NeuroNexus · neuronexus.com · Glossary
SIROF (Sputtered Iridium Oxide Film)
SIROF (sputtered iridium oxide film) is an electrode-site material that NeuroNexus offers on its silicon probes for recording and electrical stimulation. SIROF sites have lower [impedance](/resources/glossary/impedance) than plain iridium sites of the same [area](/resources/glossary/site-area) and a high charge-injection capacity, so a site records with a lower noise floor and delivers stimulation charge safely.
A 177 µm² SIROF site has a nominal impedance below 100 kΩ, against 200 kΩ to 1 MΩ for plain iridium of the same area; the measured impedance of a given configuration depends on site geometry and measurement conditions and is on the design's datasheet. The electrochemistry of iridium oxide is set out by Cogan (Cogan (2008)), and the stimulation-electrode study of sputtered films by Cogan and colleagues (Cogan et al. (2009)).
SIROF is specified at order as a site option on catalog designs and is one of the material choices of the platform, with the silicon substrate, the silicon carbide dielectric, and Z-Coat; the evidence behind each is in NeuroNexus Probe Technology: Questions and Answers.
Typical values
| Nominal impedance, 177 µm² site | below 100 kΩ |
|---|---|
| Iridium site, same area, for comparison | 200 kΩ to 1 MΩ at 1 kHz |
| Use | recording and electrical stimulation |
References
Cite this term
NeuroNexus. "SIROF (Sputtered Iridium Oxide Film)." NeuroNexus Glossary, updated 2026-10-27. https://www.neuronexus.com/resources/glossary/sirof