Functional Fluid-Based Soft Robotic Actuation

Soft robots actuated by fluids offer a series of inherent benefits, including safe human-robot interaction, cost-effectiveness, and geometry adaptability for manipulating delicate objects, making them highly promising in wearable devices, medical equipment, and bio-inspired robots, etc. However, the foremost challenge in fluidic actuation lies in developing standardized, universal actuation methods that are flexible, portable, powerful, fast, low-cost, and safe, rather than still relying on existing rigid pumps and valves originally developed for traditional mechatronic systems. Recent advancements in responsive fluid materials have enabled the emergence of novel functional fluid actuation technologies that convert electrical, magnetic, thermal, chemical, and acoustic energies into fluidic energy without mechanical movable components. These technologies have great potential to provide flexible, portable, and powerful fluidic actuation customized for soft robotics. Here, functional fluid actuation generated from different energies, and their basic principles, structure designs, and robotic applications are introduced. Finally, the advantages and disadvantages of different functional fluid actuation are discussed, and their future trends are prospected. It is hoped this review can provide guidance for the development of fluidic actuation technology specifically tailored for soft robotics.