Woodruff School of Mechanical Engineering
COE/Structural Mechanics Seminar
Bioinspired self-adaptable materials and devices : bone-inspired materials and growing cardiovascular implants
Prof. Sung Hoon Kang
Hopkins Extreme Materials Institute
Thursday, February 27, 2020 at 11:00:00 AM
MRDC Building, Room 4211
Dr. Jerry Qi
In my presentation, I will first briefly introduce research projects in my group and focus on two studies about how we can design and realize materials/devices that can adapt to loading or physiological condition changes by changing their mechanical properties or shapes. First, I will present self-adaptive materials that can change their mechanical properties depending on loading conditions. Nature produces outstanding materials for structural applications such as bones and woods that can adapt to their surrounding environment. For instance, bone regulates mineral quantity proportional to the amount of stress. It becomes stronger in locations subjected to higher mechanical loads. This leads to the formation of mechanically efficient structures for optimal bio-mechanical and energy-efficient performance. However, it has been a challenge for synthetic materials to change and adapt their structures and properties to address the changes in loading conditions. To address the challenge, we are inspired by the findings that bones are formed by the mineralization of ions from blood onto scaffolds. I will present a material system that triggers mineral deposition from ionic solutions on organic scaffolds upon mechanical loading so that it can self adapt to mechanical loading. For example, the mineralization rate within the material system could be modulated by controlling the loading condition and a 30-180% increase in the modulus of the material was observed upon cyclic loading whose range and rate of the property change could be modulated by varying the loading condition. We envision that our findings can open new strategies for making synthetic materials with self-adaptable mechanical properties. Second, I will present self-adaptive cardiovascular implant devices that can accommodate the growth of pediatric patients. Right ventricle to pulmonary artery (RV-PA) conduits are used as a surgical palliative treatment for various congenital heart diseases. Due to the growth of the infant or child, these conduits require replacement as they cannot grow, which involves several major open-heart surgeries. To address this issue, we have investigated self-adaptable RV-PA conduits that grow via tailored self-unfolding mechanisms triggered by flow and pressure change associated with growth so that fewer surgeries are required from infancy to adulthood. I will present our numerical simulation results for design of self-adaptable implants, followed by experimental results of testing 3D printed implant devices using an in-vitro testing set-up. The results showed that our self-adaptable implants can match the required shape changes to accommodate the growth of children. We are hopeful that our approaches and findings can contribute to improving patient welfare by customized designs with growth potential based on patient anatomy, which can minimize the number of required surgeries and associated danger, trauma, and expenses.
Sung Hoon Kang is an Assistant Professor in the Department of Mechanical Engineering and is an associate faculty of Hopkins Extreme Materials Institute and Institute for Nano Biotechnology. He earned a PhD degree in Applied Physics at Harvard University and MS and BS degrees in Materials Science and Engineering from MIT and Seoul National University, respectively. Sung Hoon has been investigating bio inspired solutions to address the current challenges in synthetic materials and mechanical systems with applications including protection, healthcare, sensing, and energy. His research has been supported by NSF, AFOSR, NIH, ARO, and ONR. Throughout his career, Sung Hoon has co-authored 43 papers, has given ~120 presentations (including ~70 invited talks) and has three patents. His honors include 2019 China-America Frontiers of Engineering Symposium Alumnus, 2019 Johns Hopkins University School of Engineering Research Lab Excellence Award, FY 2018 Air Force Office of Scientific Research Young Investigator Program Award, 2016 National Academy of Engineering US Frontiers of Engineering Symposium Alumnus, and 2011 Materials Research Society Graduate Students Gold Award. He has been co-organizing ~30 symposia on 3D printing, mechanical metamaterials, mechanics of soft materials, and bio inspired materials at international conferences. He is a member of the American Society of Mechanical Engineers (ASME), Society of Engineering Science SES, American Physical Society (APS), and Materials Research Society (MRS). He serves as the Chair of the ASME Technical Committee on Mechanics of Soft Materials.
Refreshments will be served.