More than ever, we want to know what we’re breathing. It’s the age of the air purifier, checking weather apps to see air quality, and shamelessly wearing masks to protect yourself from pollution and particles.
But what if your clothes changed colors to notify you of dangerous breathing conditions?
Nanotechnology scientists at Tufts University in Massachusetts have developed a simple technique that might do just that.
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“You can have certified inspectors telling you that your water or environment or food isn't good but it would be nice if people can make those judgements themselves,” Sameer Sonkusale, a mechanical and computer engineer who leads the university’s Nano Lab, told The Daily Beast. “I always feel that knowledge is power. I feel that the technology has advanced so much there is a lot of innovation that can be had with simple basic things.”
Sonkusale’s lab has been working on a variety of low cost, portable sensing platforms that can give the average person access to data about the world around them they otherwise haven’t had access to.
The color-changing technology relies on different dyes that naturally change color when they’re exposed to specific gases. For example, bromothymol blue dye responds to ammonia and methyl red dye reacts to hydrogen chloride—both gases commonly found in cleaning supplies and fertilizer. “With this one we realized we could provide a way that people can see the pollution in their environment,” he says.
The biggest challenge in developing the gas-sensing textiles wasn’t actually in getting the dye onto the fabric; it was in figuring out how to keep the dyes in place and make them sturdy enough to withstand regular wear and washing. Initially, the team attempted to chemically treat the dyes to lock them in place, but they found that technique made them less sensitive.
So instead they created a two-step process to keep the dyes sensitive and trap them in the fabric threads, making the fabric dyes durable. The chemical treatment opens up the fabric’s fibers—separating the microstructures in the threads—and allows the dyes to get into every nano-nook and cranny. Then they add a thin polymer membrane that is porous (and allows gases to enter) but holds everything in place.
The trick, Sonkusale added, is that the polymer membrane can’t be so thick or stiff that the threads no longer act like fabric. Once that was worked out, he said, in the end the technology is easy and inexpensive to implement.
“It’s amazing how this approach is fairly straightforward. It’s something that should have been done some time ago,” Sonkusale said.
In practice, small gas-detecting colored patches could be sewn into a variety of different types of clothing and used as a sort of “canary in a coal mine” to alert people to gasses in their vicinity. People could use them in their homes or their cars—and they’d also be useful as early warning systems for jobs that have potentially dangerous chemicals involved like chemistry laboratories or construction sites.
And because the polymer coating is so effective, the dyes are even able to detect gasses underwater. Sonkusale and his team have even developed a phone app that allows users to compare images of their fabrics over time in order to detect even small color changes.
So far there has been a lot of interest in further developing the technology (especially as a handheld sensor) by putting the dyes onto portable cards.
“You don’t always have to put it on a fabric,” Sonkusale said—detectors can be washable and reusable over many cycles or simply quick one-time throw-aways.
However they’re ultimately used, he says, they have the potential to give people much more control over their health and their environment. “The more we know the more we’re empowered,” he said.
