Autonomous Liquid Metal Droplets Actuated by Ion Diffusion

The autonomous systems with embodied energy and intelligence show great potential to build future robots that are inspired by living organisms. This work proposes a liquid metal droplet-based machine that can be self-propelled in a controllable way through surrounding [CuCl 4 ] 2- ions interaction. Different autonomous behaviors of liquid metal droplets can be tuned by altering the distribution [CuCl 4 ] 2- of ions and the immersing ratio of CuCl 2 solution on liquid metal droplets. The underlying mechanisms behind the deformation and locomotion of the liquid metal droplet are attributed to the unbalanced surface tension and surface Marangoni flow induced by synergistic effect of galvanic replacement reaction and in situ displacement reaction. The autonomous liquid metal droplets based on microfluidics and sodium dodecyl benzene sulfonate (SDBS)-modified CuCl 2 solution are demonstrated, which induces the realization of shuttling a narrow channel, offset correction, climbing low-rise stairs, medium transportation, circuit repair, chemotactic transfer and escape from a maze independently. This work elucidates the autonomous liquid metal droplet (ALMD) driven by surrounding [CuCl 4 ] 2- ions, highlighting motion mode switching, interpretation of motion mechanisms, multifunctional manipulation and application, which offers a new path for further development of liquid robots with autonomous capability and embodied energy, and progressing toward physically intelligent robots.