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Issue 37, 2015
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Suspended single-walled carbon nanotube fluidic sensors

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In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent with the ion depletion model. We also have measured conductance as a function of gate bias at different flow rates and have determined the flow-rate dependent effective charge density, which influences the electrostatic configuration around SWNT devices.

Graphical abstract: Suspended single-walled carbon nanotube fluidic sensors

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The article was received on 16 May 2015, accepted on 12 Aug 2015 and first published on 19 Aug 2015

Article type: Paper
DOI: 10.1039/C5NR03215F
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Nanoscale, 2015,7, 15421-15426

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    Suspended single-walled carbon nanotube fluidic sensors

    B. H. Son, J. Park, S. Lee and Y. H. Ahn, Nanoscale, 2015, 7, 15421
    DOI: 10.1039/C5NR03215F

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