Method of 3D printing that allows the user to define the molecular orientation of each volume unit.
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.
Technology 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.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 timeApplications
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 roboticsStage of Development
ConceptIP Status
Provisional patent filedRelevant publications
Mohsen Tabrizi, Taylor H. Ware, and M. Ravi Shankar. Voxelated Molecular Patterning in Three-Dimensional Freeforms. ACS Applied Materials & Interfaces. (2019) DOI: 10.1021/acsami.9b04480External links
Shankar Lab Group
Innovators
M. Ravi Shankar, PhD
Professor, Industrial Engineering, mechanical Engineering & Materials Science
University of Pittsburgh
Dr. Shankar is the recipient of the 2014 Institute of Industrial Engineers Hamid K. Eldin Outstanding Early Career in Academia Award, the Air Force Office of Scientific Research Summer Faculty Fellowship in 2012, the 2010 Society of Manufacturing Engineers’ Outstanding Young Manufacturing Engineer Award, and the William Kepler Whiteford Faculty Fellow at the University of Pittsburgh in 2009.Education
PhD, Industrial Engineering, Purdue University
MS, Industrial Engineering, Purdue University
BS, Mechanical Engineering, Indian Institute of TechnologyPublications
Ghasri-Khouzani, M., Peng, H., Attardo, R., Ostiguy, P., Neidig, J., Billo, R., Hoelzle, D., & Shankar, M.R. (2019). Comparing microstructure and hardness of direct metal laser sintered AlSi10Mg alloy between different planes. Journal of Manufacturing Processes, 37, 274-280. doi: 10.1016/j.jmapro.2018.12.005.
Saed, M.O., Ambulo, C.P., Kim, H., De, R., Raval, V., Searles, K., Siddiqui, D.A., Cue, J.M.O., Stefan, M.C., Shankar, M.R., & Ware, T.H. (2019). Molecularly-Engineered, 4D-Printed Liquid Crystal Elastomer Actuators. Advanced Functional Materials, 29(3). doi: 10.1002/adfm.201806412.
Smith, M.L., Gao, J., Skandani, A.A., Deering, N., Wang, D.H., Sicard, A.A., Plaver, M., Tan, L.S., White, T.J., & Shankar, M.R. (2019). Tuned photomechanical switching of laterally constrained arches. SMART MATERIALS AND STRUCTURES, 28(7). doi: 10.1088/1361-665X/ab1ce4.
Tabrizi, M., Ware, T.H., & Shankar, M.R. (2019). Voxelated Molecular Patterning in Three-Dimensional Freeforms. ACS APPLIED MATERIALS & INTERFACES, 11(31), 28236-28245. doi: 10.1021/acsami.9b04480.
Abolghasem, S., Basu, S., Shekhar, S., & Shankar, M.R. (2018). Mapping dislocation densities resulting from severe plastic deformation using large strain machining. JOURNAL OF MATERIALS RESEARCH, 33(22), 3762-3773. doi: 10.1557/jmr.2018.264.