Electrochemical Deposition of Conductive Polymers onto Magnesium Microwires for Neural Electrode Applications.

['Zhang C', 'Driver N', 'Tian Q', 'Jiang W', 'Liu H']
J Biomed Mater Res A. 2018 Mar 9. doi: 10.1002/jbm.a.36385. [Epub ahead of print]

Author information
['Materials Science and Engineering Program, University of California at Riverside, 900 University Avenue, Riverside, CA 92521, United States.', 'Department of Bioengineering, University of California at Riverside, 900 University Avenue, Riverside, CA 92521, United States.', 'Biomedical Sciences Program, School of Medicine, University of California at Riverside, 900 University Avenue, Riverside, CA 92521, United States.', 'Stem Cell Center, University of California at Riverside, 900 University Avenue, Riverside, CA 92521, USA.']

Abstract
['Metals are widely used in electrode design for recording neural activities because of their excellent electrical conductivity and mechanical strength. However, there are still serious problems related to these currently used metallic electrodes, including tissue damage due to the mechanical mismatch between metals and neural tissues, fibrosis, and electrode fouling and encapsulation that lead to the loss of signal and eventual failure. In this study, a biocompatible, biodegradable, and conductive electrode was created. Specifically, pure magnesium (Mg) microwire with a diameter of 127 µm was used as the electrode substrate and the conductive polymer, i.e., poly(3,4-ethylenedioxythiophene) (PEDOT), was electrochemically deposited onto Mg microwires to decrease corrosion rate and improve biocompatibility of the electrodes for potential neural electrode applications. Both chronopotentiometry and cyclic voltammetry (CV) methods and the associated parameters for electrochemical deposition of PEDOT onto Mg microwires were investigated, such as deposition current, deposition temperature, voltage, sweep rate, cycle number and duration. The CV method from -2.0 V to 1.25 V for 1 cycle at a cycle duration of 600 s with a sweep rate of 5 mV/s at 65°C led to a consistent, uniform and complete PEDOT coating on Mg microwires. The surface conditions of Mg microwires also affected the quality of PEDOT coating. The corrosion rate of PEDOT-coated Mg microwire was 0.75 mm/year, much slower than the non-coated Mg microwire that showed a corrosion rate of 1.78 mm/year. The optimal Mg microwires with PEDOT coating could potentially serve as biodegradable electrodes for neural recording and stimulation applications. This article is protected by copyright. All rights reserved.']