- 1 Introduction To Biomedical Textiles
- 2 Scope In Biomedical Textile
- 3 Scenario Of Indian Medical Textiles
- 4 What Are Biomedical Textiles?
- 5 Types Of Biomedical Textiles
- 6 Requirements For Biomedical Textiles
- 7 Properties For Implants
- 8 Applications
- 9 Conclusion
Application of textile materials in the medical field is increasing due to its important characteristics. Recent innovations in medical textiles are the BIOMEDICAL TEXTILES. The term biomaterial is defined as materials that are used in contact with tissues, blood, cells, and other living substances.
The biomedical textiles include sutures, vascular grafts, heart valves, hernia mesh, tissue implants, nerve guidance channel, corneal lenses, artificial skin, artificial joints, heart patch and biomedical smart clothes.
Advances in non-wovens have resulted in a new breed of medical textiles and advanced composite materials containing the combination of fibres and fabrics have been developed for applications where biocompatibility and strength are required. This application mentioned, which should help professionals for further research, commercial or technical.
Introduction To Biomedical Textiles
Textiles come to our help in every walk of life, in either conspicuous or inconspicuous form. The fields of application of technical textiles are unlimited and the ideas often revolutionary. An important and growing part of the textiles industry consists of the medical and related healthcare and hygiene sectors.
The extent of the growth is due to the constant improvements and innovations in both textile technology and medical procedures. There has been a sharp increase in the use of medical products not only in the hospital, hygiene and healthcare sectors but also in other environments where hygiene is required.
It is vital to have newer or enhanced medical devices should be developed to cope up the situation.
Textile materials manufactured primarily for their technical and performance properties are called as ‘technical textiles’. Out of the total technical textiles, a major part is contributed by medical textiles. ‘Medical textiles’ are those, which are associated with specialty areas where the use of direct assistance in the medical and surgical treatment of the patient.
The term biomaterial is defined as materials that are used in contact with tissue, blood, cells, and any other living substances. A biomaterial can also be defined as a systemic, pharmacologically inert substance designed for implantation or incorporation within the human body and used in contact with tissue, blood, cells.
Biomedical implants are used to aid or replace damaged tissues or organs. These materials are used in affecting repair to the body whether it is wound closure or replacement surgery.
Biomedical textiles are generally related to the inner part of the body, i.e. those areas where once the implant is attached it becomes an involuntary part of the body.
To meet up with the requirements of every individual body, the resistance of the textile is important and it depends upon the selection of the material as well as its properties, reactivity, biodegradability, nontoxicity, sterility and end use. So the study of biomedical textiles depends upon the area of operation, fibres, types of implants, etc.
Driven by the cost and quality issues, the health system in the developed countries will undergo a fundamental change in this decade from a physician operated and hospital-centered health system to consumer operated personal prevention early risk detection and wellness system.
It is highly unlikely that any textile fibres that exist today, have not, at some time or the other, been considered for use in the present day advanced medical field. Thus, the largest use of textile fibres in the medical history is for those, which do not significantly in physical specifications or chemical type from those of our domestic surroundings, except for those for specialized applications.
Scope In Biomedical Textile
The importance of textile materials in medical fields is credited to their excellent physical properties, such as strength, extensibility, flexibility, suppleness, air and moisture permeability and wicking. In the last two decades of the twentieth century saw a paradigm shift from biostable polymers to biodegradable polymers for medical applications.
The current trend predicts that in the next couple of years, many of the permanent prosthetic devices used for temporary therapeutic applications will be replaced by biodegradable devices that could help the body to repair and regenerate the damaged tissues.
The major driving force is due to the emergence of novel biomedical technologies including tissue engineering, regenerative medicine, gene therapy, controlled drug delivery, and nanotechnology, all of which require biodegradable platform materials to build on.
Scenario Of Indian Medical Textiles
The Indian healthcare sector growth is expected to be more than 20% per annum in view of the rising per capita spending on healthcare products, greater exposure to International awareness of healthcare insurance and medical tourism.
