Design, analysis and experiments of a magnetic microrobot capable of locomotion and manipulation at water surfaces

Functionalized microrobots have various potential applications in aquatic missions depending on their locomotion and manipulation capabilities. In this study, a novel star-shaped magnetic microrobot capable of locomotion and manipulating microobjects at water surfaces is reported. The aquatic microrobot, a 40 mu m-thick star-shaped sheet, could not only locomote at water surfaces freely, but also trap, transport and release non-magnetized microobjects by regulating the frequency and orientation of the rotating magnetic field. A transporting velocity of over 2 mm s(-1) which is much greater than the locomotion velocity of the microrobot itself can be achieved. A dynamic model describing the transporting process based on the microrobot is established to fully understand the mechanism of the fast transporting. It indicates that the attractive force and collision between the microrobot and microobjects contribute to the fast transporting. The delivery along specific trajectories and assembly of multiple micro balls using the magnetic microrobot are also demonstrated. Due to its agility, easy fabrication and low cost, this magnetic microrobot has potential applications in microscale aquatic missions.