Spatial control of the phase separation of Ag colloids via structured light. (A) Two adjacent regions where Ag colloids (φ = 14%) formed clusters of different sizes under two light patches of a trigger frequency of 1 (left) and 0.25 Hz (right), respectively. (B) Phase separation under light patches of different sizes. (C) Phase separation under light patches of different aspect ratios. (D) Writing letters of NANO using Ag colloidal clusters with light patches. (E) Phase separation under light patches of different shapes. In (B)‒(E), the particle density is 28% and the trigger frequency is 1 Hz. These experiments were carried out in 0.25 wt% H₂O₂ and 200 μmol L⁻¹ KCl aqueous solutions. The light patches are shown in the top panels of each figure, where the white area is irradiated by 405 nm light of ~257 mW cm⁻².