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Controlling the ionic current rectification factor of a nanofluidic/microfluidic interface with symmetric
Han Wang1, Vishal V R Nandigana2, Kyoo Dong Jo3
1#Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.
Analytical Chemistry
|March 25, 2015
Summary
Ionic current rectification in nanocapillary membranes (NCMs) is tunable by altering fluid bath asymmetry. Greater asymmetry significantly enhances rectification, enabling faster sample enrichment processes.
Area of Science:
- Nanofluidics
- Membrane Science
- Ionic Transport
Background:
- Nanocapillary membranes (NCMs) exhibit ionic current rectification, a phenomenon influenced by device geometry.
- Understanding the factors controlling rectification is crucial for optimizing NCM-based devices.
Purpose of the Study:
- To investigate the effect of fluid bath asymmetry on ionic current rectification in NCMs.
- To elucidate the primary mechanisms driving current rectification and explore contributions from electroconvection.
Main Methods:
- Fabrication of NCM devices with varying degrees of fluid bath asymmetry.
- Measurement of ionic current rectification factors under different geometric conditions.
- Analysis of current-time (I-t) data using power spectral density (PSD) to identify electroconvective phenomena.
Main Results:
- A symmetric device showed no rectification, while a device with a 32-fold bath area difference achieved a rectification factor of 75.
- Current rectification is primarily governed by changes in fluid bath cross-sectional area and concentration polarization (CP) dynamics.
- Electroconvection in macropores contributes to increased rectification with greater bath asymmetry, evidenced by chaotic oscillations in PSD analysis.
Conclusions:
- Fluidic diode rectification factors can be precisely controlled by engineering the asymmetry of connected fluid baths.
- The findings offer a simple method for fabricating tailored fluidic diodes for applications like enhanced sample enrichment.
