Figure 12: Comparative schematic representations of (a) faradaic EIS and (b) capacitive ECS biosensing [74]. (a) The faradaic impedimetric surface engineering is based in the electron transfer resistance (Rct) of the redox probe in solution to metal surface. (b) The capacitive approach does not need a redox probe in solution, but an electrode tethered one. The environmental sensitivity of this charging capability is used as the reporter of neighboring biorecognition. The associated equivalent circuits are presented in Figures 11a and 11b respectively. Reproduced with permission from reference [74].