Computed Tomography (CT) using Carbon Nanotube (CNT) x-ray source is a technique of generating reconstruction
images of the structure of teeth sample. A proto type CNT x-ray CT was designed for medical imaging to examine
whether it could be used to analysis the equipment of medical and industrial application. The CNT field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP) process. The field emission properties showed a gate turn-on field of 3.8 V/μm at an anode emission current of 0.5 mA. The author demonstrated the x-ray source with four electrode structures utilizing the CNT emitter. The acquisitioned images were reconstructed by filtered back projection (FBP) method.
We report, intrinsic fiber optic carbon nanotubes coated sensor for the detection of ammonia gas at room temperature.
Multimode step index polymethyl methacrylate (PMMA) optical fiber passive cladding is partly replaced by an active
coating of single and multi-walled carbon nanotubes following the dip coating technique and the reaction with ammonia
is studied by measuring the change in output intensity from the optical fiber under various ammonia gas concentrations
in the range 0-500 ppm in step of 50 ppm. The sensitivity is calculated for different wavelengths in the range 200-1100
nm both for single and multi-walled carbon nanotubes coated fiber. Higher sensitivities are obtained as 0.26 counts/ppm
and 0.31 counts/ppm for single-walled (average diameter 1.3 nm, 30 wt.% purity) and multi-walled (average diameter
10-15 nm, 95 wt.% purity) carbon nanotubes respectively. The role of diameter and purity of carbon nanotubes towards
the ammonia sensing is studied and the results are discussed.
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