Chlamydomonas-Inspired Water-Air Interface Mini-Robot with Intricate Tectonics, Programmable Locomotion, and Multifunctional Execution

Abstract With the rapid development of micro-robotics, non-mechanical stimulus-responsive water-air interface mini-robots have become a prominent focus in intelligent materials and environmentally responsive systems. However, their versatile application is challenged by a fundamental trade-off: simpler structures enable precise motion control, while complex configurations are often required for task execution, making it difficult to balance controllable locomotion with functional complexity. Inspired by Chlamydomonas, we have designed a water-air interface mini-robot with a sophisticated multifunctional architecture (CI-Robot), enabling both programmable motion and multifunctional execution, which demonstrated tremendous potential for application in confined aquatic environments and complex pipelines. The robot can achieve ultra-fast linear and rotational speeds (11.43 body/s, 8.98π rad/s), exceeding biological counterparts by 1.37- and 4.24-fold, via synergistic surface tension gradients and flagellar capillary mechanisms. The fluid-solid coupling simulation reveals the motion mechanism of CI-Robot in the transitional Reynolds regimes, in which the inertial force stabilizes the propulsion force, and the driving torque rapidly decreases to equilibrium (~15.21 μN, ~10⁻⁹ N·m), providing a theoretical basis for the analysis and regulation of the robot's motion behavior. The safe separation distance (~2/3 body length) without interference is determined by collective motion analysis, which guides the reasonable arrangement of CI-Robot group operation. Integrating propulsion and functional modules, the CI-Robot excels in obstacle avoidance, complex path planning, microplastic collection (up to 10 2 particles/mL), bacterial sampling (up to 100 CFU/mL) and site-specific molecular release, retaining samples for >30 minutes. This innovative mini-robot combining unparalleled speed, adaptability, and multifunctionality, will pave the way for transformative applications in cargo delivery, environmental monitoring, microplastic collection, and site-specific sampling in confined space.