Coming straight from Deakin University’s School of Engineering, a group of innovative students have released a new report detailing their experimentation with 3D printed, biocompatible enclosures for microdevices. The project, headed by Scott Adams, Abbas Kouzani, Mazher Mohammed, Clara Usma, and Susannah Tye (from the Minnesota-based Mayo Clinic), is aimed at creating 3D printed housing for electronic, medical microdevices made to be implanted for deep brain stimulation (DBS).
In DBS, the microdevice sends an electric impulse to a targeted part of the brain, helping to treat the symptoms of several different neurological disorders. What makes the 3D printed enclosures so important to these devices is the biocompatible nature of printable materials, which, in this project, includes medical-grade silicone and other viscous liquids and pastes. In their report, biocompatibility is defined as “compatibility with living tissue or a living system by not being toxic, injurious, or physiologically reactive and not causing immunological rejection”. 3D printing with certain materials can definitely help achieve this goal of biocompatibility, and this group of forward-thinking engineers proves it in their latest ongoing report on properly encasing these microdevices.
The team designed these physical casings through CAD program SolidWorks, creating three different prototypes, thus far. Using the EnvisionTEC Bioplotter 3D printer, which prints at a rapid pace and in multiple types of material, the enclosures were built with a defined form and an open inner structure. The team chose to utilize the Bioplotter over more traditional 3D printers due to it’s ability to accurately print with biocompatible silicone material. By printing with medical-grade silicone, these microdevices can be safely enclosed and implanted into the body without causing any damage or being rejected by the body, which, especially in DBS, is an important factor. The three designs (pictured below) are shaped in slightly different ways, each one modified to deal with potential issues with implanting DBS microdevices.
The first rectangular shape, is a two-piece design that, when put together, creates an inner cavity for the microdevice to be housed. The objective of this particular design was to create the most simple, easy-to-print encasing that would still be functionally implantable. The second design, which is an altered, more rounded version of the original, was created with the actual implanting in mind. This design is rounded in order to soften the sharp edges from the first prototype, allowing the encased microdevice to travel to it’s destination with causing any damage. This second prototype was still closed in the same manner as the first, with a flat lid that holds the DBS device within the inner cavity. The last design that the team produced is completely cylindrical in shape, creating a one piece case that requires no separately printed lid. By removing the lid from the design there are less parts to be sealed up, which, in turn, should provide the microdevice with better isolation from the surrounding brain tissue.
In order to test the quality of these different microdevice enclosures, the team executed both a submersion test and an operation test. The submersion test was performed in order to test the potential leak vulnerabilities in the casings. First, the team put a piece a paper inside the cavity (obviously not wanting to damage the actual DBS microdevice with this initial test); then, they submersed the individual prototypes under 10 centimeters of water for a few hours. They happily discovered that their designed enclosures did indeed completely seal the inner cavity, thus, keeping the paper inside completely dry and moisture-free. Once the encasing was proven to be water-proof, the operation test was performed to discern whether the actual DBS device would function when submerged. After sealing the device within the various designs, the team ran wires from the device to a coin cell battery and submerged the encasing once again. Like the submersion test, the operation test also proved to be successful, proving that the DBS device could still function properly when submerged underwater.
The conclusion that this team of engineers reached was that these 3D printed enclosures did, in fact, work perfectly as a biocompatible protection system for the DBS device. This experiment offers endless potential for the implanting of these DBS microdevices, in big part thanks to the 3D printed silicone material, which solves the biocompatible problems that have hindered the progress of the implanted DBS microdevice for quite some time now. It will be interesting to see how the applications of 3D printing will continue to aid the team in creating biocompatible enclosures, especially when they eventually find a way (literally) into our heads!