Scale-free, programmable design of morphable chain loops of kilobots and colloidal motors

Significance Researchers have synthesized many different types of colloidal particles that can convert an external stimulus into propulsion capable of propelling the particles, thereby making them “active.” The availability of active particles motivates building colloidal machines with controllable behavior. In biology, proteins are colloidal-scale machines that possess controlled morphing behavior as encoded in the sequence of their amino acids; this is an example of morphological control. Inspired by this idea, we show how to build finite colloidal machines that can morph and reconfigure their structure using active particles. The information that dictates the morphing behavior is encoded in the system by chaining sequences of active particles into loops, creating a type of colloidal robot.