Detecting Brain Injury with Colors

In 2014, PBS reported researchers found 76 of 79 deceased NFL players showed signs of a degenerative brain disease called chronic traumatic encephalopathy.

The disease, according to Boston Univ., is associated with “repetitive brain trauma, including symptomatic concussions, as well as asymptomatic subconcussive hits to the head.” It can manifest years, and even decades, after the last hit to the head. Symptoms include memory loss, confusion, impaired judgment, aggression, depression and progressive dementia.

Head trauma is causing brain damage to athletes and soldiers in the battlefield, said Shu Yang, of the Univ. of Pennsylvania. But how does one know a hit to the head warrants a trip to the hospital?

Yang’s research team, which includes colleagues from Villanova Univ. and Temple Univ., has developed a polymer-based patch capable of changing color depending on how hard it’s hit. Ideally, multiple patches would be applied to a helmet, allowing it to detect force from multiple angles.

Yang presented her team’s research at the 250 National Meeting & Exposition of the American Chemical Society.

According to Yang, finding brain trauma initially after a hit is difficult. Athletes and soldiers may continue their physically intensive activities without knowledge of being injured. But “using this patch, we can now detect the force of the hit,” she said.

Using holographic lithography, the research team initially created photonic crystals intentionally designed a certain color. The substance changed color when applied force deformed its internal structure. But the photonic crystal route was too expensive for mass scale production.

The team turned to polymer-based materials, finding inspiration in opal formed from silicone beads. The material ended up behaving much like the specialized photonic crystals. “To make a mold, the researchers mixed up silica particles of various sizes and allowed them to self-assemble into crystals with the desired pattern,” according to the American Chemical Society. “They heated the polymer, which infiltrated the mold, allowed it to solidify and then removed the silica mold, leaving behind the inversed polymer crystals.”

The polymer used is SU-8, a photoresist invented by IBM, Yang said.

According to the team, applying 30 mN force, equivalent to a sedan crashing into a brick wall at 80 mph, caused the material to change from red to green. A 90 mN force changed the material to purple.

The team still needs to build a correlation between color change and brain injury. A simple change of color isn’t indicative of head trauma. Yang said the team plans to work with medical practitioners to build a correlation scheme.