Turkeys may not be everyone's idea of beautiful birds, but they certainly have colorful skin on their heads. What's more, that skin changes color with the animal's mood. Scientists at the University of California, Berkeley, have now copied the process by which those color changes occur, and used it to create a biosensor that could be used to detect airborne toxins.

Turkeys have collagen fibers interspersed within an array of blood vessels in their skin. Those blood vessels either contract or swell, depending on whether the bird is angry or excited. This alters the spacing between the fibers, which in turn alters the fashion in which they scatter the rays of light being reflected off of them. As a result, the skin can appear to be red, white or blue.

A UC Berkeley team led by Prof. Seung-Wuk Lee successfully replicated this process, using viruses known as M13 bacteriophages. These microbes are similar in shape to the turkey's collagen fibers, and they also swell and contract – although in their case, it's in response to chemical vapors in the air.

The scientists were able to coax the viruses "to self-assemble into patterns that could be easily fine-tuned," so that they would produce different colors in response to different chemicals. In lab tests, they quickly and accurately responded to the presence of volatile organic compounds such as hexane, isopropyl alcohol, methanol and TNT, at concentrations of 300 parts per billion.

The team has also created a smartphone app, which uses the phone's camera to accurately read the color on a litmus strip containing the bacteriophages.

A paper on the research was published yesterday in the journal Nature Communications.

Source: UC Berkeley