Turkeys may be everyone's favorite Thanksgiving meal, but they also have really cool color-changing skin that can shift from red to blue to white depending on their mood. That color morphing inspired a team of UC Berkeley bioengineering researchers to develop a color-changing biosensor that can detect airborne pathogens and toxic vapors.
Turkey skin is able to change color because of collagen bundles within their blood vessels. The spacing between those bundles changes when the vessels expand or contract depending on whether the bird is feeling content, excited or angry. That swelling then changes how light waves are scattered, which then alters the color of the skin.
The researchers worked to mimic this color-changing ability in a biosensor that would be easy to read. They developed a smartphone app called the iColour Analyzer that uses the phone's camera to take a photo of the sensor's color bands and then detect which chemicals are present.UC Berkeley says, "Sensors that give off color readings are easier to use and read than conventional biosensors. However, the major color-based sensors in development elsewhere can only detect a limited range of chemicals and, according to the researchers, they can be very difficult to manufacture."
“Our system is convenient, and it is cheap to make,” said Seung-Wuk Lee, UC Berkeley associate professor of bioengineering. “We also showed that this technology can be adapted so that smartphones can help analyze the color fingerprint of the target chemical. In the future, we could potentially use this same technology to create a breath test to detect cancer and other diseases.”
The researchers used M13 bacteriophages, which are benign viruses, to mimic the collagen fibers in the turkey's skin. The phage self-assembled into bundles and changed color when expanding or contracting. Exposing the bundles to a range of volatile organic compounds, including hexane, isopropyl alcohol and methanol, as well as TNT, at concentrations of 300 parts per billion, resulted in rapid swelling that then left a color "fingerprint" of the chemicals the bundles were exposed to.
The biosensor coupled with the smartphone app could allow people to quickly detect specific pathogens or dangerous chemicals around them. All thanks to turkeys.