title: Note: Characterization of electrode materials for dielectric spectroscopy.
abstract: When measuring the dielectric properties of aqueous samples, the impedance of the electrode/sample interface can limit low frequency measurements. The electrode polarization problem can be reduced by increasing the effective surface area of the electrodes. In this work, impedance spectroscopy was used to characterize and compare three different electrode surfaces that can be used to mitigate this effect: platinum black, iridium oxide, and [polypyrrole/poly(styrenesulphonate)] (PPy/PSS) conducting polymer. All three materials were directly compared with a bright platinum electrode. Equivalent circuit models were used to extract the increase in the effective surface area of the electrodes: platinum black, iridium oxide and PPy/PSS increase the effective capacitance of the electrode by factors of approximately 240, 75, and 790, respectively. The practical aspects of all electrode materials are discussed. These results suggest that iridium oxide and PPy/PSS are good alternatives to the commonly used platinum black, which is prone to mechanical damage (scratches) and is potentially toxic to cells.
authors.affiliation: Nanoscale Systems Integration Group, School of Electronics and Computer Science, University of Southampton, Hampshire SO17 1BJ, United Kingdom. daniele.malleo@ogt.co.uk
authors.forename: D
authors.initials: D
authors.lastname: Malleo
authors.forename: J T
authors.initials: JT
authors.lastname: Nevill
authors.forename: A
authors.initials: A
authors.lastname: van Ooyen
authors.forename: U
authors.initials: U
authors.lastname: Schnakenberg
authors.forename: L P
authors.initials: LP
authors.lastname: Lee
authors.forename: H
authors.initials: H
authors.lastname: Morgan
mesh_terms: D001672:Biocompatible Materials / Q000633:toxicity; D025802:Electric Capacitance; D017097:Electric Impedance; D004560:Electricity; D004566:Electrodes; D007495:Iridium / Q000633:toxicity; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D010984:Platinum / Q000633:toxicity; D017671:Platinum Compounds / Q000633:toxicity; D011108:Polymers / Q000633:toxicity; D011758:Pyrroles / Q000633:toxicity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D017671:Platinum Compounds; D011108:Polymers; D011758:Pyrroles; C044458:iridium oxide; C067635:polypyrrole; D007495:Iridium; D010984:Platinum