Neural electrodes interfacing

Huang, H., Zhou, R, Li, G., and Kuiken, T. A. 2008. An analysis of EMG electrode configuration for targeted muscle reinnervation based neural machine interface. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 16(1), 37-45. 

The most charge efficient way to activate neural tissues is to use the narrowest possible cathodic pulse followed by a delay of 100 nS and then an anodic pulse. The function of the cathodic phase is to initiate a propagated action potential. The function of the delay phase is to avoid quenching the nascent action potential evoked in nerves driven to or slightly above threshold. The function of the anodic phase is to bring the interface potential back to the prepulse value. Bringing the electrode potential back to prepulse values (1) terminates reactions that can be driven by the potential across the electrode interface at the termination of the cathodic phase and (2) returns the interface potential to the prepulse value for the next succeeding stimulus pulse. 

Shah S, Hines A, Zhou D et al. (2007) Electrical properties of retinal-electrode interface. Journal of Neural Engineering 4 S24-S29. 

Recently, several conducting polymers have been explored as new electrode materials for neural interface. Polypyrrole, polythiophene, and their derivatives can be electrochemically polymerized from aqueous solution and deposited on the neural electrodes [22-28]. Bioactive molecules, such as cell-adhesion peptides, ECM proteins, growth factors, etc., can be incorporated into the polymer as dopants to promote neuronal growth and binding to the electrodes [22-25, 29-30]. Poly(3,4-ethylenedioxythiophene) (PEDOT) presents properties especially promising for... 

If a microsystem should interface a regenerating nerve, some basic demands have to be taken into consideration the system must be absolutely non toxic, it must be stable in the physiologic environment for a long time, and the mechanical load on the severed nerve should be as minimal as possible during muscle contraction and limb movement. The neural prostheses should be equipped with multiple electrodes for recording nerve signals and for stimulation of different portions of the nerve. 

The Neural Prosthesis Program, launched in 1972 and spearheaded by F. Terry Hambrecht, MD, brought funding, focus, and coordination to the multidisciplinary effort to develop technologies to restore motor function in paralyzed individuals. The initial efforts were in electrode-tissue interaction, biomaterials and neural interface development, cochlear and visual prosthesis development and control of motor function using implanted and nonimplanted electrodes. 

R.A. Green, L.A. Poole-Warren, and N.H. Lovell. Novel neural interface for vision prosthesis electrodes Improving electrical and mechanical properties through layering. In Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering, Kohala Coast, Hawaii, USA (2007). 

The Neural Stimulating Community Needs to Have a Better Understanding of the Processes that Takes Place at the Electrode-Electrolyte Interface... 

The business end of a neural prosthetic device is the electrode, the metal-tissue interface, through which the device is to do a job, safely and efficiently. Understanding how these electrodes operate will provide insight into the mechanisms of tissue injury and ways to extend their charge injection capacities. 

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