Gold vs Tin vs Ag/AgCl

Comments

• wjcroft Mount Shasta, CA

  January 2017

  All metal types you mention are compatible with all EEG amplifiers / interfaces.
  
  Ag-AgCl has the best stability and signal quality (especially for infra low frequency), but needs replacing periodically because the plating layer (AgCl on top of Ag) is very very thin.
  
  Tin is the least stable electrically, but also the least expensive. Tin is used on the Electro-caps, so widely used in clinical and research. Tin is probably the most robust in terms of longevity.
  
  A minor downside to gold is that the plating layer is also very thin, and if it chips, can create a battery like effect.
  
• PedroMen Lisbon

  January 2017

  Thank you for the answer wjcroft. Yes, I was exactly thinking of using the Electrocap that already has Tin electrodes incorporated, and select (maybe) 10 to use with OpenBCI board (I guess there's an EBA connector for this). Since the electrodes are already in place, the setup will be faster. (By the way, are the gold electrodes from OBCI kit better than the Tin?) But these are also wet electrodes and need to inject gel/paste.
  
  So, why not using the Ultracortex and Dry electrodes? How Tin wet electrodes compare to dry electrodes?
  
• wjcroft Mount Shasta, CA

  January 2017

  Paste, gel, or saline electrodes are always a bit more stable than dry, because the liquid / electrolyte layer makes a more electrically continuous contact with the skin layers. Dry works fine and Ultracortex is a great way to go.

  
  

  Gold is somewhat less noisy than tin. The hierarchy of electrode metals from highest signal quality would be something like Ag-AgCl, gold, silver, tin. You really can't go wrong with any of these. You do realize that Electro-cap requires gel injection and cleanup, which has a certain 'messy' factor. Just follow the directions and videos from Electro-cap.

  
  

  The Ultracortex / FRI dry comb / cone electrodes are Ag-AgCl.