Fig. 3: Non-linear acceleration of alignment processes via the time-shared optical induction of flow fields.

a Flow multiplexing by time-shared scanning of laser paths on time scales below the thermal relaxation time, while keeping the average heating per path constant (Fig. S4). For this, the scan period, which corresponds to the thermal relaxation time, is sub-divided to facilitate multiple scan paths, while the laser power is increased proportionally to the degree of multiplexing (Fig. S2). See also Supplementary Video 4 for a dynamic visualization of this concept. Scale bars: 15 µm. b Analysis of distance between particles and their destination and (c) convergence speed for up to 6 simultaneously applied flow fields, reveal a highly non-linear speedup, with 6 scan lines yielding a (65 ± 6)-fold acceleration over the single scan path. Curves shown in (b) represent the distance over time, averaged over all 6 particles and over 5 to 8 repetitions each; the shaded area displays the standard deviation over the repetitions. The speed in c is calculated as the inverse of the convergence time, which is measured as the time at which the average (over all 6 particles) distance to the targets is approximately halved (reduced to 8 µm, see black horizontal line in (b). Again, the average of 5 to 8 repetitions is shown, the error bars represent the standard deviation. d Visualization of a typical, topologically rich flow field as it occurs for 6-fold multiplexing. Scale bar: 15 µm. e The corresponding analytical result building on a recently published mathematical model for a single scan path²⁴, showing excellent agreement with the experiment and reproducing all 22 topological defects in the flow field. Scale bar: 15 µm. f Parallel assembly of a humanoid robot from randomly dispersed beads: The assembly can be achieved both with low (2, see Supplementary Video 5) and high degree of flow-multiplexing (8)