Fig. 2: Correlative 3D single-particle tracking and label-free thermometry.

a Representative 3D trajectory obtained from a numerically propagated depth-stack of intensity images. b, c Schematic depicting the orientation of the optofluidic platform with respect to gravity, and spatial distribution map in the XZ (top) and XY (bottom) planes of the trajectories of each tracer particle under thermal equilibrium and non-equilibrium conditions, respectively. Each track is assigned a color according to the average magnitude of the instantaneous velocity. d Experimentally measured 3D steady-state temperature distribution due to plasmon heating in the XZ (top) and XY (bottom) planes beside a cross-section along the dashed line, which led to the particle dynamics measured in (c). Scale bars: 10 µm.