Sensors: High Dynamic Range Flow Sensing with Carbon Nanotubes

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Abstract0428716James HoneColumbia UniversitySingle-walled carbon nanotubes (SWNTs), tubes of carbon as small as 1 nm in diameter, are ideal candidates for sensing because every atom of a nanotube is at the surface. The use of SWNTs as high dynamic range fluid flow sensors will be investigated in this project. This work is based on the recent discovery [Ghosh et al., Science 299, 1042 (2003)] that flow of an ionic fluid across a collection of nanotubes produces a voltage in the flow direction. This phenomenon will be verified and the initial work extend in the following ways:1. Fabrication of sensors based on thin films of nanotubes. Thin films of nanotubes with well-controlled geometry will be used for testing. This geometry will allow for better control and modeling of flow conditions2. Systematic variation of relevant parameters, such as flow velocity and shear, sample geometry, and external variables such as temperature.3. Fabrication of sensors based on single nanotubes. Ultra-long nanotubes will be grown using chemical vapor deposition, and integrated with microfluidics to make flow devices. The flow-induced voltage will be studied for different types of nanotubes, as well as for varying electrochemical potentials.Potential applications of the technology explored in this work include integration of flow sensors into lab-on-a-chip devices, in-vivo biological fluid flow sensors, and low-cost, dispersed atmospheric and oceanographic flow sensing.This is a project supported under the Sensors Initiative NSF 04-522.