Engineers have developed a colourimetric food sensor

MIT engineers have developed a colourimetric food sensor made from a collection of silk microneedles that pierces plastic packaging for signs of contamination and spoilage to sample foods.

MIT outlines that the microneedles of the sensor are moulded from a protein solution contained in silk cocoons and use capillary action to remove fluid into the sensor’s back, printed with two variants of a particular ink. When in contact with the fluid of a certain pH range, one of these bioinks changes colour, which specifies that the food has ruined – the other switches colour when it detects bacteria from contamination.

The sensor was connected to a raw fillet of fish, which was injected with a solution contaminated with E. coli and found within twenty-four hours, that part of the sensor that was printed with bacteria-sensing bioink transformed from blue to red. Following this, the pH-sensitive bioink also changed colour, which signified that the fish had been spoiled. The results were published in the Advanced Functional Materials journal.

The Paul M. Cook Career Development Assistant Professor in MIT’s Department of Civil and Environmental Engineering, Benedetto Marelli, stated: “There is a lot of food that’s wasted due to lack of proper labelling and we’re throwing food away without even knowing if it’s spoiled or not. 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.”