Multimodal Manipulation of Particles Based on Optothermal Controlled Marangoni Convection in Dynamic Microfluidics

Optical manipulation techniques have been widely applied in the biomedical field. However, the key issues limiting the efficiency of optical manipulation techniques are the weak driving force of optical scattering and the small working range of optical gradient forces. The optothermal Marangoni convection enables effective control of flow fields through optical means, and particle manipulation based on this mechanism offers advantages such as a wide working range, strong driving force, and high flexibility. In recent years, it has been applied in fields such as biological cell manipulation and micro/nanomaterial assembly. However, current research predominantly focuses on particle manipulation in static environments, overlooking the potential applications of this method in dynamic and complex flow fields. In this study, we investigate particle manipulation methods based on optothermal Marangoni convection in dynamic flow fields. Through combined simulation and experiment, we systematically characterized flow field profile and particle trajectories under coupled "optothermal-flow" control, developed manipulation schemes with extended working range (>20 μm) and multiparticle capacity for trapping, assembly, and migration. Through laser spot positioning, we achieved real-time flow field modulation in microchannels, enabling versatile multimodal particle control. These findings demonstrate the substantial potential of optothermal Marangoni convection in microfluidic applications, offering a novel methodology for dynamic flow field regulation and high-efficiency on-chip particle manipulation.