Biomedical textiles are textile products used for medical applications that come into contact with living tissue. They must be biocompatible and biostable. Medical textiles include protective clothing and wound dressings, while biomedical textiles are implantable materials used for tissue engineering and repairs. Biomedical textiles must be designed based on their intended function, biocompatibility, cost, and product approval standards. Common biocompatible polymers used include collagen, silk, PLA, PGA, and chitosan. Biomedical textiles can be classified based on their fibers and applications such as implants, scaffolds, or extracorporeal devices. Key requirements for implants include biocompatibility and appropriate porosity.

1. Submitted by
Ashish Dua

2. INTRODUCTION
 Biomedical textiles are textile products and
constructions for medical and biological
applications.
 These are used in contact with tissue, blood, cells
and other living substances.
Main attributes
 Bio stability
(It is the ability of a material to perform with an appropriate host,
responsible for a specific application)
 Biocompatibility
(It is ability of the device to perform its intended function, with the desired
degree of incorporation in the host)

3. MEDICAL TEXTILES AND BIOMEDICAL TEXTILES
 Medical textiles
These are textile products and constructions for medical applications
Applications are:
 Protective and healthcare textiles
 Dressings, bandages
 Hygiene products
 Biomedical textiles
These are fibrous structures used in specific biological environments, their
performance depends on biocompatibility with cells and biological tissue or
fluids.
Applications are:
 Implantable materials and devices
 Tissue engineering
 Neural repairs

4. The design of a biomedical textile is driven by its end function.
The main factors included are:
 Function:
The textile needs to fulfil the purpose for which it was designed.
 Biocompatibility:
This refers to the reaction of the textile with blood and tissue in the body.
 Cost:
This depends on the raw materials, manufacturing process and product
end-use.
 Product approval:
Each country has its own regulations and standards for medical textiles.

5. BIOCOMPATIBLE POLYMERS
Protein fibres of biological origin obtained from bovine skin
 Properties : Excellent biocompatibility
Low immunogenicity
 Uses: Artificial tissues
Wound dressing
Sutures
Soft contact lens
Protein fibres of biological origin and derived from small
intestine of sheep or oxen
 Properties: Hard to handle
 Uses: Sutures

6.  Polylactic acid (PLA)
Cornstarch sugar is fermented into lactic acid, which is then polymerised
 Properties: Slow degrading polymer
Good tensile strength
 Uses: Orthopaedic applications
 Polyglycolic acid (PGA)
 Properties: High tensile modulus
Greater hydrolytic susceptibility
Excellent mechanical properties
 Uses: Resorbable sutures
Salts of alginic acid occurring in seaweed.
 Properties: Generates a moist healing environment
 Uses: Wound healing

7. Natural biopolymer, contains amino sugars obtained from shells of crabs,
wings of insects, fungi. Alkali treatment of chitin yields chitosan and result
can then be spun into filament having strength similar to viscose structure of
chitin and chitosan.
 Properties: Biocompatible
Bacteriostatic
Fungistatic
 Uses: Artificial skin
High performance fibres, obtained by pyrolysing PAN
 Properties: Low strength
High elongation
 Uses: Medical and surgerical applications

8. CLASSIFICATION OF BIOMEDICAL TEXTILES
Depending upon the fibres used:
These materials are absorbed by the body after 2-3 months of implantation.
For example: Polyamide, Polyurethane
These materials are absorbed slowly by the body after implantation and take
more than 6 months to degrade.
For example: Polyester, Carbon, PTFE

9. DEPENDING ON AREA OF APPLICATION:
o Implantable materials
 Sutures
 Artificial ligaments
 Artificial tendons
 Artificial skin
 Hernia net
o Scaffolds (Tissue engineering)
 Artificial kidney
 Artificial liver
 Mechanical lung
o Neural repair

10. IMPLANTABLE TEXTILE MATERIALS
The artificial material replaces the body tissue when healing is not
possible or no replacement tissue is available. Bio hybrid organs
consists of an artificial material which combined with cells.
 REQUIREMENTS OF AN IMPLANT
 Porosity, this determines the rate at which tissue will grow
and encapsulate the implant.
 Small circular fibres are better encapsulated by human
tissue than larger fibres with irregular cross sections.
 Non-toxicity, fibre polymer or fabrication techniques must be
non-toxic and fibres should be free of contaminants.
 Biodegradability and bio-stability depending on the
application. A suitable artificial surface for body cells to adhere
to and grow on.

