Published online by Cambridge University Press: 05 October 2014
The short-range wireless transmission of sensor information finds application in several fields ranging from the monitoring of biological parameters in medicine [1–6], to the measurements of mechanical quantities in industrial applications [7–10] and robot guidance . In the last years several technologies have been developed to this purpose, and the emerging one is based on the Radio Frequency IDentification (RFID) concept . This is due to the convergence of several new ideas and approaches like RF energy harvesting [13, 14], RF carrier re-use, the load modulation method, and organic [15–23] and inkjet-printed [24–29] electronics. RF energy harvesting and RF carrier re-use, for example, make possible battery-less (i.e. passive) RFID sensors that can operate for years without any maintenance.
A detailed description of a common RFID system is given in Chapter 2; however, it is worth recalling that it is usually composed of: a reader (or interrogator), that sends an interrogation signal to an RFID tag; a tag (or transponder) which identifies the object with a code, basically implemented by an IC and an antenna; and a host computer that codes and encodes the data from the reader. Moreover, a wireless connection to a global network can be provided . Figure 9.1 shows a block diagram of a typical RFID system, including the tag, the reader, and the host computer connected to a global network.