Acoustic Mixed Photothermal Actuators for Multimodal Amphibious Robots

Abstract

Fabricating high performance light-driven soft actuators remains challenging due to the viscosity limited dispersion of photothermal agents, which induces structural defects and attenuates the resulting photomechanical response. Herein, an acoustic vibration mixing (AVM) strategy is introduced to achieve an exceptionally homogeneous and optimized loading integration of polydopamine (PDA) and polypyrrole (PPy) within a polydimethylsiloxane (PDMS) matrix. This processing paradigm ensures uniform thermal distribution and robust photomechanical transduction, enabling a bilayered microrobot to execute versatile locomotion modes. Experimental results demonstrate that our actuator achieves a 100° deflection at ∼350 mW/cm^2, and the microrobot can execute terrestrial crawling (0.1 BL/s), high-speed rolling (7.5 BL/s), and Marangoni-driven aquatic gliding (0.41 BL/s). Significantly, the superior photothermal conversion efficiency empowers the robot to generate sufficient torque to overcome interfacial capillary pinning, thereby facilitating seamless bidirectional transitions between land and water. This work provides a practical fabrication paradigm for multifunctional soft robotic systems designed for complex, cross-domain environments.