A Magnet-Driven Soft Bistable Actuator

Bistable morphing structures are widely used as actuation mechanisms in soft actuators, soft robotics, energy absorbers, mechanical computers, optical lenses, metamaterials, and flexible electronics. However, untethered actuators, repetitive actuators, and hybrid-assembly (containing in-plane-assembly and out-of-plane-assembly) actuators remain challenging to realize using existing bistable structures, which hinders the novel application of such actuators in research, engineering, and daily life. This problem is solved by fabricating a magnet-driven soft bistable actuator (MSBA) unit. The self-buckling of the circular polydimethylsiloxane (PDMS) sheet ensures the bistability of the actuator and allows it to operate as an independent unit, free of external constraints. The reorientation of neodymium-iron-boron (NdFeB) microparticles embedded in the PDMS sheet enables the dome-shaped actuators to exhibit repetitive snapping under the stimulus of a direction-switching magnetic field. The potential of this MSBA unit in bionics, electronics, and biomechanics applications is demonstrated in systematic studies involving modification of the buckling deflection and magnetic moment density. The MSBA unit exhibits excellent performance in hybrid designs and intelligent systems.
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