Neural electrodes

Neural electrodes are often used for chronic implant applications that demand chemical and electrical stability of materials. Yamato et al. found that PPy has limited electrical response under cyclic voltammetry because of structural defects along the CP backbone... 

Micromachined flexible, neural electrodes have been designed and manufactured for contacting the tightly packed neural elements in the nerve trunk [30,31], Polyimide was chosen as the substrate and insulation material for a design of multichannel sieve electrodes with integrated interconnects... 

Rao L, Zhou H, Li T, et al. Polyethylene glycol-containing polyurethane hydrogel coatings for improving the biocompatibility of neural electrodes. Acta Biomater July 2012 8(6) 2233 2. 

Klaver, C.L., Caplan, M.R., 2007. Bioactive surface for neural electrodes decreasing astrocyte prohferation via transforming growth factor beta-1. J. Biomed. Mater. Res. A 81 (4), 1011-1016. 

Polikov, V. S., Tresco, P. A. and Reichert, W. M. (2005) Response of brain tissue to chronically implanted neural electrodes. J. Neurosci. Meth. 148, 1-18. 

Koeneman BA, Lee KK, Singh A (2004) An ex vivo method for evaluating the biocompatibility of neural electrodes in rat brain slice cultures. Journal of Neuroscience Methods 137 257-263. 

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... 

The physical, chemical, and electrical properties of PPy can be easily modified by various doping agents and preparation conditions. There are many available dopant ions for the generation of good quality deposited polymer films [63-64]. Two of the most common dopants that are codeposited with PPy are polystyrene-sulfonate (PSS) and sodium dodecylbenzenesulfonate (NaDBS). PPy/PSS and PPy/NaDBS polymers have been used in many applications ranging from actuators and neural scaffolds to neural electrode coatings [22, 53, 61, 65]. It is reported that electrode materials, electrolyte solution, deposition methods (current-or potential-controlled deposition), deposition time, and solution temperature during electrochemical polymerization affect both the structure and electroactivity of PPy films [66]. 

Widge A, Jeffries-El M, Cui X (2007) Self-assembled monolayers of polythiophene conductive polymers improve biocompatibiUty and electrical impedance of neural electrodes. Biosens and Bioelectron 22 1723-1732... 

Abidian, M. Corey, J. Kipke, D. Martin, D. Conducting-polymer nanotubes improve electrical properties, mechanical adhesion, neural attachment, and neurite outgrowth of neural electrodes. Small 2010, 6,... 

Fig. 8 Applications of hydrogels, a Drug delivery. Reproduced from Ref. [81] with permission from the Wiley-VCH. b Bioelectrode. Reproduced from Ref. [119] with permission from the American Chemical Society, c Biosensors. Reproduced fixjm Ref. [120] with permission from the American Chemical Society, d Tissue engineering. Adapted with permission from Ref. [125]. National Academy of Sciences of the United States of America, e Solar cell. Reproduced from Ref. [122] with permission from the Royal Society of Chemistry, f Neural electrode. Reproduced from Ref. [123] with permission from the Wiley-VCH...

One of the advantages of the dual beam FIB/SEM systems is the ability to make cross sections through thin layers of soft polymers deposited onto hard, inorganic substrates.Figure 20 shows a cross section of an electrochemically deposited film of PEDOT deposited onto a microfabricated neural electrode... 

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