Magnetic field-programmable phase-transition fluids for dynamic pneumatic control in soft robots

Abstract

• Dynamic Mobile Soft Valves: Developed reconfigurable MRF-based valves enabling simultaneous multi-channel occlusion through magnetic field-programmed migration and splitting. • Millisecond-Responsive Shape Locking: Achieved rapid (<600 ms) phase-transition locking for soft actuators, allowing precise shape fixation and sequential deployment control. • Sequential Multi-Channel Logic Control: Demonstrated programmable pneumatic logic in double T-shaped airways using MRF’s dynamic mobility under gradient magnetic fields. Addressing the integration challenges posed by rigid solenoid valves in pneumatic soft robots, this study introduces a programmable magnetic field-regulated control strategy leveraging the phase transition characteristics of magnetorheological fluid (MRF). By embedding MRF within soft pneumatic channels, its reversible liquid-solid transition under magnetic fields is utilized to achieve dynamic gas-path on/off switching. In the absence of a magnetic field, MRF remains in a fluidic state, allowing gas flow; upon exposure to a magnetic field, it solidifies within milliseconds to effectively block the channel. The inherent fluidic nature of MRF enables the formation of reconfigurable "mobile soft valves," which can split or migrate under gradient magnetic fields for simultaneous multi-channel occlusion. This capability facilitates complex sequential logic operations and synchronization of cross-shaped pneumatic channels. Furthermore, a phase-transition locking mechanism provides rapid (<600 ms) shape fixation for soft actuators, enabling precise sequential deployment control of tri-chamber pneumatic structures. This innovative approach eliminates the reliance on multiple rigid valves, offering a unified platform for seamless structure-drive-sensing integration in soft robotics.