Biomaterials and it's applications

 Biomaterials

- Bio material is a material used in a medical device that is non-viable and interacts with the biological systems . The bio materials field has seen steady growth over  fifty years of existence  and utilises ideas from medicine, biology, chemistry, materials science and engineering.

- For the most part , bio materials are used for medical applications. Not only that , bio materials are used  to grow cells in culture in order to assay for blood proteins in the clinical laboratory, in processing bio molecules in biotechnology and for investigational cell-silicon known as "Bio Chips ".

- What makes these application common among each other is that  the interaction between biological systems and synthetic or modified natural materials. Bio materials are seldom being used on their own but then , they are often integrated into many devices or implants.

Common bio material medical devices

Area of problem	Bio material applications
Assisting in healing	Sutures , Bone plates and screws
Improve function	Cardiac pacemaker , intraocular lens
Aid to diagnosis	Probes , Catheters
Replacement of diseased or damaged part	Artificial hip joint , Kidney dialysis machine

Requirements for a bio materials  

-  Bio compatible

- Non Toxic

- Non Viable

- Sterility

- Mechanical and Performance Requirement

Here are some examples of various types of biomaterials

Metallic Biomaterials

The 'Vanadium Steel' is the first metal alloy that was being produced specifically for human usage and to manufacture bone fracture plates and screws . Various metals such as iron (Fe), chromium (Cr), cobalt (Co), nickel (Ni), titanium (Ti), molybdenum (Mo), and tungsten (W) that were used to create alloys for manufacturing implants can only be tolerated by the body in small amounts. The bio-compatibility of the metallic implant is taken into consideration as these implants can corrode in an in vivo environment . The outcome of  the corrosion are that the implant material perse will be disintegrate, weakening the implant and the deleterious effect of corrosion products on the surrounding tissues and organs .

Ceramic Biomaterials

The essential properties of bio-materials are should be non-toxic, non-carcinogenic, bio-compatible and  bio functional for its lifetime in the host. Usually ceramics are hard . Ceramics are being used  in implant fabrications can be categorized  as non-absorbable which is unreactive, bioactive or surface reactive which is semi reactive  and biodegradable or reabsorbable which is not reactive. Alumina, zirconia, silicone nitrides, and carbons are some examples of unreactive bioceramics. Certain glass ceramics and dense hydroxyapatites are semi reactive and the calcium phosphates and calcium aluminates are reabsorbable ceramics. 

Polymeric Biomaterials

The synthetic polymeric bio materials are generally used in medical disposable supplies, prosthetic materials, polymeric drug delivery systems,tissue engineered products and orthodoses like those which consist of metal and ceramics substituents. The main advantages of the polymeric bio materials are able to manufacture to produce various types of  shapes such as latex and film effortlessly, secondary processability, reasonable amount of cost and having desired mechanical and physical properties. The essential properties of polymeric bio materials are same as other bio materials which are  bio-compatibility, sterilizability, it's mechanical and physical properties.

In conclusion , you should take into consideration that which biomaterials belong to which category as this will prevent from any negative concequences to our human body . The main priorities for the biomaterials are biocompactability , bioinert , bioactive or surface reactivity , biodegradable , reasonable cost and many more. The biomaterials classification is really essential in medical industries .

References

file:///C:/Users/admin/Downloads/Classification_of_Biomaterials_used_in_Medicine.pdf

https://www.uweb.engr.washington.edu/research/tutorials/introbiomat.html

https://mse.osu.edu/research/biomaterials

Nanotechnology's impact in medicine field

Nanotechnology's impact in medicine field

Nanotechnology plays a major role in field of medicine . The usage of nanotechnology provides interesting possibilities . Well , Nanotechnology in medicine field the applications of nano particles that are currently under development. Not only that, a longer range research that involves the usage of manufactured nano-robots to make repairs at the cellular level . The use of nanotechnology could change radically the way we detect and treat the damage in our body and the disease the future. There are many applications of nanotechnology in the medicine field . The operation at nano scale allows
exploitation of physical properties different from those observed at micro scale such as volume/surface ratio. Here are some of the various examples that are the stated below here.

Medical Application : Drug Delivery

This application is being developed in the medicine field which uses nano particles to deliver drug , heat , light and other substances . The particles are engineered in order for them to be attracted to the diseased cells. which provides a  direct treatment of those cells. Not only that ,  this technique also helps decreases the  damage to healthy cells in the body and allows it for earlier detection of disease.

Medical Application : Nano medicine diagnostics

For the past few decades , imaging turned out to be an essential tool in the diagnosis of disease. The advances of the magnetic resonance and computer tomography are extraordinary , but not only that nanotechnology assures sensitive and accurate tools for in vitro and in vivo diagnostics that are far ahead of today’s state-of-the-art equipment. Well ,  the utmost target is to allow the physicians to identify the disease as soon as possible. The Nanotechnology field  is believed to make diagnosis possible at the cellular and even the sub-cellular level.

