Passive RFID

What is RFID?

Radio-frequency identification (RFID) is an automatic identification method based on wireless electromagnetic radiation in the radio frequency (RF) range. Information encoded through RF waves is transmitted wirelessly by devices called tags and received by devices called readers, sensors, scanners, detectors or interrogators. Vital information, most typically a unique serial number for the tag, can be stored on each tag and read by interrogators.

In healthcare applications, RFID tags are typically applied to movable medical equipment (such as infusion pumps and wheel chairs), hospital patients and/or clinical staff to track their location and movements. The most common application is asset management.

VIZZIA deploys both active and passive RFID systems. Passive systems can be divided into two categories: standard passive RFID and battery-assisted passive RFID. In both cases, a passive RFID tag, when mounted on an asset or staff/patient badge, must be stimulated by a signal from a reader before responding with its unique identifying code. Active RFID tags, on the other hand, send signals at several-second intervals without stimulation.



A passive RFID tag contains two major components: (1) a microchip for modulating/demodulating the RF signal, and (2) an antenna for receiving and transmitting the signal. A passive tag does not have an internal power supply and only works in close proximity to a reader. The reader transmits an RF signal as it searches for tags in its proximity. The small electrical current induced in the antenna by the incoming RF signal from the reader provides just enough power for the microchip in the tag to power up and transmit a response. In other words, the antenna of a passive tag is designed both to collect power from the incoming signal and also to transmit the outbound “backscatter” signal. The response of a passive RFID tag is typically its ID number.

Since passive tags have no batteries, they are generally small and inexpensive, but their range is typically between only 1 and 3 meters, depending on the chosen radio frequency and the design of the antenna. Such a small range makes passive tags unsuitable to the real-time tracking of patients and clinical staff in a hospital.

However, when used in combination with advanced process analysis techniques, passive tags can be extremely effective for the tracking and management of movable medical equipment (MME). VIZZIA is currently the only known provider of a proven passive RFID solution, called PassiVix, for MME distribution and management applications. The cost to deploy VIZZIA‘s PassiVix solution in a hospital is typically 10 times lower than the cost of an active RFID solution.



Battery-assisted passive RFID tags are similar to passive tags because they do not transmit unless stimulated by an RF signal. They are also similar to active RFID tags because they have their own internal power source that provides stronger transmission of the RF response. They combine some of the benefits from both kinds of technologies.

Battery-assisted passive tags have a substantially better range than standard passive RFID tags, and have better battery life than most active tags. Their cost is between a passive tag and an active tag, and they can work with some of the same portable readers designed for use with passive tags. VIZZIA‘s PassiVix solution for MME distribution and management can be deployed using battery-assisted passive tags for higher performance.


VIZZIA‘s passive RFID technology partners include Intelleflex, Motorola and ThingMagic.