Fig. 4

The velocity distribution of natural convection in the SWCNT solution heated at 100 °C. The red arrows point out the positions of DEP grooves. At two different time points with an interval of 120 s, the direction of convection is erratic and changes rapidly, and the dimensions of convection vortices are at the level of the depth (100 μm) of SWCNT solution, as indicates that the convection can bring individualized SWCNTs in the dimensions of 100 μm × 100 μm (2D) to the vicinities of DEP grooves