Characterisation of carbon paste electrodes for real-time amperometric monitoring of brain tissue oxygen.

Bolger FB
McHugh SB
Bennett R
Li J
Ishiwari K
Francois J
Conway M
Gilmour G
Bannerman DM
Fillenz M
Tricklebank MD
Lowry JP
Scientific Abstract

Tissue O₂ can be monitored using a variety of electrochemical techniques and electrodes. In vitro and in vivo characterisation studies for O₂ reduction at carbon paste electrodes (CPEs) using constant potential amperometry (CPA) are presented. Cyclic voltammetry indicated that an applied potential of -650 mV is required for O₂ reduction at CPEs. High sensitivity (-1.49 ± 0.01 nA/μM), low detection limit (ca. 0.1 μM) and good linear response characteristics (R² > 0.99) were observed in calibration experiments performed at this potential. There was also no effect of pH, temperature, and ion changes, and no dependence upon flow/fluid convection (stirring). Several compounds (e.g. dopamine and its metabolites) present in brain extracellular fluid were tested at physiological concentrations and shown not to interfere with the CPA O₂ signal. In vivo experiments confirmed a sub-second response time observed in vitro and demonstrated long-term stability extending over twelve weeks, with minimal O₂ consumption (ca. 1 nmol/h). These results indicate that CPEs operating amperometrically at a constant potential of -650 mV (vs. SCE) can be used reliably to continuously monitor brain extracellular tissue O₂.


2011.J. Neurosci. Methods, 195(2):135-42.

Shah SA, Tan H, Tinkhauser G, Brown P
2018.IEEE Trans Neural Syst Rehabil Eng, 26(7):1460-1468.
Shah SA, Tan H, Brown P
2016. Conf Proc IEEE Eng Med Biol Soc, 2016(): 5717-5720.
Cagnan H, Pedrosa D, Little S, Pogosyan A, Cheeran B, Aziz TZ, Green AL, Fitzgerald J, Foltynie T, Limousin P, Zrinzo L, Hariz M, Friston KJ, Denison T, Brown P
2017. Brain, 140(1):132-145.
Cagnan H, Denison T, McIntyre C, Brown P
2019. Nat. Biotechnol., 37(9):1024-1033.