Electrophysiological Study Of Artificial Tactile Sensation Through Intrafascicular CNT Yarn Electrodes

In recent years,the number of the disabled has increased because of diseases,natural disasters,traffic accidents,etc.The intelligent prosthesis can partially reconstruct the activity function for them.The prosthetic hand with sensory feedback can not only improve the accuracy of the prosthesis,but also strengthen the connection between the user and the prosthesis,then improve the acceptance rate of the prosthesis.The choice of neural interface electrodes is the key to restore sensory feedback.Ideal electrodes should maintain certain stability and high selectivity over long period.The current electrodes mainly include percutaneous electrodes,extraneural electrodes,and intrafascicular electrodes.The percutaneous electrode and the extraneural electrodes have lower selectivity,and they are difficult to control the prosthesis precisely;while the intrafascicular electrodes have high selectivity and can accurately distinguish different fingers.However,since the electrodes are mostly made of metals,they can be corroded during long-term implantation,since the electrodes are mostly made of metals.Therefore,a material owning better electrical properties,mechanical properties,and biocompatibility is urgently needed.Previous studies have shown that carbon nanotube yarn(CNT yarn)performs good electrical properties,conductivity and charge injection;excellent flexibility,which is similar to nerve flexibility;biocompatibility,as neural cells can grow on it.All of these imply that it is an ideal material for neural interface.However,the spatial selectivity of CNT yarn as intrafascicular electrodes has not been verified yet.In this study,the performance of CNT yarn electrodes coated by Teflon and C-Parylene(PC)were compared and examined by scanning electron microscopy.It is found that the latter is more suitable for insulation of CNT yarn.Then,the insulated CNT yarn electrodes and Pt/Ir electrodes were respectively implanted into the tibial nerve of the rats,which is one of branch of the sciatic nerve.It was found that the noise and the impedance of the CNT yarn are less than the other one.Increasing the stimulus amplitude would change the number and types of activated fibers.The CNT yarn electrodes also performed high selectivity in acute experiments to distinguish different toes.The preliminary study of CNT yarn electrodes in this paper may provide a new choice for the neural interface technology of intelligent prosthesis.