Fig. 3. Z-shaped migration properties of PS particles driven by TOT.

a Schematic diagram of PS particle migration through double-track PTWs with a spacing of 100 μm. The solid white line depicts the trajectory of the PS particle. The solid blue line depicts the moving track of the SFL. Inset: Trapping force distributions of the SFL. The color bar indicates the amplitude, and the arrows denote the directions of the trapping force. b Experimental migration results of a single particle. The solid white line represents the trajectory of the PS particle. The dashed blue line indicates the moving track of the SFL. The laser is focused on the center of the dashed blue circle. The incident beam power is 9.8 mW. Scale bar: 25 μm. c Transport of the PS particle on the x‒y plane. The circles with dashed blue lines represent the laser positions. The solid green circles mark the positions of the PS particles. The black arrows show the direction of PS particle transport. d The trajectories vary with time along the x- and y-axes