Design, fabrication, and characterization of a hydrostatic electroactive soft actuator for bio-inspired robots

In this paper, we design a hydrostatic electroactive soft actuator (HESA) inspired by octopus transverse musculature. We introduce the advantage of laser processing technology in HESA fabrication compared with existing similar actuators and discuss the effect of laser processing on the outer membrane of the actuator. In addition, a mathematical model is established for the single channel of the actuator, and the geometric parameters of the actuator are optimized by mathematical model simulation and experiments. We demonstrate the motion effect of the actuator. Our experiments show that the single piece of the actuator can achieve 32.2% strain in the axial direction and 7.8% strain in the radius direction. Furthermore, we stack three actuators together and describe their motion characteristics at different frequencies. The stacked actuators can realize axial elongation, radial shrinkage, and bend, which covers all the motion modes of the octopus biological transverse musculature. This study may lay a foundation for implementing the biomimetic soft actuator mimicking the octopus's transverse musculature, which is one less discussed but crucial muscular composition in the octopus-inspired arm research.