Closed bipolar electrochemical biosensor based on ohmic loss mechanism for noncontact measurements

Abstract

Resistance is of great importance for controlling the current flow through bipolar electrodes (BPEs) and the electrochemiluminescence (ECL) signal at the BPE anode. In this work, we firstly studied the effect of the iR drop between the BPE cathode and anode on the electrochemical performance of a closed BPE device. Due to the significant iR loss between the two poles of the BPE, an increased external voltage, applied on the driving electrodes, was required to trigger the redox reactions at the BPE. Accordingly, the peak voltages (forward and reverse scan) shifted to larger values, whereas the current flow through the BPE was remarkably reduced. Moreover, these factors were closely dependent on the concentration of Fe(CN)63−/Fe(CN)64−, the scan rate, and the resistance wired between glassy carbon electrodes (GCEs). Principally, it was proven that the peak-to-peak separation was enlarged as the scan rate and the concentration of Fe(CN)63−/Fe(CN)64− increased, even when the resistance between the two BPE poles was zero, indicating that the ohmic effect of the electrochemical cell is significant. Excellent linear relationships could be observed between the peak voltages and the resistance, enabling the designation of novel biosensors by connecting sensing units with tunable resistance between the GCEs. The noncontact electrochemical measurement could therefore be promising in biosensing applications.