When exposed to target gases, the dyed threads change colors. Photo by Rachel Owyeung/Tufts University/Nano Lab
April 7 (UPI) -- Engineers at Tufts University have developed threads that change colors when they detect specific gases. The threads can be sewn into clothing, making gas detection technology wearable.
"Current methods to monitor pollution or harmful gases require dedicated sensors and equipment," Sameer Sonkusale, professor of electrical and computer engineering at Tufts, told UPI. "In my mind, the power of our new approach is our sensor platform can be integrated into something you would already be wearing, such as a lab coat or even a t-shirt."
For the proof-of-concept study, Sonkusale and his research partner, Rachel Owyeung, an engineering grad student at Tufts, soaked threads in gas-detecting dyes, including manganese-based dye, MnTPP, methyl red and bromothymol blue. The MnTPP and bromothymol blue dyes react to ammonia, while methyl red detects hydrogen chloride.
After dying the threads, scientists treated them with acetic acid, which causes the threads to swell, increasing the dyed surface area, increasing the odds of the thread reacting with target gas molecules. Finally, the threads were treated with polydimethylsiloxane, which is gas permeable but repels water and prevents the dye from leeching during washing.
Scientists used dyes that change color when they react to gas molecules with specific chemical properties. The color change reflected the strength of the target gas concentration.
In addition to aiding scientific observations, the new technology could help keep people safe from dangerous gases.
"You don't have to be cognizant of a hazardous environment before you've exposed yourself to dangerous levels," Sonkusale said. "The sensor is already there with you and working."
The dyes tested are sensitive to a variety of air pollution gases, including nitrogen oxides, sulfur dioxide and acetylaldehyde.
"It is just a matter of choosing a proper suite of optical dyes for distinguishing power of these chemicals," Sonkusale said. "One benefit of our entrapment method is that it can be used on different dye types, which is helpful for creating the sensor diversity needed for this distinguishing power."
Researchers hope to integrate their gas-detection threads with other technologies to create smart clothes.
"Our lab has recently explored many possible avenues where sensing threads can be used such as electrochemical sensors, microfluidics, and drug delivery, to name a few," Sonkusale said. "These could be integrated with the optical threads presented here."
Scientists described the new gas-detection threads in a paper published this month in the journal Scientific Reports. For future studies, researchers plan to target a wide array of gases and test the technology in a variety of environments.