4 Point Perspective was a project that was started in a Biomedical Engineering Design Class. We were tasked with choosing a medical device and redesigning it towards a specific user population. Prosthetics always fascinated me and I was waiting for an opportunity to work with them. So I was able to meet other students in the class who were also interested in working with prosthetic. We formed a 4 member team that made sure that everyone was a skilled in a certain area. Two of team members were good at creating crude prototypes out of easily accessible materials and at brainstorming creative ideas. The other team member was really good at SolidWorks and creating sketches of designs. Lastly, I was annointed the default Team Leader mainly because I was capable of contributing in all aspects and managing everything. So I had a role that made sure that everything fit together with the big picture.
Once we had decided on the roles, we were able to brainstorm which device we wanted to work on. Since we were all interested in prosthetics, we decided to start there. On further research, we saw that there are many different types of prosthetics. We narrowed it down to leg prosthetics and finally transfemoral prosthetics. A transfemoral prosthetic is for people who have had above knee amputations, so it includes all aspects; thigh, knee, tibia (or calf), and foot. This was by far the most complicated prosthetic to work on, but we chose this one since we wanted to be challenged and we believed that we could make the most contributions towards this one. |
GOALS
We narrowed down our user population to the majority population of male users above the age of 65 who suffered from an above knee amputation due to dysvascular diseases like diabetes and peripheral arterial diseases who have low activity levels. This target user group was chosen since we found that advanced and innovative prosthetics were being targeted towards younger populations. This led the geriatric population to be sidelined and the majority of them were still using old prosthetics that haven't been worked on in a long time.
We then conducted more research by looking at online forums, reading research papers, and by talking to experts in the applied physiology department. I conducted most of the user research and needs to see what aspects we could improve. We settled on working towards these following goals:
We then conducted more research by looking at online forums, reading research papers, and by talking to experts in the applied physiology department. I conducted most of the user research and needs to see what aspects we could improve. We settled on working towards these following goals:
- Improve the gait and mobility of the user
- Improve the comfort of the prosthetic
- Minimize instances of falling
USABILITY
To better understand the device, we took apart the prosthetic leg and broke it down to its components; thigh, knee, tibia, and foot.
Then we proceeded to make a usability flow chart to understand how the typical user would use this prosthetic leg.
ANALYSIS
To improve the prosthetic leg, we first analyzed the strengths and weaknesses of each component and identifed potential factors of improvement. We found the limitations of the device by performing engineering analysis on the components, which allowed us to formulate ideas.
PROTOTYPING
We brainstormed and generated many ideas that could be implemented. Some areas that were focused upon included creating a more comfortable thigh, changing the joints of the knee to make it more mobile, having the tibia absorb shock, and making the foot more flexible.
The first stage involved creating hand drawn sketches of ideas.
The first stage involved creating hand drawn sketches of ideas.
The second stage invovled narrowing down the best idea by using concept matrices.
The third stage consisted of creating crude prototypes of the best designs for each component. This resulted in inflatable thigh, shock absorbing tibia, flexible foot, and finally a knee that clicks on locking.
MATERIALS
The biggest aspect of this project was deciding on the correct material to use for each of the components. Each component had different requirements and our final prototypes needed to have sound engineering principles as well as contain all the necessary features that we needed. To identify the best materials, I conducted a lot of research on the different materials used for prosthetics and other similar applications. I talked to professors in the Materials Science Engineering Department to get their input and to test the materials we wanted. This allowed us to identify the best material for our purposes.
In addition to these materials, we also had to decide on the material for the knee, pylon, and foot. We conducted engineering analysis on all of these components to make sure that the prosthetic was capable of performing adequately.
FINAL CONCEPTS
After creating prototypes and obtaining feedback from various experts, including meetings I set up with professors in the Applied Physiology department, we came up with four final concepts. They included:
The final prototypes were made with the materials that were decided upon, 3D printed, and finally polished to look good.
- Inflatable Thigh: Inner socket lined with neoprene rubber with a pressure valve to pump air into the socket
- Vibrating Knee: An electrical circuit that is closed as the knee locks to initiate a vibration that informs the user
- Shock Absorbing Tibia: A bike shock absorber attached to the pylon to reduce the impact of shock from walking
- Flexible Foot: Alternating rigid (delrin acetal resin) and elastic (neoprene rubber) material in the ball of the foot to improve flexibility
The final prototypes were made with the materials that were decided upon, 3D printed, and finally polished to look good.
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