Few things on a male turkey is more noticeable than his head—a balaclava of flesh, a snood spilling over his beak in a drip of red, a warty wattle sagging down his neck. That technicolor skin is the window into the turkey tom’s soul, if you will, or at least his emotions, shifting in shade as he grows excited or nervous.
That color-changing ability piqued the interest of a team of researchers at the University of California, Berkeley, who saw the potential to tweak a bacteriophage—a virus which preys on bacteria—to mimic the collagen fibers that change the turkey’s skin color. With the right modifications, they suspected, they could engineer the virus to change color in the presence of explosives.
To do so, they coaxed the virus particles into spouting nanofibers, which served the same functions as the turkey’s collagen fibers. In the presence of certain compounds, the fibers expand or contract, causing them to reflect different wavelengths of light.
Liat Clark, writing for Wired UK:
They found the biosensor became swollen or shrunk down depending on which chemical was present, generating different colours that could be attached to a particular chemical. It could then be photographed using the accompanying iColour Analyser smartphone app, which automatically identifies the substance. It’s like a turkey-themed pH test for dangerous substances.
Similar to a litmus test, the study authors say the test is relatively inexpensive (though it’s unclear exactly how much they cost). Given that the phages react to humidity in addition to explosive chemicals, it’s possible this approach could be modified to sense a number of different phenomena.