Optically Driven Soft Micro Robotics

The miniaturization of robots and actuators down to the micrometer length scale constitutes a fascinating technological challenge. Their development faces fabrication issues due to the small dimensions and their design must take into account how physics laws behave on those length scales. Last but not least, a major issue is energy delivery and management. In this scenario, light emerges as a versatile tool for the fabrication and, even more importantly, as an energy source. Optically driven micromachinesin which optical stimuli can be efficiently converted into mechanical workhave been realized in various contexts. This Review collects recent advances in this field, focusing on optical micro robots realized in soft polymers. Starting from an overview of the photoresponsive materials that have been employed, the various designs and realizations of such devices are shown exhibiting tasks and capabilities like swimming, walking, and the manipulation of microscopic objects. In the last part, frontiers studies in the integration of polymeric structures with biological organisms are shown. In many of the reported studies, untethered operation is a key issue, seen as a fundamental requirement toward the development of smart robots that can autonomously perform tasks and respond to their environment.