There is a lot of clever stuff in RFID ... but I reckon that the way RFID readers work with passive tags is the "cleverest" bit of all - backscatter!
As the name implies, passive tags wait for a signal from an RFID reader. The reader sends energy to an antenna which converts that energy into an RF wave that is sent into the read zone. If a passive RFID tag is within the read zone, its internal antenna draws in energy from the RF wave. The energy moves from the tag’s antenna to power the chip which generates a signal back to the RF system. This is called backscatter. The backscatter, or change in the electromagnetic or RF wave, is detected by the reader (via the antenna), which interprets the information.
Passive RFID tags have no internal power source, and a standard passive RFID tag consists only of a chip and internal antenna; this basic structure is commonly referred to as an RFID inlay. Countless other types of passive RFID tags exist on the market, but all tags generally fall into two categories - inlays or hard tags. Hard RFID tags are durable and made of plastic, metal, ceramic and even rubber. They come in all shapes and sizes and are typically designed for a unique function, material, or application.
Certain industries, like healthcare, track the number of cycles that instruments undergo in punishing autoclaves. Specific passive RFID tags are designed to withstand extreme temperatures and accommodate for those types of applications.
