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.