3-D Micro Swimming Drone with Maneuverability

Wirelessly powered and controllable microscale propulsion in 3-D space is of critical importance to micro swimming drones serving as an active and maneuverable in vivo cargo for medical uses. This aritcle describes a 3-D micro swimming drone navigating in 3-D space, propelled by unidirectional microstreaming flow from acoutsically oscillating bubbles. 3-D propulsion is enabled by multiple bubbles with different lengths embedded in different orientations inside the drone body. Each bubble generats propulsion by applying acoustic field at its resonance frequency. Therefore, 3-D propulsion in any direction is achievable by resonating bubbles individually or jointly. The drone with such a complex design was fabricated by a two-photon polymerization 3-D printer. For stable maneuverability, a non-uniform mass distribution of the drone is designed to restore the drone to the designated posture under any disturbances. The restoration mechanism is formulated by a mathematical model, predicting the restoring time and shows an excellent agreemnt with the experimental results. This 3-D micro swimning drone proves its robustness as a manueverable microrobot navigating along programmble path in a 3-D space through selective and joint actuation of microbubbles.