A multi-stimuli responsive, growing liquid robot

Stimuli responsive soft robots are recently gaining significant interest in a range of applications including flexible electronics and biomedicine. However, most soft robots are still limited in their responses to responding to stimuli by deforming in a pre-programmed, nastic manner. Therefore, implementing the adaptability of living organisms, which grow and actively respond to the environmental stimuli, in an artificial system is an important scientific challenge that remains to be solved. Inspired by tip growing cells of nature, here we report a multi-stimuli responsive, growing liquid robot based on non-solvent induced phase separation of polymeric solution. Because the growth is driven by the balance between internal pressure and wall strength as in pollen tubes and fungal hyphae, the size of the robot can be precisely controlled during growth. The robot can sense the direction of multiple stimuli–gravity, mechanical contact, and light–and adjust its growing direction. Owing to its unique characteristics, the robot can transport another liquid, print 3D structures in a confined space, and bypass mechanical obstacles.