title: The effect of electrode geometry on electrochemical properties measured in saline.
abstract: The impedance, cyclic voltammetry, and charge-injection properties of rectangular, sputtered iridium oxide (SIROF) electrodes have been measured in buffered physiological saline over a range of geometric surface areas (GSA) and perimeter-to-area ratios (P/A). Electrodes with a higher P/A are expected to have a lower impedance and higher charge injection capacity (Q(inj)), and both these effects were evident for SIROF electrodes with a GSA in the range 0.0023-0.0031 mm(2). However, the magnitude of the effect was modest. The increase in Q(inj) for rectangular electrodes with a P/A ranging from 94 to 255 mm(-1) was 21-26% depending on pulse width. There was a corresponding decrease in impedance (0.1 to 10(5) Hz) with increasing P/A and an increase in the SIROF charge storage capacity calculated from cyclic voltammetry. To assess the full usefulness of high P/A electrodes for increasing the reversible Q(inj) of an electrode, measurements should now be extended to chronic in vivo preparations.
authors.forename: Stuart F
authors.initials: SF
authors.lastname: Cogan
authors.forename: Julia
authors.initials: J
authors.lastname: Ehrlich
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Plante
mesh_terms: D004058:Diffusion; D017097:Electric Impedance; D004563:Electrochemistry / Q000379:methods*; D004567:Electrodes, Implanted; D004867:Equipment Design; D007204:Indium / Q000737:chemistry; D007495:Iridium; D008839:Microelectrodes; D012044:Regression Analysis; D012965:Sodium Chloride / Q000737:chemistry*
chemical_list: D007204:Indium; C044458:iridium oxide; D007495:Iridium; D012965:Sodium Chloride; C047711:indium oxide