Light-fueled polymeric machines: Multiple actions at the microscale

Manipulating objects at the micro and nano scale is still an open fascinating challenge that scientists are addressing by proposing different approaches to obtain machines with basic or complex functions. Combining shape changing polymers that differently respond to optical stimuli on the basis of the molecular alignment, together with 3D structuration at the microscale (with nanometric features), we demonstrated synthetic microrobots entirely powered by light. The arbitrary design allowed to mimic diverse animal and even humanoid tasks as walking, grabbing or manipulating objects, even overcoming natural limitations present at such small scale. Liquid crystalline networks offer the possibility to perform different movements depending on their molecular alignment and, controlling by light their elastic deformation, wireless activation of micro-machines was obtained. We report here how tuning intrinsic parameters, as the lithographic ones, and an external setting as the actuation power, it is possible to induce diverse deformations and time responses. Such results can be exploited to tailor the working mechanism and actuation speed of different micro robots. Engineering a proper structural design and combining different time responding materials would generate not reciprocal motion, basic and necessary property to achieve swimming at the microscale. This first technical demonstration paves the way to a micro swimmer fueled by light.