The Quantum dots had taken the step from pure demonstration experiments to real applications in imaging. In recent years, the scientists have discovered that these nano crystals allows researchers to study and comprehend cell processes at the level of a single molecule. This drastically enhance the diagnosis and treatment of cancers.

The fluorescent semiconductor quantum dots prove to be extremely beneficial for medical applications, such as high-resolution cellular imaging. Whereas , the quantum dots  could change medicine radically but the drawback is that most of it are toxic . Well , recently studies has shown protective coatings for quantum dots may eliminate toxicity.

References

http://www.understandingnano.com/medicine.html

http://www.nanowerk.com/nanotechnology-in-medicine.php

How Nanotechnology can save the environment ?

How Nanotechnology can save the environment ?

Nanotechnology plays a crucial  role in today's world. It also plays a massive role in saving the environment by saving raw materials , energy , water. Not only that , it reduces the greenhouse gases and hazardous wastes. Nano materials are environment-friendly products as they do have unique physical and chemical properties .

The Benefits of Nanotechnology to the environment

There are various benefits of nanotechnology can save the environment . The benefits are the it helps to increase the useful life due to the increased amount of durability of the material against the mechanical strength . The nanotechnology - based dirt and the water resistant coating helps to decrease the cleaning efforts . Nano materials also helps to advance the energy efficiency of the building .The other benefits , the nano particles are being added to decrease the weight and save energy from the transport.

There are also other examples too . In the chemical industry , the nano materials are being applied according to their special catalytic properties which is to boost the energy and the resource efficiency . Not only that the nano materials also helps to take over from the environmentally problematic chemicals in certain fields . The nano technologically optimized products are at the development phase which will help significantly for the protection of the climate and also resolving other energy problems in future.


Nano materials are also useful in cleaning up the air , water and ground pollutants . Well , special filters and processes are being used to that makes the nano particles to bind with the pollutants are the basis for these new developments as this might be essential in cleaning up the contaminated water. For the air pollutants ,  the face mask made form nano materials will help to degrade and absorb the viruses present in the atmosphere.

The titanium oxide nano particles are well known for breaking down dirt when the sun shines on the nano particles .  The layers of the titanium oxide nano particles are being placed on the glass of the windows as they are self-cleaning . In terms of reducing the emissions form the car fuels that increases the efficiency of the combustion and gases are being broken down into lesser harmful compounds .The Nano products will use the heat and then convert it to energy.

Stronger and lighter materials are being created by nano materials . A well known examples are the carbon nano tubes. They make a massive positive  environmental impact as by making the air planes lighter making it last longer to decrease the amount of material in landfills and recycle.

Nanotechnology Applications that are beneficial to the environment

Nanomaterials for radioactive waste clean-up in water


For the radioactive waste clean-up , the scientist are working on nanotechnology solution , mainly using the nano fibres the absorbents to remove the radioactive ions from the water. Researchers have also indicated that the titanate nano tubes and nano fibres unique structural properties lead them to becoming a superior materials for removing the radioactive cesium and iodine ions in the water.

For Carbon Dioxide capture

Before the carbon dioxide could be stored in the carbon dioxide capture and storage schemes , it needs to separated from the other waste gases that results from combustion or industrial process . The currents that are being used are expensive and require the usage of chemicals . To resolve this issue , nanotechnology techniques are being implemented to fabricate the nanoscale thin membranes which result to a new membrane technology to change that.

References

http://www.nanowerk.com/nanotechnology-and-the-environment.php

http://www.nanoandme.org/nano-products/environment/

Failure Analysis

This blog page can be used for a last minute revision on the topic of ' Failure Analysis' from the material science course.

Failure Analysis

What is failure ?

- It is a machine or a component that is unable to function as intended. Types of failures are distortion , fracture and wear.

What is failure analysis ?

- It is an examination of the failed component and of the failed situation which will help us to determine the causes of the failure.

Types of failure and it's description

Fracture - It is the separation of  an object or material into two or more pieces under the action of stress .

Wear - Wear is a failure where the fracture toughness causes the material to degrade . Undesirable removal of the materials from the contacting surfaces .

Fatigue - Material fatigue is the weakening of the materials due to repeatedly applied loads . The progressive and the localised strutural damage happens when a material undergoes cyclic loading . The maximum stress values are less than the ultimate tensile stress limit .

Corrosion -  It is the gradual destruction of materials due to the chemical reaction with it's environment.

Distortion - Undesirable alteration in shape of the material

Creep - It is the tendency of a material to move slowly or to be deformed permanently due to mechanical stresses. 

