Materials for Biomedical Engineering. Mohamed N. Rahaman
polymers. Explain why.
7 3.7 Explain why copper forms a substitutional solid solution with zinc whereas carbon forms an interstitial solid solution with iron.
8 3.8 Using a diagram, explain how dislocations reduce the amount of stress required to cause plastic deformation.
9 3.9 Explain the meaning and significance of microstructure.
10 3.10 What microstructural features would be desirable for (i) a hydroxyapatite implant for healing bone defects; (ii) a lithium disilicate glass‐ceramic for use as a crown in dental restoration; (iii) a degradable polymer such as PLA reinforced with hydroxyapatite particles for healing bone defects? Explain.
11 3.11 Using the axes in Figure 3.25, sketch (i) two planes with Miller indices (122); (ii) a plane with Miller indices (322).
12 3.12 Determine the lattice directions of the lines OI, DE, FG, and HI in Figure 3.26.
13 3.13 Aluminum atoms (radius = 0.1431 nm) pack to form a FCC structure. Determine the number of atoms per square meter in the (100) and (111) planes of aluminum.
14 3.14 Using a unit cell, show the ions in the {100} and {111} planes of sodium chloride.
References
1 Bonfield, W., Grynpas, M.D., Tully, A.E. et al. (1981). Hydroxyapatite reinforced polyethylene – a mechanically compatible implant material for bone replacement. Biomaterials 2: 185–186.
2 Dearnaley, G. and Arps, J.H. (2005). Biomedical applications of diamond‐like carbon (DLC) coatings: a review. Surface and Coatings Technology 200: 2518–2524.
3 Eatemadi, A., Daraee, H., Karimkhanloo, H. et al. (2014). Carbon nanotubes: properties, synthesis, purification, and medical applications. Nanoscale Research Letters 9: 393 (13 pages).
4 Geim, A.K. and Novoselov, K.S. (2007). The rise of graphene. Nature Materials 6: 183–191.
5 Giacolone, F. and Martin, N. (2006). Fullerene polymers: synthesis and properties. Chemical Reviews 106: 5136–5190.
6 Holand, W. and Beall, G.H. (2012). Glass Ceramic Technology. Wiley.
7 Iijima, S. and Ichlhashi, T. (1993). Single‐shell carbon nanotubes of 1 nm diameter. Nature 363: 603–605.
8 Karageorgiou, V. and Kaplan, D. (2005). Porosity of 3D biomaterial scaffolds and osteogenesis. Biomaterials 26: 5474–5491.
9 Peters, M., Heptenmacher, J., Kumpfert, J., and Leyens, C. (2003). Structure and properties of titanium and titanium alloys. In: Titanium and Titanium Alloys. Fundamental and Applications (eds. C. Leyens and M. Peters), 1–36. Wiley‐VCH.
10 Posner, A.S. and Betts, F. (1975). Synthetic amorphous calcium phosphate and its relation to bone mineral structure. Accounts of Chemical Research 8: 273–281.
11 Russias, J., Saiz, E., Deville, S. et al. (2007). Fabrication and in vitro characterization of three‐dimensional organic/inorganic scaffolds by robocasting. Journal of Biomedical Materials Research Part A 83 (2): 434–445.
12 Schoof, H., Apel, J., Heschel, I., and Rau, G. (2001). Control of pore structure and size in freeze‐dried collagen sponges. Journal of Biomedical Materials Research 58: 352–357.
13 Zhao, H., Ding, R., Zhao, X. et al. (2017). Graphene‐based nanomaterials for drug and/or gene delivery, bioimaging, and tissue engineering. Drug Discovery Today 22: 1302–1317.
Further Reading
1 Callister, W.D. (2007). Materials Science and Engineering: An Introduction, 7the. New York: Wiley.
2 Dorozhkin, S.V. (2009). Calcium orthophosphates in nature, biology and medicine. Materials 2: 399–498.
3 Jones, D.R.H. and Ashby, M.F. (2018). Engineering Materials I, 5th Edition, An Introduction to Properties, Applications and Design. Oxford (UK): Butterworth‐Heinemann.
4 LeGeros, R.Z. (2002). Properties of osteoconductive biomaterials: calcium phosphates. Clinical Orthopaedics and Related Research 395: 81–98.
4 Bulk Properties of Materials
4.1 Introduction
The atoms at the free surface of a solid have a different atomic environment and, often, a different composition than those within the solid itself. On this basis, we can divide the properties of materials into two broad categories:
Bulk properties, that is, the properties of the three‐dimensional solid itself
Surface properties, the properties of the surface of the solid that interfaces with its environment, such as the biological environment in vivo.
Bulk properties include mechanical properties such as strength and elastic modulus, electrical properties, magnetic properties, and optical properties, commonly grouped together as physical properties. In comparison, surface properties include topography (surface roughness or smoothness), contact angle and surface charge. Together, the bulk properties and surface properties determine the performance of a biomaterial in vivo.
In this chapter, we will consider the physical properties of three‐dimensional solids that are relevant to their use as biomaterials. Surface properties are discussed in the next chapter. To round off our treatment of the combination of properties relevant to the applications of biomaterials, chemical properties such as degradation and corrosion are discussed in Chapters 14 and 15 while biocompatibility phenomena are discussed in Chapters 16–22.
Mechanical properties are often among the most important physical properties because many biomaterials are subjected to loads (forces) at some point or during almost their entire application and catastrophic failure of an implant in vivo is a serious complication. Biomaterials should have the requisite mechanical properties to support physiological loads when used, for example, as a prosthetic hip and knee joint, or to withstand the pressure pulsations of blood flow through the arterial vessels when used as a stent. In addition, biomaterials are typically designed to have some desirable combination of properties that normally depend on the intended application and not just adequate mechanical properties (Chapter 1). The electrodes in a cardiac pacemaker, for example, have to deliver an electric charge to the heart muscle. Consequently, in addition to having adequate mechanical reliability, the electrode material should have a strong ability to conduct electrical signals, that is, a high electrical conductivity. Dental restorations such as crowns and bridges, designed to restore the function and appearance of tooth structure, should have not just the requisite mechanical properties to avoid fracture but a low thermal conductivity comparable to the tooth itself and the right color for esthetic appearance as well.
The physical properties of materials cover a very broad field and, consequently, we will discuss only the properties relevant to the applications of biomaterials in this chapter. Whereas mechanical properties form the major part of this discussion because of its aforementioned importance, other properties such as electrical, magnetic, thermal, and optical properties are discussed as well. In general, the following main issues will be considered:
Response of a biomaterial to a physical stimulus, such as a mechanical force, an electric or magnetic field, or a change in temperature
The origins of this response and its dependence on atomic bonding and microstructure of the biomaterial
Relation among the physical