Single-particle tracking (SPT) experiments were conducted to validate the efficacy of the method. Figure shows the evolution of x and y position of the particles over time. Before UV irradiation, particles inside the optical matter are dynamic but move relatively slow constrained by the surrounding particles, while particle outside (particle 1-4, figure inset) are much more dynamic. Upon UV-365 light irradiation, photopolymerization occurs within 2 seconds, as indicated by the particle traces, which show decreasing fluctuations until they eventually stabilize at zero (Figure ). Post UV irradiation, no movement is observed, confirming the formation of permanent optical matter by photopolymerization. The evolution of the dynamic assembly before UV light irradiation into permanent structure after photopolymerization is displayed in Figure . The optical matter can then be transported to other characterization tools such as confocal or electron microscope. We note here that while the method was showcased on optical matters, it can be applied to any other type of self-assembly if they can form in the hydrogel solution.