Failure Analysis process

Step 1 : Background review

Step 2 : Catalogue Evidence

Step 3 : Examine and Test Evidence

Step 4 : Analyse all Data

Step 5 : Conclusions and Recommendation

Macroscopic Examination

- The macroscopic examination are being conducted with an  unaided eye , magnifying glass or microscope at lower magnification . The magnification ranges from 1 to 50 times .

Microscopic Examination

- The microscopic examination are conducted at higher magnifications . The magnification ranges up to 200000 times . This examination is essential for providing micro structure feature of failed surface and also to provide the evidences of the failed mechanism,

Non- Destructive Testing

- It is a test method that allows physical properties of the failue mechanism to be examined without taking the samples out of service. The test must not destroy the material taht is being examined or damage it's future serviceability .

- Examples are radiographic and ultrasonic .

Destructive Testing

- This test involves removing a metal component form service and sectioning the component for analysis. The purpose for this test is to find out whether the design met the required standards with the process or not and also find out the process defect .

- Examples are tensile testing , impact testing

Nano Materials

This blog page can be used for a last minute revision on the topic of 'Nano materials' from the material science course.

Nano materials

- The scientific notation for the prefix nano is 1 x 10^-9 

- It is equal to the one-billionth of a meter .

- Nanomaterials are very small in size , having at least one  dimension of 100 nm and below .

 Examples of objects on a nanometer scale 

- Virus ( 50nm)

- DNA (2.5 nm )

Properties of Nano materials

- Materials at the nanoscale have unusual physical , chemical and biological properties.

- Nanomaterials are stronger and have different magnetic properties compared to the  other various  forms , sizes or the same material.

- Nanomaterials are really good conductors of heat and electricity .

- Nanomaterials are more chemically reactive  , reflect light better and also the colour varies when their size or the structure is being modified.

What is so great about Nanoscale ?

Surface effects

- Nanomaterials have a larger surface area compared to other similar masses of large scale materials.

- 1cm³  of the cubic nanoparticles will have total-surface area one third larger than a football field. When the surface area of the material increases, a larger amount of material can come in contact with the surrounding materials . This leads to affecting the reactivity of the material.

Surface-area-to-volume (SAV) ratio

'a' represents each side of cube length 

- Surface Area of the Cube of length a = 6a²

- Volume of the cube = a³

- Thus the SAV ratio will be 6/a

 - The SAV ratio of a cube increases  when the dimensions of the cube increases .

- The S.I Unit for SAV ratio is m^-1

- There will be a higher SAV ratio under the nanoscale when compared to the corresponding ratio at the macroscale.

- A heavy material that is being subdivided into a group of individual nanomaterials , the total will remain the same but the total surface area will be largely increased .

Colour

- The changes in colour are due to the various manner in which the photons interacts with the nanomaterials when compared to other materials.

Reactivity

Can drinks made up of aluminium

-  Aluminium is being used to make can drinks.

-  At the nanoscale , the aluminium particles are very reactive and thus will explode.

- When the surface area of the aluminium increases , the size of the aluminiun will decrease . A larger    amount of aluminum will come in contact with surrounding materials  , hence making the material      very reactive.

Electrical Conductivity

Carbon nanotubes

- Carbon nanotubes possesses a high electrical conductivity .

- The reason for the possession of high electrical conductivity is because of the unique cylindrical nanostructure of the carbon nanotubes.

Quantum Effects

What are quantum effects ?

- When the material is at the nanoscale , it's properties will vary drastically . These changes are known as quantum effects.

- When the particle size is at nanoscale range , it's properties such as colour , mechanical strength , electrical conductivity and reactivity  change as a function of the size of the particle.

- Scientists can make small adjustments to a nano material's property of interest such as colour , mechanical strength by changing the size of the material.

Applications of Nanomaterials

-  Zinc oxide nanoparticles dispersed in industrial coatings in order to protect wood, textiles from exposure to UV rays
- Miniaturised electrodes for biosensors

Composites

This blog page can be used for a last minute revision on the topic of 'Composites' from the material science course.

Composites

- Composites are made up of  matrix and reinforcement .

Matrix 

- To bind the reinforcement together

- Distribute stress

- Maintain ductility and toughness
- To protect the reinforcement against abrasion and environmental effects.
- To transfer the load to the reinforcement

Reinforcement

- Carry the load

- Give strength and the stiffness

Properties of Composites

- Isotropic which is independent of direction

- Anisotropic which is dependent of direction

Unidirectional continuous fibre reinforced composite

-  The composite will be  stronger in the vertical direction . As the tensile strength will be stronger in the direction which is parallel to the fibers arrangement.

