STATE UNIVERSITY OF SANTA CATARINA
CENTER FOR TECHNOLOGICAL SCIENCES
POSTGRADUATE PROGRAM ON ELECTRICAL ENGINEERING
RESEARCH GROUP ON BIOMEDICAL ENGINEERING
INTRODUCTION ON BIOMEDICAL ENGINEERING - IBME
Prof. Dr. Pedro Bertemes-FilhoProf. Dr. Pedro Bertemes-Filho
[email protected]@gmail.com+55 (47) 34817848
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Chapter 04 – Biomaterial and Tissue Eng.
� MATERIALS IN MEDICINE
� Aseptic surgical technique by Dr. Joseph Lister in the 1860s;
� End of 1890s - metal devices to fix bone fractures;
� 1938 - total hip replacement prosthesis;
� 1950s and 1960s - polymers for cornea and blood vessel replacements;
INTRODUCTION ON BIOMEDICAL ENGINEERING
� 1950s and 1960s - polymers for cornea and blood vessel replacements;
� USA numbers for 2002:
� Total hip joint replacements: 448,000
� & Knee joint replacements: 452,000
� & Shoulder joint replacements: 24,000
� & Dental implants: 854,000
� Coronary stents: 1,204,000
� & Coronary catheters: 1,328,000
� DEFINITION: biomaterial is nonviable material used in a medical device, intended to
interact with biological systems (Williams, 1987)
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Chapter 04 – Biomaterial and Tissue Eng.
� MATERIALS IN MEDICINE
� Impact of biomaterials:
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Chapter 04 – Biomaterial and Tissue Eng.
� MATERIALS IN MEDICINE
� Biomaterials are expected to be “bioactive”;
� Bioactive: capability to initiate a biological response after implantation;
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� Biomaterials are guided by design, selection, synthesis, and fabrication;
� Biomimetics: involves imitating aspects of natural materials or living tissues such as
their chemistry, microstructure, or fabrication method.
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Mechanical Properties and Testing
� The most common way to determine mechanical properties is to pull a specimen
apart and measure the force and deformation;
� Force is measured in Newtons & deformation in millimeters, then Stress is
calculated as: σ(N/m2) = force/cross-sectional area
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Measuring the stiffness of the material, which is called the elastic modulus (E=σ/ε) or Young’s modulus
Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Mechanical Properties and Testing
� Summary of mechanical properties of cortical bone and biomaterial:
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MaterialTensile strength
(MPa)Compressive
strength (MPa)Elastic modulus
(GPa)Fracture toughness
(MPa. m-1/2)
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Bioglass 42 500 35 2
Cortical Bone 50-151 100-230 7-30 2-12
Titanium 345 250-600 102.7 58-66
Stainless steel 465-950 1000 200 55-95
Ti-Alloys 596-1100 450-1850 55-114 40-92
Alumina 270-500 3000-5000 380-410 5-6
Hydroxyapatites 40-300 500-1000 80-120 0.6-
Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Metals
� Used as biomaterials have high strength and resistance to fracture and are
designed to resist corrosion
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Metals
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Metals: examples
INTRODUCTION ON BIOMEDICAL ENGINEERING
Metal plates and screws used to
hold fractured bone segments
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total hip joint
replacement
artificial
knee joint
hold fractured bone segments
together during healing
Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Metals:
� Advantages of metals over other materials such as ceramics and polymers are
that they are strong, tough, and ductile (or deformable);
� Disadvantages include: susceptibility to corrosion due to the nature of the
metallic bond (free electrons);
INTRODUCTION ON BIOMEDICAL ENGINEERING
metallic bond (free electrons);
� In the 1900s, steels used for hip implants had corrosion in the body THEN they
changed to alloys of titanium or cobalt-chrome for hip, knee, and dental
implants;
� Metals are also applied in eye glasses and coronary artery stents that are
inserted through a catheter (i.e., nitinol – a shape memory alloys).
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Ceramics and Glasses
� The advantages of the ceramics are that they are biocompatible, are inert, have
low wear rates, are resistant to microbial attack, and are strong in compression;
� Some disadvantages include: fragility, and being difficult to machine;
� Ceramics do not conduct heat or electricity, but Ceramics have very high melting
points, generally above 10008C, and are brittle;
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points, generally above 10008C, and are brittle;
� Bioactive ceramics (i.e., compositions of ceramics, glasses, glass-ceramics, and
composites) are used stimulate direct bone bonding for securing orthopedic
medical devices
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synthetic bone graft
substitutes: made of
calcium phosphate or
calcium sulfate
Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Polymers
� Advantages: flexibility , stiffness, low/high strength, resistant or not to protein
attachment, biodegradable or permanent, and fabricated into complex shapes by
many methods;
� Disadvantages: they tend to have lower strengths than metals or ceramics,
deform with time, may deteriorate during sterilization, and may degrade in the
INTRODUCTION ON BIOMEDICAL ENGINEERING
deform with time, may deteriorate during sterilization, and may degrade in the
body by releasing toxic products;
� Fillers, plasticizers, stabilizers, and colorants typically are used in polymer
synthesis to enhance the mechanical, chemical, and physical properties;
� Polymers can be classified as thermoplastic or thermosetting;
� Thermoplastic polymers can be heated, melted, molded, and recycled;
� Thermosetting is a three-dimensional cross-linked structure, then it cannot be
heated and reused (i.e., Hydrogels);
� Applications of hydrogels: contact lenses, drug delivery vehicles, wound healing
adhesives, sexual organ reconstruction materials, artificial kidney membranes,
and vocal chord replacement materials.
