  Through billions of years of evolution, microorganisms mastered unique
swimming behaviors to thrive in complex fluid environments. Limitations in
nanofabrication have thus far hindered the ability to design and program
synthetic swimmers with the same abilities. Here we encode multi-behavioral
responses in artificial swimmers such as microscopic, self-propelled tori using
nanoscale 3D printing. We show experimentally and theoretically that the tori
continuously transition between two primary swimming modes in response to a
magnetic field. The tori also manipulate and transport other artificial
swimmers, bimetallic nanorods, as well as passive colloidal particles. In the
first behavioral mode, the tori accumulate and transport nanorods; in the
second mode, nanorods align along the tori's self-generated streamlines. Our
results indicate that such shape-programmed microswimmers have the potential to
manipulate biological active matter, e.g. bacteria or cells.
