Measurement of the direct-current (Faradic) resistance of the electrode-electrolyte interface for commonly used electrode materials.
The direct-current (Faradic) resistance is important because it is the highest impedance that an electrode-electrolyte interface can attain. In this study, the Faradic resistance (Rf) of identical pairs of 0.5 cm2 electrodes of bare and chlorided silver, tin and chlorided tin, nickel-silver, copper, and carbon was measured in contact with 0.9% saline at room temperature. It was found that for positive and negative current flow, the data fit the expression Rf=Rf0 e(-alpha i) (with a high coefficient of determination), where Rf0 is the zero-current Faradic resistance and alpha is a constant that describes the manner in which Rf decreases with increasing current (i). It was found that chlorided silver exhibited the lowest Rf0; removing the chloride deposit increased Rf0 by more than sixfold. Likewise, chloriding tin reduced Rf0 by a factor of about 2. Electrolytically cleaning an electrode reduced Rf0. The highest value for Rf0 was for carbon. This paper concludes with a summary of the data for Rf0 scaled to 1 cm2 electrode area for the electrode materials measured in the present study and data from the published literature.
Geddes
L A
LA
Department of Biomedical Engineering, Purdue University, W. Lafayettte, IN, USA. geddes@ecn.purdue.edu
Roeder
R
R
D001698:Biomedical Engineering; D002244:Carbon; D003300:Copper; D017097:Electric Impedance; D004566:Electrodes; D004573:Electrolytes; D009532:Nickel; D012834:Silver; D014001:Tin
D004573:Electrolytes; D012834:Silver; D014001:Tin; D002244:Carbon; D003300:Copper; D009532:Nickel