Effects of electrode size and surface morphology on electrode polarization in physiological buffers

Abstract

Electrode polarization (EP) is inevitable in high conductivity buffers at low AC frequencies due to the accumulation of free charges at the electrode/electrolyte interface. Electrode miniaturization increases EP effect on impedance measurements. In this paper, six gold planar (GP) electrodes having different diameters ( ) were used to investigate the size effect on EP with parallel plate electrode geometry. GP electrode surface was electrochemically deposited with gold nanostructures (GNs) to minimize the EP effect. Equivalent circuit model was used to attain electrode/electrolyte interfacial impedance. Constant phase element model was used to analyze the relation between the size and morphology of electrodes on EP. The surface morphology of gold nanostructured electrodes was examined using SEM, and the influence of different applied potential on the growth of GNs was elucidated with Nernst equilibrium condition. Surface roughness and wettability characteristics were examined performing surface roughness and contact angle measurements, respectively. The improvement of GNs deposited electrode performance was investigated by analytically generated Jurkat cell suspension spectra. The results show that the error in estimating the subcellular properties can be drastically reduced by using GNs deposited electrodes.

Characterization of Temperature Rise in Alternating Current Electrothermal Flow Using Thermoreflectance Method

“…Therefore, the resistance of the microfluidic system is required to be able to accurately quantify the rate of heat generation. Microfluidic-based impedance spectroscopy is a useful technique for identifying the resistance of the system in a frequency spectrum. − A high-precision impedance analyzer (4194A, Agilent) is used to measure the impedance spectrum of the microfluidic device when filled with 1.4 S/m conductive PBS solution. The terminals of the side electrodes are connected to the low and high terminals of the impedance analyzer using a test fixture (HP 16047A) in a four terminal configuration and the measurements are carried out at 401 discrete frequency points from 100 Hz to 10 MHz at 20 mV.…”

Self-assembled Imprinted Polymer Film-Based Sensor System for Spermidine on Screen Printed Electrodes

“…The stability of modified electrode was also crucial to the subsequence results. Many studies show that the electrode surface was not absolutely smooth [41], thus make the MIP films coated on the surface tightly during the UV polymerization process. Furthermore, after elution, a threedimensional network porous structure formed on the MIP modified electrode surface.…”

Rapid and Sensitive Detection of Nanomolecules by an AC Electrothermal Flow Facilitated Impedance Immunosensor

“…3D nanostructured electrodes can be introduced to enhance sensor sensitivity because they increase the amount of the active binding sites, and consequently, the absorbed volume of target molecules [47][48][49][50] . Another fundamental limitation of usage of planar surface electrodes is the onset of electrode polarization (EP) that potentially overwhelms the impedance spectra at the low-frequency range (< 10 MHz) depending on electrode size 51,52 . Ions in the electrolyte move towards the electrode surface, leading to a massive interfacial impedance and causing a high-applied voltage drop, which decreases the sensitivity of the measurement.…”

“…47−50 Another fundamental limitation of usage of planar surface electrodes is the onset of electrode polarization (EP) that potentially overwhelms the impedance spectra at the low-frequency range (<10 MHz) depending on electrode size. 51,52 Ions in the electrolyte move toward the electrode surface, leading to a massive interfacial impedance and causing a high-applied voltage drop, which decreases the sensitivity of the measurement. The most effective way to diminish the EP is to enlarge the electrode's effective surface area by depositing nanostructures on the electrode surface.…”