Bio-inspired shape morphing soft magnetic locomotion actuators - a novel method of preparation and testing

Abstract

Soft magnetic materials have drawn the attention of researchers worldwide due to their field response actuation, reversible shape morphing capability, remote controllability, an extensive penetration range in numerous circumstances, and diverse applications in the field of engineering, robotics, and medical science. The fabrication and programming of these actuators have been difficult, expensive, and complex, specifically in generating locomotion. This work aims at achieving the kinetic locomotion in actuators inspired by the caterpillar, inchworm, and centipede using a very simplistic approach. To achieve this, a programming technique has been developed through which a magnetic elastomer can be programmed on the curing bed to mimic the motion of the organisms mentioned above. The Carbonyl Iron (CI) particles dispersed in a viscous thermoplastic polyurethane (TPU) solution are cured under a magnetic field generated using a rotating permanent magnet. In the presence of a magnetic field, the magnetic particles tend to align in the direction of the magnetic field in the matrix. After curing, the actuator has an initial shape that changes to the programmed shape upon applying the magnetic field. The change in shape depends on the intensity of the magnetic field, i.e. if the magnetic field during programming was 0.5 T, then to achieve the programmed shape, we need to maintain the field value greater than or equal to 0.5 T. At the lower field values, the change in shape is slow. Thus, locomotion of the sample has been achieved by controlling the magnetic field intensity.