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Classes of Biomaterials Used in the Body Advantages Disadvantages Metals Corrosion Density Processing Ceramics Brittle – f...
(Source: Park; p. 3) Biomaterials for Biological Tissue Replacements Example Metals Joint replacement  Dental roots Orthop...
Density (g/cm 3 ) Elastic modulus  (GPa) Yield strength (MPa) Tensile Strength (MPa) % Elongation at break Stainless Steel...
Density (g/cm 3 ) Elastic modulus  (GPa) Yield strength (MPa) Tensile Strength (MPa) % Elongation at break cp-Titanium and...
<ul><li>Types of Tissues: </li></ul><ul><li>Epithelial tissue :  </li></ul><ul><li>covers the  body surface  and forms the...
<ul><li>Soft Tissues :  </li></ul><ul><li>Connect, support, or surround other structures and organs of the body </li></ul>...
Biological Tissues: Mechanical Properties Tissue Modulus  (MPa)  Tensile Strength  (MPa) Strain at Break (%) Soft Tissues ...
Elastic Modulus “ Mechanical Mismatch Issues ”:  A biomaterial that replaces or repairs a tissue but has, for instance, hi...
f04_01_pg6 f04_01_pg6 Elastic Modulus
Density A biomaterial that replaces an equivalent volume of tissue may have different  weight   as a result of the differe...
f03_01_pg6 f03_01_pg6 Density
Metallic Biomaterials <ul><li>Source: Ratner, B.D. et al. “Biomaterials Science: An Introduction to Materials in Medicine,...
 
Categories of Metallic Biomaterials <ul><li>Stainless Steel </li></ul><ul><li>Cobalt-based Alloys </li></ul><ul><li>Titani...
Stainless Steel 316L (SS 316L) <ul><li>ASTM F138, F139 </li></ul><ul><li>Composition: </li></ul><ul><li>- Fe: 60-65 wt% </...
(2) Mechanical Properties of SS 316L <ul><li>SS316L is “ austenitic ” </li></ul><ul><li> -Fe ,  FCC </li></ul><ul><li>Sta...
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Classes of Biomaterials Used in the Body

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Transcript of "Classes of Biomaterials Used in the Body"

  1. 1. Classes of Biomaterials Used in the Body Advantages Disadvantages Metals Corrosion Density Processing Ceramics Brittle – fractures easily in tension Polymers Not strong Not rigid Time-dependent deformation (creep; stress relaxation) Degradation
  2. 2. (Source: Park; p. 3) Biomaterials for Biological Tissue Replacements Example Metals Joint replacement Dental roots Orthopedic fixation Stents Ceramics Dental implants Orthopedic implants (some) Polymers Sutures Blood vessels (e.g. vascular grafts) Joint socket (knee, shoulder) Ear, nose Soft tissues in general
  3. 3. Density (g/cm 3 ) Elastic modulus (GPa) Yield strength (MPa) Tensile Strength (MPa) % Elongation at break Stainless Steels SS 316L Annealed 7.9 172 485 40% SS 316L 30% Cold Worked 7.9 690 860 12% Cobalt-Based Alloys Haynes-Stellite 21 or ASTM F75 Cast Co-Cr-Mo 8.3 450 655 8% Haynes-Stellite 25 or ASTM F90 Wrought Co-Cr-W-Ni; Annealed 9.2 445 970 62% Haynes-Stellite 25 or ASTM F90 Wrought Co-Cr-W-Ni: 44% Cold-worked 9.2 1610 1900 10% ASTM-F562 or MP35N Wrought Co-Ni-Cr-Mo-Ti Hot forged ~9.2 965 1210 50% ASTM-F562 or MP35N Wrought Co-Ni-Cr-Mo-Ti Cold worked ~9.2 1500 1800 8%
  4. 4. Density (g/cm 3 ) Elastic modulus (GPa) Yield strength (MPa) Tensile Strength (MPa) % Elongation at break cp-Titanium and Titanium Alloys cp-Ti (Grade 4) or ASTM F67 30 % Cold Worked 4.5 485 760 15% Ti-6Al-4V or ASTM F136 annealed 4.5 830 900 14% Tantalum Tantalum Annealed 16.6 138 345 20-30% Tantalum 30% Cold Worked 16.6 207 517 2%
