Equivalent Impedance Models for Electrochemical Nanosensor-Based Integrated System Design

Abstract

Models of electrochemical sensors play a critical role for electronic engineers in designing electrochemical nanosensor-based integrated systems and are also widely used in analyzing chemical reactions to model the current, electrical potential, and impedance occurring at the surface of an electrode. However, the use of jargon and the different perspectives of scientists and electronic engineers often result in different viewpoints on principles of electrochemical models, which can impede the effective development of sensor technology. This paper is aimed to fill the knowledge gap between electronic engineers and scientists by providing a review and an analysis of electrochemical models. First, a brief review of the electrochemical sensor mechanism from a scientist’s perspective is presented. Then a general model, which reflects a more realistic situation of nanosensors is proposed from an electronic engineer point of view and a comparison between the Randles Model is given with its application in electrochemical impedance spectroscopy and general sensor design. Finally, with the help of the proposed equivalent model, a cohesive explanation of the scan rate of cyclic voltammetry is discussed. The information of this paper can contribute to enriching the knowledge of electrochemical sensor models for scientists and is also able to guide the electronic engineer on designing next-generation sensor layouts.

PEDOT-AuNPs-based impedimetric immunosensor for the detection of SARS-CoV-2 antibodies

“…To further investigate the electrochemical interfacial process of the modified electrodes, EIS experiments were carried out and the Nyquist plots are shown in Figure 1 (b). The analysis of EIS data from conducting polymers and nanocomposites could be subject of different interpretation, so the choice of the correct equivalent circuit model that represents the electrical effects of the electrochemical systems, as well as describes the mechanism of the reaction, needs a careful understating of the individual physical properties of each system [ 58 , 59 ]. After a careful consideration of the different approaches reported elsewhere [58] , [59] , [60] , [61] to interpret the EIS results of conducting polymers, also considering the factors governing the electrochemical impedance on protein-modified surface, the results presented here were fitted using an equivalent circuit model composed by a combination of resistors and capacitors.…”

Electrochemical Characterization of Modified Glassy Carbon Electrodes for Non-Enzymatic Glucose Sensors

“…The first loop composed of R and CPE in parallel can be assigned to the bulk material impedance of polymer/GCE. Electrode processes controlled by diffusional mechanisms are presented as a parallel connection of CPE CT and Faradic impedance [ 23 ]. Faradic impedance can be expressed as a series combination of the charge transfer resistance (R CT ) and the Warburg element (W CT ).…”

“…Another field of application of EIS is the direct investigation of the sensors’ analytical response [ 15 , 16 , 17 , 18 , 19 ]. Nonetheless, to fully exploit the potential of this technique, it remains crucial to ensure a reliable interpretation of obtained data and to relate them to the electrode sensing properties [ 19 , 23 ].…”

Physical Surface Modification of Carbon-Nanotube/Polydimethylsiloxane Composite Electrodes for High-Sensitivity DNA Detection

“…The circuit model is widely used for describing processes at the electrochemical interfaces [35,36], consisting of the active electrolyte resistance (R Ω ), double-layer capacitance (C d ), charge transfer resistance (R ct ), and Warburg impedance (Z w ). R ct and Z w describe the electron transfer and the mass transport of the electroactive species near the solution-electrode interface, respectively [37]. The R ct of the film decreased when increasing the number of dip coating cycles, as shown in Figure 4b; as compared to R ct for no dip coating (5500 Ω), that for 60 dip coatings (200 Ω) was about 27.5 times smaller.…”