Real‐Time Non‐Faradaic Potentiodynamic Impedance Sensing Using Screen‐Printed Carbon Electrodes

Electrochemical impedance spectroscopy (EIS) is a suitable analytical technique to detect interfacial phenomena and analyte binding at electrode surfaces. In contrast to metallic electrodes, carbon‐based electrodes are more suited due to the low cost and the availability of more versatile methods for chemical functionalization. For (bio) sensing, often the Faradaic version of EIS in a three‐electrode configuration is used, where a redox‐active species is used as a marker. In order to avoid interference due to the redox‐active marker with the interfacial interaction, we focus here on the use of non‐Faradaic EIS in the absence of any added markers. First, we utilize the sedimentation of silica beads as a model system, which reduces the complexity of the interaction simplifying the interpretation of the measured signals. Moreover, we introduce two improvements. First, impedance measurements are performed in a three‐electrode configuration with applied potential as an additional variable, which serves as a handle to optimize the sensitivity. Secondly, we present a time‐differential strategy to detect subtle changes and demonstrate that we can consistently follow the sedimentation of beads using the non‐Faradaic impedance as a function of the applied potential. Finally, we show a proof‐of‐principle demonstration for the biosensing of cell attachment on the electrodes in real‐time using the proposed technique.