Self-folding origami implants for the treatment of brain aneurysms

• Applicant: Dr.-Ing. Prasanth Velvaluri
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 527449568

Intracranial aneurysms are balloon-like expansions along blood vessels in the brain. Such aneurysms could rupture, leading to death when left untreated. Currently, state-of-the-art treatments include placing a braided stent made of NiTi wires along the diseased blood vessel or inside the aneurysm to reduce the blood flow. Though braided implants have high success, they have specific limitations: torsional collapse, simple geometries, and passive operation. The next jump in innovation is to have implants with sensing capabilities, including antennas and sensors that could monitor the implant function and trigger a response if vital values reach a critical limit. Current innovations in microsystem technologies allow implants to be fabricated with additional functionalities. But the challenge lies in delivering such implants using minimally invasive treatments, which require the implants to be crimped and placed into a small catheter. Expected shortcomings occur while crimping as sensitive sensors and antennas could be damaged. Origami, the ancient art of folding, provides ideal solutions to fold implants to a fraction of their initial size while keeping certain regions stress-free. A proof-of-concept study was investigated previously in my own work. An origami design approach is very attractive as the stress-free regions on the implant can be used to integrate the sensitive components, which could be safe during the folding/unfolding of the implants. Moreover, such designs give a pathway to fabricate patient-specific implants, which are essential to treat patients with complex aneurysm geometries. Origami-based implants for neurological use can be realized using thin-film technology. The only limitation is that such small origami implants are impossible to be manually folded into their crease pattern for folding and loading in the catheter. Therefore, a dedicated self-folding mechanism that can be monolithically integrated into the microsystem technology is necessary to realize the goal of intelligent implants. Thus, in the current proposal, I propose a novel approach for self-folding using NiTi/Mo/NiTi tri-layer composites along with the hinges of the origami implant. The hinges bend due to bimetallic stress paired with shape memory alloy transformation when subjected to a temperature pulse. This allows the implant to be slightly folded as per the predetermined origami crease pattern, after which the complete folding of the implant can be done in a crimping setup. If succeeded, this work gives a pathway to fabricate intelligent patient-specific brain implants The key objectives of this proposal are: • Proposing a new self-folding mechanism, which can be monolithically integrated with the microsystem technology. • To investigate origami-based flexible designs with the potential to be used as intelligent implants. • To investigate self-foldable patient-specific origami-based implants for treating patients with complex aneurysm geometries.

• DFG Programme: Research Grants
• International Connection: USA
• Cooperation Partner: Professor Dr. Richard D. James