Ordinary office printers can be used to create sensors which can help to monitor the environment and detect disease. How can it work? Claire O'Connellreports
When you think of high-tech scientific equipment, a desktop printer hardly springs to mind. But scientists at Dublin City University (DCU) have harnessed the humble office printer to develop cheap and effective plastic sensors, and their approach could revolutionise how we monitor the environment and even detect disease.
"Using a printer to make sensors makes it feel very accessible all of a sudden, doesn't it?" says Dr Tony Killard, a principal investigator at the National Centre for Sensor Research in DCU. The idea came from working a conductive plastic called polyaniline, which was nasty stuff to work with in the lab, he explains.
"For starters the monomeric form, aniline, is carcinogenic," he says.
"Then when you polymerise it, it loses its carcinogenicity but it pretty much becomes insoluble in everything and it's very difficult to handle or process."
Working with a team in Wollongong, Australia, the DCU scientists decided to make nanoparticles of polyaniline, and found that at this tiny scale, the material suddenly became easier to play with.
"We now had these nice little particles and they were very well-behaved - they were distributed in this green, uniform solution," he explains.
"We reckoned that these would probably be very easy to deposit in some kind of simple, straightforward way, and we hit on the idea of just using inkjet printing with a desktop printer. We took out the ink cartridge, washed it out and put the polyaniline in. We put it on print and, lo and behold, lovely green ink," he says.
To make the sensor, the team simply designed and drew out the pattern on a standard graphics programme and printed it in polyaniline "ink" onto thin sheets of polyester, which had been primed with a carbon or silver track to connect the sensor back to a device. "When these sensors are printed and dry they are very environmentally stable, very robust.
Potentially it's low-cost, mass-producible technology," says Dr Killard, whose research us funded by Enterprise Ireland.
But the next question was what to do with the new technology.
A group of business students at DCU looked into how the new sensors could be used and identified the refrigerant gas ammonia as a prime target - the sensors could detect leaks in industrial settings.
"The current ammonia-sensing technology is based on really old-fashioned systems that are expensive and their performance isn't that good. The industry has been demanding and waiting for a much-improved ammonia sensor for a long time," says Dr Killard.
He notes that their approach could provide an answer: leaving small, inexpensive sensors in situ to detect any leaks from pipes. The plastic sensors could also be used in healthcare, he adds.
"We are looking at applications where disposability might be of benefit, like personal monitoring devices that can be quickly activated and disposed of."
And the potential will open up further as measuring devices linked to sensors move into the realm of printed electronics too, according to Killard.
One of the most elegant scenarios he foresees is where their tiny sensors sit in food packaging and detect spoilage. "Our materials bring this to the mass market potentially. These can be cheap enough to go into every packet."