Senior Design Project
I completed two Senior Design courses at the University of Pittsburgh during during subsequent semesters from September 2020 to April 2021. The goal of these classes was to identify unmet clinical needs and proceed through the entire design process, including verification and validation. Additionally, these courses aimed to teach about FDA regulations regarding medical device design.
During these two Senior Design courses, I learned how to develop and carry out ethnographic plans, perform risk analysis, generating the proper procession of prototypes and researching the FDA procedures relevant to my group's project. My group consists of six other senior bioengineering students, all with a similar interest in biomechanics.
Ethnographic Data Collection
After each member of my group performed individual unmet clinical need identification, we settled on three possible topics that we would conduct further ethnographic efforts in order to narrow our project to a single device. The three topics that we initially researched were: Prosthetics, Lung Rehabilitation and Surgical Simulation.
An ethnographic plan was created for each topic containing detailed methods for conducting observational analysis, task analysis and anthropometry. Each plan provided specific contacts along with questions we would ask and how we would contact them. Our group spent nearly three weeks conducting meetings and gaining more information on the three topics and the unmet clinical needs associated with each.
I spent most of my efforts on conducting ethnographic data collection on surgical simulation, since I have prior experience with developing simulators. I attended multiple meetings with directors or surgical simulations centers and developed an online survey that was sent to residents via one of our main contacts. This survey was completed by 14 residents, providing us data on unmet needs in surgical simulation as well as accessibility of fabrication tools.
The main unmet needs relayed through the survey were:
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Lack of access to the simulator (no portability)
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Current simulators are too basic
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Current simulators do not have a realistic feel
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Current simulators are too specific/only have one use
Project: Foregut Surgical Simulator
After completing our initial ethnographic data collection, my group did not receive enough feedback on lung rehabilitation to pursue it further. Additionally, my group decided that a project in prosthetics would be too challenging to complete in the time frame of our Senior Design course. We chose to pursue additional ethnographic data in surgical simulation.
Based on the unmet needs acquired through the survey I generated and additional ethnographic data collection on surgical simulators, we settled on developing a simulator of the foregut that would be portable, reusable and have realistic features. I helped organize a virtual Project Canvas for our project to plan out what we will do and produce (documentation wise) in the future.
Initial Prototype Development
Now that the future steps of the project were planned out, we began developing a Minimum Viable Prototype (MVP) for a foregut surgical simulator that we would begin conducting "killer" experiments on to determine what components we would have to change.
Our MVP was composed of foam core for the overall box structure with a plastic tube held in place to resemble the esophagus. The other organs were drawn in the place we believed they would positioned in a simulator. Additionally, a rope handle was included to allow for the prototype to be portable.
After consulting out clinical contacts and performing "killer" experiments, we realized that our anatomical positioning of the organs was not accurate, so we began research in order to understand the locations and interactions between the stomach, liver and esophagus since they were our organs of interest. This image on the right is our second prototype developed with 2D foam core organs to better show anatomical positioning.
We advanced to a more complex prototype by purchasing a life-size 3D model of the GI tract off of a design website. Myself and another member of the group trimmed the model in SOLIDWORKS and MeshMixer to produce a single stomach and liver model.
These stomach and liver models were then 3D printed using a hard resin, since our next step was to show 3D positioning of the organs rather than provide a realistic feel for the organs. The image on the right shows the stomach being printed on an Ender 3D printer.
The image on the right is our current prototype (as of December 2020)! Using laser cut polypropylene sheets, we constructed the outer box. We used an electric foam cutter to trim the foam into a shape that would fit into the box, and I cut the pockets for the 3D printed organs to sit in. A firm handle was attached to the box to allow for portability.
Virtual Design Expo
Every year, all senior design teams from every engineering department present their projects at a design expo for faculty, students and the general public. Due to the COVID-19 pandemic, though, the Fall 2020 Design Expo was held virtually.
Spring Semester Prototyping
Our main priority before beginning V&V testing was to update our prototype. We ordered a medical grade briefcase to use as the housing for our simulator and to enable portability, and created dividers for the case to hold organ molds and laparoscopic tools. The other major task was creating a tissue-like stomach that is pliable enough for operations like Laparoscopic Nissen Fundoplications but holds its shape. We decided to use Smooth-On DragonSkin with Slacker added for more tissue-like qualities. Pictured to the right is Isaiah pouring the silicone mixture into our two-piece stomach mold.
Pictured below is a top-down view of the simulator where you can see a 3D printed liver made out of Ninja Flex TPU and our molded stomach made out of DragonSkin. You can also see two rubber bands with a hook inserted into the stomach and bolted to the divider, which helps act as connective tissue and a form of resistance which is important for surgeons to feel when practicing. The two-piece mold is also pictured on the right to showcase the reusability aspect of our product - the idea being that residents can continue molding their own stomachs as they cut and go through the stomach that comes with the simulator. Also not pictured is an inner lid we created to mimic the exterior of the human body, with laparoscopic ports that allow the trainee to practice laparoscopic procedures where they wouldn't be able to directly see the organs they're operating on.
Verification and Validation Testing
After our group's verification testing completed, we took the prototype to various clinicians and students to validate our design and give us constructive feedback on how it could be improved.
Pictured to the left is Dr. Rajeev Dhupar at UPMC Shadyside, who I along with a few other teammates went to visit so he could take a look at the simulator and give feedback. He liked the overall functionality of the prototype as a whole, especially the reusability and portability aspect. As suggestions, he recommended making our inner lid at an angle so that the tools can be inserted laterally rather than from above, and suggested adding more ports to the lid to allow trainees a plethora of options for different feels and practices. Lastly, he explained that making the molded stomach hollow would allow for more pliability, and that our current stomach was too stiff to perform certain procedures. However, he felt the feel of the silicone was close to tissue when cutting or prodding it.
FINAL PROTOTYPE +
RECOMMENDATIONS FOR FUTURE IMPROVEMENT
Taking our clinicians' feedback into consideration, we modified the inner lid to include a "kickstand" to allow it to be propped up for more realistic tool movements, and added more ports (shown plugged) for increased variability in choosing ports to use for practices.
In the future, we would need to design a hollow stomach mold (which we did not have time to do), which would allow the stomach to have more flexibility and be pulled around the esophagus, which is what happens in a Laparoscopic Nissen Fundoplication. We would also include an omentum, which is a thin layer of tissue that covers the organs and needs to be cut away at before performing certain procedures.
