New graphene gas sensor inspired by dog noses

Man’s best friend enjoys one of the best noses on the planet. That’s why a Chinese-led study based its newly-developed electronic nose on a dog’s nose by using biomimetic graphene materials, reported a Nanowerk article.

A dog’s excellent sense of smell comes from the hundreds of millions of capillaries that line the inside of its nose. The large surface area covered by the nasal capillaries allows dogs to pick up the slightest odors in the air.

In comparison, a typical human has only around five million capillaries in the nose and can detect a mere 10,000 scents.

Many researchers have used the dog’s nasal structure as the baseline to build artificial gas detectors and electronic noses. None of those devices came close to matching a canine’s nose.

The National Center for International Research on Green Optoelectronics research team is the first to report meeting those high standards. They used a new type of graphene nanoscroll (GNS) for their sensor.

They published their findings under the title “Mimicking a Dog’s Nose: Scrolling Graphene Nanosheets” in the ACS Nano journal of the American Chemistry Society.

Artificial sniffer is made from altered carbon nanoscrolls

GNS are nanometer-thick sheets of graphene that have been rolled up in a continuous and uniform manner. These nanoscrolls have a large surface area, can stay stable at high temperatures, and exhibit great strength and durability for their thin dimensions.

These atom-thick scrolls can capture molecules in much the same way a dog’s sensitive capillaries can catch the smallest particles of scent.

The problem with using GNS is that the material resists scaling up for mass production. The manufacture of graphene nanoscrolls is also a complicated process that uses up a lot of energy.

Earlier research found out that cheaper and more common forms of graphene could not be used to create nanoscrolls. Using raw graphene resulted in unrolled structures, while modified forms like graphene oxide resulted in shriveled and clustered material.

Therefore, the Chinese research team decided to make high-quality nanoscrolls by using a polymer to alter the graphene base. They chose poly(sodium-p-stryrenesulfonate), an ion-exchange resin that strips ions like calcium, potassium, and sodium from solutions.

After adding the polymer to the GNS, the researchers applied the freeze-drying method to make homogeneous structures that were free of aggregation.

PGNS enables superior odor detection capability

The resulting artificial nanostructures are called poly(sodium-p-stryrenesulfonate)-functionalized reduced graphene oxide nanoscrolls – shortened to PGNS.

In direct contrast to their previous appearance, PGNS are shaped like wide-open tubes. The researchers reported that all of the graphene material were rolled up, which makes for a very efficient process.

Once added to an electronic nose, the nanoscrolls permitted a high level of odor selectivity and sensitivity. The device exhibited reliability, excellent linear sensibility, and a very high response towards nitrogen dioxide (NO2).

According to the Chinese researchers, their method of producing PGNS was cheap and easy enough to be adopted for mass-production. This could potentially solve the production bottleneck encountered by many graphene-based products. (Related: Materials science researchers create monolayer graphene using honey as an essential ingredient.)

Potential uses for PGNS include gas detectors and chemical trace sensors that look for a variety of odors. These e-noses can detect air pollution, rotten food, illegal contraband, or dangerous chemicals.

Perhaps one day, there will be sensors that could match or exceed the nose of dogs. When that day comes, animals involved in dangerous jobs like sniffing out bombs and drugs can be retired from those hazardous duties and serve as man’s best friend on a full-time basis.

More articles on groundbreaking technological developments can be found at Inventions.news.

Sources include:

Nanowerk.com

Pubs.ACS.org