Gel-Based Marangoni Actuators: Mechanisms, Material Designs, Driving Modes, and Cross-Scale Applications.

Marangoni actuators, rooted in interfacial tension gradients, stand as a significant advancement in micro-nano engineering. This review synthesizes their core mechanisms, which hinge on establishing gradients via temperature or solute concentration, with structural designs facilitating directional motion. Key actuation modalities, encompassing light, chemical, and electric driving, exhibit distinct characteristics in controllability and responsiveness. Their applications span cross-scale scenarios, from microscopic operations to macroscopic functional implementations. Current challenges involve optimizing performance and enhancing multi-field coordination, while future directions focus on advanced materials, intelligent regulation, and scalable fabrication. These actuators hold substantial potential in interdisciplinary fields, such as biomedicine, environmental engineering, and microfluidics.