hCG (ng/mL) Equivalent circuit elements for nonfaradaic interface
R   (kΩ) C  (mF) R  (kΩ)

Blank

3.27 ± 0.18 3.16 ± 0.18 5.98 ± 0.12

0.2

4.97 ± 0.20 2.78 ± 0.18 6.02 ± 0.11

0.3

5.68 ± 0.26 2.76 ± 0.07 6.03 ± 0.13

0.5

5.88 ± 0.20 2.69 ± 0.08 6.02 ± 0.12

1.0

6.26 ± 0.17 2.89 ± 0.14 6.02 ± 0.15

2.0

6.78 ± 0.32 2.69 ± 0.11 6.03 ± 0.12

3.0

7.88 ± 0.22 2.92 ± 0.18 5.99 ± 0.11

4.0

9.82 ± 0.48 3.13 ± 0.17 6.05 ± 0.14

5.0

10.86 ± 0.59 2.69 ± 0.13 6.10 ± 0.18

7.0

12.02 ± 0.51 2.78 ± 0.16 6.06 ± 0.11

10

14.15 ± 0.82 2.47 ± 0.10 6.02 ± 0.12

15

14.84 ± 1.85 2.54 ± 0.19 5.99 ± 0.13

20

15.85 ± 1.20 2.57 ± 0.11 6.05 ± 0.13

30

16.99 ± 1.41 2.58 ± 0.06 5.99 ± 0.13
Table 2: Impedance parameters were obtained from the equivalent circuit fit to the impedance spectra of immunosensor B, which is illustrated in Figure 4b.