The heart of the RFID tracing system developed is a smart tag
and a reader/writer module. The smart tag, attached on the product
to be tracked, integrates light, temperature and humidity sensors,
a microcontroller, a memory chip, low power electronics and
an antenna for RFID communications with the reader/writer
RFID technology in the high frequency (HF) band at 13.56 MHz
was considered the best frequency for integration on flexible tags,
specially for foods with an important water content. Furthermore,
in order to be compliant with recent RFID developments, the ISO
15693 communication standard was selected for data transmission.
Low power readers operating at 13.56 MHz RFID technology
have a limited reading distance of about 10 cm. However, by
proper High Frequency Amplification, the standard permits to
increase the reading distance up to 1 m. The developed tag is compatible
with commercial readers, like the evaluation module
TRF7960_EVM (Texas Instruments, USA) used for this work. The
communication between the reader and the host computer is made
by means of a USB connection. A photograph of the tag prototypes,
developed on both Printed Circuit Boards (PCBs) and flexible substrates,
together with the commercial reader used for this work
are shown in Fig. 1.