Today, I woke up excited to pay another visit to Suite 420 at the Chesterfield Lab in Durham, working on refining yesterday’s project and exploring a new realm of creation. In the morning, Dr. Kirillova and I worked with 3D printing expert Rex; he explained the fundamentals of using a rather sophisticated software to 3D print a model that Dr. Kirillova had in mind. Rex clarified that there are many careful considerations when choosing settings to 3D print a model! These include factors like the material used (PLA, polylactic acid, or PVA, polyvinyl alcohol), the nozzle and Printcore used, the temperature of the Printcore, and the speed at which the object is filled.
At first, the settings we had used to print the object did not make the printer happy and it wouldn’t complete the job at all. After spending a good hour troubleshooting the machine, we finally got our first model. However, it wasn’t our best model because it lacked an outer perimeter, so the volume percent of the filler was not entirely accurate since the model was not a perfect cube. We tried a second time, adding a perimeter layer so that the object would be more substantial and accurate. Surprisingly, it worked well! After Olivia’s return later in the afternoon, we all printed several more models. Dr. Kirillova also brought to my attention that there are several other types of 3D printing used for different applications. Today, we used one called fuse deposition, whereby solid material is melted to print the new models. Other techniques include carbon printing, titanium printing, printing that uses liquid resin, and even bioprinting, whereby living cells are printed in hydrogels!
The purpose of the print today was to combine it with the bone adhesive to test its structural durability. In other words, the PGLA fiber filler that I mentioned yesterday is similar to the PLA (Polylactic Acid) material used today to print the models. We printed porous cubes of different designs, all 28% PLA and 72% open space by volume, so that tetranite could later be applied inside the open spaces within the cube and solidify to create a strong structure. The PLA housing acts almost like a scaffold for the tetranite. These filled cubes can later be strength tested to see how much the PLA structure will help reinforce the brittle tetranite. In theory, these PLA cubes (or those of other shapes) can be used alongside the tetranite to create the most durable, efficient, and biodegradable solution to help mend broken bones together inside bodies! More complex bone repairs will of course require more durability relative to the size of the combination used. Lucky for us, PLA is a biodegradable material despite its plastic-like appearance.
In the afternoon, Olivia and I polished the bone adhesive samples we made yesterday (her titanium and my salt sample). The process consists of placing the cylindrical sample in a mold that will hold it in place while it is sanded against fine sandpaper with water. This helps to smoothen the top and bottom surfaces of the cylinder, so when it undergoes compression testing later, the data collected will be more accurate. In addition, we measured the lengths and widths of the polished samples with a caliper, something I had actually never used before this day! Olivia’s titanium samples were quite easy to polish, and they even gave off a nice shine after they were completed. My salt samples, however, proved to be more brittle, so I was only able to successfully polish two of my four original samples. Nevertheless, I am thankful that I was granted permission to collect my samples and one of the 3D printed models today to bring home; they will serve as a lasting souvenir of an incredibly captivating project!
Tomorrow, I am assigned to work in a compression lab to witness some of the actual strength tests that are performed on the polished bone adhesive samples. This lab will be on Duke’s campus, so I am eager to take the next step of this invigorating journey in a fresh environment!