Conductive bioplastics that will boost the performance of bionic devices such as the cochlear ear and the proposed bionic eye has been developed by biomedical engineer Rylie Green of University of New South Wales (UNSW). 'Our plastics will lead to smaller devices that use safer smaller currents and that encourage nerve interaction,' says Green. Her plastics are already being tested in prototype bionic eyes and she hopes they will find application wherever researchers are attempting to integrate electronics with the human body.
Bionic devices -- electronic devices and mechanical parts that assist humans in performing difficult, dangerous, or intricate tasks connect into the nervous system. At present, the electrodes they use are made from metals such as platinum and iridium. Since metals have smooth surfaces, the body immediately tags them as foreign material and tries to wall them off by growing fibrous, scar tissue around the implant. As a result, larger and larger electrical currents must be used to stimulate the nerves through the scar tissue. This eventually results in the surrounding tissue and body fluids being subjected to unnatural changes in acidity and to toxins produced from the metal contacts, both of which damage cells.
Conductive plastics or polymers are an alternative to metals. They have rough surfaces which encourage the attachment of cells, meaning they offer potential for improved performance and longevity when implanted in the body as electrodes. 'The plastics can carry natural proteins which will aid the survival of damaged and diseased nerves,' Green says. The highly textured polymer surface can pass electrical current to cells more efficiently than smooth metals. Performance has been improved by incorporating natural body proteins. Upon implantation, these proteins help the cells near the electrode to survive and grow, and can reduce the formation of scar tissue. This is especially important in implant recipients where the existing tissue is damaged, as is the case with most deaf and blind patients, said an UNSW release.