Design A Heart Valve

Evidence of Work:

The challenge for this project, as stated by Mr. Tronconi on his website is to have students be, "a team of engineers for a bio-materials company that has a cardiovascular systems client who wants you to develop a model that can be used to test the properties of heart valves without using real specimens." This means that we need to create an atomically correct model of the human heart that can undergo the same stress and functions as the human heart. 

To achieve this, the project was broken into multiple pieces including a research phase, a testing phase, a building phase, and a redesigning phase. In the first part, we brainstormed ideas and took note of any basic knowledge about the heart our group already had. We then further researched to learn a lot about the heart's function and its components. This included reading information about the heart and drawing sketches of the human heart. 

Shown below are the sketches of a human heart along with the Young's Modulus practice problems. These equations are used to determine the elasticity of a material which we used to determine which materials to use in our heart valve since the layers of the valve have elastic components to them. 

This was the next step toward the final part of the project.  

First, we chose materials we thought we might want to use for the model, and designed and ran an experiment to test find the Young's Modulus of our chosen materials. We wanted to use the most elastic materials that could bend but not break under the pressure we would be putting it under. Therefore we needed to run tests on these materials. This was achieved through the creation of an apparatus that would hang the material we were testing which was also attached to a weight. This was all hung from a height such that gravity acted as the only force on the system. Using our knowledge of the surface area of the materials, the forces acting on the system (gravity), and the weight of the suspended mass, we then were able to plug all of those values into an equation where the only unknown was Young's modulus. We then solved and found the theraband to be the least elastic meaning it would require lots of force for it to change shape. This was perfect for what we needed our model to do. 

Next, we had to build the model of the heart. We connected tubes to a glove by cutting off a finger of the glove and where the hand enters. This glove was our heart, and we could squeeze it to apply pressure and force the water (blood) through the tube. To make the valve, we first pushed an elastic material through the tube and it would take a good amount of pressure for the water to get past it. This was supposed to stop water from pushing backward after getting through and causing a leak. Then, we superglued 2 fast food drink cups and a Gatorade cap to the end of the tube. The water would have enough pressure to break through the lids and cap when the "heart" was "pumping", but it wasn't strong enough to push through when the heart was idle. This was successful in preventing the backflow of blood and allowing water through the valve. 

Within our lab write-up, there are pictures as well as a more in-depth analysis of our valve and its creation. 

Reflection:

Overall, I feel as if the project went very well. However, I feel two aspects our group could have improved upon would be the blueprinting stage as we didn't have a concrete plan going into the building aspect which led to some material waste since we didn't entirely know how to go about designing the model. This will be an important lesson to learn from as we go into the blueprinting and building stages of the Capstone project next semester. Another aspect that could be improved upon was the lack of communication. I didn't properly delegate the work to my team members, especially since one of them was home sick for the last two weeks of the project. 

We did work very well as a team though. I feel that was a strong suit for us since we all though about the problem in different ways and each contributed at least one piece of the final model. I also feel as if our group was very well organized since we made sure to be aware of deadlines which is an important skill to think about as we get deeper into the Capstone project next semester.