Sensors that can provide people with a better view of their environment and health are some of the promise of wearable technology. Researchers at Tufts University have created a new fabrication process for dyed threads that can act as sensors for textiles and change color upon detection of different types of gas.
The threads can be woven into clothing for people in jobs in the medical field, military, rescue environments, and certain types of workplaces where there is potential for exposure to harmful gases. This would allow people to take better control of their own health and safety in these situations and provide a safer environment for them to perform their tasks, researchers said.
|Sensing threads turn different colors depending on their exposure to certain types of gas. Developed at Tufts University, the threads can be woven into clothing to protect people in various workplace and other scenarios. (Image source: Tufts University)|
Aware of the Hazards
Optical sensors and other techniques for environmental monitoring of hazardous gas have existed for some time, Rachel Owyeung, a graduate student in the Tufts Department of Chemical and Biological Engineering who worked on the research, told Design News. However, the current solutions require the user to be cognizant of a hazard before they arrive to the site, requiring that they bring the sensor and readout system.
Since it’s not always possible to know of the hazards of gas in some situations, using sensors is another way to keep users safe from any potential hazards, and can be used alongside existing solutions, she said.
“With our solution, these thread-based sensors can be integrated into textiles you would already be wearing, making our approach more practical for a real-world setting,” Owyeung said.
Threads with Dyes
Researchers used a manganese-based dye, MnTPP, methyl red, and bromothymol blue to prove their concept. MnTPP and bromothymol blue can detect ammonia while methyl red can detect hydrogen chloride, researchers said. Cleaning supplies, fertilizer, and chemical and materials production commonly release these gases.
“Our threads are made through a series of simple dip and dry steps,” Owyeung explained. “First, the cotton threads are dipped in a certain dye solution, then they are dipped in an acetic acid solution, and finally, in polydimethylsiloxane (PDMS). The acetic acid and PDMS steps are both essential to ensuring the stability of these sensors in water, such that they can be washed.”
As for the sensing mechanism, each dye molecule includes a specific structural orientation that undergoes a conformation change in the presence of a certain compound chemistry that is present in the gas, she said. “This change affects how light interacts with the dye molecule, thus our eyes perceive a color change,” Owyeung said. Researchers published a paper of their work in the journal Scientific Reports, with Owyeung as first author.
Using a Smartphone Camera
In their work, researchers demonstrated that the threads can be read visually, or even more precisely by use of a smartphone camera, to detect changes of color due to analytes as low as 50 parts per million. They can be woven into clothing that is reusable, washable, and affordable for a variety of applications, they said.
“Our unique fabrication allows these sensors to be washable and still retain their sensing function,” Owyeung explained. “This not only makes them ideal for wearable applications, but also allows them to be used as dissolved gas sensors. This further extends the environments in which these sensors can be used.”
The coating method for the sensors also doesn’t limit the dye chemistry that can be used in their fabrication, she added.
“It is a universal entrapment method that can be used on multiple dye types, which allows us to extend our sensor diversity,” Owyeung explained. “This is essential for expanding the potential applications for which these sensors can be used.”
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.
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