Microfluidics and Nanofluidics

, Volume 9, Issue 6, pp 1033–1039 | Cite as

Entrance effect on ion transport in nanochannels

  • Li-Jing Cheng
  • L. Jay Guo
Research Paper


We investigate the effect of the surface charge at channel entrances upon ion conductance, which has been overlooked in the study of nanofluidics. Nonlinear ion transport behaviors were observed in 20-nm thick nanochannels having opposite surface charge polarity on the entrance side-walls with respect to that in the nanochannel. The heterogeneous distribution of surface charge at the channel entrance functions as a parasitic diode, which can cause ion current saturation under high voltage biases. Such effect becomes crucial at low bath concentration at which the electric double layers originated from the bath sidewalls pinch off the channel entrance. The experimental results are clarified by theoretical calculations based on 2D Poisson–Nernst–Planck equations. With such strong effect on ionic conductance of nanochannels, the change of surface charge polarity at the entrance sidewalls may find applications in chemical and biological sensing.


Nanofluidic entrance effect Ion depletion Nanofluidic diode Ionic rectification Heterogeneous nanochannel 



This work was supported by a Riethmiller Fellowship and the NSFC (grant no. 60528003).

Supplementary material

10404_2010_621_MOESM1_ESM.doc (94 kb)
Supplementary material 1 (DOC 94 kb)


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Advanced Diagnostics and Therapeutics, Department of Chemical and Biomolecular EngineeringUniversity of Notre DameNotre DameUSA
  2. 2.Department of Electrical Engineering and Computer ScienceThe University of MichiganAnn ArborUSA

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