Low Impedance Conducting Polymer Microelectrode Coatings

“Fuzzy”, Low Impedance Conducting Polymer Coatings for Microelectrodes on Neural Prosthetic Devices

Biomaterials for the Central Nervous System

Recent developments have made it possible to synthesize novel poly(peptides) from bacteria using genetic engineering techniques. The flexibility and degree of control in the sequencing of amino acids by recombinant DNA procedures means it is now possible to exercise unprecedented precision and fidelity in constructing new macromolecules. Our studies are concentrating on the local structure and nature of self-assembly of these novel materials.

We have developed processing schemes to create microstructured films and fibers of genetically engineered proteins. By understanding and manipulating the stability of the protein in solution, it is possible to create films with controlled morphologies. These films are of interest for biocompatibilization of surfaces and for scaffolds for wound healing and tissue engineering.

Our primary interest is in the development of biocompatible surfaces for neural prosthetics. Our work involves the processing and characterization of biologically active polymers and polymer blends onto the surfaces of silicon micromachined substrates. We have been developing an electric field-mediated deposition process that allows us to reliably and quickly create thin fibrous coatings on solid substrates.

Most recently we have been developing electrochemical deposition process that allow us to deposit blends of conducting polymers and bioactive proteins or peptides directly on the active electrode sites of microfabricated prosthetic devices. We are also collaborating with Patrick Tresco’s group at the University of Utah to examine the biological response of coated probes in-vitro and in-vivo.


EDOT is a substituted derivative of polythiophene that carries alkoxy substituents along its backbones. Capitalizing on the EDOT core, a number of derivatives have been synthesized. PEDOT/PSS coatings on the specific elevtrode sites can be formed by electrodeposition. But PEDOT/peptide coatings could be hardly obtained due to the poor solubility of EDOT in water and the weaker charge transportation ability of peptide. Hence, two derivatives of EDOT, sulfonatoalkoxy EDOT(EDOTS)and hydroxymethylated EDOT(EDT-MeOH)
were introduced and good coatings were obtained with EDOT/EDOTS, EDT-MeOH/PSS, and EDT-MeOH/peptide. Electical properties such as Impedance Spectroscopy and Cyclic Voltammetry and morphology characterization of these systems were studied.


Protein Polymer Technologies, Inc., National Institutes of Health, The Whitaker Foundation


Kim DH, Abidian M, Martin DC. Conducting polymers grown in hydrogel scaffolds coated on neural prosthetic devices. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 71A (4): 577-585 DEC 15 2004

Xiao YH, Cui XY, Martin DC. Electrochemical polymerization and properties of PEDOT/S-EDOT on neural microelectrode arrays. JOURNAL OF ELECTROANALYTICAL CHEMISTRY 573 (1): 43-48 NOV 15 2004

Yang JY, Martin DC. Microporous conducting polymers on neural microelectrode arrays II. Physical characterization. SENSORS AND ACTUATORS A-PHYSICAL 113 (2): 204-211 JUL 5 2004

Yang JY, Martin DC. Microporous conducting polymers on neural microelectrode arrays – I – Electrochemical deposition. SENSORS AND ACTUATORS B-CHEMICAL 101 (1-2): 133-142 JUN 15 2004

Xiao YH, Cui XY, Hancock JM, et al. Electrochemical polymerization of poly(hydroxymethylated-3,4-ethylenedioxythiophene) (PEDOT-MeOH) on multichannel neural probes. SENSORS AND ACTUATORS B-CHEMICAL 99 (2-3): 437-443 MAY 1 2004

Cui XY, Martin DC. Fuzzy gold electrodes for lowering impedance and improving adhesion with electrodeposited conducting polymer films. SENSORS AND ACTUATORS A-PHYSICAL 103 (3): 384-394 FEB 15 2003

Cui XY, Wiler J, Dzaman M, et al. In vivo studies of polypyrrole/peptide coated neural probes. BIOMATERIALS 24 (5): 777-787 FEB 2003

Cui, X., J. F. Hetke, J. A. Wiler, D. J. Anderson and D. C. Martin, “Electrochemical deposition and characterization of conducting polymer polypyrrole/PSS on multichannel neural probes” Sensors and Actuators A:Physical, 93(1): 8-18, (2001).

Cui, X., V. A. Lee, Y. Raphael, J. A. Wiler, J. F. Hetke, D. J. Anderson and D. C. Martin, “Surface modification of neural recording electrodes with conducting polymer/biomolecule blends” Journal of Biomedical Materials Research, 56(2): 261-272, (2001).

Mensinger, A. F., D. J. Anderson, C. J. Buchko, M. A. Johnson, D. C. Martin, P. A. Tresco, R. B. Silver and S. M. Highstein, “Chronic recording of regenerating VIIIth nerve axons with a sieve electrode” Journal of Neurophysiology, 83(1): 611-615, (2000).

Buchko, C. J., M. J. Slattery, K. M. Kozloff and D. C. Martin, “Mechanical properties of biocompatible protein polymer thin films” Journal of Materials Research, 15(1): 231-242, (2000).

Buchko, C. J., L. C. Chen, Y. Shen and D. C. Martin, “Processing and microstructural characterization of porous biocompatible protein polymer thin films” Polymer, 40(26): 7397-7407, (1999).

Shen, Y., M. A. Johnson and D. C. Martin, “Microstructural characterization of Bombyx mori silk fibers” Macromolecules, 31(25): 8857-8864, (1998).

Athreya, S. and D. C. Martin, “Impedance spectroscopy of protein polymer modified silicon micromachined probes” Sensors and Actuators a-Physical, 72(3): 203-216, (1999).

Johnson, M. A. and D. C. Martin, “Finite element modeling of banded structures in Bombyx mori silk fibres” International Journal of Biological Macromolecules, 24(2-3): 139-144, (1999).

David C. Martin, Christopher J. Buchko, and Tao Jiang, “Processing and Characterization of Protein Polymers”, Protein-based Materials, K. McGrath and D. Kaplan, eds. (1996).

Christopher J. Buchko and David C. Martin, “Electrospinning of Protein Polymer Fibers”, Proceedings of the Materials Research Society, Boston, MA, (1995).

J. Philip Anderson, David C. Martin, and Joseph Cappello, “Morphology and Primary Crystal Structure of SLPF: a Novel Protein Synthesized by Genetically Engineered E. Coli Bacteria”, Biopolymers, 34(8), 1049-1058, (1994).

J. Philip Anderson, Suzanne Nilsson, Neil Weissman, Randy Logan, Rupak Rajachar, and David C. Martin, “Bioactive Genetically Engineered Protein Polymer Films on Silicon Devices”, Biomolecular Materials by Design, M. Alper, H. Bayley, D. Kaplan, and M. Navia, eds., Materials Research Society Symposium Proceedings, v. 330, Materials Research Society, Pittsburgh, PA, 171-177, (1994).

J. Philip Anderson, Matthew Stephen-Hassard, and David C. Martin, “Structural Evolution of SLPF: a Genetically Engineered Silk-like Protein Polymer”, Chapter 12 in Silk Polymers: Materials Science and Biotechnology, D. Kaplan, W. W. Adams, B. Farmer, and C. Viney, eds., American Chemical Society Symposium Series, American Chemical Society, Volume 544, 137-147, (1994).