Bacteria inspired soft robots with responsive flagellar bundles

When sensing favorable signals, peritrichous bacteria such as E. coli can switch from the “running” to the “tumbling” mode by reversing the rotation direction, resulting in the unbundling of flagella. Inspired by this adaptive behavior, we have developed bi-flagellated soft robots using 3D-printed liquid crystal elastomers/gels. These artificial flagella exhibit helicity reversal when the environmental temperature exceeds the nematic-to-isotropic temperature. The structural parameter transition allows individual flagella to change from helical to planar structures. Meanwhile, the bundling states between the flagella can be manipulated through the hydrodynamic couplings during rotation, thus altering the propulsion behavior of the robots. This dynamic control mechanism, akin to the bacterial chemotactic behaviors, effectively transforms material intelligence into self-adapting robots. Our design presents a novel approach to fabricating adaptive soft machines, with potential applications in various fields of robotics and beyond.