Opto-thermomechanical microfluidics: hybrid optical trapping and photothermal convection for multiscale particle manipulation

An optofluidic chip with integrated dual-mode optical manipulation is proposed by us, combining scattering force-driven propulsion with photothermal-induced convection. By embedding twelve functionalized fibers—eight dedicated to optical forces and four to optothermal actuation—the platform enables long-range (972 μm) and high-speed (72 μm/s) particle control, exceeding the limited working distance (<200 μm) of conventional optical tweezers. This hybrid mechanism facilitates multiscale operations, ranging from single-particle translocation to the collective migration of particle assemblies, with sub-micron precision. Experimental and simulation results reveal size-dependent particle dynamics under varying laser powers and channel geometries. This low-cost, modular design opens avenues for on-chip biosensing and micro-robotic systems, as validated by applications in particle sorting, patterning, and transport.