(503c) Field Effect Control of Ion Transport in a pH-Regulated Nanochannel with Overlapped Double Layers

The ability to control the ion transport, which depends exquisitely on surface charge properties and ionic concentration distributions, in nanofluidic devices plays a dominant role for emerging applications such as energy conversion, ionic diodes, and sensing of molecules. To achieve active control, nanofluidic field effect transistors (FETs), referring to gate electrode-embedded nanofluidic devices, have been developed recently. To improve the development of FET control nanofluidic devices for emerging applications, analytical expressions taking into account practical effects of the presence of hydrogen and hydroxide ions, electroosmotic flow, Stern layer effect, and surface chemistry reactions on the channel wall, are derived to study the field effect control of surface charge property and ionic conductance in a pH-regulated nanochannel with overlapped electric double layers (EDLs). We show that the EDL overlap effect is relatively significant at low pH and salt concentration when a negative gate potential is applied. If pH is low, the EDL overlap effect on the field control of zeta potential of the nanochannel is remarkable at large positive gate voltage, while that effect on ionic conductance is significant at large negative gate voltage.