"Z-Axis" Thinking: Structural Coding Enables Programmable Motion of Catalytic Micromotors

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Chemically propelled micro/nanomotors (CMNMs) typically require external fields for motion control.
• Limited autonomous capabilities restrict CMNM applications and complex task execution.

Purpose of the Study:

• To introduce a z-axis structural encoding strategy for CMNMs enabling intrinsic, time-variable motion control.
• To demonstrate programmable autonomous motion in CMNMs through multilayered catalytic structures.

Main Methods:

• Designed and fabricated Janus micromotors with radially stacked multilayers of varying catalytic activities (Au, Pt) on a polystyrene core.
• Investigated motion transition from inert-side-leading to active-side-leading using controlled H2O2 fuel permeation dynamics.
• Employed experiments and phenomenological simulations to analyze the propulsion mechanism switching.

Main Results:

• Demonstrated a tunable shift in motion from inert-side-leading to active-side-leading in polystyrene-Au-Pt Janus micromotors.
• Identified fuel (H2O2) permeation dynamics through stacked metal layers as the key mechanism for motion transformation.
• Showcased programming of motion speed, orientation, and transition time via intrinsic structural parameters (layer number, thickness, microstructure, composition).

Conclusions:

• The z-axis multilayer architecture provides a novel strategy for encoding versatile autonomous motions in CMNMs.
• Intrinsic structural parameters can program temporal sequences of motion, enhancing CMNM autonomy.
• This approach significantly expands potential applications for CMNMs in complex tasks.