title: Ion current rectification in funnel-shaped nanochannels: Hysteresis and inversion effects.
abstract: Ion current rectification inversion is observed in a funnel-shaped nanochannel above a threshold voltage roughly corresponding to the under-limiting to over-limiting current transition. Previous experimental studies have examined rectification at either low-voltages (under-limiting current region) for conical nanopores/funnel-shaped nanochannels or at high-voltages (over-limiting region) for straight nanochannels with asymmetric entrances or asymmetric interfacing microchannels. The observed rectification inversion occurs because the system resistance is shifted, beyond a threshold voltage, from being controlled by intra-channel ion concentration-polarization to that controlled by external concentration-polarization. Additionally, strong hysteresis effects, due to residual concentration-polarization, manifest themselves through the dependence of the transient current rectification on voltage scan rate.
authors.affiliation: Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion-Israel Institute of Technology, Technion City 32000, Israel.
authors.forename: Leon
authors.initials: L
authors.lastname: Rosentsvit
authors.affiliation: National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Institute of Microelectronics, Peking University, Beijing 100871, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion-Israel Institute of Technology, Technion City 32000, Israel.
authors.forename: Jarrod
authors.initials: J
authors.lastname: Schiffbauer
authors.affiliation: Department of Chemical and Biomolecular Engineering, Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Hsueh-Chia
authors.initials: HC
authors.lastname: Chang
authors.affiliation: Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion-Israel Institute of Technology, Technion City 32000, Israel.
authors.forename: Gilad
authors.initials: G
authors.lastname: Yossifon