Cold-chain monitoring is the set of devices and software that record how cold food and medicine stay on every leg of a trip, and that warn people when the temperature leaves its safe range. It uses temperature loggers, RFID tags and the refrigeration units on trucks and containers. It checks the cold chain, the unbroken series of cold stores and cold vehicles from the maker to the user.
Different goods need different temperatures. Most vaccines and insulin must stay between 2 °C and 8 °C. Frozen food must stay at minus 18 °C or below. Fresh fruit and flowers need cool air, but must not freeze. If a vaccine gets too warm, or freezes, it can lose its strength without looking any different. So the only way to know that it is still good is a record of its temperature for the whole trip.
The devices are of three kinds. A temperature logger is a small device packed with the goods, which records the temperature every few minutes. Some loggers send each reading at once over a mobile network, through IoT connectivity management. Others store their readings, which are read at the end of the trip. An RFID tag is a small radio tag fixed to a box or a pallet. A reader can scan it without seeing it, and some RFID tags also record temperature. Finally, the refrigeration unit on a truck or a container reports its own temperature, its door openings and its faults through telematics.
Consider a vaccine shipment from a maker near Pune to a district vaccine store in Odisha. The insulated boxes carry loggers that report every five minutes. On the second day, at a stop near Raipur, the truck's refrigeration unit reports that the cargo area is at 7.5 °C and rising. The software alerts the transport company and the maker's distribution team before it reaches 8 °C. The driver finds that a door seal is torn. A mechanic replaces it within the hour, and the reading falls back to 5 °C. When the district store receives the boxes, its staff check the full temperature record before they accept them.
The same data helps prevent breakdowns. The software learns how each refrigeration unit normally behaves, and warns when a compressor begins to fail, before it stops. This is predictive maintenance. Cold rooms at warehouses are watched in the same way, with sensors on their HVAC plant.
The temperature record is often shown on the same screen as the shipment's location, in supply chain visibility software. The companies that store and move cold goods are described on the page on cold-chain logistics.