RFID in the cold chain: why temperature tracking is a separate problem
In the cold chain a tag has to do more than read. It has to stay stuck and, if temperature matters, record it correctly. Those are two separate requirements colliding on one label.
A label that sticks perfectly at room temperature can lift off within days inside a freezer. This is the first thing cold chain RFID projects get wrong: tag selection needs to follow adhesive behaviour, not temperature alone.
Adhesive gets tested before the chip does
Standard acrylic adhesives stiffen at low temperature and lose their grip. Cold chain labels use rubber-based or specially formulated adhesives that stay flexible at freezing temperatures.
A test run at room temperature gives a misleading result. The correct test holds the label at the target temperature, say -18°C, for a set period and then measures adhesion. Ask the label supplier for this figure on the datasheet, and verify it on site rather than trusting lab conditions alone.
Moisture is the cold chain hidden enemy
A product coming out of cold storage picks up instant condensation on its surface. That moisture affects both the adhesive and the print, especially on items that move in and out of cold storage repeatedly. A paper label with poor moisture resistance becomes unreadable after a few such cycles.
RFID, a temperature sensor, or both
A standard UHF RFID tag carries identity, not temperature. If temperature data is required you need a sensor tag or a separate data logger. Do not conflate the two: expecting "we tagged it, so we will see the temperature too" without a sensor never gets met.
Sensor-equipped RFID tags cost more and need a larger housing, because they carry a small battery or an energy-harvesting circuit. Applying them at pallet or carton level as a sample, rather than on every item, is enough for most projects.
Read points belong at the temperature transition
The most critical piece of information in a cold chain is when a product left the cold chain. That is why readers get placed at the doors of a cold room, not inside it. The moment the chain breaks is not a moment inside storage, it is the moment of passing through a door, and that is where the record needs to be kept.
Before the project starts
Test the label at the target temperature, not at room temperature. Decide up front whether temperature data is actually needed; switching to a sensor mid-project is expensive. Place read points at the doors where temperature changes, not where the product happens to sit.