Characterization of iridium film as a stimulating neural electrode

Iridium film having near-bulk properties were formed by electron-beam evaporation with simultaneous bombardment of Ar ion beam. The charge-injection capabilities of Ir film were investigated, and the detrusor pressure induced by S2 stimulation with Ir-coated Pt electrode was measured and compared with the uncoated Pt electrode. The charge densities of Ir film were continuously increased with increase in the number of cycles in 0.1 m H2SO4 due to the accumulation of the iridium oxide phase. The iridium oxide formed contained nano-pores, and oxides had different dielectric properties. The Ir film could inject various amounts of charge in physiological solution under the identical stimulating condition depending on the degree of activation in 0.1 m H2SO4. S2 stimulation by Ir-coated Pt electrode caused more efficient bladder contraction of the male dog than the uncoated Pt electrode under the identical stimulus condition. (C) 2002 Elsevier Science Ltd. All rights reserved.