Printable materials that can undergo large, anisotropic, rapid, and reversible deformations for 4D printing applications.
3D printing revolutionized manufacturing, and now researchers are setting their sights on four-dimensional (4D) printing, a term that describes the additive manufacturing of stimuli-responsive materials that morph into distinct 3D geometries over time. These commutable structures may enable an unprecedented variety of smart devices such as soft robots or morphing medical devices, but requires fine control over material microstructures in order to influence macroscopic deformations. For example, controlling the local coefficient of thermal expansion in printed structures can create objects with a negative global coefficient of thermal expansion that contract, rather than expand, while heating. However, this deformation is limited in size and is isotropic in nature. Direct-write printing (or extrusion printing) can be used to create hydrogels that locally swell in a single direction, which can be utilized to create structures that deform on a macro scale, but hydrogel shape change is limited by diffusion speed and the requisite aqueous environment. In order to truly achieve 4D smart systems, it would be necessary to create printable materials that can undergo large, anisotropic, rapid, and reversible deformations.
Technology Description
Liquid crystal elastomers (LCEs) are mechanically-active, stimuli-responsive soft polymers that undergo large, reversible, anisotropic shape change in response to a variety of stimuli, including heat and light. These materials require neither an external load nor an aqueous environment to undergo this change. By controlling molecular orientation using shear forces, LCE shape change can be patterned spatially and hierarchically. Direct-write printing can then be used to print structures capable of being triggered to morph from one state to another. This is a scalable technique that produces 3D structures capable of reversible, untethered, and low-hysteresis shape change, enabling 4D printed materials to operate as autonomous morphing structures capable of reacting to stimuli.Advantages
Provides increased molecular control for better programming of desired outcome
Scalable technique can be implemented for applications at all scales
Shape change is comparably large
Rapid deformation is a significant improvement over 3D printed hydrogels; transitions can occur on the scale of milliseconds
Deformations at the macroscale are reversible
Shape change does not require a tethered power source or an aqueous environmentApplications
Transducing thermal, chemical, magnetic, or light energy into
mechanical work
Soft robots
Morphing medical devices, such as artificial muscles
Sensors
Aerospace systemsIP Status
US-2019-0077071-A1 (non-provisional); provisional patent filedRelevant Publications
Ambulo C P, Burroughs, J J, Boothby J M, Kim H, Shankar M R, Ware T H. 4D Printing of Liquid Crystal Elastomers. ACS Applied Materials and Interfaces. (2017) DOI: 10.1021/acsami.7b11851.External links
Shankar Lab GroupInnovators
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.