Pressure-controlled magnetic soft actuator with local stiffness modulation via tapered tube buckling

Abstract We present a novel soft tentacle actuator combining magnetic actuation with pressure-controlled local stiffness modulation. By utilizing a tapered tube design, the actuator achieves controlled buckling progression under negative internal pressure, enabling precise manipulation with a single-axis magnetic field. We developed a comprehensive deformation model incorporating the effects of cross-sectional buckling and geometric tapering, which demonstrated excellent agreement with experimental results. Through numerical optimization, we determined the optimal magnetization profile that maximizes the operational workspace. The established pressure-magnetic field mapping enabled the actuator to trace arbitrary trajectories. This design approach overcomes the limitations of conventional magnetic soft actuators by achieving multi-degree-of-freedom control without requiring complex magnetic field systems, offering potential applications in minimally invasive surgery and micro-manipulation tasks.