Out of the total Indian textile industry, only 13% contributes to technical textiles, and out of this 13%, the share of Meditech, in technical textiles market is in the range of 6-8%. Among the wide range of medical products, hygiene products which include sanitary napkins take up around 35%, surgical dressings take 30%, sutures has 20%, whereas the rest 15% contributes to diapers and orthopedic implants.
The consumer for nonwovens products in the age group of 18 to 35 is nearly 500 million. This group is well educated and has enough income to afford nonwoven disposable products.
Recently, Ministry of Textiles (MOT), Government of India (GOI) has designated The South India Textile Research Association (SITRA) as the Centre of Excellence (COE) for Meditech in India.
|Technical Textile Sector||Market Size &Potential (Rs. Crore)|
What Are Biomedical Textiles?
A Biomaterial is defined as a systemic, pharmacologically inert substance designed for implantation or incorporation within the human body and used in contact with tissue, blood, cells, and other living substances. In simpler words a Biomaterial is defined as materials that are used in contact with tissue, blood, cells etc.
Biomaterials include metals, ceramics, polymers, natural fibres and their composites. Biomedical textiles are used to aid or replace damaged tissues or organs. These materials are used in affecting repair to the body whether it is wound closure (sutures) or replacement surgery (vascular grafts, artificial ligament etc).
The following table shows the various biomedical applications of polymeric materials:
|Field||Purpose||Application in medical field|
|Therapy||Repair and replacement of injury tissue||Prosthesis of bone, joint, tooth, etc, artificial heart valve, patch grafting, artificial blood vessel, artificial shunt, contact lens, intraocular lens, artificial skin|
|Therapy||Assist or temporary substitution for physiological function of a failed organ||Artificial heart and lung, ventricular assist system, artificial heart, artificial blood, artificial kidney, artificial lever, biomedical response modifier|
|Therapy||Disposable articles in daily medical treatment||Tubing, catheters, syringe, suture, etc.|
|Drug formulation||Novel drug delivery system for amelioration of pharmacokinetics||Device for controlled release of drug, targeting design of drugs, pulsatile release devices|
|Diagnostic examination||New items in clinical laboratory tests||Reagents and tools with quick response, high accuracy, and high sensitivity, clinical test for new marker of disease, cell labeling|
|Bioengineering||New technology in tissue culture in vitro separation of the blood component||Synthetic substrate or carrier particles for cell culture, additives for cell fusion, hybrid organ Plasma separation, cell separation, removal of virus and bacteria.|
Fibres For Medical Textiles
The first recorded use of fibres in medicine was mentioned in ‘Surgical Papyrus’ nearly 4,000 years ago. In the ‘Susanta Sambita’ written approximately 2500 years ago, a variety of materials is mentioned including horse hair, leather strips, cotton, animal sinews and fibrous tree bark.
As more research has been completed, textiles have found their way into a variety of medical applications. Latterly we have witnessed major development in medical textile production, the materials they are made and the technology used to produce them.
Fibres has always occupied a fundamental position in the medical field by providing textiles in the form of fibres, monofilament and multifilament yarns, woven, knitted, nonwovens, and composite materials. The fibre used may be classified depending on whether the materials from which they are made are natural or synthetic, biodegradable or nonbiodegradable.
|NATURAL ORIGIN||SYNTHETIC POLYMERS (NONBIODEGRADABLE)||NATURAL POLYMERS (BIODEGRADABLE)
· Regenerated cellulose (viscose, lyocell)
· Bamboo fibre
· Polytetrafluoroethylene (PTFE)
· Polyvinyl alcohol(PVA)
|· Biological protein:
Collagen, catgut, branan, ferulate
· Polylactic acid(PLA)
· Polyglycolic acid(PGA)
· Spider silk
Types Of Biomedical Textiles
Based on the applications the medical textiles can be broadly classified as follows:
- Personal healthcare and hygiene products
- Nonimplantable materials or medical dressing and auxiliaries
- Implantable materials
- Extracorporeal devices
Requirements For Biomedical Textiles
A biomedical textile is such a field which has its contribution more in the areas of implantable materials and devices within the body. Such textiles have to have very stringent requirements to be fulfilled for the utilization of the human body. For achieving very high quality and at effective costs nonwovens has been used on a wide scale.
