of particle manipulation. This method possesses promising application potential in biomedicine and analytical chemistry.