Light-driven tweezers, motors, and self-assembly from scalable optofluidic vortex arrays generated by graphene oxide

Manipulating large numbers of a variety of particles/wires is essential for many lab-on-a-chip technologies. Here we generate a planar array of optofluidic vortices with photothermal gradients from an easy-fabricated graphene oxide (GO) heater to achieve high-throughput and multiform manipulation at low excitation power and low loss. As a tweezer, each vortex can rapidly capture and confine particles without restrictions on shapes and materials. The stiffness of the confinement is easily tuned by adjusting the vortex dimension. As a motor, it can actuate any traps to persistently rotate/spin in clockwise or anti-clockwise mode. As a high-performance “workshop”, this work lays the groundwork for various self-assembly ranging from colloid-based clusters, chains, capsules, shells, and ultra-thin films, through particles' surface modification and fusion, to nanowires-based architectures. Furthermore, we can create multiple vortex arrays through fabricating an array of heaters, which enables a wider range of manipulation and distributed operations all on a chip.