Cutting edge research is setting the stage for the practical deployment of carbon nanotubes as flow sensors. Studies drawing on both electrokinetic phenomena and slip boundary conditions are offering in-depth understanding of microfluid flow in restricted microchannels.
Complex experiments have now demonstrated that the Coulombic effect, involving direct scattering of free charge carriers from fluctuating Coulombic fields of ions or polar molecules in the flowing liquid, is stronger than the phonon drag effect in generating electric current/voltage.
The outcome has been the emergence of a model for a practical flow sensor, capable of being downsized to small dimensions as short as the nanotubes.
A new avenue has thereby been created to gauge flow in tiny liquid volumes, with high sensitivity at low velocities and exceptionally rapid response times.
"Many proposed applications of carbon nanotubes depend on simple mechanical or electrical properties, but nanotubes also have the potential to be devices in their own right, namely sensors," writes Shirley Savage, a contributor to Technical Insights' Nanotech Alert.
Another prospective development might entail building a voltage/current source in a flowing liquid environment. The resultant miniature energy conversion device is likely to have appealing biomedical applications.
Latest analysis seeking to understand fluid flow in microchannels uniquely combines an equation for electrokinetic effects with the familiar Navier slip condition. The ensuing equation predicts fluctuating flow in a circular microchannel. This helps resolve general time-dependent problems and offers better understanding of fluid flow in microchannels with hydrophobic walls.
The concept permits the insertion of other models of slip besides those predicted by Navier's formulation. It is also of immense use since, at present, almost all potential microchannels are likely to have circular cross-section and hydrophobic walls.
Technical Insights at Frost & Sullivan
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Nanodevice Breaks 1-GHz Barrier
Pasadena - Jan 30, 2003
Nanoscientists have achieved a milestone in their burgeoning field by creating a device that vibrates a billion times per second, or at one gigahertz (1 GHz). The accomplishment further increases the likelihood that tiny mechanical devices working at the quantum level can someday supplement electronic devices for new products.
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