11. S. No. PRODUCT FIBRE TYPE YARN OR FABRIC
APPLICATION TYPE
1. Sutures
Monofilament,
Biodegradable Collagen, Polyglycolide, Polylactide braided
Polyamide, Polyester, Teflon, Polypropylene, Monofilament,
Non-biodegradable Polyethylene braided
2. Soft tissue implants
Braided
Artificial ligaments Polyethyene, Silk
Artificial tendons
Artificial skin Polyamide, Polyester, Teflon Woven, Braided
Artificial cornea Low density polyethylene Nonwoven
Polymethyl methacrylate, silicon, collagen Nonwoven
3. Orthopaedic implants
Silicon, Polyethylene, Carbon Knitted, Woven
Artificial joint/bones
4. Cardiovascular implants
Vascular grafts
Heart valves Polyester, Teflon Knitted, Woven
Polyester Knitted, Woven

12. SUTURES
Sutures are threads, that are monofilament or multifilament which are
used to sew the open wounds after a surgery. The type of suture used
depends upon physical, biological and chemical culture of the tissue
where it is to be put into.
 Characteristics for suture materials
 Tensile strength
 Non toxic
 Strength retention
 Knot security Wound before suture
 Easy handling properties
 Infection potential
 They must lack the wick effects
Wound after suture

13. PROPERTIES OF SUTURES
 Handling:
Three properties of a suture affect its handling:
 Memory (they tend to stay in one position)
 Elasticity (measure of how a suture returns to its original length after
stretching)
 Knot strength (force needed for a knot to slip)
 Tensile strength:
It is a measure of force necessary to break a suture, the weakest part of a
suture is the knot, consideration of strength is important in areas under
tension.
 Natural or synthetic:
Sutures can be made from natural materials- e.g., catgut, silk, or linen.
Natural sutures tend to cause an inflammatory tissue reaction but these are
still useful in some fields as, silk in plastic surgery.
Sutures made from synthetic materials are – Polyester, Polypropylene

15.  Monofilament or multifilament –
Monofilament sutures are single stranded; multifilament sutures are
several strands braided together.
Braided sutures have better handling property but cause tissue drag and the
spaces between filaments can harbour bacteria.
Monofilaments do not have these problems but tend to have significant
memory and can be difficult to handle.
 Absorbable or non-absorbable--
Absorbable sutures are constructed from the materials which are broken
down in tissue after a given period of time usually from ten days to four
weeks. They are therefore applied in many inner tissues of the body.
Non Absorbable sutures are made from materials which are not
metabolized by the body, and used either on skin wound closure, where the
sutures can be removed after a few weeks, or in some inner tissues in which
absorbable sutures are in adequate.

17. o Tissue –
Ultimately, the type of suture depends on where it is to be used. In the skin,
non- absorbable sutures can be used, provided they are removed. Ideally, the
suture should be a monofilament. In the face, sutures should be removed as
quickly as possible to minimise scarring.
Production Process
Produce Filament
Braiding
Stretching & Coating
Needle Attachment

18.  Classification of implantable materials:
 Soft Tissue Implants
 Hard Tissue Implants
 Soft Tissue Implants
Strength and flexibility of textile material make it particularly suitable for
biomedical implants.
Soft tissue compatible biological polymers are collagen, silk protein,
cellulose, chitin and chitosan.
Soft tissue artificial materials include silicone rubber, polyurethane, hydro
gels and carbon fibre.
These includes:
 Artificial tendon and artificial ligament
 Artificial skin
 Hernia net
 Artificial cornea

