In layman's terms, which are the only terms in which I can relate it, we produce an antibody that would be engineered to detect a certain pathogen, be it salmonella, listeria, or whatever, in partnership with whoever's going to produce a plastic bag. The antibodies are sprayed onto a plastic bag, and then when the invading, dangerous antibody appears, it's engineered for a visual signal.
On June 10th, 2009. See this statement in context.