BME3101 Biomaterials Lab Description_KGP0

BME3101 Biomaterials Track Lab Description October 22-26

Dr. K. Gielo-Perczak, 10/15/2012 Page 1 of 3

Strength testing of biological tissue: Determine how a porcine aortic root responds to forces applied to it?

Overview

The lab will aid in your understanding of the Biomaterials Track concept.

In this laboratory you will measure strength of biological tissue during uni-axial pulling by

application of the Tinius Olsen Test Device.

The laboratory will be designed and performed in groups of four students. The result of

pulling experiment should be printed out, copied and attach to each students report. Each individual students understanding of the lab material will be assessed by an individually written laboratory report with analysis of the data collected as a team (to be clear, you will

work together to do the lab, run the statistical analysis, and write the lab report, but it is

considered academically dishonest if each student does not perform the test to gather his/her

nine measurements).

Each student is required to learn a general information about the Tinius Olsen Test Device

capacities.

Background and objectives

Aortic valve disease affects millions of people worldwide. The most common treatment for

aortic valve disease is the complete replacement of the aortic valve. During the surgery the

aortic root (the part of the aorta that houses the aortic valve) is assessed by the surgeon and

often replaced. Our biomedical engineering task is to determine how the aortic root responds

to pulling force applied to it. Understanding how the aortic root responds will allow for the

design of a better heart valve and an increased quality of life for thousands of patients.

You will perform a strength test of a porcine (pigs) aortic root. In this test you will record the Stress and Strain response curve to applied pulling force.

The lab experiment will aid in your understanding of the concepts involved in analysis of

biological tissue data. The laboratory provides a more hands-on experience in Biomaterials

Track.

Challenge

Your challenge is suggest the additional variables which will have potentially influence

on strength measurements.

Strength tests of biological tissue are complex and you may observe how many factors

can have influence on resultant pulling test. Please note, that a sample position, grip, tissue

orientation of a sample, angular position of tissue fibers, environment (temperature,

humidity) during taking strength recordings, ALL have potential influence on strength test.



Experimental approach

Each student of a team will participate in the recordings of a one sample biological tissue

strength test.

Precautions

Using the Tinius Olsen Testing Machine

Wear Safety Glasses

Pay attention to prepared measurement setup (Take a picture and describe the parts of the Tinius Olsen Testing Machine)

What steps should be taken prior to testing material (provide a list of these steps in your report)

Handling of Biological Material

Always wear gloves when handling tissue

After testing return the tissue to its container for proper disposal

DO NOT THROW TISSUE IN THE GARBAGE

Wash all tools that come into contact with the tissue

Required analysis

For the experiment, you must perform measurements the wall thickness of the aorta:

1) Measure the wall thickness of the aortic root and width of your sample at several locations to determine the average wall thickness.

Measurement T - Wall Thickness (mm) W- Width of a sample (mm)

1

2

3

4

5

Average

Table 1: Wall thickness of the aortic root and width of a sample at several locations

2) Measure the initial length (li) of your sample which is equal to a distance between the grips (mm); li _______________[mm]

3) Print out load (Force) elongation diagram, Force = f(l)



4) Calculate a final length (lf) using formula lf = li + l [mm] at maximum Force, Fmax

5) Calculate max stress = (Fmax/A) [N/mm2].

Where the cross- sectional area A= T x W [mm2]

6) Calculate max strain e= (l /lf) [mm/mm] ; lf = li + l [mm]

For your lab report (< 2 pages), you must describe measurement method and include the

results. You should also discuss your conclusions based on your findings (i.e., what

additional parameters can have on your strength tests results).

We are considering that biological tissue is nonlinear and anisotropic material. Explain

the definitions of nonlinearity and anisotropy of material.

The report must be done individually.

Documents

BME3101 Biomaterials Lab Description_KGP0