posted on 2020-03-02, 18:07authored byXi Chen, Chao Zhou, Yixin Peng, Qizhang Wang, Wei Wang
Photochemically
powered micromotors are prototype microrobots,
and spatiotemporal control is pivotal for a wide range of potential
applications. Although their spatial navigation has been extensively
studied, temporal control of photoactive micromotors remains much
less explored. Using Ag-based oscillating micromotors as a model system,
a strategy is presented for the controlled modulation of their individual
and collective dynamics via periodically switching illumination on
and off. In particular, such temporal light modulation drives individual
oscillating micromotors into a total of six regimes of distinct dynamics,
as the light-toggling frequencies vary from 0 to 103 Hz.
On an ensemble level, toggling light at 5 Hz gives rise to controlled,
reversible clustering of oscillating micromotors and self-assembly
of tracer microspheres into colloidal crystals. A qualitative mechanism
based on Ag-catalyzed decomposition of H2O2 is
given to account for some, but not all, of the above observations.
This study might potentially inspire more sophisticated temporal control
of micromotors and the development of smart, biomimetic materials
that respond to environmental stimuli that not only change in space
but also in time.