Nonwovens is a fabric-like material made from long fibres, bonded together by chemical, mechanical, heat or solvent treatment. Nonwovens are broadly defined as sheet or web structures bonded together.
Nonwovens possess the following properties due to which they are suitable for medical field:
- Porosity, weight, and thickness
- Excellent barrier properties
- Economical manufacturing process
- Better performance
- Increased protection for user
- Less potential for cross contamination
- 100%certainity for single use
- Custom made for operation theater
- Excellent uniformity
- Self-adherent edges
- Engineered stability for ETO, plasma, radiation, or steam sterilization
- Excellent water retaining capacity
- Non-allergenic and nonirritant fibres
- Good heat resistance
Properties For Implants
The various properties required for an implant to be incorporated within the body:
- Bio sterility.
- Inert as well as compatible with blood and other fluids.
- No irritation.
- No release of foreign material.
- No tumors with long-term use.
- Long life span.
- Low infection rate.
- Easy handling.
- It should be available in a wide range of sizes.
- Mechanical properties- strength
The various applications for biomedical textiles are:
- Vascular grafts.
- Heart valves.
- Hernia mesh.
- Tissue implants.
- Nerve guidance channel.
- Corneal lenses.
- Artificial skin and joints.
- Heart patch.
- Biomedical smart clothes.
Technically, Sutures are either monofilament or multifilament with a smooth surface that can pass through the skin without being caught and can be tightened into a single knot. Sutures are small lengths of yarn with the needle attached to open end and are generally used to close lacerations, cut and deliberate incision which have been made on an item or living being. In simpler words, a suture is a medical device that doctors use to hold skin, internal organs, blood vessels and all other tissues of the human body together after they have been severed by injury, incision or surgery. They must possess particular properties like:
- Strength(so that they do not break).
- Nontoxic and hypoallergenic(to avoid adverse reactions in the body).
- Flexible(so they can be tied & knotted easily).
- They must lack ‘wick effect’ which means that sutures must not allow fluids to penetrate the body through them from outside which could easily cause infections.
Sutures are divided into 2 kinds-
- Absorbable—often used internally.
- Nonabsorbable—often used externally.
ABSORBABLE SUTURES—They are ideal for wound inside the body as they dissolve and get absorbed into the body after the operation. The materials used are such that they are broken down in tissue after a given period of time. Originally these were made of catgut, but nowadays they are made of synthetic polymer fibres e.g. Polyglycolic acid (PGA).
NONABSORBABLE SUTURES—They are made of materials which are not metabolized by the body and are used therefore either on skin wound closure, where the sutures can be removed after a few weeks. Nonabsorbable sutures which are made up of nylon, polypropylene, silk, polyester, and polytetrafluoroethylene, shape memory polymer are not absorbed into the body and need to be removed by the surgeon.
Vascular Grafts –
A vascular graft is an artificial vein or artery used to replace segments of the natural cardiovascular system that are blocked or weakened. Grafts are implanted to bypass the blockages and restore the circulation. There are following criteria for an ideal vascular graft:
- It should be available in a wide range of sizes.
- Biocompatible allowing healing with a nonthrombogenic surface.
- Low infection rate.
- Durable, strong and long life span.
- Easy handling.
- Nonfraying properties.
- Stability to sterilize.
- Resistance to bacteria/viruses.
Straight or branched grafts are possible by using either the weft or warp knitted technology. Knitted vascular grafts have a porous structure, which allows the graft to be encapsulated with new tissue. The vascular grafts are sterile and single patient use only. They are of following types:
- POLYESTER GRAFTS: Used to repair thoracic and abdominal occluded arteries.
- DACRON GRAFTS: For aortic surgeries.
- POLYTETRAFLUOROETHYLENE GRAFTS: To repair occluded arteries and veins in the hands and feet and for dialyzes treatment of chronic renal failure patients.
