3.3.2.1  Linear sweep and cyclic voltammetry
Linear sweep voltammetry (LSV) methods are those in which a current is measured in response to an applied electrical potential that is swept at a constant rate across a range of electrical potentials (Bard and Faulkner, 2000). Cyclic voltammetry (CV) is a commonly used linear-sweep method in which the electrical potential is swept in both the forward and reverse directions in partial cycles, full cycles, or a series of cycles. CV is one of the most widely used voltammetric methods for pathogen detection.
Hong et al. used sweep voltammetry to detect norovirus in a sample solution with Fe(CN)6 3 - /4- extracted from lettuce (Hong et al. 2015). A typical CV response using Fe(CN)6 3 - /4- associated with pathogen detection is shown in Fig. 5 a for various concentrations of E. coli binding to a polymer composite electrode (Güner et al. 2017). A detailed overview of pathogen detection studies based on CV is provided in Table 1, Table 2.
Fig. 5 Typical responses associated with the common electrochemical methods used for pathogen detection. a) Cyclic voltammetry (CV) data using Fe(CN)63-/4- for varying concentrations of E. coli (Güner et al. 2017). b) Differential pulse voltammetry (DPV) data using Fe(CN)63-/4- for varying concentrations of S. aureus (Bhardwaj et al. 2017). c) Electrochemical impedance spectroscopy (EIS) in 100 mM LiClO4 solution in the form of a Nyquist plot and corresponding equivalent circuit model associated with biorecognition element immobilization and detection of S. typhimurium (Sheikhzadeh et al. 2016). d) Conductometry data for varying concentrations of B. subtilis (Yoo et al. 2017).