RT Journal Article SR Electronic T1 Fast and programmable locomotion of hydrogel-metal hybrids under light and magnetic fields JF Science Robotics JO Sci. Robotics FD American Association for the Advancement of Science SP eabb9822 DO 10.1126/scirobotics.abb9822 VO 5 IS 49 A1 Li, Chuang A1 Lau, Garrett C. A1 Yuan, Hang A1 Aggarwal, Aaveg A1 Dominguez, Victor Lopez A1 Liu, Shuangping A1 Sai, Hiroaki A1 Palmer, Liam C. A1 Sather, Nicholas A. A1 Pearson, Tyler J. A1 Freedman, Danna E. A1 Amiri, Pedram Khalili A1 de la Cruz, Monica Olvera A1 Stupp, Samuel I. YR 2020 UL http://robotics.sciencemag.org/content/5/49/eabb9822.abstract AB The design of soft matter in which internal fuels or an external energy input can generate locomotion and shape transformations observed in living organisms is a key challenge. Such materials could assist in productive functions that may range from robotics to smart management of chemical reactions and communication with cells. In this context, hydrated matter that can function in aqueous media would be of great interest. Here, we report the design of hydrogels containing a scaffold of high–aspect ratio ferromagnetic nanowires with nematic order dispersed in a polymer network that change shape in response to light and experience torques in rotating magnetic fields. The synergistic response enables fast walking motion of macroscopic objects in water on either flat or inclined surfaces and also guides delivery of cargo through rolling motion and light-driven shape changes. The theoretical description of the response to the external energy input allowed us to program specific trajectories of hydrogel objects that were verified experimentally.