We've seen carbon nanotubes used for everything from camouflaging objects to identifying airborne toxins, and now a team at MIT is using them for something much more mundane — keeping apples and bananas fresh. MIT chemistry professor Timothy Swager and his team have created a new sensor made from modified nanotubes that can detect ethylene, a chemical that's released as fruit ripens. The sensors are cheap enough — they cost around $0.25 each to make — that Swager wants to one day see them embedded in cardboard shipping boxes so that staff can simply scan them to see how ripe the contents are. Eventually the design could even include an RFID chip to wirelessly transmit ripeness data to a handheld device — and it would only add around $0.75 to the price tag. "If we can create equipment that will help grocery stores manage things more precisely, and maybe lower their losses by 30 percent, that would be huge," says Swager.