On University of Illinois’s Grainger College of Engineering Week: Our bodies are unique, so how do we engineer implants that work for each person?
Xiaojia Shelly Zhang, David C. Crawford faculty scholar and associate professor of civil and environmental engineering and mechanical science and engineering, explores how 3D printing can help.
Dr. Xiaojia Shelly Zhang is a David C. Crawford Faculty Scholar and Associate Professor at the Department of Civil and Environmental Engineering at the University of Illinois at Urbana Champaign (UIUC). She directs the MISSION (MuIti-functional Structures and Systems desIgn OptimizatioN) Laboratory. Dr. Zhang holds B.S. and M.S. degrees from UIUC and a Ph.D. degree from Georgia Tech. Her research explores topology optimization, inverse design, 3D/4D printing, and data-driven models to develop multi-functional, sustainable, and resilient materials, structures, and robots for applications at different scales. Dr. Zhang serves on the Executive Committee of the International Society of Structural and Multidisciplinary Optimization (ISSMO) and is a Review Editor for the Journal of Structural and Multidisciplinary Optimization and an Associate Editor for the Journal of Applied Mechanics. She is the recipient of the National Science Foundation CAREER Award, the ASME Journal of Applied Mechanics Award, the DARPA Young Faculty Award, the AFOSR Young Investigator Award, the Leonardo da Vinci Award from ASCE, Dean’s Award for Excellence in Research, Dean’s Award for Early Innovation, the DARPA Director’s Fellowship, the Thomas J.R. Hughes Young Investigator Award from ASME, UIUC Campus Distinguished Promotion Award, the Henry Hess Early Career Publication Award from ASME, the Haftka Young Investigator Award from International Society for Structural and Multidisciplinary Optimization (ISSMO).
Bio-Inspired 3D Printed Materials to Support Bone Healing
In nature, materials like bone, seashells, and wood are rarely uniform. Instead, they exhibit irregular, intricate microstructures that serve a purpose – like regulating stress or protecting tissues. Inspired by these natural designs, the MISSION Lab at Illinois Grainger Engineering asked: can we engineer materials that mimic this irregularity to better support healing in the human body?
Our team developed a computational framework to design what we call irregular architected materials. These are 3D-printed structures built from a small set of geometric building blocks, combined in varying frequencies across the material to direct mechanical stress in a controlled way. Unlike conventional materials with uniform properties, ours can locally adapt their stiffness or compliance to match the mechanical needs of surrounding tissue.
One promising application lies in orthopedic repair. After a bone fracture, mechanical stress in the healing region must be just right – not too high to damage, and not too low to inhibit regeneration. We engineered a femur support structure using our materials that achieves this balance. By programming the internal geometry of the support, we ensured that stress is evenly distributed and precisely concentrated in healing regions where it’s needed to stimulate growth.
We validated our designs both computationally and through physical testing with 3D-printed samples. The results showed remarkable agreement between target and actual stress distributions. Our materials, though disordered in appearance, perform with precision – echoing the complexity and function of natural bone.
This work opens the door to a new class of mechanically intelligent implants – ones that adapt to and support the body more like nature does, and less like traditional uniform supports.
Read More:
[Nature] – Modulate stress distribution with bio-inspired irregular architected materials towards optimal tissue support
