A color-changing patch modeled after the iridescent wings of butterflies could give soldiers a heads-up on the severity of injuries sustained on the battlefield.
About the size of a binder hole in loose-leaf paper, the patch is made of 3D photonic crystals — tiny structures whose geometry can be manipulated to control the way it interacts with light. Like butterfly wings, these crystals get their color from light bouncing off of the nanoscale lattice.
The patches could be worn on a soldier’s helmet to provide medical personnel with blast-exposure information to help them diagnose brain injury — a typical injury sustained in the wars in Afghanistan and Iraq, which are difficult to diagnose with today’s imaging technology, the researchers say.
“Similar to how an opera singer can shatter glass crystal, we chose color-changing crystals that could be designed to break apart when exposed to a blast shock wave, causing a substantial color change,” said study co-author Douglas Smith, director of the Center for Brain Injury and Repair and a professor at the University of Pennsylvania.
So far, the researchers have tested the nature-inspired patch in the lab and shown that the color intensity decreases when the patch is exposed to simulated blasts.
More work is needed “to model the relationship between structure change, color change and blast force and time,” study co-author Shu Yang, a professor at the University of Pennsylvania, told TechNewsDaily.
This and other work required to fine-tune this technology for commercial use will take at least a decade, Yang said.
To make the blast patches, Yang and her colleagues used special photonic crystals arranged in a way that resembles a stack of Swiss cheese and connected by crystal columns. These holes and columns are not visible to the human eye.
When the patch is exposed to “a sudden blast or a mechanical shock wave, it will destroy the connecting regions, for example the columns that connect between layers,” causing some of the layers to degrade and thus changing the color quality.
The hope is to create a model that relates the intensity of the blast with color intensity and then to relate this to the severity of the sustained injury.
Yang also envisions uses for the patch beyond the battlefield. For example, it could also help gauge injury in football players and cyclists, or help diagnose damage to cell phones, computers, and other electronics.
The researchers detailed their findings online Nov. 29 in the journal NeuroImage.
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