If last week’s patent by AMD came as a surprise, today’s publication of a patent application by Honda Motor Company for a graphene-based gas sensor is double that.
United States Patent Application number 20120282594 describes a sensor for atmospheric gases, such as NO, NO2 and NH3, based on graphene or carbon nanotubes. The sensitivities shown in the application are fantastic, to say the least, with detection limits in some cases down to a few hundred parts per quadrillion, fifteen orders of magnitude better than sensors available to date.
What is the trick that Honda use to bring down the sensitivity? The devices are equipped with a UV light source, which cleans the graphene (or nanotube) in-situ, during the measurement. Also, the devices are kept in vacuum, as the presence of air strongly deteriorates performance of the sensors. With these two solutions, Honda addresses two important technical issues which have come up time and again with graphene.
The downside is, as with most graphene sensors to date, the speed of operation. Figures in the patent application show that at least a few minutes are needed for gas detection to take place. It is sure that Honda is working on improving the speed, as well as sensing other, more volatile gases. This patent is a welcome addition to the graphene patent landscape, and the fact that it comes from newcomer Honda makes it twice as tasty.