  5. 5. <ul><li>Types of Tissues: </li></ul><ul><li>Epithelial tissue : </li></ul><ul><li>covers the body surface and forms the lining for most internal cavities . </li></ul><ul><li>skin is an organ made up of epithelial tissue. </li></ul><ul><li>Function: protect </li></ul><ul><li>Connective tissue : </li></ul><ul><li>Bone, cartilage , dense fibrous tissue, loose connective tissue, fat </li></ul><ul><li>Function: support, protection, binds tissues together </li></ul><ul><li>3. Muscle Tissue: </li></ul><ul><li>Skeletal: voluntary; contraction of skeletal parts; attached to bone via tendons </li></ul><ul><li>Smooth: involuntary; walls of internal organs and blood vessels </li></ul><ul><li>Cardiac: involuntary ; walls of the heart </li></ul><ul><li>Nerve Tissue: </li></ul><ul><li>Consists of nerve cell or neurons located in the brain, spinal cord, and nerves </li></ul><ul><li>Produces and conducts nervous impulses to and from all parts of the body. </li></ul><ul><li>Organ: _______________________________________________ </li></ul><ul><li>skin , bone, heart, lung, brain, eye, stomach, spleen, pancreas, kidneys, liver, </li></ul><ul><li>intestines, uterus, and bladder. </li></ul>Tissue: _______________________________________________
  6. 6. <ul><li>Soft Tissues : </li></ul><ul><li>Connect, support, or surround other structures and organs of the body </li></ul><ul><li>Muscles: support/moves bone </li></ul><ul><li>Tendons: connect muscles to bone </li></ul><ul><li>Ligaments: connect bone to bone </li></ul><ul><li>Synovial tissue: makes up joint capsule </li></ul><ul><li>Fascia: sheet or band of fibrous connective tissue enveloping, separating, or binding together muscles, organs, and other soft structures of the body. </li></ul><ul><li>Also: nerves, blood vessels, fat </li></ul><ul><li>Hard Tissues: </li></ul><ul><li>Tissues that _______________________________ </li></ul><ul><li>Cartilage and bone </li></ul>Tissues
  7. 7. Biological Tissues: Mechanical Properties Tissue Modulus (MPa) Tensile Strength (MPa) Strain at Break (%) Soft Tissues Smooth Muscle, relaxed 0.006 - 300 Smooth Muscle, contracted 0.01 - 300 Carotid Artery 0.084 ± 0.22 - - Cerebral Artery 15.69 4.34 50 Cerebral Vein 6.85 2.82 83 Pericardium 20.4 ± 1.9 - 34.9 ± 1.1 Patellar Tendon (29-50 yrs. Old) 660 ± 266 64.7±15 14 ± 6 ACL Ligament (21-30 yrs. Old) 345 ± 22.4 36.4 ± 2.5 15 ± 0.8 Hard Tissues Modulus ( G Pa) Tensile Strength (MPa) Strain at Break (%) Cortical Bone 17 - 24 90 -130 1-3 Cancellous Bone 0.1 - 4.5 10 - 20 5-7 Cartilage 0.001 - 0.01 10 - 40 15-20
  8. 8. Elastic Modulus “ Mechanical Mismatch Issues ”: A biomaterial that replaces or repairs a tissue but has, for instance, higher stiffness may be problematic (e.g. may cause “stress shielding” or neointimal hyperplasia). Similarly, if it lacks rigidity, it may also be problematic (e.g. recoil of coronary stents, plastic deformation under physiological conditions). Material E (GPa) Silicone Elastomer (Rubber) ~0.002 UHMWPE 0.69 PMMA 2.2-3.2 Soft tissue See previous table Cortical Bone 17-24 Cancellous Bone 0.1 – 4.5 Glass 73 Gold 77 Ti-6Al-4V 114 Stainless Steel 316L 190 Tantalum 190 Haynes-Stellite 21 (Cast Co-Cr-Mo) 210 Aluminum oxide 380 Diamond 700-1200
