Design a Heart Valve

The goal for this project was to design a valve system that simulates the heart valve within a human. This including the contracting of an object to force the valve open, the passage of a liquid though the valve. And lastly the automatic closing of the valve after liquid has passed through.

To create this we first had to research the human heart; learn the properties that makes such as well as key features of the heart.


To the left are two pictures on the right a detailed diagram of the human heart and all the necessary components such as valve, arteries and more. We research all components and made sure each of our group member had detailed diagrams of such so we could understand the goal of what we were trying to build.

The next step was to look for materials with different elasticity values in our classroom and start planning on how we could piece together a valve.

Materials list:

  • 2 inch PVC

    • Main body of valve, holds water (blood substitute)

  • Plastic Water Bottle

    • Adapter allowing attachment of air-loaded balloon

  • 3 Balloons

    • 2 act as gaskets, preserving water tight seal

    • 1 act acts as air tank, providing pressure to put on valve

  • 2 Medium Rubber Bands

    • Elastic bands hold valve close under zero pressure circumstances

  • 1m Duct Tape

    • Attaches water bottle to PVC

    • Act as hinge for valve “door”

  • Wooden Dowel

    • Mounting point for rubber bands

  • ½ cm thick wood board - cut into circle

    • Moving part of valve, acts as a “door” to hold water in


Material calculations: to know the young modulus values of out materials we had to do a little bit of calculations to find such.

to find the young modulus we mounted the material we would stretch to a fixed point then using a spring scale attached to the material we pulled on the spring scale and measured the dustance the material stretched then plugged in both measuremnts into the equations below.

Equations-

  • Young modulus E= Newtons/ surface area divided by the area expanded by the pressure

Calculations-

  • Using the young modulus we sourced the following results

    • Elasticity of balloon = 3N / 50.24N/cm / 1.15cm = 0.0519 N/cm^2=

      • → 0.0000519 Pascals (N/M^2)

    • Elasticity of Rubber band :

      • 2.5N / 11.5 CM/11.5 cm^2= 0.0189 N/cm^2

      • →0.0000189 pascals


Results:

  • The model is thin like an aortic valve due to the balloon which is very thing and elastic:

    • Elasticity of balloon

      • → 0.0000519 Pascals

    • Rubber band

      • Elasticity of rubber band is 0.0000189 pascals (N/M^2 )

    • This shows that we have two materials in our aortic valve, each with different elastic ratings, the rubber band at about one fifth the elasticity rating to the balloon


Design changes:

  • after receiving our young modulus values for our materials above we decided to use these rather than our prior design which consisted of a paper cup with 3 cuts in the bottom allowing water to pass through when the weight of the water had enough force to push through. However our previous design using a paper cup quickly became obsolete as the material lost its strength from the water and it consistently leaked a lot. Due to this we changed to the new design shown below. In this design there is a rubber band keeping the door at the bottom of the cup closed and only when enough force is applied from the balloon does it open. Also we used a rubber band and plastic bottle to hold our water on the inside as this prevented leaking by creating a better seal.


To the left is our finished moel of the heart valve. Inside the plastic bottle is water resembling the blood inside the heart, when the balloon is squezed the air from inside force the door on the bottom to open- symbolizing the opening of the heart valve. Next the water quickly rushing out of the valve and when all air pressure is lost, the valve closes up again due to the rubber band acting on a constant force on the door.

Conclusion: Our Heart valve is very effective at completing it's job, it simulated the contracting of the left ventricle nicely as the balloon is squeezed. The valve holds back any liquid when the ventricle is not contracted. And the valve opens and closes back again after the air pressure and water pressure open and close it. Our design can even work in all orientation, upwards, downwards and sideways.

We could still improve on our product however as there was some leakage of the water through the valve which we could work to eliminated completely if the door of our valve was properly measured maybe even by using 3d printing and if we researched better sealing materials than the balloon. cooperation collaboration, conscientious learner, character critical thinker communicator

Two things I did great during this project was using critical thinking as our project required a lot of innovative thinking to keep different from others and yet achieve the same task, this I did very well on as I constantly worked to brign ideas and keep innovatign for the group so we had a range of option. Secondly I did great as a collaborator by doing by part consistently throughout the project, for example when my group didn't know how to do the calculations I helped and took charge leading and getting us over obstacles as such.

Two things I didn't do well on were as a communicator since I didn't lead much in the project or contribute many ideas to how we could present our work. Secondly I lacked in working as a conscientious learner since I was unable to help two of my group mates understand the difficulties with 3d printing which we attempted multiple times but were unable to bring anything to fruition.