Rules of mixture

σc= σm*Vm+ σ fVf

Ec=EmVm+ EfVf

ƿc= ƿmVm+ ƿfVf

σm* = Stress in the matrix at fiber failure

σf = Tensile strength of fiber

Vf = Volume ratio of fiber

Vm = Volume ratio of matrix

E = Young’s modulus

Ƿ = Density

Ff/Fm = EfVf/EmVm

Ff/Fm = The ratio of the load carried by the fibers to that carried by the matrix

Ef = Young’s modulus of fiber

Vf = Volume ratio of fiber

Em = Young’s modulus of matrix

Vm = Volume ratio of matrix

Ceramics

This blog page can be used for a last minute revision on the topic of 'Ceramics' from the material science course.

Ceramics

- Ceramics are non-metallic and also inorganic.

- Ceramics are usually a compound between the metal and non-metal such as oxidies , nitrides.

- Ceramic are often crystalline .

- Examples of ceramics are glass , cement .

- There are two types of bonding which are based on the relative electronegativity , which are ionic and covalent .  Ceramics are usually brittle . They have high melting point , stiff and corrosion resistant. 

- The Ceramics can be made less brittle by advanced processing techniques. 

Ceramic structures are dependent on 

- Cation radius , Anion radius

- Charge neutrally

Factors affecting the brittleness of ceramics

- the strength of ionic or covalent bonding
- the presence of defects such as impurities , vacancies
- Grain boundaries
- Voids

 Techniques used to improve brittleness

- Hot Isostactic  Processing
- Reduce the voids in the ceramics

Creep Deformation

This blog page can be used for a last minute revision on the topic of 'Creep deformation' from the material science course.

Creep Deformation

- Creep Deformation is being defined as time dependent , permanent deformation and also under constant load or stress .

Examples of creep

- Sagging shelves

- Ruptured water pipe

Creep process

Part 1 : Dislocation Movement

- The low stress levels and heat energy is being applied. The dislocations in the lattice will take place slowly. Thus , the shape of the material will tend to differ slowly with time .

Part 2 : Vacancy Diffusion

- The low stress level which are less than yield strength and also heat energy is being applied. The atoms move and vacancies accumulate to form voids. Thus , the cross sectional area will decrease and  weaken the material.

- The voids are microscopic and can be detected only under a microscope. 

Creep strain vs time graph  

Creep strain vs time graph

Factors affecting the rate of the creep 

Magnitude of stress -  The greater the stress being exerted , the greater the amount of force to move the dislocations , leading to greater rate of creep.

Temperature -  When the temperature increases , the more heat energy is available for the vacancies to diffuse  , leading to a greater rate of creep .

Time -   Creep is time - dependent . The greater the amount of time  , the greater the amount of deformation.

Material Property - Creep depend on the melting point of the metal. ''T'' is the operating temperature. "T_m” . If the "T" is lower than 40% of  "T_m” ,   the creep will not occur in the metal.

Different types of crystal structures in metal

This blog page can be used for a last minute revision on the topic of ' Different types of crystal structures in metal' from the material science course.

Different types of crystal structures in metal

- There are 3 types of  crystal structures in metals . They are Face- centered cubic (FCC) , Body - centered cubic ( BCC ) and Hexagonal close packed ( HCP ) .

Keywords

 Crystalline 

- It is a material in which the atoms positioned in a repeating or a periodic array over the large atomic distances.

Crystal structure

- It is the manner in which the atoms , ions or molecules are spatially arranged .Well , there is an extremely large number of different crystal structures that comprises a long range atomic order which varies from simple structures for metals to complex ones which are being displayed by some of the ceramic and polymeric materials.

Lattice 

- It is a model which a three- dimensional array of points coinciding with the atom positions.

Face- Centered Cubic ( FCC)

Face-Centered Cubic in a unit cell

- This lattice is a cubic shape.

- There are 8 corner atoms in each unit cell and also 6 atoms on each face of the unit cell .

- The effective total number of atoms in a face-centered cubic unit cell is 4.

Body- Centered Cubic

Body-centered cubic

                                                         

- This lattice is a cubic shape.

- There are 8 corner atoms in each unit cell and 1 centre atom is each unit cell .

- The effective total number of atoms in a body-centered cubic is 2 .

Hexagonal Close- Packed Crystal Structures

- This lattice is in a hexagonal shape .

- The hexagonal plane is also known as a  basal plane.

- The top and bottom basal plane consist of 6 corner atoms.

- In the mid plane , it consist of 3 atoms .

- At the centre of the upper and lower basal planes , there is one atom .

Linear Density

- It is defined where the number of atoms per unit length where the centers lies on the direction vector for a specific crystallographic structure.

LD = Number of atoms centered on direction vector 

          length of direction vector

Planner Density

- Planner density is the number of atoms per unit area that are centered on a crystallographic plane.

PD =  Number of atoms centered on a plane 
            Area of plane