Three senior design students in the Department of Electrical and Computer Engineering at the University of Illinois have prototyped a device that could protect firefighters from an invisible danger: searing temperatures.
With modern firefighting clothing, every inch of skin is covered, insulating the firefighters from severe temperatures and exposure to gases and carcinogens. Along with fire-retardant outwear, firefighters wear a mask and self-contained breathing apparatus (SCBA), fitted over the face, keeping the air that they breathe relatively cool.
But when the SCBA facepiece reaches a certain point-about 150˚C-those protections can become compromised. The polycarbonate lens of the firefighter’s mask begins to soften (a physical limitation of the material). If the temperature continues to rise, the facepiece could fail, instantly exposing the firefighter to the dangerous temperatures.
This is where the students’ device comes into play: something to warn the firefighters to exit well before the temperatures reach that level. It fits within a firefighter’s protective headgear.
The students — Andri Teneqexhi, Lauren White, and Hyun Yi — designed the sensor while taking Senior Design during the Fall 2013 semester. They were honored with the Instructor’s Award, the highest designation granted among 45 teams last semester. Yi continues to work on the device this spring.
The sensor, which mounts behind the self-contained breathing apparatus, has an LED warning light just below the field of vision and two buzzers that would alert the firefighters to the elevated temperatures. These components are designed with intentional redundancies.
The students tested it in an enclosed variable heating chamber, ensuring that it would operate accurately and efficiently at real-world temperatures.
“This is not something that we can have very large error bars on,” said Gavin Horn, the research program director at the Illinois Fire Service Institute, who advised the students throughout the semester. “We have to know exactly where we’re at, because a 10-degree difference in temperature of the facepiece could be very important.”
To guarantee maximum practicality, the students not only attended to small design issues-using standard lithium batteries, for example, which can be easily replaced-but they also worked to keep the overall price under $30.
“Keeping that budget was the most difficult part,” said Yi. “You could use something called a thermopile sensor, and that’s also very accurate and much easier to use [than our thermistors]The reason we can’t use that though is that sensor alone cost $35, and then we’re already going to be blowing the budget on that.”
While additional testing and prototype development is still in order, everyone involved is confident that the device could become a useful component of firefighting protective gear. When the National Institute of Standards and Technology convened a workshop to address facepiece failures in 2011, a warning device was recommended as a possible solution. The students’ design responds to that call.
“There is certainly potential for this to be a marketable solution,” Horn said. “The ability to sense the environment and to provide that additional feedback to the firefighter, we feel is critical, and hopefully, this will have a chance to address that concern.”
Throughout the semester-long design process, as the students weighed conflicting needs and constraints, they would ask Horn which features would be most important in real-world scenarios.
“Some of those, we’re able to give them straightforward answers and some of them we wanted to challenge them a bit and said, ‘Well, you have to make an engineering judgment on that,'” Horn said. “But they did a very good job.”
Early in the semester, the students also realized how important the ECE ILLINOIS electronics services shop (which provides circuit board fabrication) and the machine shop (which provides chassis fabrication) would be for the finished product. They worked hard to design those components and ordered them early.
“Using all resources available to you is the key to success in this class,” Teneqexhi said. “[And] it’s good to have a group schedule and try to keep up with it.”
Yet, overall, perhaps it was the real-world value of the device that was the ultimate motivation for the team’s success.
“This is something that can actually help save lives, help reduce injuries,” White said. “You’re probably going to hear about this later. If you know a firefighter, I bet they’ll tell you, ‘I have this really cool unit made by students.'”
