Biomedical Microdevices

, Volume 11, Issue 4, pp 801-808

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

High efficient electrical stimulation of hippocampal slices with vertically aligned carbon nanofiber microbrush array

  • Edward D. de AsisJr.Affiliated withDepartments of Electrical Engineering and Bioengineering, Santa Clara University
  • , T. D. Barbara Nguyen-VuAffiliated withDepartment of Molecular Cell Physiology, Stanford University Medical School
  • , Prabhu U. ArumugamAffiliated withELORET Corporation, NASA Ames Research Center
  • , Hua ChenAffiliated withELORET Corporation, NASA Ames Research Center
  • , Alan M. CassellAffiliated withUniversity Affiliated Research Center, University of California, Santa Cruz
  • , Russell J. AndrewsAffiliated withNASA Ames Research Center
  • , Cary Y. YangAffiliated withCenter for Nanostructures, Santa Clara University
  • , Jun LiAffiliated withNASA Ames Research CenterDepartment of Chemistry, Kansas State University Email author 


Long-term neuroprostheses for functional electrical stimulation must efficiently stimulate tissue without electrolyzing water and raising the extracellular pH to toxic levels. Comparison of the stimulation efficiency of tungsten wire electrodes (W wires), platinum microelectrode arrays (PtMEA), as-grown vertically aligned carbon nanofiber microbrush arrays (VACNF MBAs), and polypyrrole coated (PPy-coated) VACNF MBAs in eliciting field potentials in the hippocampus slice indicates that, at low stimulating voltages that preclude the electrolysis of water, only the PPy-coated VACNF MBA is able to stimulate the CA3 to CA1 pathway. Unlike the W wires, PtMEA, as-grown VACNF MBA, and the PPy-coated VACNF MBA elicit only excitatory postsynaptic potentials (EPSPs). Furthermore, the PPy-coated VACNF MBA evokes somatic action potentials in addition to EPSPs. These results highlight the PPy-coated VACNF’s advantages in lower electrode impedance, ability to stimulate tissue through a biocompatible chloride flux, and stable vertical alignment in liquid that enables access to spatially confined regions of neuronal cells.


Vertically aligned carbon nanofiber Electrical stimulation Neural electrical interface Hippocampal brain slice Neural recording