Engineers at MIT have developed a Velcro-like sensor that can detect if food is contaminated or spoiled.
Microneedles attached to the sensor pierce through packaging to sample food for signs of E.coli and other pathogens.
Molded from edible proteins found in silk cocoons, the microneedles draw fluid into the sensor, which has letters printed with color-changing 'bioink' to detect impurities.
One ink is designed to go from blue to red if it comes into contact with bacteria like E. coli and the other is pH-sensitive that only changes if the food is spoiled.
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Sensors developed at MIT changed from blue to red in the presence of E.coli and spoilage in store-bought fish. One kind of bioink in the sensors is sensitive to the presence of bacteria, while another detects changes in pH
Researchers attached the sensor to pieces of raw fish that had been injected with E. coli.
The ink that detected bacteria was used to make an 'E,' while the ink that measured pH levels made a 'C.'
After less than a day, the 'E' turned from blue to red in all the samples, indicating the fish was contaminated with E.coli.
After a few hours, the pH-sensitive 'C' also changed hue, signaling the filet had also spoiled.
Microneedles made from silk can puncture plastic wrap to test if meat, fish and other products are contaminated or spoiled. Silk is nontoxic and can be used as a food ingredient
Their work, published today in Advanced Functional Materials, could lead to smart food sensors that head off outbreaks but also prevent consumers from throwing out food that is still safe to eat.
Americans throw out nearly 40 million tons of food every year, much of which is still perfectly edible.
'There is a lot of food that's wasted due to lack of proper labeling, and we're throwing food away without even knowing if it's spoiled or not,' said co-author Benedetto Marelli, a professor in MIT's Department of Civil and Environmental Engineering.
An illustration shows a proposed food quality monitoring system that uses silk microneedle with printed bioinks as colorimetric sensors. The technology could be used every step of the way, from the processing plant to the kitchen counter
'People also waste a lot of food after outbreaks, because they're not sure if the food is actually contaminated or not,' he added. 'A technology like this would give confidence to the end user to not waste food.'
Having developed a silk-based microneedle that penetrates and delivers nutrients to plants, Marelli collaborated with A. John Hart, a professor of mechanical engineering who devised a high-resolution printing technique.
'Assessing the health of food by just measuring its surface is often not good enough,' said Hart.
'At some point, Benedetto mentioned his group's microneedle work with