3D Printing of Titanium Implant with Interconnected Pore Structures
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Problem Statement
Presently, stainless steel and titanium alloys are the most commonly used implant materials for orthopaedic applications. Stainless steel has a risk of nickel toxicity leading to allergic reactions within the human body. Both non-biodegradable titanium and stainless-steel implants may require revision surgery to remove the implants after the wound healing process. Stress shielding effects arising due to the mismatch in the Young’s modulus values between the bone and the implant poses a major threat contributing to revision surgery. Therefore, it is of primary importance to adjust the Young’s modulus of implants by careful selection of biomaterials.
Objective
This project aims to design, develop, and manufacture new semi-degradable titanium-magnesium (Ti-Mg) composites utilising inkjet 3D printing of porous Ti parts followed by pressureless infiltration of Mg into Ti parts. The new porous implant design mimics natural bone structure to bring closer the Young’s modulus of implant vs bone. Using this newly proposed approach, the 3D printed porous Ti-Mg implant could aid in faster healing and leave with the remaining metal structure within the body.
Key Benefits/ Outcomes
- NUS designed and printed three implant structures (cubic, octet, TPMS) with varying porosity (40-60%, pore by design) for bone implant applications and established the correlation of porosity vs. Young’s Modulus. This will be filed as an Invention Disclosure by the research team.
- SIMTech successfully developed the Mg infiltration process of Mg into the 3D printed Ti implants. Based on SEM & EDX, Mg is well distributed in the pores of the Ti implant.
- With superior mechanical properties, low Young’s modulus (5.2GPa) and average pore size closer to 100μm (pore by process), the 3D printed Ti+Mg composite demonstrates a promising prospect in the load-bearing biomedical applications.
- Based on all in-vitro cell toxicity tests comparing Ti vs. Ti-Mg samples, it is proven that Mg is effective in reducing stress in cells and reducing cell death. The release of Mg2+ ions from the Ti-Mg composite is beneficial to bone formation and the healing process.
Principal Investigator
Associate Professor Senthil Kumar
Senthil Kumar's research focus is in the area of Micro machining and Fixture Planning. He has co-authored two books entitled "Advanced Fixture Design for FMS" by Springer-Verlag, UK and “An advanced treatise on Fixture Design and Planning” by World Scientific. He has published more than 160 papers in the International Refereed Journals and Conferences. He serves in the editorial board of the Journal of Manufacturing Processes, Journal of Advanced Manufacturing Research, International Journal of Materials, Manufacturing and Optimization and was an associate editor of the IEEE Transactions on Automation Science in Engineering. Senthil Kumar has received several awards including the IES prestigious Manufacturing Achievement Award by the Institute of Engineers Singapore, Serope Kalpakjian’s Outstanding Young Manufacturing Engineer by the Society of Manufacturing Engineers, USA in recognition of significant achievements and leadership in the area of fixture design. In addition he has also received several teaching awards such as Teaching Honors List award, Commendation award and listed among the NUS Excellent Lecturers for excellence in teaching. Senthil Kumar has received research funding worth over S$ 10 millions from several agencies for conducting research in the field of micro machining and fixture design. Senthil Kumar has also served as the Assistant Dean of the Faculty of Engineering at the National University of Singapore and also held several positions including Vice Chairman and Treasurer of the Society of Manufacturing Engineers. He has also served in the mission of the United Nations Industrial Development Organization (UNIDO), Vienna, as a technical expert in Manufacturing.