Chemistry professor Timothy Swager and his students have developed a sensor to detect minute amounts of ethylene gas that could help retailers and distributors better manage inventory, according to a news release from the university in Cambridge, Mass.
The devices could reduce retailers fresh produce losses by 30%, Swager said in the release.
But the best news, he said, is the cost of the sensors.
“This could be done with absolutely dirt-cheap electronics, with almost no power,” Swager said.
The professor has filed for a patent and hopes to start a company to offer the sensors commercially. He estimates the cost for a sensor and an accompanying radio frequency identification chip to be about $1.
The sensors consist of an array of tens of thousands of carbon nanotubes, which are sheets of carbon atoms rolled into cylinders that act as superhighways for electron flow. Swager and his students added copper atoms to the nanotubes to slow the speed of the electrons and provide something for ethylene to bind to.
The amount of ethylene can then be determined by measuring the speed of the electrons, which slow down more as the level of ethylene bound to the copper atoms increases. To make the sensors even more sensitive the research team added tiny beads of polystyrene, which absorb ethylene and concentrate it.
With the latest version, the researchers can detect ethylene as low as 0.5 parts per million. The concentration required for fruit ripening is usually somewhere between 0.1 ppm and 1 ppm.
The researchers tested their sensors on bananas, avocados, apples, pears and oranges. They were able to accurately measure their ripeness by detecting how much ethylene the fruits secreted.
Swager said in the release the sensors could be placed in cartons of produce to detect ethylene levels. The RFID chips would enable the data to be sent wirelessly to handheld devices. Retailers and distributors would then know the level of ripeness in individual cartons without having to handle the produce or rely on visual inspections.
Shipping schedules and in-store promotions could be timed based on the remaining shelf life of produce, theoretically reducing shrink by better inventory management.