  9. 9. f04_01_pg6 f04_01_pg6 Elastic Modulus
  10. 10. Density A biomaterial that replaces an equivalent volume of tissue may have different weight as a result of the differences in density . In some applications, this can be problematic. Source: J. Park & R.S. Lakes, Biomaterials: An Introduction (3 rd Ed), p. 93 ISBN 978-0-387-3789-4 Material Density (g/cm 3 ) Fat 0.94 UHMWPE 0.94 Water 1.0 Soft tissue 1.01-1.06 Silicone Elastomer (Rubber) 0.99-1.50 PMMA 1.19 Cortical Bone 1.8-2.1 Cancellous Bone ~1 Glass 2.4-2.8 Diamond 3.5 Aluminum oxide 3.98 Ti-6Al-4V 4.5 Stainless Steel 316L 7.9 Haynes-Stellite 21 (Cast Co-Cr-Mo) 8.3 Tantalum 16.6 Gold 19.3
  11. 11. f03_01_pg6 f03_01_pg6 Density
  12. 12. Metallic Biomaterials <ul><li>Source: Ratner, B.D. et al. “Biomaterials Science: An Introduction to Materials in Medicine, 2 nd Edition, Elsevier Academic Press, San Diego, CA, 2004. </li></ul><ul><li>In 2004 (unless otherwise stated) </li></ul><ul><li>*indicates all or predominantly metal </li></ul><ul><li>**indicates metal-containing </li></ul>Device Annual # of Devices in USA Intraocular Lenses (2003) 2,500,000 Vascular Grafts 300,000 Breast prostheses 250,000 **Heart Valves (rings, cages) 100,000 (some) **Pacemakers 400,000 *Coronary Stents 1,500,000 *Hip Prostheses (2002) 250,000 *Knee Prostheses (2002) 250,000 *Dental Implants 910,000
  13. 14. Categories of Metallic Biomaterials <ul><li>Stainless Steel </li></ul><ul><li>Cobalt-based Alloys </li></ul><ul><li>Titanium Alloys </li></ul><ul><li>Specialty Metallic Alloys </li></ul>Steel <ul><li>A steel alloy that is highly resistant to corrosion </li></ul><ul><li>Fe is combined/alloyed with at least 11 wt% chromium (Cr) </li></ul>1. Stainless Steel (SS) <ul><li>An Fe & C alloy </li></ul><ul><li>- cp-Fe: <0.008 wt% C </li></ul><ul><li>- steels: 0.008-2.14 wt% C </li></ul><ul><li>- cast irons: 2.14-6.7 wt% C </li></ul><ul><li>“ ferrous alloy ”: Fe is main constituent (FYI: Fig. 11.1) </li></ul><ul><li>May contain appreciable amounts of other alloying elements </li></ul>Stainless Steel
  14. 15. Stainless Steel 316L (SS 316L) <ul><li>ASTM F138, F139 </li></ul><ul><li>Composition: </li></ul><ul><li>- Fe: 60-65 wt% </li></ul><ul><li>- Cr: 17-19 wt% </li></ul><ul><li>- Ni: 12-14 wt% </li></ul><ul><li>- C: 0.03 wt% max </li></ul><ul><li>- Minor: Mn, P, Si, Mo </li></ul>Cr [O 2 ] Cr 2 O 3 (chromium oxide at surface = protective water-barrier) Low [C] (<0.03 wt%): Higher [C] (> 0.03 wt%): Cr + C [O 2 ] Cr 23 C 6 (chromium carbides) which ppt @ grain boundaries Depletes Cr at adjacent grain boundaries Cr 2 O 3 @ surface water penetration ASTM = American Society for Testing and Materials <ul><li>Name: </li></ul><ul><li>- 316 : Contains Mo </li></ul><ul><li>- L : Low C content </li></ul><ul><li>Rationale for Composition: </li></ul><ul><li>(1) Corrosion Resistance: </li></ul>Sensitized SS = SS where carbides have formed
  15. 16. (2) Mechanical Properties of SS 316L <ul><li>SS316L is “ austenitic ” </li></ul><ul><li> -Fe , FCC </li></ul><ul><li>Stabilized by Ni </li></ul><ul><li>non-magnetic , generally stronger </li></ul><ul><li>“ Ferritic ” SS </li></ul><ul><li> -Fe , BCC </li></ul><ul><li>Stabilized by Mo, Si </li></ul>FYI: Table 11.4 E (GPa)  y (Mpa) TS (MPa) %EL Cold Worked 190 690 860 12% Annealed 190 172 485 40%
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