19. ARTIFICIAL TENDONS AND LIGAMENTS
Ligaments connect bone to bone
Tendons connect muscle to bone
 Woven and knitted structures are used as
artificial ligaments.
 Braided fabrics with a stress strain
behaviour similar to natural tendons or
ligaments are the most suitable
structures.
 Braided composite textile structures
made from carbon and polyester are
particularly suitable for knee ligament
replacement.
 Bioabsorbable polymers are also
preferable for manufacturing of ligaments
and tendons.

20.  Major requirements of artificial tendons and
ligaments
 Biological
 Bio compatibility
 Long term stability
 Supporting tissue proliferation
 Bio mechanical
 Physiological progressive stress strain behaviour
 Low creeping
 High shear strength
 Porosity
 Flexibility

21.  Skin Dressing
 In order to conform to irregular surface, elastic
and flexible materials are used for skin dressing,
which are able to promote skin regeneration.
 For flexibility and absorbability of the body
fluid, skin dressing is obtained from woven and
non woven fabrics as well as also from micro
porous layer.
 Collagen and chitin are the most commonly
using skin dressing materials, besides which
there is no material which can meet the
requirements of a skin substitute exactly.

22. Two essential requirements for skin dressing:
i) It should prevent the dehydration of the wound and also able to resist the
bacterial entry.
ii) It should be permeable enough to allow the passage of discharge
through pores and cuts.
The necessary properties for a skin substitute are as follows:
 Tissue compatibility
 Inner surface structure that permit growth of fibro vascular
tissue
 Prevention of wound contraction
 Flexibility
 Pliability to permit conformation to irregular wound surface
 Elasticity to permit motion of underlying body tissues
 Resistance to linear and shear stresses
 Low cost and indefinite self life.

23.  Hernia net
Meshes are used in hernia repair and abdominal wall replacement, where
mechanical strength and fixation are important.
The composite meshes made up of polyester, polypropylene and carbon fibres.
Required properties of the mesh are:
 Strength
 Flexibility
 Appropriate pore size and pore size
distribution
 Good dimensional stability
 Easy to mould

24.  Artificial cornea
Soft contact lenses are made of transparent hydro
gel with high oxygen permeability.
Hard contact lenses are made of polymethyl
methacrylate and cellulose acetate butyrate.
Flexible contact lenses are made from silicone
rubber. A specialised polymer Poly 2-hydroxyethyl
methacrylate is commercial used to make contact
lenses.
Lenses should have following properties :
 High surface energy
 Flexibility
 Optical properties
 Should be easily wettable by tears
 Permeability of the lens to oxygen

25. HARD TISSUE IMPLANTS
 Hard tissue compatible materials must possess excellent mechanical
properties.
Properties of the polymer for hard tissue implants are
 Good processability
 Chemical stability
 Bio compatibility
 These includes:
 Orthopaedic implants
 Cardiovasclar implants

26. ORTHOPAEDIC IMPLANTS
 The applications include artificial bone, bone cement and artificial
joints. Orthopaedic implants are used to replace bones and joints,
and fixation plates are used to stabilize fractured bones. Textile
structural composites like carbon composites have replaced by metal
implants. A non woven man made from graphite and Teflon is used
around the implants to promote tissue growth.

