Sputtered iridium oxide films for neural stimulation electrodes.
Sputtered iridium oxide films (SIROFs) deposited by DC reactive sputtering from an iridium metal target have been characterized in vitro for their potential as neural recording and stimulation electrodes. SIROFs were deposited over gold metallization on flexible multielectrode arrays fabricated on thin (15 microm) polyimide substrates. SIROF thickness and electrode areas of 200-1300 nm and 1960-125,600 microm(2), respectively, were investigated. The charge-injection capacities of the SIROFs were evaluated in an inorganic interstitial fluid model in response to charge-balanced, cathodal-first current pulses. Charge injection capacities were measured as a function of cathodal pulse width (0.2-1 ms) and potential bias in the interpulse period (0.0 to 0.7 V vs. Ag|AgCl). Depending on the pulse parameters and electrode area, charge-injection capacities ranged from 1-9 mC/cm(2), comparable with activated iridium oxide films (AIROFs) pulsed under similar conditions. Other parameters relevant to the use of SIROF on nerve electrodes, including the thickness dependence of impedance (0.05-10(5) Hz) and the current necessary to maintain a bias in the interpulse region were also determined.
Cogan
Stuart F
SF
EIC Laboratories, Norwood, Massachusetts 02062.
Ehrlich
Julia
J
EIC Laboratories, Norwood, Massachusetts 02062.
Plante
Timothy D
TD
EIC Laboratories, Norwood, Massachusetts 02062.
Smirnov
Anton
A
EIC Laboratories, Norwood, Massachusetts 02062.
Shire
Douglas B
DB
Department of Veterans Affairs, Center for Innovative Visual Rehabilitation, Cornell University, Ithaca, New York 14853.|Cornell NanoScale Science and Technology Facility, Cornell University, Ithaca, New York 14853.
Gingerich
Marcus
M
Department of Veterans Affairs, Center for Innovative Visual Rehabilitation, Cornell University, Ithaca, New York 14853.|Cornell NanoScale Science and Technology Facility, Cornell University, Ithaca, New York 14853.
Rizzo
Joseph F
JF
Department of Veterans Affairs, Center for Innovative Visual Rehabilitation, Boston, Massachusetts 02062.|Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02062.
D020099:Coated Materials, Biocompatible; D004558:Electric Stimulation / Q000295:instrumentation*; D004563:Electrochemistry / Q000379:methods; D004567:Electrodes, Implanted; D004867:Equipment Design; D006046:Gold / Q000737:chemistry; D006801:Humans; D007495:Iridium / Q000737:chemistry*; D008422:Materials Testing; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D013499:Surface Properties
D020099:Coated Materials, Biocompatible; C044458:iridium oxide; D007495:Iridium; D006046:Gold