Here at FPI, we generally work with liquid level sensors, which are distinct from fluid level sensors. The difference is that the category of fluids also includes gases, a rather more complicated material to measure. But a team of MIT chemists has found an incredibly cheap and simple way to do just that: By drawing on a specially treated piece of paper with a pencil that uses compressed carbon nanotubes instead of graphite.
The paper has a very thin layer of gold in the form of stripes with gaps between them. The nanotube pencil draws lines between the electrodes to complete a simple circuit. When ammonia binds to the nanotubes, it will impede the flow of electrons and alter the current, indicating the presence of the deadly gas.
With special treatments, the nanotubes can be altered to detect a variety of dangerous substances. Not only is the process cheap and simple, it’s also much safer than previous methods which involved saturating the nanotubes with a toxic substance. With potential applications for healthcare, the military, and the food service industry, this clever invention is certainly deserving of recognition in the pantheon of level sensors.