Carbon nanotubes – tiny rolled-up sheets of carbon atoms – are one of the most intriguing new materials that could be used in a new generation of electronics. As my colleague Signe Brewster reported on Wednesday, Stanford researchers have created the first carbon nanotube computer, but the material also has a variety of other applications, particularly in the creation of new sensors.
For years now, scientists have been able to create carbon nanotube-based gas sensors. However, as with other new carbon-based materials such as graphene, very cheap manufacturing techniques are key to its widespread potential future deployment. Which is why new research from the Technische Universität München (TUM) in Germany is so interesting.
Smart food packaging
TUM researchers announced this week that they can now fabricate carbon nanotube-based gas sensors directly onto thin film, through a large-area process that basically involves spraying the stuff in a very uniform, consistent fashion. What’s more, this can be done cheaply, largely because it doesn’t require pricey clean-room facilities.
One of the most obvious applications for this new technique might be in smart food packaging, the team said. For example, these sensors could be sprayed onto the clear film protecting meat in supermarkets. Hook them up to a disposable wireless communications chip, and you have a package that can let the supermarket’s managers know when the meat is starting to go off.
“Of course, it would have to go on the inside,” Dr Alaa Abdellah (pictured above), one of the researchers, told me. “It’s still kind of early to say if it can go into food [packaging], because there you have more strict regulations.
“It’s certainly something which would in an earlier stage be [applicable] in indoor air quality monitors, but if these health concerns are sorted out, then it could also get an application like smart packaging for food.”
The TUM team is also working on carbon nanotube-based thin film transistors, which can potentially be flexible, at wafer scale. Solar cells are another avenue of exploration, as are pressure and temperature sensors — think bionic or robotic skin.
“One advantage of the technology is you can really deposit thin films with high uniformity and high reproducibility,” Abdellah said. “This is not given by many of the other technologies… The ability to process such highly uniform ultrathin films is one of the reasons why our gas sensors are so good in terms of performance, compared to other methods.”
But the researchers aren’t just spraying new carbon forms; they’re also starting to use their technique to lay down silver nanowires. As Signe reported earlier this week, silver nanowires are a great hope for those developing flexible, wearable displays. The TUM researchers see a different application, though — and again, this one could help smart, cheap food packaging hook up to the internet of things.
“To have such a reliable large area process at such low cost and getting very good performance, one can think of also spraying next to the sensor an antenna with silver nanoparticles or nanowires. It would develop towards being an RFID with an integrated sensor, preferably all sprayed,” Abdellah said.
The concept of a sprayed antenna isn’t actually new, but it is a novelty when you’re looking at cheap mass production techniques. So maybe, a few years down the line, you’ll get some near-invisible electronics with your store-bought steak. That’s assuming these intriguing new materials don’t poison you, of course.