LLNL develops metamaterials that stiffen 3D structures

Researchers injected a magnetorheological fluid into hollow lattice structures built on LLNL’s Large Area Projection Microstereolithography platform, which 3D prints objects with microscale features over wide areas using light and a photosensitive polymer resin.

Lawrence Livermore National Laboratory (LLNL) researchers have introduced a new class of metamaterials that can nearly instantly respond and stiffen 3D-printed structures when exposed to a magnetic field, a development that could be applied to next-generation helmets, wearable armor and a host of other innovations.

The Lab-developed “field-responsive mechanical metamaterials” (FRMMs) employ a viscous, magnetically responsive fluid that is manually injected into the hollow struts and beams of 3D-printed lattices. Unlike other shape morphing or so-called “4D-printed” materials, the overall structure of the FRMMs does not change. The fluid’s ferromagnetic particles located in the core of the beams form chains in response to the magnetic field, which stiffens the fluid and the lattice structure as a result. This response happens rapidly — in less than a second. The research appears on the cover of the journal Science Advances, published online.

The technology could also be applied to next-generation helmets or neck braces, housing for optical components and soft robotics, among many other applications.