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.
Bibliographical noteFunding 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
- Extracellular recording