A variety of natural and synthetic materials are used in creating prosthetics in the present day. Advancements in technology and medical field have made it possible to replace many body parts with a prosthetic. Prosthetics is a part of bio-mechatronics, the science of using mechanical devices with human muscle, skeletal and nervous systems to assist or improve motor movements and control that is lost due to injury, accident or disease.
Prosthetic devices are mostly custom-made to suit individual needs like size, weight, lifestyle and amputation and helps in improving the quality of life of the amputee. The various features to look for while selecting the materials to be used for making a prosthetic device include:
Various metals like aluminium, titanium, magnesium, copper, steel and others are used as pure metals, alloys or in mixed states. Recent trends of using titanium for its weight ratio, strength to density ration, corrosion resistance and low density have been successful. Titanium, alloyed with vanadium and aluminium, has shown to be more advantageous. It is strong, lightweight, corrosion resistant and non-allergic. It is similar to human bones in terms of elasticity, which makes it possible to distribute the weight of the body evenly between the bone of the residual limb and the implant.
Polymers, being softer materials, are more often used in phalanges, joints and other smaller body parts or when specialized features are required. Some of the polymers used in prostheses are:
Ionometic polymer metal composites (IPMC) are types of electro-active polymer actuation materials that have unique properties making it useful in making of prostheses.
Carbon fibers have properties such as high stiffness, high tensile strength, low weight, high chemical resistance, temperature tolerance, specific strength, etc. It has been found supportive to an amputee who has excessive body weight also.
Surgical tools and other objects placed inside the body have to be made of materials that are biocompatible, not causing harm to the living tissue or the skin that it is in contact with. Prosthetics are attached to the limb and are subject to constant movements. This makes them rub against the skin surface where they are attached. Mechanical stress on the skin or the part where the limb is amputated can cause tissue breakdown, skin blisters, cysts or ulcers.
Materials like nylon-reinforced silicone, Spenco, Poron, etc are used in making of prostheses after being tested for they performance during compression testing.
Small components, digital or mechanical, are added for enhancing the performance of the prostheses. These components must be well-protected from exposure to air and water for them to be durable.