Advancements in biological neural interfaces using conducting polymer: a review

Abstract

Neural interfacing machines are interfacial devices that restores the purpose of the nervous system lost due to any disease or injury. In the current scenario, conventional metal-based electrodes are employed for neural interfacing however, challenge faced with these electrodes is signal degeneration owing to filling of liquid gap (i.e., in extra systemic implants) between target tissue and electrode. Thus, this problem aroused a novel idea to use conducting polymers as it provides excellent electrical conductivity for signal transduction along with biocompatibility with human body. Implanted metal-electrode generates an immunological response in human body and attempts to eradicate it by treating it as a foreign material. Conducting polymers are generally biocompatible with the bodies' immune system and does not induce any significant long-term negative effect in-vivo and are much preferred and reliable over the conventional techniques because of its high surface area that promotes a good conductance with target tissues by reducing impedance, hence, enhances the recording and simulation applications of various neural processes. Thus, this review intends to study a number of neural interfacing applications by taking polypyrrole and PEDOT as primary conducting polymers with brief explanation on their preparation & conductance mechanisms, and then focussing on neural implanting, interfacing behaviours and superiority over other materials. Novel designing and applications of cochlear implants, bionic eyes and brain-machine interfering are hereby reviewed.