Electrochemical impedance spectroscopy chemical sensors

Rational optimization of performance should be the main goal in development of any chemical sensor. In order to do that, we must have some quantitative tools of determination of key performance parameters. As we have seen already, for electrochemical sensors those parameters are the charge-transfer resistance and the double-layer capacitance. Particularly the former plays a critical role. Here we outline two approaches the Tafel plots, which are simple, inexpensive, but with limited applicability, and the Electrochemical Impedance Spectroscopy (EIS), based on the equivalent electrical circuit model, which is more universal, more accurate, and has a greater didactic value. 

Zhang D, et al. Protein detecting with smartphone-controlled electrochemical impedance spectroscopy for point-of-care applications. Sensors and Actuators B-Chemical 2016 222 994-1002. http //dx.doi.Org/10.1016/j.snb.2015.09.041. 

Katz E, WUlner 1 (2004) Immunosensors and DNA sensors based on impedance spectroscopy. In Springer series on chemical sensors and biosensors 2 (ultrathin electrochemical chemo- and biosensor). Springer, Berlin ffeidelberg New York, p 67... 

Microelectronic technologies have also been used in nitrite biosensors and electrochemical sensors (Suzuki and Taura, 2001 Adhikari and Majumdar, 2004). Ameida et al. (2013) have also developed a method of electrochemical nitrite measurement by means of a gold working electrode covered with 1,2-diaminobenzene (DAB) integrated in a FIA system. This sensor helps improve selectivity, repeatability, stability, and sensitivity. A Nafion/lead-ruthenate pyrochlore electrode chemically modified for determination of NO2 oxidation and NO reduction based on AC-impedance spectroscopy and FIA has also been tested (Zen et al., 2000). Quan and Shin (2010) also tested an electrochemical nitrite biosensor based on co-immobilization of copper-containing nitrite reductase and viologen-modified chitosan (CHIT-V) on a glassy carbon electrode (GCE). 

Multisensor chemical arrays and aptasensors are generally electrochemical-based sensor devices (eg, potentiometry, amperometry, voltammetry, and impedance spectroscopy). 

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