Recent advances in electrohydraulic actuation from structural design to emerging applications

Electrohydraulic actuators (EHAs) have emerged as versatile soft transducers that couple electrostatic attraction with fluid redistribution to generate diverse mechanical outputs. Their performance is governed not only by electrostatic loading but also by how actuator architecture directs the enclosed dielectric fluid and converts its motion into deformation. This review examines EHAs from this architecture-centered perspective. The fundamental mechanisms of electrostatic zipping and hydraulic redistribution are first introduced together with key design parameters and performance metrics. Representative structural architectures are then classified into planar pouch and zipping structures, localized protrusion and hydraulically amplified electrostatic taxel configurations, stacked and multilayer systems, and segmented or multidirectional designs. Their mechanical characteristics are discussed in terms of force, displacement, dynamic response, geometry-dependent fluid transport, and trade-offs among voltage, stroke, force, and bandwidth. Emerging applications in wearable haptics, soft robotics, reconfigurable surfaces, and soft pumping are subsequently surveyed. Finally, challenges associated with high-voltage operation, material durability, scalability, system integration, sensing, control, and standardized performance evaluation are discussed. This review highlights fluid-redistribution pathways as a central design variable linking actuator architecture to mechanical function and application-specific performance.