Bioinspired magnetically driven liquid manipulation as microrobot

There is growing interest in controlled liquid manipulation that is crucial for microfluidic transport, medical diagnostics, and chemical analysis. Existing liquid manipulation methods are restrained in 3 aspects: velocity, space, and environment. Inspired by nature, here, we report a magnetically driven liquid precise manipulation strategy based on the adhesive force between the internal superhydrophilic iron bead and the liquid, which can drive or stop droplets within velocity and volume range of 4 orders of magnitude in an arbitrary path. The droplet velocity can reach ∼2 m/s (2,000 body lengths/s). This strategy breaks space limitation and allows droplets to move along a 360° circle in 3 dimensions and to climb/downhill with any gradient. Magnetically driven liquid manipulation on general solid surfaces or in liquid environments are reported. We propose the concept of the hydrobot and reveal its practical application potential in the fields of soft microrobotics, including cleaning and cargo transportation.