The main fibres include polyester, PTFE, polypropylene, polyacrylonitrile.
Heart Valves –
The heart valves assist cardiothoracic surgeons in treating valvular diseases. The heart valves are 2 types, namely, mechanical valves and tissue valves. The market size for artificial heart valves is estimated to grow at an average annual growth rate of 7%.
MECHANICAL VALVES: They are used for younger patients and require periodical checkups and after a particular period, the patients need to be operated a second time. Mechanical valves are made of titanium, around which is a knitted fabric to be stitched to the original tissue called as the 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. The price of the mechanical valve is in the range of Rs. 30000 to Rs. 50000. They are available in sizes ranging from 17mm to 35mm. such valves constitute about 90% of the total market.
TISSUE VALVES: They are used for slightly aged patients and do not require any periodic checkups. The life of these valves is 15-20 years and the price is in the range of Rs. 45000 to Rs. 65000. Tissue valves take over only 10% of the market share.
Hernia Mesh –
The abdominal wall has natural areas of potential weakness. Most inguinal hernias that occur in adults result from the strain on abdominal muscles that have been weakened by age or congenital factors. When a hernia forms a hole in the abdominal muscle, the inner lining of the abdomen is pushed through the weakened area. A loop of intestine or fatty tissue may push against this sac. At this stage, the patient may feel burning or tingling. As the loop of the intestine pushes into the sac formed by the weakened abdominal lining, it develops a bulge visible on the outside. Often, the loop of intestine becomes trapped and the patient loses the ability to make the bulge flatten out. A painful nonreducible hernia will be formed.
Meshes find use in hernia repair and abdominal wall replacement, where mechanical strength and fixation are very important. The composite meshes made up of polyester, polypropylene, and polyester/carbon fibre. The utilization of mesh grafts in humans for hernia operations is based on the fact that during the absorption period a geomembrane is formed at the site where the mesh has been implanted. The mesh graft prevents reoccurrence of a hernia. Fibres can be woven or knitted into a mesh with each side designed with a specific porosity and texture to optimize its long-term function. E.g. polypropylene is resistant to infection and is anti-allergenic. Gore-Tex soft tissue patch, which is used in hernia repair, is made of expanded PTFE.
Tissue Implants –
There are 2 types of implants which are incorporated within the body, namely soft tissue implants and hard tissue implants.
- SOFT TISSUE IMPLANTS: Biomedical materials are in applications such as soft tissue compatible artificial prostheses, artificial skin patches, artificial tendon and artificial corneas. Important properties that affect cell attachment and tissue growth are:
- chemical structure
- electric charge
- Roughness of the surface
- Micro heterogenous
- Material flexibility
Soft tissue compatible biological polymers are collagen, silk protein, cellulose, chitin, and Chitosan. Soft tissue artificial materials include silicone rubber, polyurethane, hydrogels and carbon fibre. Silicone rubber is a cross-linked polymer of poly (dimethyl siloxane). It has been used in artificial breasts, ears, and noses.
2. HARD TISSUE IMPLANTS: Hard tissue compatible materials must have excellent mechanical properties compatible with hard tissue. The polymer related to hard tissue should have good processability, chemical stability, and bio compatibility. Applications include artificial bone, bone cement, and artificial joints. Fixations plates are used to stabilize fracture bones. Textile structural composite is replacing metal implants for this purpose. A nonwoven fibrous mat made of graphite and Teflon is used around the implant to promote tissue growth. Orthopedic implants are used to replace bones and joints.
Corneal Lenses –
There are 3 main types of corneal lenses namely,
- HARD CORNEAL LENSES: They are made of poly (methyl methacrylate) and cellulose acetate butyrate.
- SOFT CORNEAL LENSES: Natural and synthetic hydrogels physically resemble the eye tissue and hence have been used in ophthalmology as soft corneal lenses. These are made of transparent hydrogels with high oxygen permeability.
- FLEXIBLE CORNEAL LENSES: these are made from silicon rubber.
