Programming Motion of Platinum Microparticles: From Linear to Orbital

Self-powered catalytic micromotors that swim through a fluid by harvesting energy from their environment have received increasing attention because of their potential applications in nanomachinery, nanoscale assembly, and robotics. However, persistent directional motion is required for micromotors to perform useful work. Herein, through modeling and experiments, we demonstrate the general design strategy for single-component platinum micromotors that, in the presence of hydrogen peroxide, can execute a variety of motion trajectories from extremely linear to orbital. This is achieved via a simple shape design wherein the speed and directionality of a particle are determined by overall symmetry elements. Shape design gives high reproducibility and allows a wide range of adjustments to fine-tune the desired particle motion. We observe strong agreement between experimental data and numerical predictions, indicating that our model can serve to predict directionality and speed of a particle prior to fabrication. Shape programming works on an individual-particle basis, thus enabling complex systems which require different modes of motion for the individual parts.