Heart Valve Model

Introduction: For this project we were tasked to create a working heart model. We made sure to remember the Challenge problem: "You are 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." So we decided to find a model that would be as close to the function of a real heart as possible. We found a model that shows the function of all four valves of the heart. In this experiment, we were asked to recreate a functioning heart valve and use the young modulus to test the elasticity of the materials used. We used two balloons, a stress ball, a drip pipe, a PVC pipe cap and tape to create a contraption that shows how blood flows through the arteries and veins and into the heart.

Method:

Following is what you need to determine, calculate and plot through your tests:

  1. determine the Young's modulus of each material, applying what they learned from the associated lesson. Have students use software to create stress vs. strain graphs and determine lines of best fit; as an alternative, have students use graph paper and do this by hand. For each material, have teams:

  2. create a stress vs. strain graph, plotting at least three data points determined by using at least three weights of different masses to measure and calculate stress and strain

  3. determine the line of best fit based on the three points on the graph

  4. determine the slope of the best fit line, which is the experimentally determined Young's modulus

  5. Compare its calculated values to the known Young's modulus of heart valves (or even the different layers of heart valves) as part of choosing materials that would be best for the model. For reference, the Young's modulus value for a pig's heart valve tissue and some other materials are provided below.


Materials:

-Balloons

- Iv Drip Pipe

-PVC Caps

-Stress Ball

-Electrical Tape

-Water Cup

Conclusions: We faced some problems during our design process. We faced problems like the length of our drip pipes. We found that our drip pipes were too long to accurately represent the blood flow in the heart. These longer tubes caused our “Blood” to flow much slower and made our system not function to its potential. We also faced an issue with our stress ball. We initially created a model with a stress ball that used hard rubber. This did not allow the “pumping” function of the heart to work properly. The model would not compress enough to create a realistic heart model. To solve these problems we took two steps. First, for the drip pipes, we cut two inches off of each one. To solve the stress ball issue, we used a softer, more malleable material. Overall through trial and error, we created an effective model that could represent a heart valve. We made sure our model shows both flows of blood. In and out of the heart. We also dyed our water red to make our model as realistic as possible.