MIT scientists have developed a new Velcro-like, ‘colorimetric’ food sensor to avoid food waste and stem disease outbreaks.
According to the scientists, the food sensor is made up of an array of color-changing silk microneedles that pierces through plastic packaging to sample food for signs of spoilage and bacterial contamination.
The sensor’s microneedles are molded from a solution of edible proteins found in silk cocoons, and are designed to draw fluid into the back of the sensor, which is printed with two types of specialized ink.
One of these ‘bioinks’ changes color when in contact with fluid of a certain pH range – indicating that the food has spoiled.
The other bioink turns color when it senses contaminating bacteria such as pathogenic E. coli.
To demonstrate this, the team led by assistant professor Benedetto Marelli attached the sensor to a fillet of raw fish that they had injected with a solution contaminated with E. coli.
After less than a day, they found that the part of the sensor that was printed with bacteria-sensing bioink turned from blue to red – a clear sign that the fish was contaminated.
After a few more hours, the pH-sensitive bioink also changed color, signaling that the fish had also spoiled.
“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,” says Marelli.
“People also waste a lot of food after outbreaks, because they’re not sure if the food is actually contaminated or not. A technology like this would give confidence to the end user to not waste food.”
The new food sensor was jointly developed by Marelli, whose lab harnesses the properties of silk to develop new technologies, and professor A. John Hart, whose group develops new manufacturing processes.
Hart recently developed a high-resolution floxography technique, realizing microscopic patterns that can enable low-cost printed electronics and sensors.
Marelli on the other hand had developed a silk-based microneedle stamp that penetrates and delivers nutrients to plants.
Pairing these two technologies resulted in a printed food sensor that could accurately monitor food safety.
The scientists envision that their sensor can be used at various stages along the supply chain – from operators in processing plants – to monitor products before they are shipped out.
It could also be applied on certain foods to make sure they are safe to eat.
Image and content: Felice Frankel/MIT