Researchers at IIT-Istituto Italiano di Tecnologia (Italian Institute of Technology) have developed the first self-powered defrosting sensor that may be used in future to detect improper freezing of food while the sensor is placed on it.

The sensor is fully edible, as it exploits the inherent electronic properties of commonly ingested liquids or supplements, such as water, table salt, and various electrolytes. The device is composed of two parts: a galvanic cell, operating with an aqueous electrolyte solution that generates an electrical current when defrosted; and a color-changing system indicator, based on red cabbage juice, producing an irreversible shift from reddish purple to blue when the galvanic cell produces the current. A block of beeswax keeps the two parts bound together. The temperature at which the sensor reacts can be tuned between 0 and −50 °C by changing salts or its concentration in water.

Researchers, including Ivan Ilic, working in a team coordinated by Mario Caironi at IIT’s Center for Nano Science and Technologies in Milano (Italy), believe that this proof of concept could pave the way for an inexpensive and safe technology to be largely exploited in the food and drug cold supply chains, reducing wastes and improving safety. The research study had been supported by a grant from the European Research Council.