Artificial Joints –
The artificial joints are made of stainless steel, chromium cobalt, titanium, or some other inert material. The textile material present in the joints is Ultra High Molecular Weight HDPE (UHMWHDPE). The market size for the artificial joints is estimated to grow at an annual rate of 12%.
Major requirements of dental polymers include translucency or transparency, stability, good resilience and abrasion resistance, insolubility, in oral fluids, nontoxicity, relatively high softening point and easy fabrication and repair. The most widely used polymer for dental use is poly (methyl methacrylate) (PMMA) and its derivatives. Other materials for denture base polymers are polysulfone and polyether polysulfone.
Desirable properties of artificial ligaments and tendons include:
- High strength
- Low abrasion
- Low creep
- Low stiffness
Artificial Skin –
The skin is the largest organ in the human body. Severe damage to large areas of skin exposes the human organisms to dehydration and infections that can result in death. Recently there has been progressing towards creating artificial skin. Typically a collagen scaffold is used (the protein that underlies the structure of skin) which can be seeded with patients own cells. The molecules which give skin its structure and elasticity have drastically improved burn victims chances of survival. Large sheets of the flexible mesh placed over open wounds encourage the growth of the new dermis, the bottom layer of skin, which does not regenerate under normal circumstances. Surgeons can then transplant small pieces of the patient’s epidermis, the top layer of skin, which grows and spreads over the newly grown dermis.
Recently, scientists have begun seeding the collagen scaffolds with skin cells to help to grow rather than transplanting epidermis onto newly grown skin; scientists grow epidermis cells on the collagen scaffold and then transplant the entire sheet.
Heart Patch –
Ventricle and arterial septal defects are the most common congenial heart defects. They can occur alone or along with the congenial heart disorder. It occurs when the opening in the left and right atria does not close normally during birth. The septal defect, if rectified by open heart surgery, requires the use of heart-lung cardiac bypass machine to keep the heart opened. Since the heart is exposed for surgery, it results in the significant scar. Hence, there is a need for a development of clinical heart patch. Once the patch is placed between the atria, it expands on each side of the hole. Eventually, tissue grows on the fabric and the patch becomes a permanent part of the heart.
SITRA is in process of developing polyester based heart patch material using warp knitting technology.
Medical textiles applications are directly related to the life of human being, those are required to undergo stringent testing and hygiene criteria, which led the innovative use of a variety of fibres and a lot of developments taking place in this area. Use of nanotechnology, tissue engineering, biomaterials along with basic textile structures, viz, fibres, yarns, wovens, knitted, nonwovens, and braided fabrics and composite structures made it possible to widen the horizon of medical textiles. The rapidly growing field of biomedical textiles and health care products is truly multidisciplinary in nature.
Textiles are very important in all aspects of medicine and surgery and the range and extent of applications to which these materials are used is a reflection of their enormous versatility. Advances in nonwovens have resulted in a new breed of medical textiles. Advanced composite materials containing a combination of fibres and fabrics have been developed for applications where biocompatibility and strength are required. It is predicted that the nonwovens will continue to have the greater impact in this sector owing to the large member of characteristics and performance criteria required for these materials. Further, the anticipated time of healing, the potential contamination and infection, the patients’ physical condition and the past postoperative course of the patient are other considerations, which generally, govern the choice of a particular type of biomaterial.
Medical textiles are a major growth area within the technical textiles sector and the range of applications for such products continue to grow and increase in diversity with every new development. Out of this sector of medical textiles in technical textiles, there is a small contribution of biomedical textiles which can grow if proper technology and research will be carried out in this area. Research in biomedical textiles is increasing due to the growing technology, awareness, and knowledge about the various types of diseases and its remedies.
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- Supriya Pal, “Nonwovens And Their Application In Medical Textiles” Asian Textile Journal Vol.18 No.4 May 2009 (Pg 49-55)
- Surya Nath Chaudhary & S P Borkar, “Advanced Textile Materials In Healthcare” Asian Textile Journal Vol.18 No.4 April 2009 (Pg 40-48)
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