3D-Printed Pediatric Prosthetic Devices

Purpose

The ability to 3D print prosthetics has changed the medical field. Prosthetic devices can be affordably made, and can now be completely customizable. e-NABLE is a network of volunteers who use 3D printing to donate prosthetic hands to those who need them. In my research, I pursued my interest in biomedical engineering and explored e-NABLE's available resources to learn about the process of 3D printing prosthetic devices. e-NABLE has a catalog of public STL files, which are the files that get uploaded to a 3D printer. STL (short for stereolithography) files describe the surface of a three-dimensional object. They are converted into instructions that can be followed by a 3D printer in a process called slicing. Slicing divides the 3D model into many horizontal layers that the printer will produce one by one. These instructions are written in a file called g-code, which is read by a 3D printer. Below is a diagram that displays how STL files from the internet can become 3D objects.

The process from STL to 3D object. Saidani, Amal. “3D Scanning and Printing.” 6. 3D Scanning and Printing - Amal Saidani FabAcademy 2020, http://fabacademy.org/2020/labs/kamplintfort/students/amal-saidani/assignments/week06/.

In choosing a device to 3D print and assemble, many factors were considered. e-NABLE rates each of their models on a number of different criteria such as assembling difficulty, cost of materials, and popularity. Since I had no experience with the process, I chose a model with a low level of difficulty and low cost of materials. I chose the Phoenix Hand from e-NABLE's catalog, downloaded the files STL files, uploaded those files into a slicer, converted the files to G-code, uploaded the G-code to the 3D printer, printed the materials, and assembled the hand. After I finished creating the Phoenix hand, I chose to make the Kinetic Hand, a hand with a higher level of difficulty.

Pediatric Prosthetic Hands

Hear all about the project in this interview with Dr. Nguyen and me!

Phoenix Hand vs Kinetic Hand

Phoenix Hand

This was the first hand that I had made. The process was fairly simple. After receiving a crash course in 3D printing I was able to print all of the necessary components. Click here to watch a video about how 3D printing works. Some parts, such as the rubber grips, and the wire that allowed the had to move, were provided by e-NABLE. Click here to view their shop where they sell the necessary parts for assembly. Overall, creating this hand helped me to realize how important 3D printing had become in the prosthetic industry. It was such a simple process, that can be done by anyone with a printer, that could help someone in need. The files for the Phoenix hand, along with its instruction manual can be found here.

Kinetic Hand

The Kinetic Hand was a more involved process to create. The Phoenix hand only required one type of filament, PLA, from the 3D printer, the Kinetic Hand required two different filaments, PLA and TPU. PLA is used for the base of the hand, and TPU, which is a more pliable substance, is used for the finger grips and joints. This meant that I had to find the correct settings on the 3D printer for the new filament, which is a tedious process involving trial and error. This hand is much sturdier and larger than the phoenix hand. Also, this hand also did not provide the additional materials that were needed, which meant that I had to find them on my own. These materials included braided fishing line, high strength super glue, skin-safe silicone, and M2 Philips Pan Head Self Tapping Screws. The files for the Kinetic Hand, along with its instruction manual, can be found here.

Errors

During another project, the 3D printer was damaged. There was a buildup in filament at the extruder that looked similar to the one in the photo above, the link to the photo about, along with an article on how to fix this issue can be found here. To fix this, I had to heat up the hardened filament to remove it. The heat gun however also melted parts of the printer, since most 3D printer parts are 3D printed themselves. So, I began the process to 3D print new parts and reassemble the printer. Errors are very common in 3D printing, and it is usually expected for a print to fail on the first couple of attempts. In order for a successful print, the printers settings must be exact. Here is a link to explore common 3D printing errors.

Summer Camp

Through eNable, I had the opportunity to take two virtual classes that involve 3D printing prosthetics:

3D Printing Prosthetics to Teach Engineering, Anatomy, and Empathy - this course discusses empathy toward limb differences, and explains the process of creating 3D printed prosthetics)
Prototyping with Purpose: Human-Centered Engineering Design Challenges (in Collaboration with e-NABLE) - this course explores engineering designing processes and its purpose is to explain how technology can be used to help others.

I did not get to finish in time to offer a summer camp this year, but I intended to use these classes to create and host a program at CCHS over the summer. The camp would be geared toward middle schoolers and would cover the basics of 3D printing and the engineering design process. The camp would discuss the practical uses of 3D printing, especially in the medical field. These skills are extremely useful to gain, as they allow individuals to discover what they can achieve personally, and how they can use their skills to help others in ways that they previously would have never imagined.

Reflection

This interview focuses on the learning process.

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