Design a Heart Valve
Our Goal
We were tasked with constructing a model that mimics the function of an actual heart valve to explore the field of biomedical engineering and practice the engineering design cycle. In part 1, my group of four first built an understanding of how heart valves worked, doing research on our own and reading the general descriptions of heart structures provided to us. After being able to visualize the flow of blood through an actual heart valve, we were able to brainstorm alternate representations of the controlled, one-way blow flow in our notebooks. This process allowed us to plan out each option and prepare the materials we needed. Next, in part 2, we studied elasticity, forces on the aortic valves, stress, strain, and Young's Modulus to accurately represent the organic tissues of real heart valves. Finally, in part 3 we ran tests on the valve materials to find the best fit for our design before constructing a final product. We made adjustments and redesigned the model in different ways to ensure the function was most effective.
Evidence of Work
The photos below show our initial ideas for approaching this project. On the left, it describes our idea to use air rather than water to propel objects into the upper section. The right photo portrays our later designs and what ended up being our final heart valve. In the middle shows our main notes from our background research and ideas for the design.
This is a video testing our initial model. From this test, we realized there was too much air in the system for the water to even reach the valve. We resolved to fill the bottle more for the next test and stretch out the balloon more before testing to prevent the resistance to the flow of water that we observed here.
IMG_6053.MOVHere is our working model with the alterations. You can see the balloon progressively becomes full after each pulse, and the water does not flow back the way that it comes from.
IMG_6060.MOVThese documents reveal the results of our testing for the Young's Modulus of the materials we used for the layers of the model valve, and our report of the prototype in action.
Content
Bioengineering
Applies the principles of biology and the tools of engineering to create viable products.
Elasticity
The ability of an object to return to its natural state after some applied force has been removed. We tested the elasticity of each material used in our heart valve to replicate the elasticity of a real valve.
Force
F=ma.
Young's Modulus
Measure of elasticity found by dividing stress by the strain.
Stress/Strain
The force applied to the material and the resulting deformation of the material. Measurements to determine elasticity.
stress: σ= F/A
strain: ε=Δ x/x
Laminar Flow
The regular flow of blood through the circulatory system which occurs when a valve is opened.
Heart Structure
The heart consists of four chambers; two atria and two ventricles. The ventricles pump blood out of the heart, while the atria receive incoming blood.
Aortic Valve
Oxygenated blood leaving the heart travels through the aortic valve. Semilunar shape between the left ventricle and the aorta. Ensures blood does not flow back into the ventricle.
Reflection
This project was overall very interesting to me and successful to my group. I enjoyed testing the materials and brainstorming new ways to represent a function of the human body. Although our model could have been clearer in showing the blood flowing to the balloon, it did end up working better than I originally thought. We were able to go through several variations of the product and be creative in our adaptations. We problem-solved together using our critical thinking skills to work out any issues we came across. One of these issues was the inability of the water to flow up into the balloon in the first place. We combated this issue by removing air from the system to reduce the barrier of molecules preventing the initial "blood" flow. Additionally, we opted to hold the device at an angle to utilize the force of gravity to aid our system. My group collaborated effectively to run each test and record our observations.
One thing I can improve on is asking my group members for all of their ideas before diving too far into one. Although in this project we all struggled to work out a conceivable model in the brainstorming period, once I thought of one that could work I may have neglected the designs of my other group members. Next time, I will give my group more time to plan instead of initiating my design right away.