27. CARDIOVASCLAR IMPLANTS
 Categories
Vascular grafts
Heart valves
 Vascular Grafts Woven Dacron vascular graft
Vascular graft is an artificial vein or artery
used to replace segments that are blocked or
weakened. Straight or branched grafts are
possible by using either the weft or warp
knitting technology. Knitted vascular grafts
have a porous structure, which allow the graft
to be encapsulated with new tissue.
Knitted Dacron vascular graft
Disadvantage it can cause blood leakage
through the interstices directly after the
implantation
To reduce this risk, knitted grafts with internal
and external velour surfaces are used
Knitted Dacron bifurcation graft

28.  Requirements of good vascular graft are:
 Non-fraying
 Flexibility
 Durability
 Biocompatibility
 Stability to sterilization
 Resistance to bacteria/viruses
 Blood compatibility
 Porous structure

29.  Heart valves
The heart valves assist cardiothoracic
surgeon in treating valvular diseases.
 The heart valves are of two types:
• Mechanical valve
• Tissue valve
 Mechanical valve are used for younger
patients and require periodical check-ups and
after a periodical period, the patient need to
be operated a second time. Mechanical
valves are made up of titanium, around
which is a knitted fabric to be stitched to the
original tissue called as sewing ring. The
sewing ring of the caged-disc type of
prostheses uses a silicon rubber insert under
a knitted composite PTFE and polypropylene
fibre cloth.
 Tissue valve are used for slightly aged
patients and do not require any periodic
checkups.

30.  Scaffolds
Tissue engineering support structures or „scaffolds‟ which are artificial
devices, designed to act as templates for attached cells and newly formed
tissues. The scaffolds' three-dimensional, porous structures encourage cell
attachment, proliferation and migration through an interconnected
network of pores. New tissue forms gradually and can be implanted into
the body.
 Design factors:
 Allow cell attachment and migration
 Deliver and retain cells and biochemical factors
 Enable diffusion of vital cell nutrients and expressed products
 Exert certain mechanical and biological influences to modify the
behaviour of the cell phase
 Scaffolds used in tissue engineering must also fulfill the following
requirements:
 Be biocompatible
 Resist biodegradation
 High porosity
 Adequate pore size to facilitate cell seeding and diffusion
 Rate of biodegradation should coincide with rate of tissue formation

31. EXTRACORPOREAL DEVICES
S.No. PRODUCT APPLICATION FIBRE TYPE FUNCTION
1. Artificial liver Hollow viscose Remove waste product
from patient‟s blood
2. Artificial kidney Hollow viscose Separate and dispose
body‟s Plasma proteins
3. Mechanical lung Hollow propylene, Hollow Remove carbon dioxide
silicone, silicon membrane from blood and supply
the oxygen

32.  Artificial liver
The liver has multiple functions essential to maintain life including
carbohydrate metabolism, synthesis of proteins, amino acid
metabolism, urea synthesis, lipid metabolism, drug biotransformation
and waste removal. The artificial liver utilizes the functions of separating,
disposing & supply of fresh plasma in hollow viscose fibres or membranes
similar to those used for artificial kidney to perform their function. In the
case of extracorporeal devices, cells are grown to confluence in devices
resembling dialysis cartridges, and then inserted into a „circuit‟ outside the
patient‟s body, where blood from the patient flows through the cartridge,
contacting the cells, and then back into the patient.

34.  Artificial kidney
The kidneys serve as filtering devices of
the blood. The nephrons, the working units
of the kidney, filter waste materials out of
the blood and produce urine to secrete
toxins from body. The kidneys also
maintain normal concentrations of body
fluids, which play a key role in
homeostasis.
 The material used in dialysis membranes
are regenerated cellulose, cellulose
triacetate, acrylonitrile copolymer,
poly(methyl methacrylate), ethylene-
vinyl alcohol copolymer, polusulfone
and polyamide which can be grouped as
cellulose and synthetic polymer systems.

35.  The function of the artificial kidney is achieved by circulating
the blood through a membrane, which may be either a flat
sheet or a bundle of hollow regenerated cellulose fibres in the
form of cellophane. In an external artificial kidney, a
haemodialyser, is used which can perform many of the
functions of a kidney. Since the dialyser is a foreign substance
to the human body, when the blood is circulated through the
dialyser, the leucocyte count in the blood decreases over the
first 20 minutes of dialysis, but recovers to its original value
after 1 hour. It is made up from a bundle of hollow fibres
through which the blood circulates. The objective is to
improve the surface of hollow fibres so that the leucocyte
decrease does not occur. Hemodialysis includes removal of
metabolic substances, adjustment of electrolytes and pH and
removal of excess water by ultrafiltration and dialysis, which
is usually a membrane separation process.

