Tag Archives: graphene foam

Get rid of the canary, you can use graphene foam to detect hazardous gases

While I’ve come across a number of research items regarding detection of poisonous and hazardous gases, this is the first I’ve seen an item where graphene foam is being tested for the purpose. According to the March 8, 2012 news item on physorg.com.

Fazel Yavari has developed a new sensor to detect extremely small quantities of hazardous gases. The Rensselaer Polytechnic Institute doctoral student harnessed the power of the world’s thinnest material, graphene, to create a device that is durable, inexpensive to make, and incredibly sensitive.

The Rensselaer Polytechnic Institute’s March 7, 2012 news release provides details about the importance of these gas sensors and  some of the problems with using nanomaterials for this purposed,

Detecting trace amounts of hazardous gases present within air is a critical safety and health consideration in many different situations, from industrial manufacturing and chemical processing to bomb detection and environmental monitoring. Conventional gas sensors are either too bulky and expensive, which limits their use in many applications, or they are not sensitive enough to detect trace amounts of gases. Also, many commercial sensors require very high temperatures in order to adequately detect gases, and in turn require large amounts of power.

Researchers have long sought to leverage the power of nanomaterials for gas detection. Individual nanostructures like graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chicken-wire fence, are extremely sensitive to chemical changes. However, creating a device based on a single nanostructure is costly, highly complex, and the resulting devices are extremely fragile, prone to failure, and offer inconsistent readings.

It seems that Yavari has come up with a solution,

Yavari has overcome these hurdles and created a device that combines the high sensitivity of a nanostructured material with the durability, low price, and ease of use of a macroscopic device. His new graphene foam sensor, about the size of a postage stamp and as thick as felt, works at room temperature, is considerably less expensive to make, and still very sensitive to tiny amounts of gases. The sensor works by reading the changes in the graphene foam’s electrical conductivity as it encounters gas particles and they stick to the foam’s surface. Another benefit of Yavari’s device is its ability to quickly and easily remove these stuck chemicals by applying a small electric current.

The new graphene foam sensor has been engineered to detect the gases ammonia and nitrogen dioxide, but can be configured to work with other gases as well. Ammonia detection is important as the gas is commonly used in industrial processes, and ammonia is a byproduct of several explosives. Nitrogen dioxide is also a byproduct of several explosives, as well as a closely monitored pollutant found in combustion exhaust and auto emissions. Yavari’s sensor can detect both gases in quantities as small as 0.5 parts-per-million at room temperature.

I don’t grasp how the graphene foam can be  a sensor that can be reused since foam usually dissipates after a few minutes and no details are offered in the news release or the news item. Yavari appears to holding an object (perhaps it’s a composite material based on graphene foam?),

Fazel Yavari

Cngratulations to Yavari.

For anyone who’s puzzled by my headline reference to canaries, miners used to bring them down into the bowels of the earth. The canaries weren’t pets but rather an early warning signal of poisonous gases that could be released as the miners dug into the earth. Since the canaries were more sensitive to the gases, they would die first and that’s how the miners knew when to clear out of an area.