Amperometric biosensors: Why might the response show a logarithmic dependence on analyte concentration?

Amperometric biosensors of different designs are often reported as having a logarithmic dependency on the target concentration. This paper provides a physicochemical basis for this behaviour if the adsorption of the analyte follows the Temkin Adsorption Isotherm over the range of concentrations of interest either by directly controlling the amount adsorbed or indirectly via the effect on the electrochemical rate constant. • Logarithmic biosensor response best-explained by Temkin adsorption isotherm. • Temkin model accounts for surface heterogeneity and lateral interactions. • Provides physicochemical basis for logarithmic calibration in amperometry. • Enhances reliability of biosensor design, calibration, and detection limits.