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Winter weather can be treacherous at times, especially for those trying to navigate slippery situations on foot. Fortunately, George Mason University materials scientist Shay Bagheri is working on better footwear to handle icy conditions.
Bagheri, an assistant professor in the Department of Mechanical Engineering and an affiliate scientist at Toronto Rehabilitation Institute, received a $100,000 grant from the Commonwealth Commercialization Fund (CCF) of the Virginia Innovation Partnership Corporation for her research. CCF “supports Virginia’s small business community and its colleges, universities, and nonprofit research institutes at the earliest stages of their entrepreneurial and/or commercialization journeys, seeking innovative technologies with a high potential for economic development and job creation.”
In 2016, Bagheri was working at the Toronto Rehab Institute, which has numerous labs that recreate real-world environments. Bagheri was drawn to the Winter Lab, where researchers were studying shoe safety in slippery conditions.
“WinterLab is a self-contained facility with an ice-covered floor that can be tilted at different angles," Bagheri said. "Harnessed participants walk up and down the icy slope, and the steepest angle they can manage without slipping is used to measure the slip resistance of their footwear.”
While working at the Winter Lab, she received new generations of winter footwear based on composite technology. These shoes had excellent slip resistance when they were new, but she was surprised to learn many of the boots and shoes they tested lost a significant amount of their nonslip properties after a mere 75,000 steps—barely a week for a frequent, avid walker.
“And all of them cost over $200. So, we knew something had to be done in order to improve the material and the manufacturing process.”
The commercially available composite-based footwear have soles that get traction from tiny pieces of glass. Glass is by nature very sensitive to abrasion and the fabrication of glass is very hazardous, making it less than ideal. Bagheri said, “Instead of glass, we are adding polymeric fibers that are very resistant to wear and abrasion. They are non-hazardous, soft, and capable of withstanding significant abrasion. This material is five times more effective than what’s currently on the market.”
She said that instead of using the common injection molding technique to make these composite materials, she uses additive manufacturing, allowing for more uniform distribution, with a little bio inspiration. “In order to enhance friction on ice, we incorporate polymeric microfibers that protrude to the surface, triggering the friction mechanism similar to what you would see in polar bear feet,” she said. For the second approach, she uses a 2-D material with a large surface area that triggers the friction mechanism through adhesion, similar to the way frog’s feet work.
Bagheri and colleagues hold a patent for the method of manufacturing these innovative composites. She and her student at George Mason have also filed a provisional patent through their work, using additive manufacturing technology to make these composites more efficiently.