In the second week of MSU SROP, we got to meet with our faculty mentor for the summer. I was assigned to Dr. Xiaobo Tan, the principal investigator of the Smart Microsystems Laboratory. I was interested in Dr. Tan's projects involving his robotic fish, but there were no more available spots to work on them at the time.
Instead, I was assigned to help with a new project in coordination with on of his graduate students, Thassyo, and Dr. Chunqi Qian from the Department of Radiology. The scope of the project was to develop a method of placing a inductively couple coil near the brain to enhance MRI scans of the pituitary gland.
The first task of the project, was to construct a model of the human head with a very detailed representation of the make up of the nose and nasal passages. Dr. Tan arranged a meeting between the 4 of us where I received MRI scans of a human head from Dr. Qian. I spent roughly a week researching ways to generate a 3D image from MRI a set of MRI scans. Thassyo and I both both found programs to do this, but all of them reconstructed only the surface of the scanned head and not the internal structure which we were interested in.
We changed focus to find a previously constructed model. I discovered the MIDA model and Thassyo found a website called www.zygote.com.
The MIDA Model had parts that would have sufficed for our nasal model, but the model quality was not good enough to 3D print. The Zygote model was of a very good quality, but it was not free. Still, we decided to buy it which was a several week process.
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In the mean time, the next step of the project was to research and identify candidate materials for an apparatus to perform the method. Along the way, I learned about a few different smart materials such as shape memory alloys, electro-active polymers, shape memory polymers, silicone based pneumatic actuators, and carbon nanotubes. Since the type of material had to be one that would not affect the magnetic field of the MRI scanner, the first two were quickly discarded as candidates. The rest were analyzed as candidate materials for application. More detail is given in the "Project Paper" and "Design Ideas" documents.
While studying the different materials, I also had the chance fabricate and test a 3D printed shape memory polymer and a few pneumatic actuators. The fabrication of the 3D printed shape memory polymer was fairly simple. I drafted the model from journal article about 3D printed shape memory polymers and sent it to be printed. The shape was not very complex, so it was not difficult to sketch the model in solid works.
The pnuematic actuator, on the other hand, was a little more difficult to fabricate. To make the complex shapes desired, we need a mold to pour a two part silicone solution in. Then we allowed it to cure. Curing took anywhere form an hour to a few days depending on the set of solutions. While the silicone was curing, we had to degas the it so that there would be no air bubbles that could compromise the structure of the actuator. Degassing was difficult because each type of silicone had a work time, usually less than 45 minutes, before it would solidify to a point at which you could no longer degas.
Along with the struggles of the silicone itself, the mold also had its difficulties. Like the 3D printed SMP, we drafted these in SolidWorks. The shapes were much more complex and difficult to make. Once they were printed, I found that the silicone would adhere to the mold and cause it to tear if you were not careful when removing it. This could be fixed by coating the mold with something the silicone would not bond with.
Another side project of mine was to find out how we could print a more realistic model of the sinuses. The first one that we printed from zygote.com was made of a hard polymer and had no hard dimensions. An actual human sinus would be soft and more elastic. I looked into biomedical journals to find characteristics of the sinuses such as the average size, moisture content, and temperature. I also looked for materials that mimic cartilage and tissue. I had trouble finding any, so i searched for mechanical properties such as elasticity that could be translated to the mechanical properties of materials like the modulus of elasticity. Some of the information I found is capture inside the design Ideas document along with many thoughts and other information that I located.
By the end of the summer I, had identified 3 materials that I thought would be good candidates for the project. I fabricated and tested only two because the third material took a while to find, order, and receive. From what I had tested, I concluded that the best material would probably be the pneumatic actuator. However, neither of the materials were fabricated on the scale we needed and the third material was never tested. This is explained in more detail in "Project Paper" document.
Overall, this was a wonderful experience. Even though it was not the project that I had hoped for, it still provided a challenge, forced me to build skills, and honed my ability to solve multidisciplinary engineering problems. I was also introduced to the field of soft robotics and was in contact with graduate students working on different projects including the one that I had hope to work on.