Self-sensing passive RFID: From theory to tag design and experimentation

A passive UHF RFID system may be used as a self-sensing devices able to sense the geometrical and physical variation of the tagged object without the use of any specific sensor. This possibility is constrained to the design of multi-chip tags and to the definition of proper measurements modalities. This theoretical idea is here fully demonstrated experimentally for what concerns the wireless monitoring of the change of materials inside a plastic container. The paper describes some measurement techniques and simple data inversion algorithms.