Carbon nanotube-based sensors are good at sniffing out all kinds of things, but applying the cylindrical molecules to a substrate has traditionally been a dangerous and unreliable process. Now, researchers at MIT have found a way to avoid the hazardous solvents that are currently used, by compressing commercially available nanotube powders into a pencil lead-shaped material. That allowed them to sketch the material directly onto paper imprinted with gold electrodes (as shown above), then measure the current flowing through the resisting carbon nanotubes - allowing detection of any gases that stick to the material.
Engadget , MIT pencils in carbon nanotube gas sensor that's cheaper, less hazardous (video), MIT pencils in carbon nanotube gas sensor that's cheaper, less hazardous (video)