36.  Mechanical lung
Oxygenate body‟s blood and remove cellular by products most of which
consisted of CO2.The microporous membranes of the mechanical lung
possess high permeability to gases but low permeability to liquids and
functions in the same manner as the natural lung allowing oxygen to
come into contact with the patient‟s blood.
Silicone or polypropylene fibres are used for fabricating mechanical lung so
as to allow the permeation of gases. The mechanical lung should ideally function
for at least 1 to 3 weeks. But the present mechanical lung can function only for a
week. This is because, ability to remove carbon dioxide falls off. The lung is a
form of gas exchanger to supply oxygen to the blood and remove carbon dioxide.
Microporous membranes that provide high permeability for gas flow and low
permeability for liquid flow which is similar to the natural lung where oxygen
and blood come into contact. In these devices, oxygen flows around hollow fibres
at extremely low pressure. Blood flows inside of the fibres. The oxygen
permeates the micropores of the fibres and comes in contact with the blood. The
pressure gradient between the blood and oxygen is kept near zero to prevent
mixing of oxygen and blood. Red blood cells capture oxygen by diffusion
process.
 PP hollow fibre exhibits good compatibility with blood and excellent gas
permeability. Its use allows a design of a compact artificial lung that is easy and
safe to operate. However, its long term use causes a leak of blood plasma
components.

37. Neural Repair
 Nerve guidance channel
These are used to bridge the damaged nerve endings and facilitate the
passage of molecules secreted by the nerve and bar fibrous tissue from
infiltrating the area thus preventing repair. An innovation is the use of
electrically conducting polymers such as polypyrole to promote nerve
regeneration by allowing a locally applied electrical stimulus. It is a
blossoming field of textile research, since the nerve guidance channel may
be a single continuous hollow tube, or it may be a hollow tube comprised of
fibres.
Technology: Extruded Tube In vitro: cells growing into the tube In vivo: neural implant

38. FUTURE DEVELOPMENTS
o Auxetic fibers:
Bandage made of polymers such as Teflon , polypropylene and nylon are used
in fabrics that are projected for use in wounds that swell. As the wound swells,
the auxetic bandage does as well. The inner “voids” of the bandage would
release the healing agent during the healing process and once it begins to heal,
the bandage will contract and the healing agent will stop being released. Thus,
the auxetic fibres provide a means of controlled drug delivery.
o Shape-memory:
These materials store a permanent shape to memory as well as maintain their
temporary shape, so that when they are in the compressed temporary form, they
can be inserted into the body through a small incision and then upon reaching
body temperature would change to the permanent shape. These materials can
also be biodegradable, so that repeat surgery for removal of the implant would
not be required.

39.  Electronics :
The use of electronic devices in textile implants is envisaged, for example,
as monitors in artificial arteries, stents and heart valves constructed from
textiles. When the implant begins to not function properly, they would act as
warning devices and trigger electrical pulses or the release of drugs to
overcome the problem, at least temporarily.
 Controlled drug delivery :
Drugs present as additives in resorbable fabrics would gradually be released
on breakdown of the fabrics. Another intriguing innovation is the
development of soluble glass fibres for the controlled release of drugs in a
wide range of concentrations and delivery periods.

40.  REFERENCES
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5. S. Viju, The Indian Textile Journal, June 2008, Pg 75
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15. www.expresstextile.com
16. http://www.csiro.au/science/TissueEngineering.html#
17. US Patent 6146651
18. Biomedical Textiles, Maria Cieslewski, November 13, 2006, ELE 382