Remotely Programmable Multicolor-Emitting Microswimmer with Switchable Propulsion Modes

Journal article, 2025

Efficient, adaptive, and precise operation in complex microenvironments requires the careful design and manufacturing of tiny machines that provide optical signaling, flexible navigation, and remote control. Here, chemical/photoactivated Au microswimmers capable of multi-color light signaling is presented, which exhibit distinct swimming behaviors depending on fuel availability and illumination conditions. The system's functionality is further enhanced by incorporating a second engine Fe2O3, enabling fast-switchable propulsion and remote directional control. Moreover, these microswimmers retain their optical signaling while being remotely controlled by a magnetic field and illumination. Under a rotational magnetic field, an intriguing phenomenon of orbital rotation around a motile center is observed, which occurs when fluctuations in angular displacement are suppressed. This behavior is further corroborated by Brownian dynamics simulations. The approach integrates photoemission, swimming reversal, and remote directional control into a single system, providing a strong foundation for developing orthogonal micromachines for real-time imaging and precise targeting.