Transition between Collective Behaviors of Micromotors in Response to Different Stimuli

Silver phosphate micromotors exhibit reversible transition between two collective behaviors: repulsive dispersion-like “exclusion” and attractive clustering-like “schooling” by the addition and removal of NH₃. Hierarchical particle clustering is observed when other inert particles are also present. Upon the addition of NH₃, large Ag₃PO₄ microparticles function as pumps, pushing away inert particles from their vicinity. We also find that the transition from dispersion to clustering can be halted with UV light. By combining the two external stimuli, we demonstrate that micromotor systems can be used as logic gates, with stimuli (UV and NH₃ in our system) as inputs and collective behaviors as outputs: “schooling” and “exclusion” behaviors as 1 and 0, respectively which suggests their potential for applications in computations.