Creating low-impedance tetrodes by electroplating with additives

John E. Ferguson, Chris Boldt, David Redish

Research output: Contribution to journalArticlepeer-review

86 Scopus citations


A tetrode is a bundle of four microwires that can record from multiple neurons simultaneously in the brain of a freely moving animal. Tetrodes are usually electroplated to reduce impedances from 2-3 MΩ to 200-500 kΩ (measured at 1 kHz), which increases the signal-to-noise ratio and allows for the recording of small-amplitude signals. Tetrodes with even lower impedances could improve neural recordings but cannot be made using standard electroplating methods without shorting. We were able to electroplate tetrodes to 30-70 kΩ by adding polyethylene glycol (PEG) or multi-walled carbon nanotube (MWCNT) solutions to a commercial gold-plating solution. The MWCNTs and PEG acted as inhibitors in the electroplating process and created large surface area, low-impedance coatings on the tetrode tips.

Original languageEnglish (US)
Pages (from-to)388-393
Number of pages6
JournalSensors and Actuators, A: Physical
Issue number2
StatePublished - Dec 2009

Bibliographical note

Funding Information:
This work was supported by a grant from the University of Minnesota Institute for Engineering in Medicine (IEM) and an NIH T32-EB008389 training grant. Parts of this work were carried out in the Minnesota Characterization Facility, which receives partial support from NSF through the NNIN program.


  • Carbon nanotubes
  • Electroplating
  • Extracellular recording
  • Impedance
  • Tetrodes


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