Sensing Estrogen with Electrochemical Impedance Spectroscopy

Figure 1

(a) Nyquist plots for the faradaic impedance measurements in the presence of 5.0 mM [Fe(CN)₆]^3−/4− at the estrogen biosensor before (A) and after the treatment of 3.7 × 10⁻⁴ ng/L (B), 3.7 × 10⁻³ ng/L (C), 3.7 × 10⁻² ng/L (D), 3.7 × 10⁻¹ ng/L (E), and 3.7 ng/L (F) of 17β-estradiol in gas phase. (b) Plot of versus . : electron transfer resistance at the estrogen biosensor before the treatment of 17β-estradiol; : electron transfer resistance at the estrogen biosensor after the treatment of a certain concentration of 17β-estradiol. . (c) Four-component equivalent circuit, : resistance of electron transfer, : resistance of solution, : Warburg impedance, and CPE: constant phase element.

(a)

(b)

(c)