ENME 414 CAD/CAM

Team 3: Heart Model Teaching Aid

The Team: Top: Uzma Rasheed | Jack Carmi

Bottom: Pei Lin | Hyun Jin O | James Cho

Need Analysis:
Preliminary research has indicated that current models of the human heart used to assist in teaching do not fully illustrate all of the necessary features of the heart. Specifically, surveys of current undergraduate biology students at the University of Maryland and interviews of several biology professors at Maryland have expressed a need for a teaching model that is transparent and can simulate blood circulation through the heart.

Redesign Proposal:
The redesign is to create a teaching model of the human heart that is transparent and simulates blood flow through the heart. The teaching model will consist of a model heart with hollow internal cavities, a tubing system representing the veins and arteries that connect to the heart, and an external pump that will attach to the ends of the tubes and regulate fluid flow through the model. The entire model will be made transparent material such that students can watch the flow of the fluid through the model.

Redesign Approach:
1. Conduct research on current heart models including:

Surveying biology students
Interviewing biology professors
Conducting internet search
Conducting literature search
Contacting other universities

2. Develop initial design parameters
3. Generate computer design of model using Pro/ENGINEER
4. Create an SLA model

Design Parameter:

Transparent- To be able to understand the internal functions and structure of the heart.
Pump- To simulate the actual blood circulation through the heart using two different colored liquids; one color for oxygen rich blood and the other for oxygen poor blood.
Disassembly- To be able to show the internal structures of the heart in detail.
Large Size- To be able to clearly see and demonstrate the functions and structures of the heart in a large classroom environment.
Rotational- To be able to show the different views of the heart easily.

Pro/ENGINEER Model:

Final Results:
Upon completion of the Pro/ENGINEER heart model, a physical model was created using stereolithography. A unique characteristic of this project is that the model was generated using the Quckcast process. This process differs from all other SLA models made at the University of Maryland in that the part is not made using internal support stuctures, but a "honeycomb" grid.
The "honeycomb" grid is eighty percent hollow. Furthermore, this process allows the structure to be constructed significantly faster than using a typical support structure. However, the Quickcast process requires several additional precautions and features to be made to the part model. First of all, the grid must be able to be drained from the internal section of the part. Thus, the heart model had to include several vents both at the top and bottom of the part. Also, the grid is very water sensitive therefore the curing process of the grid does not include alcohol treatment. As a matter of fact, one must take precaution as to not put alcohol on the grid section or else the grid will deform.

Future Recommendations:
There are a number of steps that can be taken in the future to further this project. The first and most tedious step would be to continue manipulating the surface of the Pro/ENGINEER heart model to make the contours of the model more closely match the contours of the heart. Second, the Pro/ENGINEER model needs to include four internal cavities that correspond to the four chambers of the human heart. Also, a pump system needs to be purchased and attached to the physical model.

Produced by Hyun Jin O

E-mail: o.hyunjin@usa.net