Probing the sensitivity of nanowire-based biosensors using liquid-gating

We have used liquid-gating to investigate the sensitivity of nanowire (NW)-based biosensors for application in the field of ultrasensitive biodetection. We developed an equivalent capacitance model of the biosensor system to explore the dependence of the sensitivity on the liquid-gate voltage (V(lg)), which was influenced by capacitive competition between the NW capacitance and the thin oxide capacitance. NW biosensors with highest sensitivity were obtained when we operated the device in the subthreshold regime while applying an appropriate value of Vlg; the influence of leakage paths through the ionic solutions led, however, to significant sensitivity degradation and narrowed the operating window in the subthreshold regime.