Microrotors with Tunable Trajectory Curvatures Driven by Chemical and Photochemical Dual Engines

A major challenge in developing smart micromachines that
can mimic
natural microorganisms is their ability to adapt to changing environments.
This study presents a matchstick-shaped microrotor consisting of a
TiO2 head and a SiO2 tail, with one side coated
by PtO. The TiO2 head provides photochemical propulsion
under UV light, while the PtO coating provides chemical propulsion
in H2O2. The microrotor rotates because of its
asymmetric structure and uneven propulsion forces. Notably, under
stronger UV light, the rotor orbits in tighter circles as the photochemical
engine counteracts the chemical engine, with the two engines located
on opposite sides of the center of mass. Additionally, microrotors
with shorter SiO2 tails moved in smaller circles and were
more sensitive to changes in light intensity.