Lab3BiomaterialsF06-1 - Laboratory 3 Biomaterials &...

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MatE 215 Lab 3: Biomaterials & Surfaces (Fall 06) Page 1 of 21 Laboratory 3 Biomaterials & Characterization of Surface Properties Goal: Experimentally determine the surface energy of a material and discuss how surface properties and surface modification could be used to design a biomaterial with a specific host response. Learning Objectives: 1. Discuss advantages and disadvantages of surface energy calculation by contact angle measurement 2. Define what a biomaterial is and why some classes of materials are more or less biocompatible than others 3. Discuss possible sources of variation 4. Mathematically fit experimental data to an equation to determine material properties 5. Explore the effects of surface treatment on the hydrophobicity of surfaces. 6. Apply basic statistics to assess the quality of data Background: Biomaterials represent a unique class of materials that are specifically designed to be in contact with a living host. A biomaterial is any material – usually engineered, but it can be derived from living tissue – which interacts systemically with the living host. A biomaterial may be used in a surgical instrument or as an implant. To be considered as a biomaterial, the material must be biocompatible. Biocompatibility may simply be thought of as meaning the material must not harm the host (such as causing cancer or poisoning), nor can the host harm the material over the intended service life of the device (such as corrosion or fatigue). The body is an aggressive environment which will attempt to break down foreign materials. Some materials we want to be broken down over time, such as stitches, but more often we want the material to remain intact permanently, such as with joint replacements or pacemakers. It is not possible at the present time to predict why some materials are biocompatible and others are not given the limited understanding the complexity of life. Currently, materials become admitted to biomaterials class by experimentation. Very few metals
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MatE 215 Lab 3: Biomaterials & Surfaces (Fall 06) Page 2 of 21 are biocompatible and therefore most metals are not biomaterials. On the other hand, many ceramics are biocompatible. The body interacts with the material through the surface . It has been estimated that the body cannot probe any more than 5 Å below the surface of any material. Therefore, it is not surprising that a lot of biomaterials research is focused on surface chemistry. There are many sophisticated methods available to measure surface properties, but the simplest is to estimate surface properties by what is called a sessile drop test. That is, to put a small drop of a liquid on the surface of the material and directly measure the maximum angle the drop makes with the surface. The sessile drop test measures what is called the surface tension. Many of us have observed this property by looking at the meniscus that forms at the liquid vapor interface when a liquid is poured into a container.
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This note was uploaded on 04/02/2008 for the course MATE 215 taught by Professor Granados during the Spring '07 term at Cal Poly.

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Lab3BiomaterialsF06-1 - Laboratory 3 Biomaterials &...

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