Elasto-magnetic Jumping Gels: Magnetic Latch-controlled Performance

Latch-Mediated Spring Actuation (LaMSA) drives the outstanding performance of many living organisms, including mantis shrimp and trap-jaw ants, which can generate high power motion without relying upon chemical reactions. In LaMSA systems, latches help to store and suddenly release elastic energy, allowing elastic recoil to dictate the power-amplified motion. A latch mechanism commonly found in natural, as well as engineered systems, is an elastic snap instability. While efficient, minimal feed-forward control can be realized with conventional snapping-based LaMSA systems. Here, we introduce a snapping soft gel device, in which the onset of the snap-through instability is mediated by a magnetic field. We fabricated disk-shaped swollen gel composites with dispersed magnetic particles. As the gels deswell, elastic internal forces develop and are resisted by an external magnetic field. Upon removing the magnetic field, the accumulated elastic energy is immediately released, driving a power-amplified snap-through instability. We present measurements that relate elastic energy storage and magnetic field dynamics to kinetic energy release in the snap-through deformation.