4D printing, in which printed objects demonstrate functional responses to stimuli, represents the very forefront of additive manufacturing technology. Programming material response in a voxel-by-voxel fashion during fabrication provides a versatile route towards the realization of soft machines that can be actuated by a range of stimuli such as heat, light, or solvent. The ability to define the molecular orientation of each volume unit will unlock a pathway to designing transformable 3D geometries, including complex active kinematic and mechanical logic units, biomimicking actuators, and magnified actuation profiles in soft robotics. Current fabrication approaches such as in-mold fabrication or deposition-based methods fail to decouple molecular patterning from the build sequence, constraining access to this revolutionary 3D design space.
Description
Molecular patterning often relies on the self-assembly of liquid crystalline polymers (LCPs) from constituent monomers. By exploiting the combination of anisotrophic magnetic susceptibility of LC monomers and a spatially-selective photopolymerization technique, it is possible to independently dictate the molecular alignment and polymerize the structure. First, monomer alignment is directed using a 300mT magnetic field generated using permanent magnets mounted on a rotating stage. A digital micromirror device (DMD) polymerizes desired regions to preserve this orientation voxel-by-voxel; there is no restriction on multiple molecular orientations within a single layer. The monomer can be changed between subsequent layers, introducing functional gradations that can elicit dynamic and varied response profiles in the finished structure. The entire process is carried out at a constant temperature,
eliminating in-process deformation and preemptive thermal curing as well as reducing process times. This platform is posed to usher in the next generation of responsive, transformable 3D geometries with microstructural and compositional gradients that until now have proved impossible.
Applications
• Freeform fabrication of light responsive topographies
• Heat responsive structures capable of generating Gaussian curvatures
from flat geometries
• Multi-responsive robotic manipulators
• Kinematic and mechanical logic units
• Biomimicry-inspired soft robotics
Advantages
• Allows user to specify the molecular orientation of each volume unit
• No restriction on how many different molecular orientations can be
contained in a single layer
• Decouples molecular patterning from the build sequence
• Eliminates in-process deformation and preemptive thermal curing
• Shorter process time
Invention Readiness
Concept
IP Status
https://patents.google.com/patent/US20220355540A1
