Electrodeposited iridium oxide for neural stimulation and recording electrodes

Iridium oxide films formed by electrodeposition onto noniridium metal substrates are compared with activated iridium oxide films (AIROFs) as a low impedance, high charge capacity coating for neural stimulation and recording electrodes. The electrodeposited iridium oxide films (EIROFs) were deposited...

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Published inIEEE transactions on neural systems and rehabilitation engineering Vol. 9; no. 1; pp. 2 - 11
Main Authors Meyer, R.D., Cogan, S.F., Nguyen, T.H., Rauh, R.D.
Format Journal Article
LanguageEnglish
Published United States IEEE 01.03.2001
Subjects
Coatings
Electric Capacitance
Electric Impedance
Electric Stimulation
Electrochemical impedance spectroscopy
Electrochemistry
Electrodes
Electroplating
Gold
Iridium - physiology
Metallization
Microelectrodes
Models, Neurological
Neural Conduction - physiology
Polyimides
Protocols
Signal Transduction - physiology
Silicon
Stability
Steel
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Summary:Iridium oxide films formed by electrodeposition onto noniridium metal substrates are compared with activated iridium oxide films (AIROFs) as a low impedance, high charge capacity coating for neural stimulation and recording electrodes. The electrodeposited iridium oxide films (EIROFs) were deposited on Au, Pt, PtIr, and 316 LVM stainless steel substrates from a solution of IrCl/sub 4/, oxalic acid, and K/sub 2/CO/sub 3/. A deposition protocol involving 50 potential sweeps at 50 mV/s between limits of 0.0 V and 0.55 V (versus Ag|AgCl) followed by potential pulsing between the same limits produced adherent films with a charge storage capacity of >25 mC/cm/sup 2/. Characterization by cyclic voltammetry and impedance spectroscopy revealed no differences in the electrochemical behavior of EIROF on non-Ir substrates and AIROF. The mechanical stability of the oxides was evaluated by ultrasonication in distilled water followed by dehydration and rehydration. Stability under charge injection was evaluated using 200 /spl mu/s, 5.9 A/cm/sup 2/ (1.2 mC/cm/sup 2/) cathodal pulses. Loss of iridium oxide charge capacity was comparable for AIROFs and the EIROFs, ranging from 1% to 8% of the capacity immediately after activation or deposition. The EIROFs were deposited and evaluated on silicon microprobe electrodes and on metallized polyimide electrodes being developed for neural recording and stimulation applications.
ISSN:1534-4320
1558-0210
DOI:10.1109/7333.918271