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Ion transport in nanofluidic funnels.
John M Perry1, Kaimeng Zhou, Zachary D Harms
1Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA.
ACS Nano
|July 2, 2010
Summary
Researchers created nanofluidic funnels with precise dimensions using electron beam lithography. These asymmetric nanofluidic devices demonstrated ion current rectification, with the 5-degree funnel showing the highest ratio.
Area of Science:
- Nanotechnology
- Materials Science
- Physical Chemistry
Background:
- Nanofluidic devices offer unique transport properties at the nanoscale.
- Asymmetric structures are crucial for controlling ion flow and creating functional devices.
- Poly(dimethylsiloxane) (PDMS) is a versatile material for micro- and nanofluidic fabrication.
Purpose of the Study:
- To fabricate nanofluidic channels with asymmetric funnel-like geometries.
- To investigate the ion transport characteristics of these fabricated funnels.
- To correlate funnel geometry with ion current rectification and enrichment phenomena.
Main Methods:
- Electron beam lithography was used to create master molds in SU-8 resist.
- High modulus poly(dimethylsiloxane) (PDMS) was employed for casting nanofluidic funnels.
- Fabricated funnels were characterized using electrical measurements and fluorescence microscopy.
Main Results:
- Nanofluidic funnels with well-defined geometries (80 nm tip width, 120 nm depth) and taper angles (5°, 10°, 20°) were successfully fabricated.
- All funnel designs exhibited ion current rectification, indicating directional ion flow.
- The 5-degree funnel displayed the highest rectification ratio, signifying efficient ion control.
Conclusions:
- Asymmetric nanofluidic funnels can be reliably fabricated with precise control over dimensions.
- These devices effectively rectify ion current, with performance dependent on the funnel's taper angle.
- The observed ion enrichment/depletion phenomena highlight the potential for nanofluidic devices in separation and sensing applications.
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