A one-dimensional model capturing selective ion transport effects in nanofluidic devices

Brice T. Hughes, Jordan M. Berg, Darryl L. James, Akif Ibraguimov, Shaorong Liu, Henryk Temkin

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

This paper presents a numerical model of one-dimensional, steady-state, multi-species, ion transport along a channel of variable width and depth. It is intended for computationally efficient simulation of devices with large variations in characteristic length scale-for example those incorporating both micro- and nanochannels. The model represents both volume charge in the fluid and surface charge on the channel walls as equivalent linear charge densities. The relative importance of the surface terms is captured by a so-called "overlap parameter" that accounts for electric double-layer effects, such as selective ion transport. Scale transitions are implemented using position-dependent area and perimeter functions. The model is validated against experimental results previously reported in the literature. In particular, model predictions are compared to measurements of fluorescent tracer species in nanochannels, of nanochannel conductivity, and of the relative enhancement and depletion of negatively and positively charged tracer species in a device combining microand nanochannels. Surface charge density is a critical model parameter, but in practice it is often poorly known. Therefore it is also shown how the model may be used to estimate surface charge density based on measurements. In two of the three experiments studied the externally applied voltage is low, and excellent results are achieved with electroosmotic terms neglected. In the remaining case a large external potential ( 1 kV) is applied, necessitating an additional adjustable parameter to capture convective transport. With this addition, model performance is excellent.

Original languageEnglish
Title of host publicationMicro and Nano Systems
PublisherAmerican Society of Mechanical Engineers (ASME)
Pages985-992
Number of pages8
ISBN (Electronic)079184305X
DOIs
StatePublished - 2007
EventASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007 - Seattle, United States
Duration: Nov 11 2007Nov 15 2007

Publication series

NameASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
Volume11

Conference

ConferenceASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007
CountryUnited States
CitySeattle
Period11/11/0711/15/07

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