A Porous Liquid-metal enabled Ubiquitous Soft Material (PLUS-M) was fabricated through loading chemically reactive iron nanoparticles into eutectic gallium–indium alloys (EGaIn), whose porosity and shape could be easily regulated via remote control. Such a PLUS-M could expand to a surprisingly large magnitude in a short time, say seven times its original volume, and generate adjustable closed cell foams inside. Owing to this unique property, the density of the PLUS-M can be easily controlled, allowing the PLUS-M to float on water or even pull up underwater heavy objects above the surface when subjected to heating. What's more, this porous material can transform between liquid and solid states through controlling the oxidation level of gallium using methods like heating and stirring. The reversible transformation between the solid porous structure and liquid state could be achieved more than 100 times without obvious performance degradation.

Rigid solenoid coils have long been indispensable in modern intelligent devices. However, their sparse structure and challenging preparation of flexible coils for soft robots impose limitations. Here, a transformable 3D curved high-density liquid metal coil (HD-LMC) is introduced that surpasses the structural density level of enameled wire. The fabrication technique employed for high-density channels in elastomers is universally applicable. Such HD-LMCs demonstrated excellent performance in pressure, temperature, non-contact distance sensors, and near-field communication. Soft electromagnetic actuators thus achieved significantly improved the electromagnetic force and power density. Moreover, precise control of swinging tail motion enables a bionic pufferfish to swim. Finally, HD-LMC is further utilized to successfully implement a soft rotary robot with integrated sensing and actuation capabilities. This groundbreaking research provides a theoretical and experimental basis for expanding the applications of liquid metal-based multi-dimensional complex flexible electronics and is expected to be widely used in liquid metal-integrated robotic systems.

The robust self-cleaning of a lotus leaf is the most classic and powerful phenomenon in nature, whose hybrid papillae and biological wax guarantee its functions.