Broadly, the reagentless, single-step E-DNA sensors could be classified into “signal-on” and “signal-off” two types. In the “signal-off” sensors, target hybridization sequesters the redox moiety from the electrode, reducing the observed Faradaic current. However,“signal-off” sensors suffer from false positives when either the probe DNA or the redox tag become degraded and are limited in their signal gain