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.

Performance characterization of a vanadium redox flow battery at different operating parameters under a standardized test-bed system

“…Two different images are observed for the carbon felt after being exposed to vanadium electrolyte. The positive electrode has visibly grown while showing some degree of micro-structural roughness due to the charging process in the highly oxidative electrolyte [32]. Nevertheless, the discharge current density of a V-RFB equipped with carbon-felt electrodes is significantly higher than that of a two-dimensional planar electrode as shown in Fig.…”

Front-end electronics for impedimetric microfluidic devices

“…1, the resistance Rs and capacitance Cs are connected in parallel with the cell resistances, Rm and Rcy, and the capacitances Cm. The electrode-electrolyte interface area can be also increased by using electrochemical treatments that produce a porous or fractal electrode surface with a large effective surface area [5].The microfluidic device that we present in this article incorporates an impedance sensor, which consists of an array of two sequential pairs of parallel plate microelectrodes. These two pairs of electrodes are used for the differential measurements.…”

Protein Dielectrophoresis and The Link to Dielectric Properties

“…In other words, high surface area (rougher/porous electrodes) and highly conductive electrode materials will reduce EP [129]. This can be achieved either by mechanical or electrochemical treatments that produce porous or fractal metal interfaces with a large effective surface area [131] or by selecting electrodes such as conductive polymers [132] and carbon electrodes [133,134] which are porous and therefore have higher surface area. Carbon electrodes have already been used in DEP applications [8,135] and their use could be advantageous for DS measurements of proteins.…”