Smart Microdevices Laying Breadcrumbs to Find the Way Home: Chemotactic Homing TiO2/Pt Janus Microrobots

Synthetic microrobots or micromotors are known to show intelligent behavior such as magnetotaxis, phototaxis, chemotaxis, active detection, and chemical communication. Herein, we present the concept of micromotors laying breadcrumbs; that is, these micromachines can move/return to a home position without external guidance after their external energy input is stopped. As a demonstration, TiO2/Pt Janus micromotors that move forward with UV light can return back following the previous path when the UV light is turned off. Such autonomy of motion opens the door for truly independent applications of micromotors in the deliver-and-return fashion.