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Polymers: synthetic polymer scaffolds for tissue engineering:
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Natural Materials
� Proteins and polysaccharides are nature’s form of polymers and are used in
medical devices;
� Types: Nylon, silk, calcium phosphate bone crystals or calcium carbonate coral
or sea shells, collagen, biopolymers;
It also encompasses donor tissue such as bone or skin which may be patient
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� It also encompasses donor tissue such as bone or skin which may be patient
derived (autograft), from another human (allograft), or from a different species
such as bovine or porcine (xenograft);
� Advantages: lower incidence of toxicity and inflammation as compared to
synthetic materials;
� Disadvantages: expensive to produce or isolate natural materials; variability
between lots of natural materials;
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Composites
� The term composite is reserved for materials consisting of two of more chemically
distinct constituents that are separated by a distinct interface;
� Composites are made by mixing two components and molding, compacting, or
chemically reacting them together;
Advantages: the properties can be tailored to fit nearly any application;
INTRODUCTION ON BIOMEDICAL ENGINEERING
� Advantages: the properties can be tailored to fit nearly any application;
� Disadvantages: difficult to make a composite with an ideal structure;
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Composites
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Composites
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
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Chapter 04 – Biomaterial and Tissue Eng.
� BIOMATERIALS: PROPERTIES, TYPES, AND APPLICATIONS
� Other examples
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Chapter 04 – Biomaterial and Tissue Eng.
� TISSUE–BIOMATERIAL INTERACTIONS
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Chapter 04 – Biomaterial and Tissue Eng.
� TISSUE–BIOMATERIAL INTERACTIONS
� Interactions with Blood and Proteins
� It makes first contact with the implanted biomaterial;
� Proteins play an important role in determining the final nature of the tissue–
implant interface: immunoglobulins, fibrinogen;
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� The Wound Healing Response after Biomaterial Implantation
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(a) Protein attachment to the biomaterial
surface guides cellular interactions;
(b) Hemostasis is accomplished by clot
formation;
(c) Cells found in blood and other
inflammatory cells attempt to process the
foreign biomaterial and repair adjacent
material;
(d) The host protects itself from the foreign
biomaterial through encapsulation with
fibrous tissue.
Chapter 04 – Biomaterial and Tissue Eng.
� TISSUE–BIOMATERIAL INTERACTIONS
� Metallic Corrosion:
� Corrosion resistance is one of the most important properties of metals used for
implants: galvanic (or mixed metal) corrosion, crevice corrosion, and fretting
corrosion;
WHY? - when two dissimilar metals are connected in an electrochemical cell, one
INTRODUCTION ON BIOMEDICAL ENGINEERING
� WHY? - when two dissimilar metals are connected in an electrochemical cell, one
will act as an anode while the other will be the cathode;
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Chapter 04 – Biomaterial and Tissue Eng.
� TISSUE–BIOMATERIAL INTERACTIONS
� Biomaterial Degradation and Resorption:
� Biomaterials may be permanent or degradable;
� Bioresorbable implants are designed to degrade gradually over time in the
biological environment and be replaced with natural tissues;
INTRODUCTION ON BIOMEDICAL ENGINEERING
� Collagen and the lactic acid and/or glycolic acid polymers are the most
commonly used for resorbable applications;
� Immunogenicity
� It is the tendency for an object to stimulate the immune response;
� Examples: bacteria, pollen from grass or trees, small or absorbable biomaterials,
and proteins in food that lead to allergies or inflammation;
� Corrosion of metallic implants releases metal ions that can cause metal sensitivity
or allergic reactions in some individuals. Allergic reactions can lead to slow or
inadequate bone fusion or skin dermatitis.
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Chapter 04 – Biomaterial and Tissue Eng.
� WHAT IS TISSUE ENGINEERING?
� Tissue engineering is a biomedical engineering discipline integrating biology with
engineering to create tissues or cellular products outside the body (ex vivo) or to make
use of gained knowledge to better manage the repair of tissues within the body (in
vivo).
� It also requires knowledge of many engineering fields, including biochemical and
mechanical engineering, polymer sciences, bioreactor design and application, mass
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mechanical engineering, polymer sciences, bioreactor design and application, mass
transfer analysis of gas and liquid metabolites, and biomaterials.
� Clinical trials with cell therapies or extracorporeal organs: cartilage, bone, skin,
neural, and liver tissues;
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Chapter 04 – Biomaterial and Tissue Eng.
� WHAT IS TISSUE ENGINEERING?
� Challenges Facing the Tissue Engineer
� The four principal size scales in
tissue engineering and cellular
therapies---------------------------�
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Chapter 04 – Biomaterial and Tissue Eng.
� WHAT IS TISSUE ENGINEERING?
� Cellular Therapies, Grafts, and Extracorporeal Bioartificial Organs
� It requires organized culture control and exploitation of cell metabolites;
� Bioengineering challenges: i) cell therapies include injection needle design and
procedure protocols; ii) bioreactors — the function, choice, manufacturing, and
treatment of biomaterials for cell growth and device construction;
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� Human Cells and Grafts as Therapeutic Agents
� Cell therapies use human cells as therapeutic agents to alleviate a pathological
condition (i.e., blood transfusion, platelets, bone marrow, hematopoietic stem
cells);
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Chapter 04 – Biomaterial and Tissue Eng.
� WHAT IS TISSUE ENGINEERING?
� Mechanisms Governing Tissues
� The number of cells required to replace the physiological functions defines the
overall dimension of an engineered product.
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Chapter 04 – Biomaterial and Tissue Eng.
� WHAT IS TISSUE ENGINEERING?
� Resume:
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