Journal
NANO LETTERS
Volume 12, Issue 7, Pages 3437-3442Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nl300673r
Keywords
Nanofluidics; membranes; separations; ion channels; ionic circuits; electrochemistry
Categories
Funding
- NSF CMMI [0854881]
- NIH, NIH Roadmap for Medical Research [DP2-OD004346-01]
- Div Of Civil, Mechanical, & Manufact Inn
- Directorate For Engineering [0854881] Funding Source: National Science Foundation
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Nanopores with conical geometries have been found to rectify ionic current in electrolytes. While nanopores in semiconducting membranes are known to modulate ionic transport through gated modification of pore surface charge, the fabrication of conical nanopores in silicon (Si) has proven challenging. Here, we report the discovery that gold (Au) nanoparticle (NP)-assisted plasma etching results in the formation of conical etch profiles in Si. These conical profiles result due to enhanced Si etch rates in the vicinity of the Au NPs. We show that this process provides a convenient and versatile means to fabricate conical nanopores in Si membranes and crystals with variable pore-diameters and cone-angles. We investigated ionic transport through these pores and observed that rectification ratios could be enhanced by a factor of over 100 by voltage gating alone, and that these pores could function as ionic switches with high on off ratios of approximately 260. Further, we demonstrate voltage gated control over protein transport, which is of importance in lab-on-a-chip devices and biomolecular separations.
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