Module 1

Question 1

Biomaterial

Answer 1

A nonviable material used in a medical device, intended to interact with biological systems

Question 2

Bioinert

Answer 2

Materials that do not initiate an immunological response when implanted

Question 3

Bioactive

Answer 3

Materials that induce a specific or desired biological response

Question 4

Regenerative

Answer 4

Materials that stimulate a response targeted toward regenerating diseased tissue (tissue engineering)

Question 5

Biocompatibility

Answer 5

Ability of a material to perform with an appropriate host response in a specific application
- Resistance to blood clotting
- Resistance to bacterial colonization
- Normal healing

Question 6

Issues affecting biomaterials

Answer 6

Toxicity, wear

Question 7

Classes of Biomaterials

Answer 7

Polymers, metals, ceramics, composites

Question 8

Types of Polymers

Answer 8

Silicones, polyurethanes, hydrogeis

Question 9

Types of Metals

Answer 9

Stainless steel, titanium alloy, cobalt chromium alloy

Question 10

Types of Ceramics

Answer 10

hydroxyapatite, tricalcium phosphate, silica

Question 11

Bulk properties

Answer 11

• Determines the toughness, strength and stiffness of a material
• Directly influence dynamic interactions with biological systems

Question 12

Structure of Atoms

Answer 12

Electron, proton, neutron

Question 13

Electron (e-)

Answer 13

lightest of the 3, negatively charged, and responsible for conductivity
- Charge = 1.602 x 10^-19 coulombs
- Mass = 9.1 x 10^-31 kg

Question 14

Proton (p)

Answer 14

Mass 2000x e-, positively charged, and dictate atomic number or element
- Charge = 1.602 x 10^-19 coulombs
- Mass = 1.6 7 x 10^-27 kg

Question 15

Neutron (n)

Answer 15

Mass similar to p, no charge, no chemical behavior, responsible for isotopes

Question 16

Theory of Electronegativity

Answer 16

• Ranks the relative strength of each element to attract electrons to complete outer shell
• Electronegativity increases L to R in periodic table (1.0 for Li, 4.0 for F)

Question 17

Ionic Bonding

Answer 17

• Electron donor atom (metal; cation)
• Electron acceptor atom (non-metal; anion)
• Larger the difference in electronegativity, the stronger the bond
• Cation is surrounded by as many anions as possible
• Form highly ordered crystal structures
• No discrete molecules exist
• Electrons no longer serve as charge carries

Question 18

Ionic Solids

Answer 18

• Poor electrical conductors
• Relatively unreactive
• Have high melting points
• soluble in water

Question 19

Covalent Bonding

Answer 19

• Elements bordering metal/non-metals have 4 valence electrons
• Have equal tendency to donate or accept e-
• Instead, share valence e- to form covalent bond
• C atom with 4 covalent bonds has stable outer shell
• Extremely strong bond
• Poor electrical conductors

Question 20

Metallic Bonding

Answer 20

• Metal atoms do not bond by either ionic or covalent bonding
• Materials are very strong and have high melting points
• A positive core of metal atoms exist
• Delocalized valence e- circulate around ions
• Alloys have very low difference in electronegativity
• Strength increases as ion core becomes more tightly packed

Question 21

Non-localized bonds

Answer 21

• Permits plastic deformation
• Accounts for electrical and thermal conductivity
• Chemical reactivity

Question 22

Weak Bonding

Answer 22

• Van der Waals bonds do not rely on gaining/sharing e-
• Polarization
• H-bonding special case involving H atoms

Question 23

Polarization

Answer 23

Separation of positive and negative charges within molecules, oppositely charged parts attract

Question 24

Materials used in biomedical & biotech industry

Answer 24

Metals, ceramics, polymers (synthetic & biological)

Question 25

Alloys

Answer 25

Mixtures of metals

Question 26

Metals

Answer 26

Materials with metallic bonds

Question 27

Ceramics

Answer 27

- Inorganic compounds with mixture of ionic and covalent bonding - Structures not as closely packed as metals - Packing limited by charge and size - Inorganic glasses

Question 28

Inorganic glasses

Answer 28

- Crystal structure forms after melting and cooling - Orderly structure not maintained - Amorphous state

Question 29

Polymers

Answer 29

- Constituent atoms are C - Covalent bonding forms linear, chainlike structure - Two e- used in chain, two e- free - Thermoplastic or thermosetting

Question 30

Thermoplastic Polymers

Answer 30

- Basic chains are straight, no branching - Can be melted and remelted without change in structure - Neighboring chains held together by H bonding or van der Waals forces - Weak bonding means weak solid - Lower strength and melting point than thermoset polymers

Question 31

Thermosetting Polymers

Answer 31

- Has branches and side chains - Covalent bonds between branches form = cross linking - Crosslinked polymers have 3 D network - Do not melt uniformly when reheated

Question 32

Hooke's Law

Answer 32

Solid material will extend in the direction of traction in an amount proportional to load when subjected to force

Question 33

Stiffness

Answer 33

- Ability of material to resist deformation - E & G are used to characterize stiffness of material

Question 34

Elastic Strain

Answer 34

Increasing inter-atomic distances (stretching the bonds)

Question 35

Isotropic Materials

Answer 35

- Material whose properties are same in all directions (longitudinal, transverse) - Metals, alloys, and ceramics have E & G values that are highly reproducible

Question 36

Anisotropic

Answer 36

- Polymers and tissue samples - Stronger in longitudinal than transverse direction

Question 37

Elastic deformation

Answer 37

when load is removed the material returns to original dimension

Question 38

Plastic deformation

Answer 38

material does NOT return to original dimensions - Large scale displacement of atoms without complete rupture (irreversible) - Strains produced are much greater than in elastic deformation

Question 39

Ultimate Tensile Strength

Answer 39

The maximum stress that a sample can support. This happens in portions of the stress strain curve beyond the elastic limit

Question 40

Brittle Materials

Answer 40

Exhibit little or no plasticity before fracture

Question 41

Ductile

Answer 41

Large amount of plasticity under tension

Question 42

Malleable

Answer 42

Large amount of plasticity under compression

Question 43

Toughness

Answer 43

- Total area under the curve - The ability to store both elastic and plastic energy

Question 44

Resilience

Answer 44

- Area under the linear portion of the curve - The ability to store only elastic energy

Question 45

Elastic Response

Answer 45

Instantaneous elongation is stress applied

Question 46

Creep

Answer 46

Continuous, time-dependent extension

Question 47

Stress Relaxation

Answer 47

Continuous drop in load at a constant extension

Question 48

Fatigue

Answer 48

Occurs when loads are applied and removed for a large number of cycles

Question 49

Fatigue Strength (Endurance)

Answer 49

Stress which provides low probability of failure after 10^6 to 10^8 cycles (endurance limit)

Question 50

Hydrophilic

Answer 50

Surface on which water spreads - more biocompatible

Question 51

Hydrophobic

Answer 51

Surface on which water beads

Question 52

Surface energy

Answer 52

The balance of cohesive force and adhesive force

Question 53

Cohesive force

Answer 53

the force of liquid molecules attracted to each other

Question 54

Adhesive force

Answer 54

The force of the liquid drop attracted to the surface