RFID Location Sensors: Children's Study ...

Final Report Use of 1) Sensors and 2) Radio Frequency ID (RFID) for the National Children’s Study ...

... "Location sensors are mostly used by commercial agencies for tracking their goods and products during shipping and storage. Radio frequency identification (RFID) tags are the most common type of location sensor, due to their low cost and small size. RFID tags essentially serve as a barcode that can be read by radio frequency transmission. These tags can carry all sorts of information about the product, such as the serial number, model number, color, location, or any other relevant information. The RFID tags will identify themselves when they detect a signal from a compatible device, such as an RFID reader. RFID tags can be active, passive, or semi-active. The passive tags are cheaper ($0.05 to $0.50) and smaller, but do not contain their own power source and are powered by the RFID reader through an antenna. Because these tags do not rely on battery power, they can last indefinitely. Active tags have their own battery and can transmit a signal to an RFID reader antenna, but are significantly more expensive at around $20. It is projected that active tags will eventually cost about $5 by 2005, however. Semi-active tags are a compromise between passive and active tags and cost around $1. " ...