Delivering the Perfect Banana
To ensure that no banana is too green or too brown when it reaches the store, bunches are packed so they ripen in transit. However this can create a logistics nightmare as timing is everything, so being too early is as bad as being too late.
Wal-Mart wanted to know if there was a way to use RFID technology to help improve this banana supply chain, as well as the supply chains of other produce. However, other factors than just time have to be taken into account, particularly use of the gas ethylene. The bright yellow colour of bananas on the shelves is a result of artificial ripening by ethylene as naturally ripened bananas tend to be greener.
While RFID tags can help track, trace and time the bananas, they would be able to do a much better job if they were equipped with sensors to detect the gases associated with ripening. RFID plus sensing looked like the perfect solution. But cost was a major obstacle.
Enter a chemistry professor at the Massachusetts Institute of Technology (MIT). Timothy Swager has come up with a 25-cent sensor, based on carbon nanotubes, that can detect ethylene and relay its data to the outside world via an RFID tag. The patented device, which he hopes to commercialize, can be attached to produce crates to ensure that only perfectly ripe fruit arrives in stores. This helps to eliminate the estimated 10 percent of waste caused every year, it is claimed.
