Innovative Sensor Tied to RFID Could Lead to Much Improved Produce Inventory Management, but will Farmers or Retailers Bear the Cost?
Almost everyone agrees that a substantial amount of fresh fruits and vegetable are lost to spoilage every day in grocery stores and other retail locations.
Would the capability to monitor the freshness of such produce before the spoilage becomes visible and the goods unsellable help to reduce the amount of fruits and vegetables that have to be thrown away, and better ensure consumers get fresh product?
Swager says he is also pursuing monitors that could detect when food becomes moldy or develops bacterial growth.
That's the idea MIT chemistry professor Dr. Timothy Swager and his graduate students Birgit Esser and Jan Schnorr have, who say that using a new type of sensor plus RFID can provide better visibility to freshness levels.
The new sensors, described in the most recent edition of the chemical journal Angewandte Chemie, can detect tiny amounts of ethylene, a gas that promotes ripening in plants. Swager envisions that inexpensive sensors attached to cardboard boxes of produce and scanned with a handheld device would reveal the contents'ripeness. That way, grocers would know when to put certain items on sale to move them before they get too ripe and no one will buy them at any price.
About 10% of fruits and vegetables has to be thrown away due to spoilage, according to the Department of Agriculture. Some estimates put the figure at an even higher level. Walmart has made several announcements over the past few years about strategies it is employing or considering to decrease such spoilage, such as by reducing the time it takes to get fruits and vegetables from the field to on to store shelves, increasing the effective shelf life.
"If we can create equipment that will help grocery stores manage things more precisely and maybe lower their losses by 30%, that would be huge,"says Swager, the John D. MacArthur Professor of Chemistry at MIT.
Swager's research was funded by the U.S. Army Office of Research through MIT's Institute for Soldier Nanotechnologies. Swager and his team built a sensor consisting of an array of tens of thousands of carbon nanotubes that become sheets of carbon atoms rolled into cylinders that act as "superhighways" for electron flow.
To modify the tubes to detect ethylene gas, the researchers added copper atoms, which serve as "speed bumps" to slow the flowing electrons. "Anytime you put something on these nanotubes, you're making speed bumps, because you're taking this perfect, pristine system and you're putting something on it," Swager says.
Copper atoms slow the electrons a little bit, but when ethylene is present, it binds to the copper atoms and slows the electrons even more. By measuring how much the electrons slow down (i.e., the level of resistance) the researchers can determine how much ethylene is present.
To make the device even more sensitive, the researchers added tiny beads of polystyrene, which absorbs ethylene and concentrates it near the carbon nanotubes. With their latest version, the researchers can detect concentrations of ethylene as low as 0.5 ppm. The concentration required for fruit ripening is usually between 0.1 and 1 ppm (parts per million).
The researchers tested their sensors on several types of fruit (banana, avocado, apple, pear, and orange) and were able to accurately measure their ripeness by detecting how much ethylene the fruits are secreting. The total system would also have to have the intelligence to know what type of produce is being monitored, as the level of ethylene emitted relative to ripeness varies by each type of fruit.
Many fruit distributors already employ monitors that use gas chromatography or mass spectroscopy to monitor overall ethylene levels, which can separate gases and analyze their composition. Those systems cost around $1,200 each.
"Right now, the only time people monitor ethylene is in these huge facilities, because the equipment's very expensive,"Swager says.
Swager has filed for a patent on the technology and hopes to start a company to commercialize the sensors. That includes plans to add a radio frequency identification (RFID) chip to the sensor so it can communicate wirelessly with a handheld device that would display ethylene levels.
Despite all the technology, Swager said the system would be relatively inexpensive, about 25 cents for the carbon nanotube sensor plus another 75 cents for the RFID chip. However, he later told SCDigest that the tag cast was based on a small lot buy, and is well above what would be achievable in volume purchases.
Swager also told SCDigest that the system could use a passive tag, which sell for 10 cents or less currently with any kind of volume. However, he added that for more sophisticated applications, it is possible that some form of battery-powered tag might make sense.
How high a cost will the market bear to add this sensing system at the case level that is the usual handling unit in grocery stores? That will be the key question as Swager takes the concept forward.
"Food is something that is really important to create sensors around, and we're going after food in a broad sense," Swager says. He is also pursuing monitors that could detect when food becomes moldy or develops bacterial growth.
What's your take on Swager's sensor and RFID system for produce monitoring? How low would the costs need to go at the case level for this to be economically viable? Let us know your thoughts at the Feedback button below.
The best question I heard was regarding the market impact. Along with this question comes modes of transportation and seasons with respect to certain fruits. With these perishable products, would weather play a factor, is the RFID chip compliant with FDA regulations, and can it be placed on all types of containers?--pallets. cases, etc? I believe this is a great idea and Tempreture Control as well as Tampering are big issues regarding pershible products and pharmaceuticals. Good Job, I hope to read more about this!