title: PEDOT electrochemical polymerization improves electrode fidelity and sensitivity.
abstract: BACKGROUND
  The goal of the authors is to restore fine motor control and sensation for high-arm amputees. They developed a regenerative peripheral nerve interface with the aim of attaining closed loop neural control by integrating directly with the amputee's residual motor and sensory peripheral nerves. PEDOT, poly(3,4-ethylenedioxythiophene), has both electrical and ionic conduction characteristics. This hybrid character could help bridge the salutatory conduction of the nervous system to an electrode. The purpose of this study was to determine whether electrodes polymerized with PEDOT have improved ability to both record and stimulate peripheral nerve action potentials.
  
  
  METHODS
  Impedance spectroscopy and cyclic voltammetry were performed on electrodes before and after polymerization to measure electrode impedance and charge capacity. Both recording needle and bipolar stimulating electrodes were polymerized with PEDOT. Plain and PEDOT electrodes were tested using rat (n = 18) in situ nerve conduction studies. The peroneal nerve was stimulated using a bipolar electrode at multiple locations along the nerve. Action potentials were measured in the extensor digitorum longus muscle.
  
  
  RESULTS
  Bench testing showed PEDOT electrodes had a higher charge capacity and lower impedance than plain electrodes, indicating significantly improved electrode fidelity. Nerve conduction testing indicated a significant reduction in the stimulus threshold for both PEDOT recording and PEDOT stimulatory electrodes when compared with plain electrodes, indicating an increase in sensitivity.
  
  
  CONCLUSIONS
  PEDOT electrochemical polymerization improves electrode fidelity. Electrodes that have been electropolymerized with PEDOT show improved sensitivity when recording or stimulating action potentials at the tissue-electrode interface.
authors.affiliation: Ann Arbor, Mich. From the Section of Plastic Surgery, Department of Surgery, University of Michigan, and the Department of Biomedical Engineering, University of Michigan College of Engineering.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Frost
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wei
authors.forename: Ziya
authors.initials: Z
authors.lastname: Baghmanli
authors.forename: Paul S
authors.initials: PS
authors.lastname: Cederna
authors.forename: Melanie G
authors.initials: MG
authors.lastname: Urbanchek
mesh_terms: D000200:Action Potentials; D000672:Amputation Stumps / Q000294:innervation; D000818:Animals; D001132:Arm; D019086:Bridged Bicyclo Compounds, Heterocyclic; D020099:Coated Materials, Biocompatible; D004599:Electric Stimulation Therapy; D004567:Electrodes, Implanted; D006801:Humans; D008297:Male; D009431:Neural Conduction; D010543:Peroneal Nerve / Q000502:physiology; D011108:Polymers; D051381:Rats; D011916:Rats, Inbred F344; D012684:Sensory Thresholds
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D020099:Coated Materials, Biocompatible; D011108:Polymers; C121383:poly(3,4-ethylene dioxythiophene)