Patent ID: 8618581

Claim:
A field-effect transistor device comprising: a reservoir separated into two parts, said reservoir comprising an insulating material; a membrane that separates the reservoir into the two parts, said membrane comprising three layers: two electrically insulating layers; and an electrically conductive gate disposed between the two electrically insulating layers, wherein said electrically conductive gate comprises a surface charge polarity different from at least one of the two electrically insulating layers when they are in contact with an ionic solution; a nanochannel through the membrane that connects the two parts of the reservoir; said ionic solution introduced into the nanochannel for filling the reservoir to produce an ionic channel, producing a surface-charge-modulated ionic channel through the membrane, wherein the modulated surface charge is due to different surface properties of the two electrically insulating layers and the electrically conductive gate; a drain electrode; a source electrode; and a voltage applied between the source and drain electrodes and a voltage applied on the electrically conductive gate layer in the membrane, turning on an ionic current through the ionic channel; wherein the voltage on the electrically conductive gate gates transportation of ions through the ionic channel; and wherein the nanochannel comprises a diameter less than twice of a Debye length of the ionic solution, which ranges from 0.3 nm to 10 nm, depending on ionic strength of said ionic solution.